seven polaris - dp fmea

Client: Subsea 7 Date: 07.09.2012 Page: 2 of 122

Title: Seven Polaris FMEA upgrade Rev.: 1 Made: KJ

Global Maritime AS GM Doc. No.: GM-712-059-R001

REVISION SHEET

Rev. Reason Page(s)

This FMEA document supersedes the FMEA report GM-670-170-R01_Rev2

1 Update of old FMEA Whole report




TABLE OF CONTENTS

1 INTRODUCTION ............................................................................................................ 6

1.1 General ........................................................................................................................... 6 1.2 Scope of Work ................................................................................................................ 6 1.3 Reference Standards ....................................................................................................... 6 1.4 Objective ........................................................................................................................ 7 1.5 Definition of DP Class 3 ................................................................................................ 8

1.6 Vessel Particular ............................................................................................................. 9

2 SUMMARY ..................................................................................................................... 11

2.1 General ......................................................................................................................... 11

3 ABBREVATION ............................................................................................................ 13

4 GENERAL LAYOUT .................................................................................................... 15

4.1 General ......................................................................................................................... 15

4.2 Cable Routing ............................................................................................................... 15 4.3 Effect of Fire & Flooding Protection ........................................................................... 18

4.4 Communications ........................................................................................................... 19

5 POWER GENERATION .............................................................................................. 20

5.1 General ......................................................................................................................... 20 5.2 Generators G1, G2 and G3 ........................................................................................... 20

5.3 Generators G4 and G5 .................................................................................................. 21 5.4 Thruster Engine and Generator .................................................................................... 22

6 POWER DISTRIBUTION ............................................................................................ 24

6.1 General ......................................................................................................................... 24 6.2 460V Distribution ......................................................................................................... 26 6.3 230V Distribution ......................................................................................................... 28

6.4 Uninterrupted Power Supply unit, UPS ....................................................................... 30

7 POWER, AUTOMATION & CONTROL SYSTEMS ............................................... 31

7.1 General ......................................................................................................................... 31 7.2 Diesel Generators Control System ............................................................................... 31

7.3 Integrated Automation System ..................................................................................... 32 7.4 Thruster Engines Control System ................................................................................ 37 7.5 Generator Protection .................................................................................................... 37

7.6 Thruster Control System, HELICON ........................................................................... 38 7.7 Clutch Control .............................................................................................................. 40

7.8 Tunnel Thrusters Control System ................................................................................ 41 7.9 Emergency Stop System ............................................................................................... 42 7.10 Fire Switch ................................................................................................................... 42

8 FUEL OIL SYSTEMS ................................................................................................... 43

8.1 General ......................................................................................................................... 43

8.2 Fuel Oil System Diesel Generators .............................................................................. 44




8.3 Fuel Oil System Thruster Engines ............................................................................... 45 8.4 Quick Closing Valves ................................................................................................... 45

9 COOLING WATER SYSTEMS ................................................................................... 46

9.1 General ......................................................................................................................... 46 9.2 Cooling System Generators .......................................................................................... 46 9.3 Cooling System Thruster Engines ................................................................................ 47




10 LUBRICATION SYSTEMS .......................................................................................... 49

10.1 General ......................................................................................................................... 49 10.2 Lubrication system Diesel Generators ......................................................................... 49

10.3 Lubrication System Thruster Engines .......................................................................... 49 10.4 Lubrication System Gear/ Clutch ................................................................................. 50

11 COMPRESSED AIR SYSTEM .................................................................................... 51

11.1 General ......................................................................................................................... 51 11.2 Starting Air System to Generators ............................................................................... 51

11.3 Starting Air System to Thruster Engines ...................................................................... 52

11.4 Service air system ......................................................................................................... 53

12 VENTILATION ............................................................................................................. 54

12.1 General description ...................................................................................................... 54 12.2 Ventilation & AC Units ................................................................................................ 54

13 THRUSTERS .................................................................................................................. 56

13.1 General ......................................................................................................................... 56 13.2 Azimuth Thrusters ........................................................................................................ 56 13.3 Tunnel Thrusters .......................................................................................................... 58

14 DP CONTROL SYSTEMS ............................................................................................ 59

14.1 General ......................................................................................................................... 59 14.2 Operator Stations .......................................................................................................... 61 14.3 DP Computers and Network ........................................................................................ 62

14.4 DP Control Modes and Functions ................................................................................ 63 14.5 DP Sensors ................................................................................................................... 65

14.6 Position Reference Systems ......................................................................................... 68 14.7 DP Control System Power Supply ............................................................................... 74

15 FAILURE ANALYSIS – “SEVEN POLARIS” ........................................................... 75

15.1 Configuration and assumptions .................................................................................... 75 15.2 Failure Analysis – Fire & Flooding .............................................................................. 77

15.3 Failure Analysis - Power Generation ........................................................................... 79

15.4 Failure Analysis - Power Distribution .......................................................................... 81

15.5 Failure Analysis – Power Automation and Propulsion Control ................................... 86 15.6 Failure Analysis - Fuel Oil System .............................................................................. 95 15.7 Failure Analysis - Cooling Water Systems .................................................................. 99 15.8 Failure Analysis - Lube Oil Systems .......................................................................... 103 15.9 Failure Analysis - Compressed Air System ............................................................... 107

15.10 Failure Analysis - Ventilation ................................................................................ 110 15.11 Failure Analysis – Propulsion System ................................................................... 111 15.12 Failure Analysis - DP Control System ................................................................... 115

16 REFERENCES ............................................................................................................. 122

APPENDIX A Text

APPENDIX B Text




1 INTRODUCTION

1.1 General

1.1.1 Global Maritime A/S received instructions from Mr. Julien Manach of Subsea

7 to carry out the scope of work listed below for the vessel Seven Polaris.

1.2 Scope of Work

1.2.1 The scope of work consists of:

Update the FMEA, with new power management system.

Prepare the Annual DP Trials.

Witness the trials and report any findings.

Produce a final report for the Annual Trials including the DP control

system and all related vessel equipment including the trial findings.

1.3 Reference Standards

1.3.1 Global Maritime AS is verifying the systems and design towards the regulation

“IMO 1994 Guidelines for Vessels with Dynamic Positioning Systems (IMO

1994 MSC/Circ. 645)”for vessel to comply with guidelines for IMO DP class

III (3).

1.3.2 IMCA Guidelines for the Design and Operation of DP Vessels, rev1,

December 2007.

1.3.3 The FMEA is carried out in accordance with industry, IMO and IMCA

guidelines relating to DP Class 3 vessels.




1.4 Objective

1.4.1 The objective of the FMEA is to provide a complete, systematic and

documented investigation of the dynamic positioning systems of the vessel.

This means to identify the failures and their effects on the vessels position

keeping performance. Based on the analysis, possible recommendations will be

made to improve the performance or the safety of the vessel.

1.4.2 The FMEA is an independent document containing a system description of the

DP system including propulsion systems, steering systems, thruster systems,

machinery systems, electrical systems, alarm and control systems.

1.4.3 The Vessel is classed by BV with the following notation:

I 3/3 (E)

Offshore Service Unit/ Pipe Laying Barge/ AP

Deep Sea

PDY MA TA RS

AUT CC

1.4.4 The notation PDY MA TA RS is corresponding to IMO MSC/ Circ. 645

Guideline as the vessel is a class 3 vessel. The essential feature of the DP class

3 philosophies is to identify the worst single failure that can occur within the

total system of the dynamic positioning of the vessel, without losing station

keeping capabilities, fire and flooding in compartments included. I.e. a loss of

position is not to occur in the event of a single fault in any “active or static“

component or system, fire and flooding in compartment included. By the term

“active” component, it is defined generators, thrusters, switchboards, remote

controlled valves, coolers etc. and “static” component are like cables, pipes

manual valves etc.

1.4.5 The FMEA is limited to specific failure conditions of individual components

and the subsequent effect on the overall position keeping of the vessel. If not

evident, procedures are assumed to ensure that inherent redundancy is

available and used correctly.

1.4.6 It is assumed that the electrical switchboard and distribution system is designed

in accordance with Regulation relating to Maritime Electrical Installations.

1.4.7 System drawings/ illustrations included in this report is not accurate and is

included to simplify the understanding of the various systems, and should

therefore be seen as such.




1.5 Definition of DP Class 3

1.5.1 Quote from IMO MSC Circ. 645 for DP classes

1.5.2 As per IMO MSC Circ. 645 DP class 3 the vessel must be designed and

commissioned to comply with the following basic rules:

Automatic and manual position and heading control under specified

maximum environmental conditions, during and following any single fault

including loss of a compartment due to fire or flood.

Three independent computer systems with a separate back-up system must

be installed and separated by A60 class division. The cabling must be

arranged in such a way that loss of one compartment (fire or flood) will

still allow control of the thrusters.

At least three different position references and three sets of sensors (MRU,

wind sensor, gyrocompass) must be provided. Of these, the third reference

system and the third set of sensors must be provided for the back-up

system.

The generators and the distribution systems must be arranged in different

compartments separated by A60 class division.

2.2 The equipment classes are defined by their worst case failure modes as

follows:

.2 For equipment class 2, a loss of position is not to occur in the event of

a single fault in any active component or system. Normally static

components will not be considered to fail where adequate protection

from damage is demonstrated, and reliability is to the satisfaction of

the Administration., Single failure criteria include:

.1 Any active component or system (generators, thrusters,

switchboards, remote controlled valves. etc.).

.2 Any normally static component (cables, pipes, manual valves,

etc.) which is not properly documented with respect to

protection and reliability.

.3 For equipment class 3, a single failure includes:

.1 Items listed above for class 2, and any normally static

component is assumed to fail

.2 All components in any one watertight compartment, from fire

or flooding.

.3 All components in any one fire sub-division, from fire or

flooding (for cables see also 3.5.1).

2.3 For equipment classes 2 and 3, a single inadvertent act should be

considered as a single fault if such an act is reasonably probable.




The physical separation of generators, thrusters and DP control systems

plays an essential part to classify a vessel as class 3. Cable routes and the

location of cable terminations have to be considered with respect to fire

and water damage in each compartment.

1.6 Vessel Particular

1.6.1 The vessel Seven Polaris is an Offshore Service Unit / Lay Barge operated by

Subsea 7 and the owner is Class 3 Shipping Ltd.

1.6.2 The vessel was built in 1979 at Mitsui Ocean Development as Yard S133.

Previous names are DLB Polaris (87), Seaway Polaris (2000), Acergy Polaris

(2006) and Seven Polaris (2012)

1.6.3 The bridge and accommodation is located forward and accommodation is also

provided within the hull on Quarters deck. The barge is fitted with an S-lay

pipe laying system and a 1500T Clyde fully revolving crane on aft centre.

Main power generation and other machinery systems are located in Hold Deck.

In addition there are two generators and a switchboard located in the crane

pedestal, which are also included in the main power generation.

1.6.4 Vessel Particulars:

Length (Loa): 137,6 m

Length (Lpp): 137,16 m

Breadth(mld): 39 m

Operating Draft on DP 5,5 to 6 m

Design Draught 9,5 m

Crew 266 Persons

Deck Cargo 5000 Tons

Displacement 28700 Tons

Call Sign HO2654

IMO No.: 8756772

Nationality/ Flag PAN

Port of Registry: Panama

1.6.5 The vessel is equipped with a power generation system consisting in total of

five main diesel generators named G1 to G5. These engines are divided among

the two generator rooms. The one on Hold deck includes three generators and

two are placed in the Crane pedestal. The emergency generator with an

emergency switchboard and auto start facilities is installed in the emergency

generator room.




1.6.6 The main propulsion drive is by four azimuth thrusters, each are driven directly

with by an engine via a gearbox. The thrusters with engine and all related

auxiliary systems are located in respective thruster rooms. The thrusters are

self-sustained with power; this is achieved by a PTO generator.

1.6.7 In addition there are two tunnel thrusters fitted in separate water tight

compartments, one fore and aft centre of the vessel. These thrusters are

powered from the main switchboard (MS4). A single failure causing loss of

either or both can be “ignored” as there are four totally independent main

azimuth thruster fitted. The thrusters have a slight influence on the heading

ability and the weather window will increase with the tunnel thrusters

connected.

1.6.8 The thruster numbering and assignment to switchboard are illustrated in Figure

1-1 below:

T6

T4

T3

Switchboard MS4

T2

T1

T5

Figure 1-1: Thruster numbering and assignment to switchboard

1.6.9 The DP control system comprises of a Kongsberg Maritime SDP-21 and a

SDP-11 system. Three individual UPS’s powers the various related DP

systems. The DP system was updated during dry docking in 2008, among

others are new controllers (SBC500), software change from NT to XP and new

DP reference systems and sensors were fitted.

Fwd




2 SUMMARY

2.1 General

2.1.1 Global Maritime AS has performed an upgrade of the existing Failure Mode

and Effects Analysis (FMEA) of the vessel “Seven Polaris” to reflect the new

changes that are to be made while the vessel is undergoing a ten year dry-dock

survey.

2.1.2 This FMEA document supersedes the FMEA report GM-670-170-R01_Rev2,

made by Global Maritime.

2.1.3 The complete FMEA proving trials program can be found in report GM-712-

059-R002_1, last DP trials.

2.1.4 The FMEA report is based upon that during DP operations all thrusters will be

running, that the vessel will be able to keep position after loss of either one of

the main thrusters or of both T5 and T6, and that there are no external

operational loads applied to the vessel.

2.1.5 Both tunnel thrusters can be lost as a single failure can cause simultaneously

loss of them both. Failure of one or both tunnel thrusters will not give a great

impact on the station keeping performance as the vessel does have four main

azimuth thrusters, placed in separate thruster rooms.

2.1.6 All four azimuth thrusters are individual and independent of each other. Only

common is the FO from the settling tank to the individual day tanks and the IO

cards. Each day tank has a capacity of 5m3 and continues filling off all tanks

are done. A failure causing stop in filling the day tanks will still give sufficient

time to secure and abandon the on-going operation.

2.1.7 The main power plant is for tunnel thrusters and all vessel service systems.

Each Azimuth thruster has its own power generator with a possible backup

from the main power plant. Therefore a single failure causing a blackout of

main power plant will not cause loss of azimuth thrusters; however DP related

consumers will change over to backup supply (UPS).

2.1.8 There are several single failures that can cause loss of an azimuth thruster;

however such a failure will be for that particular thruster only.




2.1.9 The worst case fire scenario is fire in control room A and loss of DPC21

cabinet and or main thruster control panel. Procedures are in place that in event

of fire the DPO shall take control from control room B.

2.1.10 Worst single system failure defined should be loss of two azimuth thrusters

and one tunnel thruster. This failure scenario will not cause loss of station

keeping ability. Complete list of I/O configuration can be found in Appendix

A.

2.1.11 Failure analysis in review of a fire or flooding based on the provided

information and observation made should not exceed worst case failure if

procedures implemented are followed. Each azimuth thruster is in its own

compartment, cabling is to be split and will cause loss of one network only.

Fire in control room A will be the most critical if the DPO does not take

control from control room B in time.

2.1.12 Based on the FMEA proving trials results the following can be stated as worst

case scenarios:

a) Worst single mechanical or electrical failure that can occur will result in

loss of an azimuth thruster only or loss of both tunnel thrusters.

b) A failure of the main power plant or emergency switchboard will affect the

DP system by causing loss of main power to the UPS’s they are powered

through. DP UPS’s have the possibility to be powered from either main or

emergency switchboard.

c) A single failure in the DP control system can cause simultaneously loss of

two azimuth thrusters and a tunnel thruster. This is being a result of failure

of I/O card where the thruster signals are handled. The powering to the

Galvanic isolation units are also configured in pairs, though only one fuse

is for two azimuth thrusters, being fuse F1 at X15A. Loss of power to

galvanic isolator results in loss of thruster in DP too. In both cases two

azimuth thrusters on same side will be lost.

2.1.13 On the basis of compliance with IMO 1994 MSC/Circ. 645 ‘Guidelines for

vessels with dynamic positioning system’ and the correction of any unexpected

results listed as ‘A’ recommendations, the vessel is considered fit for the

purpose of carrying out DP operations within it’s known operational

limitations. The FMEA proving trials and any recommendations are to be

found in report GM-712-059-R002_1, last DP trials. The vessel should be

operated in accordance with the provisions of the Marine DP Operations

Manual.




3 ABBREVATION AC Air Condition

Accom Accommodation

AHU Air Handling Unit

AUTOPOS Auto Positioning (DP terminology)

Aux. Auxiliary

AVR Automatic Voltage Regulator

BU Back Up

BV Bureau Veritas

Cab. Cabinet

CMID Common Marine Inspection Document

CP Controllable Pitch

CPU Controllable Processor Unit

Ctlr. Controller

Deg Degrees

DG# Diesel Generator

DGPS Differential Global Positioning System

DP Dynamic Positioning

DPO Dynamic Positioning Operator

DPC Dynamic Positioning Computer or Cabinet

ECR Engine Control Room

ER Engine Room

FMEA Failure Mode and Effect Analysis

FO Fuel Oil

FP Fixed Pitch

FW Fresh Water

Fwd Forward

G# Diesel Generator

GM Global Maritime

GPS Global Positioning System

GS Emergency Generator

HiPAP High Precision Acoustic Positioning

HPU Hydraulic Power Unit

HT High Temperature

HTFW High Temperature Fresh Water

IALA International Association of Lighthouse Authorities

IAS Integrated Alarm System

IMCA International Marine Contractors Association

I/O In/ Out (signal terminology)

IMO International Maritime Organization

KM Kongsberg Maritime

SDP Kongsberg Dynamic Positioning system

kW kilo Watt

kVA kilo Volt Ampere

LAN Local Area Network

LAL Level Alarm Low

LALL Level Alarm Low-low




LBL Long Base Line

LO Lube Oil

LT Low Temperature

LTFW Low Temperature Fresh Water

LWT Light Weight Tautwire

MDO Marine Diesel Oil

MRU Motion Reference Unit

MS# Main Switchboard

NDU Network Distribution Unit

OS Operator Station

PCU Process Control Unit

PMS Power Management

PS Port Side

PSU Power Supply Unit

PTO Power Take Out

QCV Quick Closing Valve

RPM Revolutions per Minute

SB Starboard Side

SW Sea Water

SWBD Switchboard

T# Thruster number

TCC Thruster Control Cabinet

TCV Temperature Control Valve

TBA To Be Announced

Thr. Thruster

USBL Ultra Short Base Line

UPS Uninterrupted Power Supply

VMS Vessel Monitoring System

VRS Vertical Reference System




4 GENERAL LAYOUT

4.1 General

4.1.1 The vessel consists of four Decks being:

Plan View

Main Deck

Quarter Deck

Hold Plan

4.2 Cable Routing

4.2.1 In general all cables (power, DP, K-Chief etc.) that have to be routed from one

compartment to another have to be segregated between the redundant systems.

4.2.2 All bushings where cables are going through shall be packed in accordance to

regulations, to maintain A-60 segregation. Where the cabling is crossing into

the other DP zone, the cables are put in A-60 insulated cable ducts.

4.2.3 Cabling for the SDP21 is called the main control cabling. This cabling from

control room A to all six thrusters, the HiPAP 1 and the HIPAP 2 is all routed

through a common cable way in the centre of the vessel.

4.2.4 Cabling from the SDP11 is called emergency control cabling. This cabling is

routed from Control Room B to the thrusters in two groups. The first group

emergency cabling runs to thrusters 2 and 4, the HIPAP and the HPR via the

port side of the vessel. The second connects to thrusters 1, 3, 5 and 6 via the

starboard side of the vessel.

4.2.5 The purpose of the split in main and emergency cabling is to ensure that if a

fire or fault occurs anywhere on the main cabling, emergency control over all

thrusters can always be restored. This purpose has been met. A consequence of

this split must also be that a fire or fault in emergency cabling should not cause

loss of DP capability either. The current design is such that control will remain

from room A, and this is satisfactory. Note that operators should be aware of

the cable routing so that they will not attempt to switch over to control room B

when the emergency cables are on fire.




4.2.6 A principle layout of the DP system is shown below:

DPC-21 DPC-11

2 x Wind 2x Wind

3x MRU 2x MRU

2x Gyro 2x Gyro

DGPS 1

DGPS 3Fanbeam

HiPAP 1

HiPAP 2

DGPS 2

Tautwire

DP Net A Routing DP Net B Routing

Main DP Backup DP

Isolator

Spiltter

Spiltter

Figure 4-1: Layout of DP system




4.2.7 A principle layout of the DP network is shown below:

T6

T4

T3

Switc

hboa

rd M

S4

T2

T1

T5

Main DP net A

Backup DP net B

HiPAP 1

HiPAP 2

Control room AMain DP

Control room BBackup DP

Figure 4-2: Layout of DP network




4.3 Effect of Fire & Flooding Protection

4.3.1 The thruster rooms are segregated and there are bulkheads and open spaces/

tanks between these compartments equal to A60 segregation. The doors to the

different compartments are all combined Fire (A-60) and Flooding doors.

4.3.2 A fire in control room A or in the safety control room could damage remote

safety stop cabling to all thruster room fire dampers. As a result from this all

four main thrusters could be lost.

4.3.3 The cable way in the centre of the vessel contains no equipment aside the

cables themselves. A fire here could cause loss of control over T5 and T6, the

both HIPAP(s), and normal (SDP21) control over thrusters T1 to 4. Running

thrusters may stop or declutch automatically as a result of shorts in the normal

cabling caused by the fire. This process can be stopped by changing over to

Control Room B and activate the BU DP fire switch. Procedures are in place

that in event of fire the DPO shall take control from control room B.

4.3.4 A fire in the port cable tunnel could cause loss of emergency control over T2

and T4. T2 and T4 will be forced to (or to stay in) normal control, from room

A. None of the thrusters should stop or declutch automatically as a result of the

fire.

4.3.5 A fire in the starboard cable tunnel could cause loss of emergency control over

T1, T3 and T5. T1, T3 and T5 will be forced to (or to stay in) normal control,

from room A. None of the thrusters should stop or declutch automatically as a

result of the fire.

4.3.6 A fire in an individual thruster room will cause loss of that thruster. It is

possible to isolate fuel and start air supply to that thruster room as well as

shutting the fire damper/ ventilation for that room.

4.3.7 A fire in the generator room can cause loss of G1 to G3, and hence loss of

power to MS1 and MS2. MS3 can still be powered from MS4 in Crane

pedestal by opening bustie breaker between MS3 and MS1.

4.3.8 A fire in the Crane pedestal can cause loss of G4 & G5 and hence loss of MS4.

This will lead to loss of both tunnel thrusters, as these are powered from MS4.

By opening the bustie breaker between MS 3 and MS4 the switchboards MS1

to MS3 can still be intact.

4.3.9 A fire in the engine control room can cause loss of generators G1 to G3 as the

MS1 and their breaker controls are placed here.




4.3.10 A fire in control room A would disable normal SDP21 control. It should be

possible to resume control from Control Room B. Thrusters could stop as a

result of shorts in cabling until control has been transferred to that room.

Thrusters 1-4 could stop from lack of air if safety stops are activated.

4.3.11 A fire in control room B would disable emergency (SDP11) control and

respective systems. Individual thruster control PLC’s should select normal

control automatically whenever a signal failure is detected, so that normal

control continues without interruption All thrusters should keep on running.

4.4 Communications

4.4.1 The Control rooms are equipped with a telephone systems and a sound

powered telephone system that connects the DP control rooms with the thruster

rooms, the ECR and the safety rooms. However communication is mainly by

VHF. The vessel is also equipped with a DP alert system.

4.4.2 There is no sort of telephone or talk back systems in close vicinity of the DP

desk only VHF.

4.4.3 The DP alert system is of “traffic light” type and the activation box is placed

far back inside the new built cabinet for DP alarm printer and Fanbeam. Lights

are located at strategic places.




5 POWER GENERATION

5.1 General

5.1.1 The vessel is equipped with three generators being G1 to G3 in the generator

room and in the crane pedestal generator G4 and G5 are placed. Further each

thruster is engine driven, which also drives a PTO generator via the gear box.

This solely powers the electrical consumers needed for that particular thruster.

5.1.2 The two main generator pairs are segregated with regard to fire and the same

applies for the switchboard they serve. As each main thruster has its own

engine and power generation the vessel has a robust redundancy concept

regarding position keeping ability.

5.1.3 All diesel engines are kept ready for start by pre-heating and pre-lubrication of

the engine.

5.2 Generators G1, G2 and G3

5.2.1 These three generators were installed in 2006. The engines are of type Wärtsilä

SL20 and each drives an ABB alternator with a capacity of 1987kVA, 460V

60Hz at 900 rpm.

5.2.2 The generators can be started remotely by the engineer from the ECR or

locally at the engine. Emergency stop can be done locally and remotely from

ECR.

5.2.3 Starting of the generator is performed by using starting air taken from the

generators starting air system; separate from the thruster engine’s starting air

system. The shutdown solenoids require control air to operate the fuel rack and

the solenoids have to be energised to shut down the engine.

5.2.4 Each engine is equipped with an engine driven LO pump, SW pump, a LT &

HT pump and a FO pump. A pneumatic emergency FO booster pump is also

fitted that will deliver to all three DG’s. Each generator has electrical driven

priming pump and a standby LO pump.

5.2.5 Each generator has an electric hydraulic actuator of make Woodward that is

controlled by an electric governor of type Woodward 723+ speed controller.

This controller together with Basler excitation is placed inside each generator

governor speed cabinet. Load sharing and synchronisation is by the Woodward

DSLC and synch modules placed inside the PMS cabinet in ECR.

5.2.6 Each generator has its own monitor control system named Wärtsilä Engine

Control System (WECS) that is connected up to the K-Chief.




5.2.7 The alternator is air cooled by a force driven fan. The AVR is placed on the

non-drive end and is of make Precilec, Magnet AVR.

5.3 Generators G4 and G5

5.3.1 Generator G4 and G5 are of make Caterpillar, each has a capacity of 1800kVA

460V, 60Hz. These were also installed in 2006 and both power the

switchboard MS4.

5.3.2 The generators can be started remotely by the engineer from the ECR or

locally at the engine. Emergency stop can be done locally and remotely from

ECR. These two generators are also connected to the PMS system.

5.3.3 These generators are started by use of starting air, which is taken from the

“Clyde system” (air compressor in the crane pedestal).

5.3.4 Each engine is equipped with an engine driven LO pump, a FW cooling pump

and a FO pump. There is an electrical driven LO priming pump per engine.

5.3.5 Each generator has an electric hydraulic actuator of make Woodward load

sharing is by Woodward droop mode.

5.3.6 Each generator has its own monitor control system that is connected up to the

K-Chief.




5.4 Thruster Engine and Generator

5.4.1 The thruster engines are of type Ulstein Bergen 8 cylinder BRM type engines

with an MCR of 3530 kW at 750 rpm. The engines are connected to the

gearbox and clutch via a flexible coupling, and have an extra PTO for driving

the local generator.

5.4.2 The thruster engines can be started locally at the engine and semi auto start

from the VMS. Engine control panels are placed in both control rooms. The

panel in control room B offers only an emergency stop button and RPM

indication, whilst the panel in control room A also offers a normal stop button,

a reset shutdown button and a turbine-RPM indicator. Emergency stop can be

done locally and remotely from both control rooms.

5.4.3 Starting of the generator is performed by using starting air taken from the

generators starting air system; separate from the thruster engine’s starting air

system. The shutdown solenoids require control air to operate the fuel rack and

the solenoids have to be energised to shut down the engine.

5.4.4 After starting the engine will run at idle speed 450 rpm, until the clutch is

engaged. After that the engine speed will ramp towards the speed order of the

thruster control PLC which is set at 750 rpm.

5.4.5 Each engine is equipped with an engine driven LO pump, a LTFW & HTFW

pump and a FO pump. In addition, each engine has an electrical driven LO,

FO, LTFW and HTFW standby pump and a LO priming pump. All powered

from respective thruster switchboard.

5.4.6 Each generator has an electric hydraulic actuator of make Woodward that is

controlled by an electric governor of type Woodward 723+ digital governor.

Speed input is by two pickups, one mounted on the engine and one after the

flexible coupling so that torsional stress vibrations across this coupling can be

measured and filtered out before the speed signal is used in the control loop.

Each generator has its own monitor control system named WECS that is

connected up to the K-Chief.

5.4.7 Each thruster engine drives a PTO generator (GT#) via a belt arrangement.

This generator supplies the thruster switchboard with sufficient power making

the thruster independent of the main power distribution system. The generator

has a capacity of 250kVA 460V, 60Hz.




5.4.8 When the engine is running at nominal speed the thruster switchboard is

isolated from switchboard MS3, and the PTO generator (GT#) takes over

power supply. The starter solenoids for all pumps fans etc. in the thruster room

are all supplied with 24V from the local UPS (1 to 4). This, to ensure that

pumps, fans etc. do not trip during the changeover of power supply between

switchboard MS3 and PTO generator.

5.4.9 The thruster switchboard is powered from switchboard MS3 when engine is

not running to maintain running of pre-lube and pre-heating pumps and

powering the critical systems to make sure that the thruster is ready for start. A

generator failure does not necessary mean that the changeover relay will allow

thruster to continue running by having its auxiliary systems powered from the

MS3. Observed during FMEA trial was that there will be a short period of

power loss, this can trip the thruster. Anyhow this will only affect one azimuth

thruster.




6 POWER DISTRIBUTION

6.1 General

6.1.1 A general layout of the power distribution is shown in figure 6-1 below.

4ES

2ES

2CRBSB 1CRBSB

UPS 7

220V

220V

460V

Control room B

2CRASB 1CRASB

UPS 6

220V

Control room A

GS G4G5

4CSB6

4CSB7

460V 460V

460V

460V

ES MS4 MS3460V

T6 T5

4FSB

Sea ChestRemote ctrl

2SKB

2FC

4FC

Safety room

460V

220V

460V2FSB

220V

1FSB

Common Aux.SWB

T1 to T4

From MS3 BU supply

G1 G3 G2

MS1460V

MS2460V

J-boxP449aft future

J-boxP450bow winch

4CSB1

GT1

2CSB1

UPS 1

1CSB1

TR1

Generator room

ECRCraneTube

Emergency generator room

4CSB2

GT2

2CSB2

UPS 2

1CSB2

TR2

4CSB3

GT3

2CSB3

UPS 3

1CSB3

TR3

4CSB4

GT4

2CSB4

UPS 4

1CSB4

TR4

460V 460V 460V 460V

220V 220V 220V 220V

24V

24V

24V 24V 24V 24V

UPS 5

Figure 6-1: Switchboard Layout

6.1.2 The main power distribution consists of 4-four switchboards (MS1 to 4). There

are bustie breakers installed between the switchboards, however only MS1 and

MS 4 are connected to generators. The main power rating is 460V and sub-

distribution boards have ratings from 460V, 230V via transformer and 24V via

an UPS.

6.1.3 Generators G1 to G3 are connected to switchboard MS1 located in ECR

together with switchboard MS3. Switchboard MS2 is placed in the generator

room and switchboard MS4 is placed inside the crane pedestal and is powered

by generator G4 and G5.




6.1.4 The emergency switchboard ES is normally powered from MS1. In an event of

power loss the emergency generator GS will start up and connect to the board

when the voltage is right. This is handled by the PLC logic within the ES. This

generator is fitted with electrical start motor and has a dedicated power pack

for such and its control system.

6.1.5 The main thrusters are engine driven and a PTO generator is installed

providing all necessary power needed for the thruster related systems. I.e. each

thruster is self-sustained; in addition there is a backup feed to each thruster

from the switchboard MS3. A Merlin Gerin automatic change over unit

controls the two circuit breakers. In automatic mode the unit selects PTO

supply whenever this is available. When a thruster is not running, power from

the common aux. switchboard is used to keep fans running, to pre-lubricate the

engine etc. It is possible to start an engine without power from the common

aux. board, by directly actuating the local start air valve. This overrides the

priming pump interlock.

6.1.6 The design philosophy is that each thruster is independent of each other and

the main power distribution system. A failure of the latter (i.e. blackout) will

therefore only cause loss of the two tunnel thrusters, with no influence on the

main azimuth thrusters.

6.1.7 During normal DP operations the main power plant is common, i.e. closed

bustie breakers and that thruster 1 to 4 are all powered by their own auxiliary

board via the PTO generator, and that both 230V control room switchboards

are powered by the 230V emergency switchboard, 2ES.




6.2 460V Distribution

6.2.1 The 460V distribution consists of the main switchboards MS1 to MS4 and sub-

distribution boards. The table below shows the distributor and respective

consumers.

460V distribution # Consumers

MS1 Welding equipment, general barge consumers

MS2 Anchor Winches

Generator aux panel P419:

G3 preheater

G2 oil prime pump

G3 oil prime pump

Fan Generator room starter panel

FO transfer pump

LO separator 1

LO separator 2

LO heater 1 + 2

LO filter PALL

Start air compressor 2

SW Dosing treatment unit

MS3 Ventilation T5

Backup supply to T5 drive

Common aux. switchboard 4FSB

Safety room 4FSC

Backup power to T1 to T4

ROV

MS4 Supply to transformer TE6 to T6

Supply to transformer TE5 to T5

Distribution 4CSB6 crane pedestal –

fans / SW pump T5/T6 & G4/G5

ROV panel

ROV SB (mid) / ROV PS (aft)

Aux. to G4 & G5

4FSB

(Common aux.

switchboard,

safety control

room)

MDO Separator #2 (DOS 501B)

Thruster room supply and exhaust fans for T5 and T6

HiPAP deployment motor unit

Tautwire hydraulic unit

SW cooling pumps generator G5/T5/T6 2 off

Transformer #5 (for 2FSB)

Thruster 5 and 6 cooling fans converters

HPU pump 1 to T5

HPU pump 1 to T6




4FSC

(safety control

room)

Thruster 6 cooling fans

Thruster 5 cooling fan

HPU pump 2 to T6

HPU pump 2 to T5

4CSB1

(Thruster room 1)

2 supply and 1 exhaust fan to thruster room 1

Sea water cooling pumps (2 off)

Waste oil pump

Start air compressor #1 (K101)

Preheating control box Ulstein

Standby HT and LT cooling water pumps

Lube oil priming pump Ulstein

Lube oil stand by pump

Oil separator

Turning gear starter

Thruster pitch pump starters (2 off)

Gear/ Clutch standby pump starter

Transformer to 2CSB1

MDO cabinet (4CSB1 only)

4CSB2

(Thruster room 2)

Same consumers as for 4CSB1 except

No starting air and no oil compressor

Small control air compressor is included

4CSB3

(Thruster room 3)

Same consumers as for 4CSB2

4CSB4

(Thruster room 4)

Same consumers as for 4CSB1

4ES

(Emergency

switchboard room)

MDO separator 1

SW pump to G1-G3

Prelube & Preheating G5

Diving equipment PS side

HiPAP deployment motor

Start air compressor 2

230V CO cabinet

460V/ 230V transformer to 2ES G1 oil prime pump

Tautwire

GS battery charger

Tensioners

Fire pumps

AC Units 1 & 2

++

Table 6-1: 460 distribution.




6.3 230V Distribution

6.3.1 There are two main 230V distribution switchboards, which are the 2ES and the

2FSB. These two are powered from the 460V system via a transformer. The

2ES is powered from the 4ES and the 2FSB from the MS1. Downstream these

to switchboards there are other 230V distribution boards.

6.3.2 In addition there is one 230V switchboard in each thruster room, totally

independent of each other and power solely thruster consumers.

6.3.3 The table below shows the 230V distribution board and respective consumers.

230V distribution # Consumers

2FSB

(from MS1 via

transformer, located

in common aux.

room)

Alternate supplies for 2CRASB and 2CRBSB

Thrusters 5 and 6 variator switchboards (heating

resistors)

ECR lighting and G5 room lighting

UPS 5

G5 alternator heater

CO2 room lighting

2FC

(from 2FSB,

located in safety

control room)

Socket 230V

Alarm panel

FO tk. alarm panel

Waste Oil tk. alarm panel

2ES

(from 4ES via

transformer, located

in emergency

generator room)

Supplies for 2CRASB and 2CRBSB

Emergency lighting for all 6 thruster rooms and for the

control rooms

CO2 control cabinet (relays and valves)

UPS 8 (for generator 5 control functions)

Sea chest actuators (from 2SRSB, safety room)

2CRASB

(normal power is

from 2ES, operator

can change to

alternate supply

from 2FSB by

operating a selector

switch)

Kongsberg UPS/PDU 1

Kongsberg UPS/PDU 2

UPS 6 (to 24V 1CRASB)

Control room A lighting

Radars (X and S band)

GMDSS

Echo sounder and Log

Lights for life raft launching area port 7 starboard

Fire alarm system

Compass lighting

AIS/SSAS

2CRBSB

(from 2ES, located

in control room B)

Kongsberg UPS/PDU 3

A/C unit

Lighting for Control Room B

UPS 7




2CSB1

(Thruster room 1)

Thruster room lighting

Pitch pump heater starters 1 & 2

Clutch standby pump heater starter

Alternator heating

Ulstein UN 41 Electronic unit 230 V supply

SW filter box

Closing flap and butterfly actuators.

UPS 1

Control box for waste oil pump

2CSB2

(Thruster room 2)

Same as 2CSB1

2CSB3

(Thruster room 3)

Same as 2CSB1

2CSB4

(Thruster room 4)

Same as 2CSB1

Table 6-2: 230V distribution.




6.4 Uninterrupted Power Supply unit, UPS

6.4.1 There are 15 UPS’s feeding the essential 24 V and 230 V consumers. UPS 1 to

4 are identical and each feeds the 24 VDC consumers for one thruster, as listed

below. UPS 5 feeds the CO2 cabinet and UPS 6 and 7 feed the 24 VDC

consumers for DP. UPS 8 feeds the controls for generators G4 & G5. The

UPS/PDU 1, 2 & 3 are Kongsberg 230 VAC supplies for the DP system. Also

the new K-Chief 700 system have four UPS’s

6.4.2 The table below shows the UPS distribution board and respective consumers.

UPS # V Consumers

UPS 1-4/ 1CSB

1-4

(from 2CSB1-4,

located in thruster

room 1-4)

24V

Ulstein in/out control box UN50

All pump starter control supplies

PLC control cabinet Ulstein BW100A&B

Ulstein UN41 supply

SW filter box

UPS 5 / 1FSB

(from 2ES, located

near common aux.

room)

24V

Generators G4 & G5 + thruster T5& T6 SW

cooling pumps starter

CO2 control cabinet

UPS 6 / 1CRASB

(from control

room A)

24V

Thruster 5: electrical shaft

SDP21 OS 1 & 2 Kongsberg

Gyro 1

HiPAP OS Kongsberg

UPS 7 / 1CRBSB

(control room B) 24V

Gyro 4

Thruster 6 electrical shaft

SDP 11 Kongsberg

UPS 8 /

(in MS4 24V

MS4

Rear Artemis

DP UPS’s 230V Reference is made to section 14.7

K-Chief 700

UPS’s 230V Reference is made to section 7.3.18

Table 6-3: UPS distribution board.




7 POWER, AUTOMATION & CONTROL SYSTEMS

7.1 General

7.1.1 This section describes the different control, alarm and monitoring systems

which are related to DP operations.

7.1.2 The following systems are described further within this chapter:

Diesel Generator Control System

The Integrated Automation System

Power Management System

Thruster Engine Control System

Generator Protection

Thruster Control System, Helicon

Clutch Control

Tunnel Thruster Control system

Emergency Stop System

Fire Switch

7.1.3 The DP control system is described in section 14 of this report.

7.2 Diesel Generators Control System

7.2.1 The speed governor for the Wärtsilä and Caterpillars are Woodward 723+ and

the DSLC is the synchronizing controller. The main functions provided in the

PMS for diesel engine control are as follows:

Engine start & stop, on request or automatically from PMS

Engine pre- and post lubrication

Alarm and monitoring of the engines

Safety systems for the engines are local PLC, WECS for Wärtsilä and

AutoMaskin for the Caterpillars

7.2.2 Automatic shutdown of a diesel generator is activated by any of the following

conditions:

Over speed (governor/mechanical)

Low-low LO pressure

High-high Jacket water temperature




7.2.3 The generator breaker should trip in the event of following:

Over and under voltage protection

Over and under frequency

Overload

Unbalanced current

Over excitation

Reverse power

7.3 Integrated Automation System

7.3.1 The Kongsberg K-Chief system consists of the following main components:

Field stations (FS)

Process Stations (PS)

Operator Stations (OS)

Remote IO cards (RIO)

Network switches

Printers

Figure 7-1: Layout of K-Chief configuration Courtesy Kongsberg Maritime




7.3.2 The K-Chief System is a distributed monitoring and control system. All

operator stations and field stations with processors are self-contained units and

independent of the other units, i.e. a failure in one station will not cause any

other station to break down. All process logic including equipment safety and

control functions are contained in the respective process stations. Each

operator station contains a hard disc with all system configuration and acts as

backup for each other during system start-up. System configuration/update can

be done on-line without need of any additional equipment.

7.3.3 The main functions of the K-Chief system as installed are as follows:

Alarm/event recording

Engine room alarm and monitoring

Primary Trend functionality

Thruster alarm and monitoring

Auxiliary alarm and monitoring

Ballast alarm and monitoring

Diesel Generator control, alarm and monitoring

Power Management System control, alarm and monitoring

Fire Central interface

DP system interface

Tensioner interface

Engineer Call system

Stinger interface

Crane interface

7.3.4 For system navigation the operator panel comprises 28 navigation buttons for

quick access to the most commonly used mimics. The mimic will normally

have hotspots for further navigation to related views or sub-views. Each

navigation button has an alarm indicator lamp. The lamp will start to blink if

an alarm occurs at the mimic linked to the navigation button or to one of the

related views. An acknowledged, but still active alarm will cause a steady

light.




7.3.5 The Remote Operator Stations (OS) positioned throughout the vessel provide

user access to configuration and control. The OS’s are, in general, connected

to all three networks, LAN A, B and LAN C, and are located in the various key

zones around the vessel. LAN A and B provide the main functions of the

system; LAN C is only for admin network.

OS Groups Location OS

BRG Bridge OS032

ECR Engine Control Room OS035, OS036

Monitor

Thr2. Room

Electrical Work shop

DP Backup Room

Ballast

OS033

OS034

OS031

OS038

Table 7-1 OS stations

7.3.6 The OS’s comprise of a Main Computer Unit (MCU), with one or two LCD

display, touch control pad (TCP) and tracker ball panel (CRP or INP/ALC),

and are personal computers with an input device of Human Machine Interface

(HMI) and output monitor. The HMI is a console comprising of a number of

function and operation buttons used to navigate the mimics and control the

field devices. The computers will be running on a Windows XP platform. The

key areas for control of vessel equipment are the Bridge and Engine Control

Room. In ECR there are two OSs provided for redundancy and also for ease of

use/monitoring by more than one operator.

7.3.7 There are 15 RCU that belong to the K-Chief system. The Field Station is the

interface between the K-Chief system and various machinery and equipment.

There are different types of terminals. Analogue input, digital input, analogue

output, digital output, process input for analogue values, process input for

digital values, process output for analogue values and process output for digital

values.

7.3.8 Each process station has an RCU (remote control unit) and process station 41

and 42 have a redundant set of RCU’s. The RCU processes receive inputs and

send outputs through the I/O modules. Each RCU has a double net interface.

The RCU and the Field Stations (FS) are powered from the K-Chief UPS’s and

PS 41 & PS 42 has a redundant set of supplies.

7.3.9 For the redundant sets of RCU, one controller acts as master and the other as

slave, both controllers receive the same inputs but only one of them act as

active and can send output signals. If the master controller fails, the slave

controller will automatically take over as active controller without interruption

to the external machinery.




7.3.10 The following table shows the PCU Stations number, location and its power

supplies

PCU# Location Control Power supply

31 Thruster room 1 Thr Room 1 230V

UPS 1


UPS 2


UPS 3


UPS 4


UPS 1


UPS 3

37 Captain office Fire,System, tensioner/Stinger,

DP interface etc 230V

UPS 1

38 SWBD Room Alarms etc 230V

UPS 1

39 Sewage Room Tank gauging, etc. 230V

UPS 4

41

MS1( Master

Redundant with

141)

PMS, SwBd1/3, Engine 1/2/3, + etc.

230V

UPS 3

42

MS4(Master

Redundant with

142)

PMS, SwBd 4, Engine 4/5,BusTie 230V

UPS 4

141 MS1(Slave) PMS, SwBd1/3, Engine 1/2/3, + etc. 142 MS4(Slave) PMS, SwBd1/3, Engine 1/2/3, + etc.

Table 7-2: RCU & RIO units, courtesy Kongsberg Maritime

7.3.11 Where field stations have two controllers (RCU) both controllers read the same

data. The inputs are evaluated separately and for the output signal a Hot

Standby Voting will ensure that the output signal comes from the one in

command. The self-diagnostic feature will in the event of a failure generate an

alarm further the watchdog function will activate if the watchdog timer is not

updated. For the latter the watchdog output will be activated and the controller

and respective systems will stop.




7.3.12 The redundant Network is based on the Ethernet principle and there are three

networks A, B and C. Network Distribution Units (NDU) and each unit

contains one or more switches as illustrated in the table below. The location of

the NDU’s and their power sources are shown below:

NDU# Location Power supply

NDU A1/C1 Room A 230V & UPS 1

NDU A2/C2 Crane Tub, Emergency Generator 230V & UPS 4

NDU B1 Thruster 5 Compartment 230V & UPS 2

NDU B2 Electric Control Room 230V & UPS 3

Table 7-3: NDU locations and supply.

7.3.13 The connections between NDUs are by optical fiber cables. Both networks are

in service at the same time and both carry the same information. Duplicated

data is then rejected at the destination (field stations). The NDUs also provide

data filtering to guard against interference and corrupted data.

7.3.14 The Network C1 is Administration Network for communication links between

printers and remote diagnostic with onshore over Internet.

7.3.15 The illustration below shows a typical configuration of the Network, Field

Stations and Operator Stations.

Figure 7-2: General K-Chief Network redundancy configuration,

courtesy Kongsberg Maritime




7.3.16 The K-Chief 700 system is powered by four Kongsberg 230VAC UPS’s.

7.3.17 The computer, HMI panel and LCD monitor uses all 230V supply.

7.3.18 The K-Chief UPS’s are configured as follow:

UPS 1 supply 230V EP-200 Q3

UPS 2 supply 230V EP-200 Q4

UPS 3 supply 230V EDC01 Q6

UPS 4 supply 230V EDC01 Q7

UPS1 UPS2 UPS3 UPS4

FS 31 FS 32 FS 33 FS 34

FS 35 FS 37 FS 36 FS 39-01

K-CHIEF OS 31 K-CHIEF OS 32 FS 41 FS 42

K-CHIEF OS 33 K-CHIEF OS 33 K-CHIEF OS 35 K-CHIEF OS 36

NDU B1 NDU A1/C1 K-CHIEF OS 37 K-CHIEF OS 38

NDU B2 NDU A2/C2

PRINTER 1 PRINTER 2

FS 38

Table 7-4: K-Chief UPS’s

7.4 Thruster Engines Control System

7.4.1 There are five auto stop functions for the engines being:

Overspeed (mech. & el.)

Low-low LO pressure

High-high Jacket water temperature

Activation of oil mist

Low-low Gear oil pressure

7.4.2 These auto stops are activated 30 seconds after the initial command is given.

All auto stop sensors are hardwired and have wire break detection, giving an

alarm to the K-Chief. Loss of 24 V supply to the shutdown solenoid circuit will

give an alarm, though no stop of engine.

7.5 Generator Protection

7.5.1 Each generator is fitted with Merlin Gerin Sepam series 80 protection relay.

This is a standard current, voltage and frequency protection relay, with a large

flexibility and upgrading capability if changes are needed in the future. The

electrician can access the data from the front panel or by use a computer

connected to the Sepam. Programming and settings are done on the computer

and then transferred to each and every unit afterwards. The Sepam is powered

from respective generator cubicle.




7.5.2 Among the settings for generator protections are:

Reverse power (reactive overpower): 596kVAR in 3s

Reverse power (active overpower): 75kW in 3s

Phase overcurrent: 6.4kA in 100ms

Earth fault: 210A in 100ms

Negative sequence current/ unbalanced: 30% in 1s

Overcurrent: 2.86kA in 1s

Under voltage: 80% in 100ms

Over voltage: 120% in 100ms

Over frequency (62,5Hz): 100ms

Under frequency (55m5Hz): 100ms

7.6 Thruster Control System, HELICON

7.6.1 All four thruster engines and thrusters are controlled by Ulstein/ Rolls Royce

control system HELICON. This remote control system, which consists of an

electronic unit and control station located in control room A (UN63) and a

slave unit in control room B (UN66), controls each thruster engine. The UN66

is serial connected to the UN63. A complete loss of UN63 will also cause loss

of UN66, backup control.

7.6.2 The electronic unit (UN41) contains the microprocessor card, the supervisor

card and the power supply of the unit. Each unit is dual supplied from

respective 230V and 24V DC system placed in each thruster room. Within this

cabinet there are two disconnect units, one is for the main system and the other

is for the backup system which includes the backup DP system (SDP11)

only and the fire switch to break the normal configuration. When the fire

switch is activated there is not possible to activate/ deactivate thruster control

from thruster panels (main & BU) or from main DP OS in control room A. A

fire backup switch is also placed inside the thruster cabinets. This switch

overrides the main fire switch in control room B.

7.6.3 When in normal configuration thrusters can be controlled from the thruster

panel or by DP (SDP21), a changeover switch allows the DPO to select which

of the two systems the thrusters are to be operated from.

7.6.4 Order and feedback signals are fed to the electronic unit, which calculates and

gives output signals to the interfaces and the actuator units. Switches are read

and signal lamps and indicators are controlled from the two circuit cards in the

electronic unit. The actuator unit translate the electrical signal to hydraulic

mechanic movements. The main servo requires a hydraulic/ mechanic input

command in order to position the propeller blades.

7.6.5 A micro terminal is fitted and from this the engineer can change or adjust

settings if required.




7.6.6 There are four different types of control: pitch control, direction control, load

control and engine rpm control. These different modes are controlled by the

HELICON system.

7.6.7 Load Control

The load control system is designed to protect the engines from overload. It

monitors continuously the engine load and reduces the thruster pitch

automatically if the load should exceed a pre-set load limit. The load control

calculates the main engine load based on the measurements of the fuel rack

position, engine speed and generator load. The load control has a “built in”

programmed limit curve which shows the relationship between the rpm and the

fuel consumption (fuel rack). The rpm signal is compared to the load curve.

The load controller calculates the result and decides the maximum load

allowed on the engine by the actual rpm. If the load is higher than the high

limit, the load controller gives a pitch reduction of the thruster. The pitch

reduction speed is proportional with the amount of overload. When the load is

below the low limit the load controller will give a pitch increase signal. The

signal from the load controller (increase/decrease) is fed into the pitch

controller.

The load controller will no longer work as intend upon loss of either rpm or

load signal. If the load controller fails acceleration limits (speed of pitch

adjustments) are automatically activated. This means that when a new pitch

order is given, to prevent an overload situation the pitch is decreased or

increased very slowly when reaching -100% or +100% pitch. When the load

controller is operational the load control signal is included in the pitch control.

This means that in case of an overload of the engine the pitch is automatically

reduced (Ulstein pitch reduction).

7.6.8 Engine rpm control

The rpm control is regulating the speed signals to the main engine governor.

When starting and stopping the engine variable rpm is used. As soon as the

thruster is clutched in the revolution of the engine can be increased and fixed

rpm is selected. When fixed speed mode is selected for the engine, a ready

contact (generator enable) is given to the switchboard allowing the PTO

generator to be synchronised on the board. When synchronised a closing

contact (lock constant rpm) from the switchboard to the electronic unit locks

the rpm signal to the fixed rpm for the main engine. The breaker for supply

from MS3 will open and the thruster is self-supplied with power.

7.6.9 Pitch control

The function of the pitch controller is to position the propeller blades. The

actual position is done by the main servo system reference is made to section

13.2. The pitch controller calculates the difference between two signals: the

pitch command and the pitch feedback. It then gives an output order to the

actuator unit to move the pitch to the correct position. The program scales the

command and feedback signals into a percentage and checks them against pre-

set limits. By discrepancy an alarm is given.




7.6.10 Direction control

Function of the direction controller is to calculate the wanted direction of

thruster force. As for the pitch control, the new direction is based upon

calculation between order and feedback and the new order signal is sent to the

direction control valve that will divert the direction of oil flow to a hydraulic

motor until the thruster is in wanted position.

7.7 Clutch Control

7.7.1 The clutch is remotely controlled by the Helicon, electronic unit (UN41). It is

activated electrically using two solenoids that control a hydraulic valve.

Normal procedure is that clutch in/out commands are given at the clutch

control panel mounted in the thruster room, J/B cabinet UN33. The order

signals are then sent to the Clutch connection box mounted next to the Kumera

Clutch unit, which will control the clutch control valve to engage or disengage.

This connection box is for alarm and control monitoring of the clutch system.

7.7.2 Clutching in is only possible under the following conditions:

Engine at idle RPM

Thruster at zero pitch

Clutch lube and system oil pressures OK

Pitch oil pressures OK

Change over switch in off position

Thruster Locked out

7.7.3 The clutch automatically disengages if the clutch system oil pressure is too

low, the pitch oil pressure is too low, or if the signal ‘thruster locked out’

disappears.

7.7.4 Clutch out is available in DP control rooms A and B. The thruster control panel

in control room A also allows clutching out. This option uses a normally open

contact which makes the system vulnerable to shorts due to fire or otherwise.

A fire in main cabling or in Control Room A affecting the Ulstein propeller

control panel could cause random unwanted declutching of all four thrusters.

However, this can be prevented altogether by changing over to Control Room

B in good time. Note that each thruster is isolated electrically from its

neighbour and each electrical feed is from the thrusters own 24V supply loop.

In an emergency situation the clutch can also be controlled by manually

operating the hydraulic valve.




7.8 Tunnel Thrusters Control System

7.8.1 The heart of the control system around thrusters 5 and 6 is the ‘Electric Shaft

Control Box,’ made by ABB and located beneath Control Room A. This

‘Electric Shaft Control Box’ takes care of the actual change over between

control rooms, and selection between DP or joystick control. The joystick

panel in room A is the ‘Master’ joystick panel, versus the ‘Slave’ panel in

room B. Similarly the SDP 21 is the ‘Master DP’, while the SDP11 is the

slave. The following functions are provided by the box:

Selection room A or B according to the fire switch position

Selection DP or joystick panel according to the switch in room A

Connect emergency stop from selected room to converter.

7.8.2 When in DP:

Connect speed reference from selected DP to converter

Connect direction of rotation from selected DP to converter

7.8.3 When in joystick control:

Connect speed reference from selected joystick to converter

Connect direction of rotation from selected joystick to converter

Make inactive joystick follow the active one.

7.8.4 The Electric shaft control box is common for both thrusters and generates

alarm outputs for converter failure, shaft system failure and power failure. A

failure causing damage to the shaft control box will cause simultaneously loss

of both thrusters.

7.8.5 Thrusters 5 and 6 can be set to either individual joystick control or DP control

using two switches mounted on the master panel for these thrusters.

7.8.6 There are emergency stop buttons on both the A-room and the B-room panel.

Whereas the Ulstein propeller control panel is inactive in Control Room B on

transfer to that control room, the ABB panel remains active. The non-active

panel in Control Room A is disconnected from the frequency converter so that

no fire or other damage to a panel that is not in use can stop the drive.

7.8.7 The master panel has a start drive and a stop drive button for each thruster.

These buttons control the logic of the frequency converter rather than switch

power supplies. Whilst the thruster is in DP control, the stop buttons are

active. There is however a switch on the electric shaft, which allows Control

Room B to be isolated.

7.8.8 Under normal operating conditions the switch on the electric shaft means that

both Control Room A and Control Room B have active panels. The thruster

cannot be set to DP control before the converter has been started.




7.8.9 The frequency converters provide the actual speed control and protection of the

motor. The new speed based on feedback from the thrusters speed and the new

order given. The deviation calculated will give the new speed order signal to

motor. If the difference between the calculated speed and the actual speed is

too big, the drive will trip since a prolonged speed control difference occurs.

7.9 Emergency Stop System

7.9.1 The emergency stop system is based on an open/closed contact circuit. The

same philosophy is used for the clutch control to the azimuth thrusters.

7.9.2 The emergency stop system is individual per thruster and the clutch system is

the same. The biggest concern with a system like this for a DP 3 vessel is a

fire, and will in worst case cause activation of emergency stop. Even using an

NO and NC pole could lead to the e-stop activating as it cannot be determined

how the switch will melt.

7.9.3 Procedures are in place that in event of fire inside thruster console in control

room A. Operator shall immediately take control in control room B and operate

the fire switch there. All thrusters and control will be transferred to the backup

DP station. The Helicon control unit UN41 will now receive control data from

the backup DP. The disconnect unit inside the UN41 shall now be inactive and

any signals shall be disregarded by the unit.

7.10 Fire Switch

7.10.1 The fire switch in Control Room B determines what room is in control using

two contacts that should always be each other’s inverse. All wires for the fire

switch are routed through emergency cabling. If a fire switch signal fault

occurs, control will stay at control room A.

7.10.2 Within the Helicon control cabinet to each thruster there is a separate fire

switch, this switch overrides the main fire switch in control room B.

7.10.3 The fire switch is built up on two contacts open/closed. These two have to

change status to activate the fire switch. Contact 1 from closed to open and

contact 2 from open to closed position.




8 FUEL OIL SYSTEMS

8.1 General

8.1.1 The vessel runs on MDO, which is stored in four FO storage tanks, one of

347m3, one of 454 m

3, and two of 829 m

3 each. The overflow tank is 47m

3.

There are two pumps that can be used to transfer fuel from these storage tanks,

being the service pump (46 m3/hr) and the transfer pump (136 m

3/hr). Both of

these pumps are operated manually.

8.1.2 There is one common settling tank 57m3 placed in the sewage treatment room

that supplies all day tanks with FO by use of a FO separator. Two FO

separators are installed one at same location as the settling tank; the other FO

separator is placed in the AC room.

8.1.3 From the separator there is a distribution line to all day tanks for thruster

engines and generators. The day tanks have an overflow line fitted to the

overflow tank. The filling of the day tanks is a manual process. All tanks are

fitted with level alarms. An illustration of the common FO distribution is

shown below.

Settling tk.

FO Separator

FO Separator

Day tank generators G4 & G5

Day tanks generators G1 to G3

Day tank Thruster Engine

Day tank Thruster EngineDay tank Thruster Engine

Day tank Thruster Engine

Figure 8-1: Fuel oil transfer system




8.1.4 Related to biological contamination is water contamination. This could occur

from bad supplies, tank leakage and possible other causes. Normally the

separators will remove any water from the FO before it is distributed to the day

tanks. Regular oil samples and draining of the tank will reduce the risk of

water contamination. Not only is water often a prelude to biological

contamination but also the separator may not be capable of removing extreme

quantities of water.

8.2 Fuel Oil System Diesel Generators

8.2.1 The FO supply to the generators G1 to G3 is taken from one of the service

tanks, the other is used as an additional settling tank where a separate FO

separator circulates the FO from one day tank to the other. This separator is

dedicated to these generators only.

8.2.2 The FO to generators is through a common line from the day tank through a

filter unit and then to each engine driven FO booster pump, which discharges

the FO through an engine mounted filter and to the injectors.

8.2.3 A pneumatic driven FO backup booster pump is installed that when started will

deliver to all engines. A simplified schematic illustration of the system is

illustrated below.

Day tank Day tank

Em. booster pump

Filter unit

Figure 8-2: Fuel oil system diesel generators

8.2.4 FO supply to the generators G4 and G5 is from a single day tank, through a

common line with T-off to each generator. The engine driven pump discharges

the FO through an engine mounted filter and to the injectors. These generators

are not fitted with a standby booster pump.

8.2.5 For all generators excessive FO is lead back to the day tank.




8.3 Fuel Oil System Thruster Engines

8.3.1 The FO system for each thruster engine is independent; the only common is

filling of day tank from the settling tank by use of the FO separator.

8.3.2 In the respective thruster room there is a day tank, FO to the engine is gravity

fed from the day tank through a flow meter and directly to the engine driven

FO pump, which discharges the FO through an engine mounted filter and to

the injectors. A simplified schematic illustration is shown below.

FO cooler

Flowmeter

Day tank

MStandby pump

FO Truster room

Figure 8-3: Fuel oil system Thruster Engines

8.4 Quick Closing Valves

8.4.1 The outlet valves on the FO tanks are of hydraulic operated type quick closing

valves. Remote closing for the generators is placed inside a cabinet next to the

stairway up from mezzanine in pump room port side. There is one common

lever and one for each individual generator.

8.4.2 For the thruster engines there is a remote lever placed outside respective

thruster room that will shut the outlet valve from the day tank.

8.4.3 All levers are protected against mal-operation and needs hydraulic pressure to

close. It is not possible to inadvertently shut off the FO supply to all engines.




9 COOLING WATER SYSTEMS

9.1 General

9.1.1 Each thruster unit has its own SW cooling system totally independent of each

other. As for the generators G1, G2, G3 these have suction from a common

SW manifold and generators G4 and G5 share the same common SW system

with suction from thruster room 6.

9.1.2 The FW cooling system for each engine / generator is totally independent. A

failure will only affect that engine/ generator pair.

9.1.3 A FW pre-heater pump is fitted, one for each engine. This pump circulates the

medium through the heater and engine to keep it warm while the engine is

stand-still to maintain engine ready for start.

9.1.4 There are no standby LTFW and HTFW pumps fitted. Temperature Control

Valves (TCV) are either electro- pneumatic operated or of element type.

Manual operation of TCV’s is possible.

9.1.5 Service air is available to clear the sea chests if necessary.

9.2 Cooling System Generators

9.2.1 The cooling system for generators G1, G2 and G3 are illustrated below.

SW ManifoldLowSuction

High Suction

Overboard

G3

FO Cooler

SW/FW central cooler

SW-LTFW-HTFW- Pumps

G1 G2

Figure 9-1: Cooling system Generators

9.2.2 The SW system (solid line) comprises of a low and high suction sea chest with

remote operated inlet valve. A strainer (filter) and the common SW manifold.

Each engine driven SW pump has suction from this manifold, discharges the

SW through the SW/FW cooler and FO cooler. There is a common overboard

line for all three generators.




9.2.3 Each generator has a LT/HT cooling circuit the LT circuit is illustrated as the

dotted line. The header/ expansion tanks (one each) are placed outside fwd of

the crane on starboard side and are equipped with a low level alarm. Each

generator has a direct driven LTFW and HTFW pump. The LTFW pump

draws the coolant from the outlet line of the cooler.

9.2.4 A TCV ensures that the coolant holds the set temperature. The LT pumps the

coolant to the various coolers such as LO and LT charge air cooler. On the

return line there are two T-off’s, for suction and discharge from the HTFW

system.

9.2.5 Downstream the HTFW pump there is the HT charge air cooler and cylinder

cooling. A TCV on the engine outlet will divert the flow into round circulation

and when the coolant reaches pre-set temperature. It will divert the coolant into

the LTFW common return line.

9.2.6 Generators G4 and G5 have a common SW cooling line together with systems

of thruster 5 and 6, whereby two SW pumps (duty/standby) with suction from

thruster room 6 discharges the SW for thruster cooling and for generators

through respective FO-, SW/FW cooler and overboard. These two pumps are

powered from 460V distribution 4SFB.

9.2.7 The engine driven FW cooling pump with suction from the engine mounted

expansion tank circulates the coolant through the SW/FW cooler and the

engine.

9.3 Cooling System Thruster Engines

9.3.1 The SW cooling system for a thruster engine is illustrated below.

SW ManifoldLowSuction

High Suction

SW pumps2 x 100%

2 x Central Coolers

ClutchCooler

Thr. oil Cooler

Overboard

Figure 9-2: Cooling system thruster engines




9.3.2 Each system has two sea chests -one high, one low- feeding two 100% pumps

(duty/standby). The pumps supply water to the two FW coolers, the clutch and

the hydraulic power pack to thruster.

9.3.3 Each engine has a direct driven LTFW and HTFW pump. From the coolers a

TCV is fitted on the suction line regulating the coolant temperature by mixing

the flow from the coolers with the flow directly from the return line that

bypasses the coolers. Downstream the LTFW pump the coolant passes through

the FO cooler, PTO generator, charge air cooler and the LO cooler. On the

return line there are two T-off’s, for suction and discharge from the HTFW

system.

9.3.4 The HTFW cooling system consists of a direct driven HTFW pump that

circulates the coolant through the engine cooling system. Downstream the

HTFW pump there is the HT charge air cooler and cylinder cooling. A TCV on

the engine outlet will divert the flow into round circulation and when the

coolant reaches pre-set temperature. It will divert the coolant into the LTFW

common return line.

9.3.5 The thruster engines cooling system is fitted with an electric standby LT and a

HT pump. Both pumps are powered from thruster switchboard.

9.3.6 Failure of a SW or FW system will be confined to that thruster only. Failure of

the SW cooling to the thruster hydraulics will give rapid rise in the hydraulic

temperature; there is no shut down function related to this only to engine jacket

water system. Regular maintenance routines for cleaning of cooler will reduce

this risk.




10 LUBRICATION SYSTEMS

10.1 General

10.1.1 The lubrication system for each thruster and generator engine is independent,

further thruster engines and generator engines G4 & G5 are not connected to

any LO separator. Only the generators G1, G2 and G3 are connected to the two

LO separators that are arranged in parallel.

10.1.2 Purifying of the LO is a manual operation and inlet/ outlet valves have to be

opened. There is no interlock of these valves to the separator, this gives a

potential of mal-operation by emptying one and filling another engine.

Procedure implemented ensures that this risk is highly unlikely to happen.

10.1.3 LO for the thruster engines and generator G4 & G5 are changed out based on

running hours according to planned maintenance system.

10.2 Lubrication system Diesel Generators

10.2.1 The engine drive LO pump has suction from the sump and circulates the LO

through the cooler, LO filter and to the oil distributor and by gravity back to

the sump. The electrical driven priming pump is used prior to start of engine to

build up the LO pressure keeping it ready for start, and when shutting down the

engine, especially for lubrication of the turbo charger. The priming pump is

connected to a T-off on the main LO pumps suction line and discharges into

the LO line before of the LO cooler. This pump is also used for maintenance to

empty the LO sump.

10.3 Lubrication System Thruster Engines

10.3.1 The LO system for thruster engine is independent. The only thing common is

that they all share the same LO storage tank and transfer pump. Valves have to

be open before start of filling an engine. There are two LO separators: one

placed in thruster room 1 for thruster engines 1 & 2 and the other is placed in

thruster room 4 for thruster engines 3 & 4. There are 3-way valves that are

interlocked, not possible to take oil from one engine and discharge to the other.

10.3.2 The main engine LO system comprises of a LO sump, an engine driven LO

pump and an electrical driven standby and a priming pump. The main pump

has suction from the sump and discharges LO through LO cooler and a TCV,

that regulates the LO temperature by regulating the flow through the cooler.

From the TCV the LO is diverted through a dual filter prior to the oil manifold

distributor and lubrication points of the engine and by gravity back to the

sump.




10.3.3 Lubrication points are among others:

Turbo charger

Rocker arms

Injector pump

10.3.4 Each engine control cabinet controls the solenoid valve for letting oil to the

injector pump.

10.3.5 The priming pump is used prior to start of engine to build up the LO pressure

and is also used for maintenance to empty the LO sump. The standby pump

will kick in if the LO pressure drops below a set limit and when shutting down

the engine, especially for lubrication of the turbo charger. Both pumps have

suction from the sump and discharges into the LO line before of the LO cooler.

10.3.6 These pumps and related control systems are powered from respective thruster

switchboard.

10.4 Lubrication System Gear/ Clutch

10.4.1 The clutch is hydraulic operated from the gear’s oil system and is controlled by

solenoids valves (24V). The valve control is pulse operated i.e. needs an active

pulse to operate solenoid valve and the valve will therefore stay in position

upon loss of control power.

10.4.2 The gear’s LO system is independent of each other and comprises of a gear

driven pump, filter unit, cooler and an electrical standby pump. The pump

draws LO from the sump and diverts it through the cooler and into the various

lubrication points for the gear and for clutch operation.




11 COMPRESSED AIR SYSTEM

11.1 General

11.1.1 There are three compressed air systems that are used by the engines for starting

and control air. All three systems are independent of each other and these

systems are:

Starting air system to generators G1, G2 and G3

Starting air system to thruster engines

Compressed air system to Clyde (Crane) used as starting air to generators

G4 and G5.

11.1.2 The starting air for the thruster engines is built as a ring line with isolation

valves and reservoir tanks for the control air. The reservoir tanks have a

capacity of 200 litres and upon a leakage causing loss of air this will give

ample time for the engineer to close the isolation valves.

11.2 Starting Air System to Generators

11.2.1 The compressed air system to the three generators is illustrated in Figure 11-1

below:

Start aircompressor 1

Start air receiver 1 & 2


Air filter

Working airline

Generators G1, G2 & G3

NC

NO

Figure 11-1: Starting Air System Generators G1 to G3

11.2.2 The air compressors discharge via an oil/water separator into two air receivers.

On this line there is also a crossover to the working air system, this valve is

normally closed (NC). Both the air compressor and the receivers have relief

valves fitted and those from the receivers are piped clear to deck in order to

avoid feeding any fire with air. The compressors will start/stop upon low/high

air pressure.




11.2.3 Form the air receivers there is a common line to the three generators. Prior to

the generators there is an air filter.

11.2.4 The air supply to generators G4 and G5 is from the service air system.

11.3 Starting Air System to Thruster Engines

11.3.1 The compressed starting air system to the thruster engines is illustrated in

Figure 11-12 below:


Control air reciever

Control air

30 - 8 bars Starting airreciever

Control air

30 - 8 bars



Control air

30 - 8 bars Starting airreciever


Control air

30 - 8 bars


NC

NC

Figure 11-2: Starting Air System Thruster Engines

11.3.2 There are two start air compressors, one in thruster room 1 and one in room 4.

Each compressors feed into their own 1000 litres start air receivers placed in

respective thrusters room. From there both vessels are connected to a piping

network that connects all thruster rooms, ring line. Valves are installed so that

crossovers between thruster rooms can be closed. During normal operation the

air receiver in thruster room 1 will feed into thruster room 3, whilst air receiver

in thruster room 4 feeds thruster room 2. I.e. the system is segregated into a

port and a starboard system.




11.3.3 Each of the main thrusters T1 to T4 has its own 200 litres control air receiver

which is filled from the start air loop via a reducer unit and a non-return valve.

This control air supplies all thruster related consumers such as diesel engine

over speed protection, TCV and the local fire dampers. There is an alternative

supply from the service air that bypasses the control air receiver (not

illustrated).

11.3.4 Within thruster room 2 and 3 there is a separate service air compressor for that

thruster (not illustrated). This is a 7 bar compressor that is connected into the

line after the pressure reducer and before the receiver as illustrated.

11.4 Service air system

11.4.1 There is one common service air system on board. The service air system is

based on the same principle as for the other compressed air systems. This

system supplies the following systems/components with air:

Starting air generator G4 & G5

FO separators

LO Separators

SW inlet valves

Service outlets

Tautwire

Alternate control air supply to thruster rooms (backup only)




12 VENTILATION

12.1 General description

12.1.1 The vessel is equipped with several ventilation systems located over the

various areas. The vessel is divided into different hazardous areas, giving with

it the various rules and regulations applicable with regards to the ventilation

systems in those areas.

12.1.2 For IMO equipment class 2/3, systems not directly being a part of the DP-

system, but which in case of failure, could cause failure of the DP-system

(such as a ventilation system) should also comply with relevant requirements

of the IMO guidelines).

12.2 Ventilation & AC Units

12.2.1 Each generator and thruster room has two supply fans and an exhaust fan,

where one supply fan is reversible. These fans are powered from respective

thruster- or switchboard MS1/ MS4.

12.2.2 There are standalone AC units and supply fans for technical rooms, there is no

temperature monitoring but usually most of these rooms are manned.

12.2.3 There are two remote stopping panels for the ventilation systems. One panel is

placed in the control room A and the other is in the safety control room. The

latter is the master panel and do also stop the MDO separators. These panels

stop the following fans:

T5 Fan starters

T6 Fan starters

Crane Tube fans starters

Thruster room 1 fans




(MDO Separator 1 + 2)

12.2.4 The CO2 cabinet is also configured to shut down fans in thruster room(s) when

activation of CO2 release.

12.2.5 Failure of a supply fan has no effect on the running machinery within the

spaces served by the affected fan. The thruster allocated within the affected

area will not be cooled by the air only, but also by the FW cooling system as

described earlier in this report.




12.2.6 It should be noted that loss of cooling to a technical room such as instrument -,

thruster room can if no action is taken result in overheating of electrical

components, with worst case result of systems shutting down. Important rooms

that are not normally manned should have temperature sensor fitted to alert the

engineer of the change of status and to initiate corrective actions, if required.




13 THRUSTERS

13.1 General

13.1.1 The main propulsion is by four engine driven azimuth thrusters in addition

there are two electrically driven tunnel thrusters. The main thrusters are

numerically numbered from 1 to 4 and the two electrical are thruster 5 and 6.

13.1.2 Each of the main thrusters is located in its own thruster room, which contains

all necessary equipment for running that thruster, such as a fuel tank, cooling

system, control air receiver, etc. This independence of thrusters T1 to 4 is one

of the attractive aspects of the overall redundancy of the installation. T1 is

located starboard fwd, T2 port fwd, T3 starboard aft and T4 port aft, as

illustrated below:

T6

T4

T3

Switchboard MS4

T2

T1

T5

Fwd

Figure 13-1: Thruster configuration

13.2 Azimuth Thrusters

13.2.1 All four azimuth thrusters are of the same type Ulstein TCNS 120/85 – 280

swing-up CPP thrusters driven by diesel engines.

13.2.2 This type of thruster swings up into an housing in the hull when not in use, by

two hydraulic cylinders powered from the Hydraulic Power Unit. In the

retracted position the thruster is disengaged from the engine by the clutch.

13.2.3 Each thruster consists of the following main components:

Thruster unit with nozzle

Steering gear with top bevel gear

Hydraulic system, HPU

Starter cabinet for the HPU

Gravity tank, oil reservoir

Remote control system, Helicon

Diesel engine as drive motor with clutch




13.2.4 The propeller diameter is 2800mm. As the thruster is of variable pitch type the

engine speed is set steady at 750 rpm and via a clutch and gears giving 218.5

rpm on the propeller. The thruster force is changed by operating the blade

angle (pitch).

13.2.5 The hydraulic systems for the thrusters are independent and identical; therefore

only one thruster is described.

13.2.6 There is one HPU per thruster that consists of a reservoir tank, two 100% pitch

pumps and steering pumps. Starter cabinet for control of pumps normally one

pump is running and the other act as standby. In retract/ deploy mode both

steering pumps are running.

13.2.7 The steering and lift/ lowering system is supplied with oil diverted from the

running hydraulic pump, discharging oil via a filter to the steering control

valve and lift/ lower control valve block. The steering control valve diverts oil

to either side of the hydraulic steering motor depending on the order given

from the electronic unit, Helicon. The lift/ lower control valve diverts the oil

to the load control valves mounted on the lifting cylinders. The locking

cylinders are directly supplied from the discharge line of this pump via a

pressure reducing valve, operating the locking cylinders for the upper and

lowered positions.

13.2.8 Downstream the pitch pump there is a non-return valve and the oil is

discharged via a filter set, to the pitch control valve. The solenoid valve diverts

the oil to the pitch unit, which operates the blades.

13.2.9 For both systems the filters do have a bypass line with a spring loaded bypass

valve. Relief valves are installed to protect the systems. Return oil is diverted

via an oil cooler, equipped with a thermostatic valve. This oil cooler is cooled

by the thrusters SW cooling system, reference is made to section 9.3.

13.2.10 The thruster is alarmed for start interlock pitch not zero, low pitch and steering

oil pressure. The system is equipped with a header tank and reservoirs are

fitted with a low-level alarm.




13.3 Tunnel Thrusters

13.3.1 Thrusters 5 (fore) and 6 (aft) are Ulstein TM800 electrically driven fixed pitch

tunnel thrusters. The driving motors are 1700 kW squirrel cage rotor machines

suitable for direct air/sea water cooling. The motors are controlled by a 12

pulse frequency converter which allows the motor to run at any speed between

900 rpm CW and CCW. The frequency converters are air cooled.

13.3.2 Both thrusters are powered from same switchboard. A failure causing loss of

one or both tunnels will not give great impact on the DP capability as the

vessel will have the four main thrusters available for station keeping

performance. Though, a switchboard fault will have more impact on other DP

control systems in general rather than for thrusters.




14 DP CONTROL SYSTEMS

14.1 General

14.1.1 The Vessel is fitted with a Kongsberg Maritime SDP-21 dual redundant and

SDP-11 single Dynamic Positioning Control system in order to comply with

BV’s PDY MA TA RS (IMO DP Class 3). The SDP-21 is placed in control

room A and SDP-11 in control room B. These two DP systems are segregated

by A60 fire wall and that’s also the case for auxiliary systems connected to

respective DP system.

14.1.2 The DP system has been upgraded with, new control computers from SBC 500

to MP8200 August 2012, new operator PC’s (COS).

14.1.3 The DP operator stations and computers, communicates with each other on a

dual redundant Network. The DP controllers which are the “brain” of the DP

system are communicating with each individual Thruster Control Cabinet

(TCC, thruster vendors control system (Helicon/ SITCON)). The DP

computers also receive commands from the position and environmental sensors

in order to give the thruster controls accurate commands by building a

mathematical model of the vessel and its environment. The DP uses a feed

forward loop to predict the forces required to hold position.

14.1.4 The DPO can manually switch the thruster controls between the main DP and

backup DP system; this is achieved by operating the fire switch at the backup

DP console. Prior to this the backup DP has to be set in “HOT” stand-by

allowing it to continuously update inputs from sensors, position reference

systems, thruster feedbacks etc. This to have a smooth transfer of control, if the

backup DP is not set in standby the transfer can cause loss of position. The

vessel operator needs to make sure that procedures are followed and crew is

familiarized with them. Switching over from main to backup DP should not

affect the position keeping ability or change of the vessel’s heading. SDP11

also has its own independent reference systems.

14.1.5 In Class 2/3 operations at least three position references must be available,

whereby the system can exclude any unsteady reference data and still keep a

good position with some quality degradation. The three reference systems must

be at least two different measurement principles to meet IMCA guidelines. The

median test function within the KM does solely look at three DP reference

systems and not on their type. Neither does the consequence analysis warning

function given by KM take this into account as it reacts purely on low power

availability or insufficient thrust (thrusters and generators).

14.1.6 Vessel owner to ensure procedures are in place and systems operated according

to DP operation manual.




14.1.7 The DP consequence analysis software function will be activated automatically

when mode DP class 2/3 is selected. The consequence analysis function within

the DP software only runs when the vessel is in present position and on present

heading. I.e. if the vessel is in auto track mode, or on the move towards a set

point in AUTOPOS mode, the analysis will not run. There is no information

about this within the DP system help functions. The operator has to be aware

of this.

14.1.8 The DPO should be aware of that a failure causing loss of the SDP-21

controllers caused by a fire or internal cabinet damage, resulting in loss of the

SDP-21 system. This will also cause loss of all thrusters as their ready signal is

lost, this will also include for the SDP-11. In that case the DPO has to enable

all thrusters in DP after changing over the fire switch.

14.1.9 The layout of the DP control systems are as follows:

Main DP SDP-21 BU DP SDP-11

Equip. Location Equip. Location

SDP-21 OS’s Control room A SDP-11 OS Control room B

DPC-21 Control room A DPC-11 Control room B

Gyro 1

Gyro 2

Control room A

Gyro 3

Gyro 4

Control room B

VRS 1

VRS 2

VRS Seapath

Fire station 7

VRS3

VRS4

Control room B

Wind 1

Wind 2

Mast mounted

next to aft of

Helideck SB side

Wind 3

Wind 4

Mast mounted

above Control

room B PS side

DGPS 1

DGPS 2

Seapath

Control room A

Rack

DGPS 3 Control room B

HiPAP 1

APC11

Control room A

Rack

HiPAP 2

APC11

Control room B

HiPAP 1

Transducer

Fwd HiPAP

Trunk

HiPAP 2

Transducer

Aft HiPAP Trunk

HiPAP OS Control room A

LWTW Mk12

Operator panel

Control room A

LWTW interface Control room A

Fanbeam

Operator panel

Control room A




14.2 Operator Stations

14.2.1 The DP desk in control room A consists of three operator stations (OS’s),

being the two DP OS1 & OS2 and the HiPAP OS. In control room B there is

one DP OS (OS3) and one HiPAP OS. Each OS consists of the following

components:

Operator panel with joystick and pushbuttons

Monitor

OS computer

14.2.2 The OS has minimum hardware; the computer (COS) interfaces the operator

with the operating panel and the display. The sensors, references and thrusters

are selected and deselected using a Windows XP configuration. Alternatively

buttons are also provided on the console for quick operations and operational

mode selection. A joystick is provided on the OS desk for manual control of

the thrusters and for semi-automatic yaw, surge and sway control. Operator can

select joystick control of either or of two movements and the DP controls the

other.

14.2.3 The screen of the console is divided into one large area on the right and two

smaller areas on the left, the size of these areas cannot be changed but a zoom

function is available. Each of the areas can display a separate page of

information, which can be selected by the operator.

14.2.4 Alarms are displayed when the “Alarm view” button on the keypad is pushed.

All the alarms are presented on an overlapping window on the screen of the

console where the button is pushed. When an operator has to input information

this is also done using overlapping windows, which always show up at the

same location on the screen. The cursor is positioned directly on the input

window. The pointer can be moved using a trackball and selections are made

using three buttons in front of the trackball.

14.2.5 Colours can be selected from different palettes, (e.g. Daylight, Dusk and

Night). The 'Night' palette has different colours and easy to split information

and commands. The push buttons on the keypad are either light blue or dark

blue. The light blue buttons are “double push” buttons, while the blue buttons

are “single push” buttons. Several buttons have an indicator light which will be

lit when ‘selected’.

14.2.6 The vessel is also fitted with a DP operator terminal that can be connected up

to the DP system, this allows the operator to bring control of vessel from the

DP desk to another part of the bridge/ control room A.




14.3 DP Computers and Network

Figure 14-1: SDP-21 Courtesy Kongsberg Maritime

14.3.1 There are two independent but linked microprocessors (Single Board

Computer – MP8200 based on Intel 960 RISC processor) which monitor input

data received from a range of sensors using a master/slave relationship and

generate the signals to the thrusters required for position and heading control

(SDP-21). The Backup DP SDP-11 has its own controller. The controller units

and the operator station communicate via a dual network. The hub is located

inside the operator station console.

14.3.2 The operating system for the console computers is Windows™

XP. This is a

shell used for display purposes only. The actual control is done by the

computers (MP8200) in the Kongsberg computer cabinet.

14.3.3 Computers and all interface boards in the DPC-21/ DPC11 are located in the

upper cabinet whereas power supplies are placed in the lower cabinet. There

are analogue boards for reference system signals, and there are isolation

amplifiers on the signals for thrusters. Although the CPU’s and the power

supplies are separated, the interface boards are serial linked but common and

both computers are connected to each board. The layout in the SDP-11 is the

same, except that there are only a single computer and power supply.

14.3.4 The function of the Power Supply Units (PSU) within the DP cabinet is,

amongst others, to generate a stable reference voltage for the potentiometers

used for the feedback signals.




14.3.5 The two computers in the SDP-21 operate in parallel each receiving inputs

from sensors, reference systems, thrusters and operator and each performing

the necessary calculations. However, only the on-line computer (master)

controls the thrusters. Switchover between the computers (master/slave) may

be either automatic or manual. It is automatic if failure is detected in the on-

line computer. Continuous comparison tests are performed to check that the

two computers read the same inputs and give the same outputs.

14.3.6 If a difference occurs, warnings and alarms are reported from each computer.

The weak point in a dual redundant system is in determining which computer

is wrong. The operator therefore could choose the wrong one.

14.3.7 When operating in accordance to DP class 3, the system will also alert if the

BU DP controller is not in “hot standby” configuration and an alarm is issued.

This will also apply if there is a deviation between all three controllers. The

backup DP is updated by inputs from sensors, position reference systems,

thruster feedbacks and etc. to be able to take control when necessary.

Switching over from main to backup DP should not affect the position keeping

or the vessel heading.

14.4 DP Control Modes and Functions

Figure 14-2: Forces and motions, courtesy: Kongsberg Maritime

14.4.1 The standard DP control modes are implemented which are standby, manual

(joystick) and auto position. Mixed modes between manual and auto are

automatic control of yaw, surge-axis and sway-axis either separately or

combined. When all three are selected an automatic switch to AUTOPOS

mode is made. Furthermore different control modes such as ROV (follow sub),

Auto-track, are implemented.




14.4.2 The wind, gyro or VRS sensors used by the DP Control System cannot be

directly selected from the keypad. Instead, a dialogue box on the screen is used

where the preferred sensor has to be selected. Note! If a gyro falls out it has to

be manually enabled/reselected in the dialogue box. This is not the case for the

other sensors. Operators should be aware of this.

14.4.3 A standard median test is implemented which will detect a seemingly perfect

position measurement, e.g. dragging transponder or frozen DGPS signal. A

parameter is that at least three position reference systems have to be selected

and accepted by the DP computer. Also a high variance test is used to deselect

those position reference systems which show a high variance pattern over a

prolonged time period. It is required that sufficient position reference systems

are selected and accepted by the DP Control System.

14.4.4 The DP mathematical model is using various historical input data to predict

values/position and compare with actual readings. The computer calculates the

required force and thrusters to be used in order to keep required set-points. To

achieve a good mathematical model the vessel has to be in position for some

time in order to build up the model.

14.4.5 The thruster allocations can be set in various modes being:

Variable, thrusters are operating individually and freely.

Force Bias, Azimuth thrusters are operating against each other’s, setting

can be made from a separate pop-up menu and also thrust tonnage can be

set. Configuration is that T2 & T4 works against each other, same for T1 &

T3.

Fixed, in this mode the azimuth thrusters can be set to a pre-defined

direction.

Environmental Fixed, DP set the thrusters to a calculated defined direction

based on environmental forces.




14.5 DP Sensors

14.5.1 The vessel is fitted with following DP Sensors:

4 x Wind sensors

4 x Gyro’s

4 x VRS

Lay Tension sensors

14.5.2 Extra sensors have been installed beyond the class requirements this to

increase the operational redundancy of the vessel.

14.5.3 Wind sensor

The vessel is furnished with a total of four wind sensors; all are of make Gill

Instruments and all were installed in last quarter of 2008. The wind sensors are

located in two different Masts. Both Masts are placed very close to the

Helideck and the DPO should be aware to have the wind sensors deselected

prior to arrival/ departure of a Helicopter.

The wind data from the Wind sensors are sent to the following systems:

Wind 1: DPC-21

Wind 2: DPC-21

Wind 3: DPC-11

Wind 4: DPC-11

14.5.4 Gyro Compass

Four new gyros were installed in last quarter of 2008 during dry-docking and

all are of make SG Brown Meridian. The vessels heading signal from the gyros

are sent to the systems as follows:

Gyro 1: DPC-21, via serial splitter to HiPAP 1 + Seapath 200

Gyro 2: DPC-21

Gyro 3: DPC-11, via serial splitter to HiPAP 2

Gyro 4: DPC-11,

Gyro 1 & 2 are both placed under desk PS forward in Control room A. While

Gyro 3 is placed in rack under HiPAP APC-11 next to the BU DP OS in

Control room B and the Gyro 4 is paced in the next room.

The Latitude correction to a gyro is from manual input only.




14.5.5 Vertical Reference System (VRS)

The VRS systems are of make MRU delivered by Kongsberg Maritime. The

MRU system uses solid state device to measure the roll, pitch and heave rate

(MRU 5 only). The MRU’s have power supply from respective DPC cabinet.

The MRU’s signals are sent to the following systems:

DP VRS 1 - MRU-5: DPC-21 and HiPAP 1 + Survey box via serial splitter

DP VRS 2 - MRU-2: DPC-21

DP VRS 3 - MRU-H(1355): DPC-11 & DPC 21 and via serial splitter to,

HiPAP 2

DP VRS 4 - MRU-2(0734): DPC-11

VRS5 MRU5 (3752): Seapath only

Having DP VRS 3 to be configured to DPC-21 allows the DP system to have

voting on the VRS’s.

The VRS’s are located at two locations, main VRS’s are located in a cabinet

next to fire station #7 and DP VRS 3 and DP VRS 4 are located in Control

Room B.

14.5.6 Lay Tensioner

The DP receives pipe lay tension information directly from the new lay control

system.

The two pipe lay tensioners, each have two load cells. The load cells interface

to a single PLC, which is located in control room A. If either a load cell or its

cabling were damaged, the automatic sensing of pipe tension would be lost.

The DPO would then have to either select a fixed tension value i.e. a manual

input, or let the DP resolve the external forces through the current resolution.

The latter option would take too long and an excursion would take place so it is

not recommended.

If the PLC fails then the DP will remember the last sensed figure and use that

as if it was continuing to receive that information. There is a possible danger

where the sensing cells break down and send false signals, in that circumstance

an excursion could take place and relies on the swift intervention of the DPO.

In an emergency, where the former options (use of DP) are not available, resort

may be made to the joystick, but it is certain that manual compensation would

be highly insensitive.




Each load cell has two strain-gauge bridges so that failure of a single bridge

can be detected and alarmed. It would then be up to the operator to decide

which one has failed. The switching off of the faulty load cell must be done at

the pipe machine and the operation could continue with the one remaining cell.

The information from the load cells is used to calculate the actual pipe tension,

which is sent to the DP in serial format. There is a ‘signal valid’ section in this

data string. If the DP loses the pipe tension signal completely or if the

measurements exceed a pre-set maximum limit set by the DPO, the value will

revert to the last valid measurement used by the DP that was within the clip

limit, or the DPO does one of the following:

Uses the last measurement

Enters a manual value

Deselects pipe tension altogether and then the external forces would be

resolved as current.

It would be the best option to use a manual setting similar to the last automatic

reading.

The DPO may also enter a minimum limit also, below which the pipe tension

input will not be allowed to fall. During a recovery from a tension input

failure the function ‘Filter Constant’ may be used, in general terms this assists

the transition between the absence of a tension value or a value of less than the

real value to the operational tension value.

Any jump in the compensation value will result in a disturbance of the position

so the values, be they manual or automatic have to be as close as possible to

the real tension.

In the DP system the pipe tension is low pass filtered before being used for

compensation which means that the peaks in tension are ironed out to make the

signal more usable The DPO has to set up this filter to adapt it to the stiffness

of the pipe, and may enter a correction factor called bias, which is a figure that

will be added to the automatic reading, thereby in fact setting the amount of

compensation. It should be noted that these values are crucial to the system’s

behaviour. Of all settings allowed by the DP system none should result in

instability. Careful testing is required to prove this

The DPO at all times has the option to change from automatic compensation

using the measured values, to a fixed value which is entered manually. The

DPO should take care when making changes to this value since a transient

disturbance of the position keeping will follow each change, the extent of

which is related to the size of the change in the compensation.




A further problem with the use of fixed values for compensation is that the real

tension varies with the vessel’s position. The effect of this could be oscillating

motions with possibly increasing amplitude. A procedure should be developed

to prevent this problem.

Since there are several single failures that would fail tension measurement, the

automatic pipe tension compensation system is not consistent with the

philosophy of class 2 or 3 requirements. Thus, for class 2 or 3 operations the

vessel must always have the manual backup ready for use.

14.6 Position Reference Systems

14.6.1 The vessel is fitted with following positioning reference systems:

Main DP (SDP-21):

2 x DGPS (Veripos LHD2-GG)

1 x Seapath 200 (only for heading and VRS to HiPAP’s no DP interface)

1 x HiPAP 500

1 x Fanbeam

1 x LWTW (also interface to Backup DP)

Backup DP (SDP-11):

1 x DGPS (Veripos LHD2-GG)

1 x HiPAP 500

14.6.2 DGPS

There are three DGPS systems fitted all of make Veripos, two DGPS’s for the

SDP-21 located in control room A and one for the SDP-11 in control room B.

Each DGPS system is set up with Inmarsat corrections.

The GPS antennas are mounted on the fwd edge of the Helideck with a proved

distance between the two (DGPS 1 & DGPS 2 is 2 meters).




14.6.3 Seapath 200

Figure 14-3: Example of DGPS configuration Courtesy Kongsberg Maritime

The Seapath is not used as a DGPS system to DP, but is used by the HiPAP’s

as vessel sensor and gyro and therefore included in this report. As seen from

the illustration this system comprises of two GPS antennas mounted on a

bracket with a known distance between the two. One of the advantages with

the Seapath compare to traditional DGPS’s is that it can also be used as a

heading reference and motion reference.

The Seapath 200 system has its own MRU-5 sensor placed together with the

main DP MRU’s. The MRU signal can be used in main DP as a backup for the

other two. The gyro (gyro1) signal to the Seapath is needed for calibration

only.




14.6.4 HiPAP

Figure 14-4: HiPAP Courtesy: Kongsberg Maritime

The vessel is equipped with two HiPAP 500 hydro acoustic systems. Both

HiPAP’s are setup for USBL and LBL. The HiPAP Hull units are located in

respective HiPAP trunk fore and aft amidships centre walkway Quarter deck

and down.

The system is named from “High Precision Acoustic Positioning” system and

is designed for all water depths from very shallow looking horizontally at a

transponder to deep water (2000m) looking straight down with a standard unit.

The transducer extends below the hull and uses a semi spherical transducer

with over 230 elements and electronic controls that enables narrow beam

transmission and focused reception in the direction of the transponder, thus

reducing the noise that would otherwise be received from other areas of the

sphere.




The system calculates a three dimensional subsea position of a transponder

relative to the vessel mounted transducer unit. The directional stability of the

unit is obtained firstly fixing the transponder location by a wide beam and

subsequently by aiming a narrow reception beam towards the transponder. The

system uses a digital beam form, which takes its input from all the transducer

elements.

The system controls the beam dynamically so it is always pointing towards the

target, roll, pitch and yaw is input to the tracking algorithm to direct the beam

in the correct direction thus enabling the correction for these motions to be

effectively applied continuously.

The system calculates a variance for its measurements; determine the known

system accuracy and standard deviation. The HiPAP has a built-in Kalman

filter, which improves the stability and accuracy of the initial narrow beam

guidance but does not interfere with raw fixed data being sent to the DP

control computers.

The HiPAP needs a heading signal and a VRS signal to operate, the following

shows the different combinations that can be configured for each HiPAP.

HiPAP 1 HiPAP 2 (backup DP)

Seapath Seapath (HiPAP# Gyro 1 & VRS1)

Gyro 1 Gyro 3 (HiPAP# Gyro 2)

DP VRS1 DP VRS3 (HiPAP# VRS 2)

The HiPAP signals are sent via fibre optic link to the APC 11 computer and

from there to the DP system via the dual network.

The configuration of the Seapath, gyro and VRS into the HiPAP is to be in

according to DP operational manual. When calibrating the HiPAP’s the

Seapath will be used, and for operating according to DP class 3 HiPAP 2 can

only use Gyro 2 and VRS3.

The HiPAP operator station can operate in a master/slave setup. Further

configurations reference is made to vessels DP operational manual.

Note! The configuration of the HiPAP’s is that the Survey have their own

HiPAP OS (3) that is connected by the network and by that can communicate

with both HiPAP units. Survey can only control mobile units. The HiPAP 1

will solely be used for the main DP for positioning on the Fixed Transponder

at seabed. Survey will only be allowed to operate mobile transponders by use

of HiPAP 2. When operating in accordance to DP class 3, the Survey team

cannot operate the HiPAP 2. Reference is made to the DP Operations Manual

for configurations and procedures.




14.6.5 Fanbeam

Figure 14-5: Fanbeam Courtesy: MDL

The Fanbeam system, of make MDL is an auto tracking laser radar system.

It’s measuring range and bearing to a target by using a reflected laser beam.

This is a short range reference system targeting either a reflector or a prism.

The Fanbeam system comprises a laser unit, a monitor and a control unit, in

addition to the reflector or prism. The Fanbeam position signals are fed into the

DP computers.

The maximum range with a single prism is 1 km. With a stack of prisms this

can be increased to over 2 km under ideal circumstances. The system can also

be used with a simple reflector. The maximum range is then limited to 200-250

metres.

The main limitation on use for DP is the resolution of the bearing measurement

which will limit the useable range for DP to about 100m.

The most serious failure of Fanbeam is it could track an erroneous target,

although the system does have features to reject false targets. The use of the

Fanbeam system can be limited by weather conditions, especially fog, which

limits the maximum range of the system because it uses an infrared laser beam

(905 nm) and infrared light is easily absorbed by moist air.

The position of the unit is corrected for roll and pitch in the DP system by VRS

input.

The vessel should be supplied with reflectors or prisms.




14.6.6 Tautwire

A LWTW of type Bandak Mk 8-15 are installed as a DP reference system. The

LWTW is located in the bow of the vessel and is controlled locally at the unit

or remotely from control room A. The LWTW is supplied from the 460V 4FSB

distribution. The power supply is to the systems HPU, which is used to deploy

the weights and to maintain constant tension when the clump weight is at the

seabed. The 230V power supply is for the LWTW cabinet and the separate

Tautwire remote unit placed in control room A.

The LWTW uses instrument air to compensate higher frequency motions (roll,

pitch and heave). Small motions are corrected by air held in the twin

accumulator bottles fitted on the boom of the LWTW unit while the winch

corrects excess motions.

The LWTW has a gimbal head, measuring the athwart-ships angles and along-

ship angles. The pitch and roll signals from VRS is considered in reading the

angles in the gimbal head.

The illustration below shows the operational area and angle of the wire,

typically limits for warning is set in DP to 19o and alarm rejection from DP is

22o.

Figure 14-6: LWTW working area Courtesy: Kongsberg Maritime




14.7 DP Control System Power Supply

14.7.1 The vessel is equipped with three independent UPS’s for the DP system and its

reference systems. The power supply to the UPS’s are configured as follows:

DP UPS 1 CB Q7 in panel 4P208 (Radio Room)

DP UPS 2 CB Q2 in panel 2CRASB (control room A)

DP UPS BU: CB Q1 in panel 2CRBSB (control room B)

14.7.2 Each UPS provides 230V AC to the DPC, references and peripherals. The UPS

-distribution is as shown in below:

DP UPS 1 DP UPS 2 DP UPS 3 (BU)

- F1: Spare - F1: Spare DGPS 2 - F1: Spare

- F2: DPC 21A - F2: DPC 21B - F2: SDP 11

- F3: SDP OS1 - F3: SDP OS2 - F3: Backup OS

- F4: Spare - F4: DP printer - F4: Repeater Gyro 1

- F5: WIND n° 3

Wind 2

- F5: Wind n° 2 wind 1 - F5: Wind n° 1 3

- F6: GPS n° 2 & 3

unknown

- F6: Spare gyro 2 - F6: GPS 1 unknown

- F7: NDU 1

network distribution

unit

- F7: Fanbeam - F7: NDU 2

- F8: Spare Fan

beam fwd

- F8: HIPAP OS fed

from pdu3

- F8: Spare wind 4

- F9: Spare DGPS 1 - F9: HIPAP

transceiver Fwd

- F9: HIPAP

transceiver Aft

- F10: Repeater Gyro

3

- F10: LTW (Taut wire) - F10: Spare wind 4

- F11: Spare Seapath - F11: DPAL Alarm

light

- F11: Spare DP printer

- F12: Spare pilot

radar

- F12: Artemis Mat DP

survey

- F12: HIPAP OS

printer

14.7.3 In addition, some DP important consumers have power supplies as follows:

VRS 1: DPC-21

VRS 2: DPC-21

VRS 3: DPC-11

VRS 4: DPC-11

Gyro 1 UPS 6

Gyro 4 UPS 7

HiPAP 1 Hoist Control: 4FSB

HiPAP 2 Hoist Control: 4 ES




15 FAILURE ANALYSIS – “SEVEN POLARIS”

15.1 Configuration and assumptions

15.1.1 All four main engines are running and driving respective azimuth thruster. These systems are independent of each other, and the

power supply for auxiliary systems is generated from the PTO generators.

15.1.2 This failure analyses show effects while operating according to DP Class 2/3 criteria with closed 460V bustie breaker if no other is

listed and the following switchboard configuration:

Generators G1 to G3 ready for start if not running

Generators G4 and G5 ready for start if not running

At least one generator connected to MS4 and MS1

460V 4ES is powered from MS1

GS is ready for start

All monitoring, automation and K-Chief working as designed

15.1.3 For power distribution configuration, reference is made to section 6 in this report.

15.1.4 The failure analysis shows effects with the auxiliary system set-up as follows:

FO system all systems available

SW system no alarms, all pumps available

FW system no alarms, all circulation pumps available (duty/ standby)

LO system all systems available

Compressed air system all systems available

HVAC/ Chilled Water systems, all systems available and no alarms

15.1.5 All position reference systems and all vessel sensors are to be available and in operations and DP system are set for DP class 3

with consequence analysis and median test functions running.




15.1.6 In this failure analysis, the comment “Loss of redundancy” reflects that the vessel does not fulfil requirements in accordance with

IMO DP Class 2/3, after a single failure has occurred. This does not mean that there has to be an effect on the station keeping

performance, a failure can occur without affecting the performance.

15.1.7 The failure analysis is based on the available documentation listed in section 16 “References “in this report.




15.2 Failure Analysis – Fire & Flooding

Description of failure

Effect of failure

Function/

comp.

Failure mode Failure

mech./cause

Detection

of failure

On component in subsystem Effect on DP

operation/position

keeping

Comments

Vessel

Layout

Control

room A

Fire in

control room

A

Electric failure

Technical failure

Personnel

Alarm

DPO to immediately take control

on BU DP and switch over the

Fire Switch. Abandon control

room A and take control from

control room B

No effect on station

keeping but loss of

redundancy

A fire in control room A or in

the safety control room could

damage remote safety stop

cabling to all thruster room fire

dampers. As a result from this

all four main thrusters could be

lost.

Control

room B

Fire in

control room

B

Electric failure

Technical failure

Personnel

Alarm

Fire here will damage equipment

and system in that room, else no

effect as all systems are run from

control room A


keeping but loss of DP

class 3 or redundancy

Quarter

Deck

Fire in a

compartment

Electric failure

Technical failure

Personnel

Alarm

Fire doors will shut to prevent

spreading of fire.

Depending on where the fire has

broken out and spread to it can

result in loss of a HiPAP, loss of a

network (Main Net is in corridor

centre)

Cables for respective DP zone is

A-60 insulated + there are shall be

distance between the cable

routing


keeping but loss of

redundancy

Both HiPAP’s are located in

centre walkway, distance and

fire doors/ bulkheads between

them





Effect of failure

Function/

comp.


mech./cause

Detection

of failure


operation/position

keeping

Comments

Hold

Deck

Fire /

flooding in a

compartment

Electric failure

Technical failure

Pipe burst

Hull damage

Personnel

Alarm

Loss / damage of systems in that

compartment.

This deck houses among others

the generator room/ thruster

rooms etc.

At this level all doors are to be

water tight


keeping but loss of

redundancy. Reduced

thruster/ power capacity

Each thruster room is self-

contained.

Generator room includes G1 to

G3 + MS2.

Generators G4 G5 + MS are

located in crane pedestal

Fire/

Flooding of

a thruster

room

Electric failure

Technical failure

Pipe/ hull damage

Personnel

Alarm

Loss of that particular thruster

Each thruster room is segregated.


keeping but loss of

redundancy. Loss of one

thruster only

Generator

room

Electric failure

Technical failure

Pipe/ hull damage

Personnel

Alarm

Loss of generators G1 to G3 +

MS2

None Both generators G4 and G5 can

run supply MS4, feeding MS3

and MS1. As MS1 and MS3 are

placed in a different

compartment as MS2.

Fire in

Sewage

room

Electric failure

Technical failure

Personnel

Alarm

Have to close outlet valve from

settling tank, and stop transferring

of FO to all day tanks.

None Enough FO in day tanks to

abandon operation. Each

thruster engine day tank has a

capacity of 5m3 estimated 5

hours running time.

Fire in pump

room

Electric failure

Technical failure

Pipe/ hull damage

Personnel

Alarm

Generators run out of day tank.

None

Crane

Pedestal

Fire in Crane

pedestal

Electric failure

Technical failure

Pipe/ hull damage

Personnel

Alarm

Loss of generators G4 & G5 +

MS4


keeping but loss of both

tunnel thrusters (MS4)

One tunnel has a secondary

supply from MS3 that can be

used.




15.3 Failure Analysis - Power Generation


Effect of failure

Function/

comp.


mech./cause

Detection

of failure


operation/position

keeping

Comments

Thruster

Engines

Thruster

Engine

Shut down of

engine

Mechanical

failure: piston,

valve,

camshaft,

bearings,

turbocharger

Aux. systems

Alarm Stop of affected engine, de-clutch

from main gear. Loss of that

thruster.


keeping

Reduced thruster capacity

Pre-warning of

engine

Aux. systems

i.e. LO pressure

FW cooling

Alarm Request stop of engine,

Governor

failure

Input failure

Output failure

Power failure

Alarm Trip of affected engine

Gear Gear failure Mech. failure

Alarm Loss of drive to thruster and PTO

generator

PTO

generator

PTO generator

failure

Internal short

circuit.

Excitation

failure, AVR

failure.

Overload

Belt drive

failure

Alarm. Trip of generator breaker, hence

loss of supply to thruster

switchboard.

Automatic changeover to power

supply from MS3.

None if quick enough,

otherwise loss of thruster


Thruster switchboards have a

supply from MS3 when in

standstill. A relay contactor will

change over the supply.

If thruster stops it can be started

to be run with power from MS3.





Effect of failure

Function/

comp.


mech./cause

Detection

of failure


operation/position

keeping

Comments

Diesel

Generators (G1-G5)

Diesel

Generator

Shut down of a

DG

Mechanical

failure: piston,

valve,

camshaft,

bearings,

turbocharger

Aux. systems

Alarm Stop of affected DG, the other DG

in parallel will pick up the load

DP system will perform load

reduction of tunnel thrusters if

required.


keeping

Reduced power capacity

If G1 to G3 is set in Auto then

PMS will automatically start the

one in 1st standby. Otherwise

engineer has to manually start

generator “Semi-automatic”

Pre-warning of

ME

Aux. systems

i.e. LO pressure

FW cooling

Alarm No automatic function for start of

next standby generator

None Engineer has to start next

generator manually and take the

faulty one off the board.

Governor

failure

Input failure

Output failure

Power failure

Alarm Trip of affected generator No effect on station

keeping


Alternator Alternator

failure

Internal short

circuit.

Excitation

failure, AVR

failure.

Overload

Alarm. Trip of generator breaker, hence

reduced power capacity

An AVR failure/ overspeed can

result in also tripping of the other

DG on reverse power, hence

blackout


keeping performance


and power capacity, or

blackout

A full blackout will not directly

affect the vessel as it has four

independent running main

thrusters. The vessel will run on

UPS supply. FO to their day

tank will eventually be the

limiting factor. Day tanks are

each on 5 m3 which will give

ample time to take corrective

actions.

Emergency.

Generator

(GS)

Engine failure

Alternator

failure

Mech. or

electrical

Alarm Stop of engine None Normally GS is not running.

The GS will start up when loss

of power to 4ES.




15.4 Failure Analysis - Power Distribution


Effect of failure

Function/

comp.


mech./cause

Detection of

failure


operation/position

keeping

Comments

Ships 460V SWBDs

Main

switchboards

Powerless MS1 Internal short

circuit.

Alarm. Loss of MS1 and generators G1 to

G3 as these can only connect to

MS1.

None

Trip of bus tie to segregate fault.


circuit.

Alarm. Loss of MS2 and related

consumers such as FO transfer

pump, LO sep 1&2 and starting

air compressor 2.

None

Trip of bus tie to segregate fault.


circuit.


consumers such as ventilation T5,

distribution 4FSB and 4FSC, and

backup power to T1 to T4.

4FSB loss of Tautwire, HiPAP +

SW pumps to G4& G5

Loss of both tunnel thrusters as

loss of their HPU

4FSC loss of thruster cooling fan

+ 2nd

pumps to tunnel thruster

HPU’s

None or


The efficiency of the two tunnel

thrusters is normally very low.

Used to assist with heading

control.


circuit.


consumers such both tunnel

thrusters, T5 can be connected to

MS3. Loss of generators G4 &

G5 as these are connected to

MS4.

None





Effect of failure

Function/

comp.


mech./cause

Detection of

failure


operation/position

keeping

Comments

Bustie

Breakers

Fails to open Internal failure Alarm A fault on these breakers such

that it does not open in case of a

major failure (i.e. a hidden

failure) can cause a blackout. If it

opens too late the transients on

the distribution can trip many

auxiliaries on under voltage due

to transients.

Worst case full blackout

Important systems on backup

supplies and azimuth thrusters

still running

None

There are two bustie breakers

for each SWBD; simultaneously

failure of them both is seen as

highly unlikely.

Thruster

room

switchboard

Loss of power

to thruster

switchboard

4CSB1-4

Internal short

circuit.

Alarm. Loss of power to that

switchboard, hence that thruster

will stop.






Effect of failure

Function/

comp.


mech./cause

Detection of

failure


operation/position

keeping

Comments

Distribution

boards

4 FSB Loss of power Breaker trip

Short circuit

Alarm. Loss of consumers from that

board HiPAP deployment motor

LWTW, HPU pumps 1 to tunnel

thrusters auto changeover to 2nd

pumps


keeping performance

Loss of LWTW

4FSC Loss of power Breaker trip

Short circuit


board

Loss of pump no. 2 to tunnel

thrusters + cooling fans


keeping performance

4ES Loss of power Breaker trip

Short circuit


board

Loss of power to 2 ES and to

control room A & B


keeping performance

If not restored power to control

room distribution eventually DP

UPS’s fails

Loss of redundancy

30 min battery endurance on

UPS





Effect of failure

Function/

comp.


mech./cause

Detection of

failure


operation/position

keeping

Comments

230V Distribution

Transformer

(460V/

230V

Transformer

failure

Mech. failure

El. Failure

Breaker fault

Alarm Loss of power to affected 230V

distribution. Important consumers

runs on redundant supply


keeping performance



UPS’s fails

Loss of redundancy

If the transformer to 2ES fails

then the alternate supply from

2FSB to control rooms should

be connected

230V

Distribution

board

Loss of power

to 2 ES

Breaker trip

Transformer

failure

Short circuit

Alarm. Loss of related consumer,

alternate supply to control room

to be instated.


keeping performance



UPS’s fails

Loss of redundancy

Loss of power

to 2 FSB

Breaker trip

Transformer

failure

Short circuit

Alarm. Loss of related consumer, such as

UPS 5

VMS ST2U

2FC

None

Loss of power

to 2 FC

Breaker trip

Short circuit

Alarm. Loss of related consumer, such as

VMS LC22

VMS LC23

Alarm panels

None

Loss of power

to 2 CRASB or

2CRBSB

Breaker trip

Short circuit

Alarm. Loss of related consumer such as

DP UPS(s)

NAV equipment

None

Eventually DP UPS(s) will

run out

Loss of redundancy

DP UPS 1&2 are powered from

same distribution 2CRASB.

Failure of this both systems on

30 min battery endurance





Effect of failure

Function/

comp.


mech./cause

Detection of

failure


operation/position

keeping

Comments

24V Distribution

24V

Distribution

Battery failure Internal failure

due to lack of

maintenance

None None None Battery failure should be found

on maintenance routines.

Battery change interval 3- 5

years, check with Vendor

UPS

Failure

Internal failure Alarm Loss of charging, system

continues to run on battery

None,

eventually loss of system

powered from that UPS

Loss of

UPS 1-4

Internal failure

Alarm Loss of corresponding thruster to

affected UPS

Reduced thruster capacity,

loss of redundancy

Loss of UPS 5 Internal failure

Alarm Loss of control power to pumps

start cabinet G4 & G5 etc.

None


Alarm Loss of thruster T5 alarming

power to SDP 21 OS 1 & OS2

None


Alarm Loss of Thruster T6, alarming

power to SDP 11 OS

None


Alarm Loss of control voltage to MS4 None

Loss of UPS

17

Internal failure

Alarm Loss of control voltage to G4 and

G5

None




15.5 Failure Analysis – Power Automation and Propulsion Control

Function/

component


Effect of failure

Failure mode Cause of

failure

Detection

of failure


operation/position

keeping

Comments

K-Chief 500

OS and

computers

Power failure Short circuit,

fuse failure,

loose wire.

Alarm Loss of affected ROS, other ROS

available

None

Tank sounding Not

functioning Power failure

Internal failure

Alarm No data of level status No effect on station

keeping performance

Valve control Not

functioning Power failure

Internal failure

Alarm No operation of valves or status

monitoring


keeping performance

Watch Call

System

Not

functioning

Any failure

mode

Alarm No alarming on duty station No effect on station

keeping performance

Thruster Engines

Control System

Engine

Control

Cabinet/ panel

Loss of a 24V

power

Fuse failure

Wire break

Alarm None, engine runs on redundant

supply

None

Loss of 230V

power supply

Fuse failure

Wire break

230V/24V

inverter failure


supply

None

Loss of both

supplies

Short circuit,

Distr. failure

Alarm Trip of engine, hence loss of

thruster


Loss of power

to safety PLC

Fuse failure

Wire break

PLC failure

Alarm Loss of electronic safety, engine

safety still intact

None




Function/

component


Effect of failure


failure

Detection

of failure


operation/position

keeping

Comments

Governor Instability of

regulator

Hydraulic leak Alarm A hydraulic leak of oil from the

governor/ regulator can result in

engine hunting and oscillating

Engine to be stopped, hence loss

of a thruster


Shutdown

initiated

Engine

shutdown

Overspeed

LO pressure ME

Cooling water

temp.

LO pres. MG

Alarm Affected engine shuts down,

hence loss of a thruster


keeping performance


Diesel Generator

Control System

DG Control

Cabinet/ panel

Loss of a 24V

power

Fuse failure

Wire break


supply

None

Loss of 230V

power supply

Fuse failure

Wire break

230V/24V

inverter failure


supply

None

Loss of both

supplies

Short circuit,

Distr. failure

Alarm Trip of engine

Engineer to start standby

generator

None

Loss of power

to safety PLC

Fuse failure

Wire break

PLC failure

Alarm Loss of electronic safety, engine

safety still intact

None Load sharing com lines are

between DSLCs and from

DSLC to 723

Woodward

723+

load & Speed

control unit

Not working Power failure Alarm Trip of affected DG

None

Load sharing

line

Wire break Alarm Not Applicable None Load sharing is by governor

DROOP No load sharing lines




Function/

component


Effect of failure


failure

Detection

of failure


operation/position

keeping

Comments

Governor Instability of

regulator

Hydraulic leak Alarm A hydraulic leak of oil from the

governor/ regulator can result in

engine hunting and oscillating of

the frequency.

None Engine to be stopped

AVR Over / under

excitation

Internal failure Alarm Trip of Generator breaker

None

Shut down

function of a

Generator

Engine shut

down

Overspeed

LO pressure ME

Cooling water

temp.

LO pres. MG

Alarm Stop of affected G#

If the Overspeed is not quick

enough this can result in

unsymmetrical load and the other

generator(s) can trip on reverse

power before the affected

generator trips.

None


In case of blackout all

important systems on

backup supply

This can cause a blackout if

“faulty” DG takes all load and

then trip.

Note this will cause loss of

LWTW if used




Function/

component


Effect of failure


failure

Detection

of failure


operation/position

keeping

Comments

IAS / PMS system

Field Station Power failure UPS failure

Fuse failure

Alarm Loss of Field station with

belonging components

None Field stations (PS41 &PS42)

with important equipment

connected have redundant

power supply from both UPS’s.

Internal failure Alarm Loss of components/ controller

powered from that RCU

None PS 41 & 42 have redundant

controllers and power supply

Controller

failure Power failure

Internal failure

Alarm Automatic changeover to backup

controller if master fails, else no

affect

None Loss of Field station with

equipment if no redundancy

Network HUB Power failure

Internal failure

Alarm None, works on redundant

network

None

Software error Wrong

programming,

None Cause wrong configuration wrong

commands.

None This is eliminated trough use

and testing

Data Virus Data virus in all

computer

system on net

None A virus can result in “crash” of

computer systems

None To prevent this Vessel operator

should make sure to have

procedures available to restrict

the use of computers connected

to the network

Network

RBus

Serial line

NMEA

Comm. failure

Wire break

Alarm Loss of communication from

affected equipment

None

Ethernet Comm. failure

Wire break

Alarm None None

Runs on redundant network

ModBus Comm. failure

Wire break

Alarm Loss of communication from

affected Equipment

None




Function/

component


Effect of failure


failure

Detection

of failure


operation/position

keeping

Comments

IAS OS

Stopped, not

working

PCU stop

Power failure

Internal failure

Alarm Loss of control/ monitoring from

that operator station

None

Operator to use other operator

station

Thruster Drive Not

communicatin

g to IAS/PMS

Power failure

Unit failure

Alarm Loss of remote ctrl and

monitoring of propulsion drives

No effect on propulsion drives.

None

Generator

Breaker

measurement

Loss of circuit

breaker signal

from SWBD

Wire break

Sensor failure

Alarm Affected DG runs in droop mode Could lead to reduced

thrust capacity

SWBD Hz

measurement

Loss of Hz

signal from

SWBD

Wire break

Sensor failure

Alarm No effect only alarm given None

SWBD Voltage

measurement

Loss of V

signal from

SWBD

Wire break

Sensor failure


DG kW

measurement

Over / under

range or lost

Wire break


Valve control Not

functioning

Power failure

Internal failure

Alarm No operation of valves or status

monitoring

None

Tank sounding Not

functioning

Power failure

Internal failure

Alarm No data of level status None

Watch Call

System

Not

functioning

Any failure

mode

Alarm No alarming on duty station None




Function/

component


Effect of failure


failure

Detection

of failure


operation/position

keeping

Comments

PMS

Network Loss of comm.

line

Wire break Alarm Dual ring line network all systems

comm. on remaining line.

None G1 to G5 can be fully controlled

by PMS.

PLC Loss of comm.

/ control

server

PLC failure

Power failure

Alarm Systems controlled by secondary

server

None

Generator

Protection Unit

Sepam Loss of Sepam Power failure

Internal failure

Alarm Loss of Sepam will trip the

generator breaker

None


The Sepam is powered from

respective generator cubicle.

Thruster &

Propulsion Control Systems

There is no loop monitoring for signal failure for any of the azimuth, pitch or RPM signals: Only a

prediction error warning is given when sufficient difference has occurred between demand and

feedback. Failure of the feedback signals from the thrusters should raise an alarm and de-selection

of the thruster –either automatically or by the operator.

Tunnel

Thrusters

Control

cabinet

Loss of power

supply to

control cabinet

Fuse failure

Short circuit

Alarm

Loss of one tunnel thruster


keeping performance


Loss of

control unit

Short circuit

Internal failure.

Alarm




Function/

component


Effect of failure


failure

Detection

of failure


operation/position

keeping

Comments

Comm.

between DP

and E-shaft

Rpm

command

signal failure

Wire break Alarm Thruster # prediction

Rpm to idle


keeping performance


Rpm

feedback

signal failure

Wire break Alarm Thruster # input error, works as

normal

None DP uses calculated feedback

Comm.

between

E-shaft &

Converter

rpm

command

signal failure

Wire break Alarm Thruster # prediction error

Rpm to idle


keeping performance


rpm

feedback

signal failure

Wire break Alarm Thruster # not ready, rpm to idle


keeping performance


Converter Converter

signal failure

Wire break

Pulse Encoder

Interface

Module

Alarm Thruster # not ready, rpm to idle


keeping performance


Azimuth

Thrusters

Control

cabinet

Loss of either

power supply

to control

cabinet

Fuse failure

Short circuit

Alarm Automatic changeover to other

supply

None Power supply connected by

diode bridge

Loss of

control unit

Short circuit

Internal failure.

Alarm Loss of one azimuth thruster in

DP and from Bridge control


keeping performance





Function/

component


Effect of failure


failure

Detection

of failure


operation/position

keeping

Comments

Comm.

between DP

and TCC

Azimuth

command

signal failure

Wire break Alarm Thruster # Not ready deselected

from DP

Pitch and Azi to zero,


keeping performance


Azimuth

feedback

signal failure

Wire break Alarm Thruster # Prediction / input error

Depending on wire broken, the

Azi will either freeze, rotate to

zero position

Pitch

command

signal failure

Wire break Alarm Thruster # Not ready deselected

from DP

Pitch and Azi to zero,


keeping performance


Pitch feedback

signal failure

Wire break Alarm Thruster # prediction/ input error

Thruster works as normal

None DP uses calculated feedback

Comm.

between TCC

and thruster

Azimuth

command

signal failure


Pitch works

Azi freezes or rotates depending

on wire taken


keeping performance


Azimuth

feedback

signal failure

Wire break Alarm Thruster # error azimuth, freezes,

pitch works Local alarm on thruster panel

for emergency ctrl is sounded

way before any affect noted in

DP. This will alert DPO too.

Pitch

command

signal failure


Pitch freezes, then slow down to 0


keeping performance


Pitch feedback

signal failure

Wire break Alarm Thruster #not ready

Thruster deselects out of DP

Emergency ctrl from thruster

panel possible




Function/

component


Effect of failure


failure

Detection

of failure


operation/position

keeping

Comments

Thruster Engine

Control Helicon

Control

cabinet

Speed signal

Rpm feedback

Lost comm. Wire break Alarm Loss of engine rpm to UN

Thruster # not ready

Engine runs at fixed speed


keeping performance


Speed order will give alarm in

IAS Woodward minor alarm

None

Load signal Lost comm. Wire break Alarm Alarm in IAS None




15.6 Failure Analysis - Fuel Oil System


Effect of failure

Function/

comp.


mech./cause

Detection

of failure


operation/position

keeping

Comments

FO System General

Remote

operated

QCV’s

Closing of

valve

Manual act Alarm Stop of engine(s) due to FO

starvation.

QCV layout one lever for all and

one lever per engine / tanks

None This is highly unlikely the QCV

cabinets are protected against

inadvertent operation and valves

need oil pressure close.

Some are also by pulling a wire,

Loss of oil/

wire break

Leakage

Wire snaps /

stuck

No affect, The QCV’s needs oil

pressure to close

Same with wire type needs to pull

wire to close valve

None

FO day tank High level

alarm failure.

Sensor failure,

broken wire

None Can result in overfilling from

separator. Normally overflow to

FO overflow tank

None Valves are adjusted manually to

allow continues filling of all day

tanks.

Low level

alarm failure

Sensor failure,

broken wire

None No affect, Normally continuous

purification from settling to

service tank

None Periodic maintenance should

prevent this.

During trials testing for level

alarms were done by open

circuit, this is not testing of the

sensor itself. This is not testing

of sensor, rather the alarm

system only.

FO day tanks to the thruster

engines has a capacity of 5m3





Effect of failure

Function/

comp.


mech./cause

Detection

of failure


operation/position

keeping

Comments

FO settling

tank

High level

alarm failure.

Sensor failure,

broken wire

None Can result in overfilling

Manual operation by use of FO

transfer pump

None Periodic maintenance should

prevent this.

Low level

alarm failure

Sensor failure,

broken wire

None No affect, None Operator to manually fill

settling tank

Periodic maintenance should

prevent this.

FO transfer

pump

Mech. Failure,

electrical

failure

Fatigue,

bearing,

coupling,

damage of

motor, short

circuit

Alarm Loss of affected pump.

FO separator can also have

suction from cargo manifold

None

FO

Separator

feed pump

Mech. Failure,

electric power

supply

Fatigue,

bearing,

coupling,

damage of

motor, short

circuit

Alarm FO feeding to the separator does

not work hence loss of

purification.

None Tank capacity is sufficient to

give enough time for operator to

repair/ fix separator feed pump

or use the other separator

FO separator Internal failure Mech.

Electrical

or dirt/ water

Alarm Worst case can cause engine

damage. Separator failure can in

worst case result in dirt/ water

into the affected FO tanks.

None; however in worst

case loss of engines caused

by water/ dirt.

As the separator delivers to all

tanks simultaneously this can

affect all engines/ generators.

This can cause engine damage,

correct maintenance and

regularly samples reduces the

risk of this.





Effect of failure

Function/

comp.


mech./cause

Detection

of failure


operation/position

keeping

Comments

FO system FO

Contamination

Microbiological

growth,

water

Fuel oil

samples

Clogged filters, stop of engines. None; however in worst

case loss of engines caused

by water or other

contamination.

Procedures for periodic samples

to give a pre warning and

regular draining of any water

from tanks. FO storage tanks are

common

FO System

Thruster Engines

Generators

FO Filter

(Coarse type

Racor)

(Generator

only)

Reduced flow

through filter

Clogged filter Alarm Operator can change over to

bypass.

None Assume enough time from

alarm given allowing the

operator to change over filter.

Periodic maintenance should

prevent this.

Flow meter

Reduced flow

over flow

meter

Internal failure Alarm If for some reason an internal

failure will cause flow restriction

there is a bypass line that can be

used

None Assume enough time from

alarm given allowing the

operator to open for bypass.

One flow meter per engine

FO Booster

pump

(engine

driven)

Mech. Failure

Fatigue,

bearing,

coupling,

Internal pump

failure

Alarm Reduced FO pressure, start of

standby booster pump


keeping performance


Once this pump fails it is highly

doubtful that the operation of

engine will continue. Engineer

will stop the engine to reduce

escalation of failure





Effect of failure

Function/

comp.


mech./cause

Detection

of failure


operation/position

keeping

Comments

FO standby

booster

pump

(electrical

driven)

Mech. Failure

Fatigue,

bearing,

coupling,

Internal pump

failure

Alarm

FO standby booster pump is not

working.

Loss of affected thruster engine

As this pump is only used if

engine driven id not working.


keeping performance


One electrical standby booster

pump per thruster engine.

Generators 1 -3 has a pneumatic

backup pump.

Electrical

failure

Breaker failure

Internal failure

Motor failure

FO Filter

(fine, engine

mounted)

Clogged filter Clogged filter Alarm Clogged filter causing reduced

FO flow to injectors.

Assume enough time to take

corrective actions. This will affect

one engine only.


keeping performance


Injectors Not

functioning

Mechanical

failure

Alarm Damage on affected engine and it

will be stopped

FO System GS

FO System

GS

Failure of GS

FO system

Any failure Alarm FO failure will only affect this

engine.

Normally not in use, but is fitted

as class of SOLAS.

None Service tank has LAL that

allows ample time (15 hours

continuous run from alarm is

activated)




15.7 Failure Analysis - Cooling Water Systems


Effect of failure

Function/

comp.

Failure mode Failure mech./cause Detection

of failure

On component in

subsystem

Effect on DP

operation/position keeping

Comments

SW Cooling System

Generators

Sea chest Clogged

Not filled with

SW

Debris (weeds etc.)

Clogged vent pipe

Alarm Reduced cooling of FW

system

None Can affect a generator pair

SW Strainer

(filter)

Filter failure Clogged, dirt Alarm Can use other sea chest

and filter on the other

side.

None

SW manifold Aeration

Not filled with

water

Air taken in from sea

chest(s)

Clogged vent pipe

Ice/ weed blowing

Alarm Loss of suction and

cooling to generators, if

not restored in time,

engines will stop on

HTFW

None Generator G4 & G5 have a

separate system as of G1-G3

SW

overboard

valve

Flow restrictions Closed,

remote ctrl valve

If closed this will cause

no circulation of SW

through generators

None Generator G4 & G5 have a

separate system as of G1-G3

SW Pump

Engine

driven

(G1-G3)

Mechanical

failure of pump

Fatigue, bearing,

coupling, damage of

motor, overload

Alarm Loss of cooling to that

particular generator

None Loss of a generator, Engineer

starts another generator and

take it online

SW Pump

Electric

(G4& G5)

Mechanical

failure of pump

Fatigue, bearing,

coupling, damage of

motor, overload

Alarm Loss of running pump,

start of standby pump.

None SWBD failure hence loss of

both pumps and eventually

loss of G4 & G5 due to lack of

cooling Electrical failure

of pump

Fuse failure

Short circuit

SWBD failure





Effect of failure

Function/

comp.


of failure

On component in

subsystem

Effect on DP


Comments

SW/ FW

Central

cooler

Reduced

capacity/Failure

of cooler

Leakage

Clogging

Damage/ rupture

Corrosion

Alarm Loss of cooling for

effected generator(s),

slow increase of FW

temperature for affected

system.

None

Loss of a generator, Engineer


take it online

SW Cooling System

Thruster Engines

Sea chest Clogged

Not filled with

SW

Debris (weeds etc.)

Clogged vent pipe

Alarm Reduced cooling of FW

system

SW Strainer

(filter)

Filter failure Clogged, dirt Alarm Reduced cooling of FW

system

SW manifold Aeration

Not filled with

water

Air taken in from sea

chest(s)

Clogged vent pipe

Ice/ weed blowing

Alarm Loss of suction and

cooling to engine, if not

restored in time, engine

will stop on HTFW

No effect on station keeping

performance


SW cooling system to thruster

engines are independent of

each other this will affect only

one thruster engine/ thruster

SW

overboard

valve

Flow restrictions Closed,

remote ctrl valve

If closed this will cause

no circulation of SW

through generators

SW cooling

Pump

Mechanical

failure of pump

Fatigue, bearing,

coupling, damage of

motor, overload

Alarm Running pump stops,

start of standby pump

None

Electrical failure

of pump

Breaker failure

Short circuit

Central

cooler

Mech. failure Damage

Corrosion

Clogged

Alarm No circulation through

cooler, reduced cooling


performance










Effect of failure

Function/

comp.


of failure

On component in

subsystem

Effect on DP


Comments

Clutch cooler Mech. failure Damage

Corrosion

Clogged


cooler, increased clutch

oil temperature


performance






Thruster Oil

cooler


Corrosion

Clogged


cooler, increased thruster

oil temperature.

Thruster to be stopped

FW Cooling System

Generators

LTFW pump

Mechanical

failure of pump

Fatigue, bearing,

coupling,

Alarm Stop of affected

generator due to lack of

cooling.

None Loss of a generator, Engineer


take it online

HTFW pump Mechanical

failure of pump

Fatigue, bearing,

coupling,

Alarm

TCV TCV valves not

working properly

Mech. Failure

Electrical failure

Pneumatic failure

Out of calibration

Alarm TCV fails as set or to full

open

None

Manual operation of TCV

If TCV fails to full open it can

cause under cooling of engine

FW header

tank

Drain of water Leakage in system Alarm Loss of a generator None Regular maintenance should

reduce this risk.

Each generator has its own

FW cooling system. Heat

Exchanger


Corrosion

Clogged


that heat exchanger

Temperature increase on

that system, hence

generator has to be shut

down

FW Pre-

heater

Not working Pump failure

Heater failure

Alarm Affected engine not

ready for start

None





Effect of failure

Function/

comp.


of failure

On component in

subsystem

Effect on DP


Comments

FW Cooling System

Thruster Engines

FW cooling

system

Any See generators above Alarm Stop of affected engine,

hence loss of that

thruster


performance


Any failure of an engine will

only affect one thruster.




15.8 Failure Analysis - Lube Oil Systems


Effect of failure

Function/comp. Failure mode Failure mech./cause Detection of

failure

On component in

subsystem

Effect on DP


Comments

LO system

Generators

The LO system for each

engine is independent

LO direct

driven pump

Failure of

pump

Fatigue, pinion/gear

failure

Alarm Stop of affected

generator and auto start

of priming pump.

None

Engineer starts another

generator

Priming pump Mech. failure

El. failure

Fatigue, bearing,

coupling, damage of

motor, short circuit,

power supply

Alarm None if engine is

running

No start of G# if

standby, G# will be start

blocked

None Good practice is to have the

pump available at all time

LO cooler Leakage Rupture Alarm Due to higher pressure

in LO system, LO will

get in the FW system.

Loss of pressure

depending on size of

leak. Stop of affected

generator

None

Engineer starts another

generator

TCV TCV valves

not working

properly

Mech. failure, out of

calibration

Alarm TCV fails as set None Manual operation possible

LO filters Failure of filter Clogging, dirt Alarm Should not affect

running of generator

If not corrected stop of

affected engine.

None

Regular maintenance should

avoid this

LO sump Leakage Rupture or leak in

system.

Alarm Low level alarm before

low-low pressure and

stop of affected engine

None Regular maintenance should

avoid this





Effect of failure


failure

On component in

subsystem

Effect on DP


Comments

LO system Micro bacterial

growth

Stop of an engine LO sample This can cause engine

damage and clogging of

filters

None

This should be detected by

regular oil analysis.

LO separator Failure Power supply, internal

error

Alarm No effect on a running

engine. Worst case can

cause engine damage.

Separator failure can

result in dirt/ water into

the LO system.

None

This can cause engine

damage, correct maintenance

and regularly samples will

reduce the risk

Only generators G1, G2 and

G3 can have its LO purified

All other engines have oil

change.





Effect of failure


failure

On component in

subsystem

Effect on DP


Comments

LO system

Thruster Engine

The LO system for each

engine is independent

Engine LO

system

Any See generators Alarm A LO system failure

will only cause stop of

one engine, hence loss

of an azimuth thruster.


performance


These engines do also have a

standby LO pump in addition

to priming pump. That will

automatically start up upon

low LO pressure.

It is highly unlikely that the

engine will be running for a

long time if the standby pump

starts up. Engineer will mostly

stop the engine to reduce risk

of escalating the failure.

LO system

Gear/ Clutch

LO direct

driven pump

Failure of

pump

Fatigue, pinion/gear

failure

Alarm, noise Loss of that pump

Start of standby pump

None

Standby LO

pump MG

Mech.

failure/power

failure

Fatigue, bearing,

coupling, damage of

motor, short circuit,

power supply loss

Alarm Not in use when engine

is running.

No effect on running

machinery.

None Good practice is to have the

pump available for service at

all time.

LO filters MG Failure of filter Clogging, dirt Alarm Filters are fitted with

pressure differential

alarm to warn the

operator.

None, if proper actions

taken.





Effect of failure


failure

On component in

subsystem

Effect on DP


Comments

LO cooler MG Reduced

capacity /

Failure of

cooler

Leakage, clogging,

dirt

Alarm Due to higher LO

pressure the LO will

leak into the coolant

system and result in low

pressure, hence declutch

of ME’s.


performance


MG clutch Loss of oil

pressure to

clutch

Leakage Alarm A low pressure of gear

oil will initiate shut

down of engine


performance


Loss of control

power (24V)

Fuse failure Alarm Clutch stays as set None




15.9 Failure Analysis - Compressed Air System


Effect of failure

Function/ comp. Failure mode Failure mech./cause Detection of

failure

On component in

subsystem

Effect on DP


Comments

Starting Air System

Generators

Start air to generators G1 to

G3 is from one system, and to

G4 & G5 is from another

system.

Starting air

compressor

Mech. or

electrical

failure

Valve failure, fatigue,

bearing failure, loss

of power supply,

protection trip

Alarm Loss of one compressor

Air remains in two

receivers

None All engines running

Starting air

receivers/ valves

Leakage Rupture or leaking

valves

Alarm Isolate that receiver and

use the other one

None Each engine room has two

receivers

Starting air to

generator

No air

pressure or to

low

Start disk failure

Distributor failure

Alarm No start of generator None Assumed engines are running.

If not, no start and reduced

power capacity

Control air to

generators

No air

pressure or to

low

Pressure reduced

clogged, not working

Alarm No air to engine shut

down safety functions

None





Effect of failure


failure

On component in

subsystem

Effect on DP


Comments

Staring Air System

Thruster Engines

Starting air to the thruster

engines is from a common

system “ring line” this is

normally split as thruster room

1 and 3 shares the compressor

in thruster room 1. The second

compressor in thruster room 4

is shared amongst thruster

room 2 and 4. Each engine

room has a control air receiver

fitted with none return valve.

Starting air

compressor

Mech. or

electrical

failure



of power supply,

protection trip


Air remains in receivers

None All engines running

Starting air

receivers/ valves

Leakage Rupture or leaking

valves

Alarm Isolate that receiver, still

have control air in its

receiver.

None When totally drained this will

affect control air to two

engines rooms only. Engineer

shall have ample time to

isolate faulty receiver and

open isolation valves for air

supply from the PS/SB

system.

Starting air to

Engines

No air

pressure or to

low

Start disk failure

Distributor failure

No start of engine None Assumed engines are running.

If not, no start

Pressure

reducing panel

Not working Mech. Failure

Clogged

Alarm Loss of instr. Control air

feed. Eventually low

pressure alarm

None

If no action taken loss of an

engine


Assume ample time for

engineer to open for air from

service air system.





Effect of failure


failure

On component in

subsystem

Effect on DP


Comments

Control air No air

pressure or too

low to engines

Loss of air

Reduction panel

failure

Alarm Loss of control air

TCV to full open

Loss of air to engine shut

down safety

Fire dampers will

eventually close as they

are pneumatic controlled

None

Assume ample time for

engineer to open for air from

service air system, this will

prevent fire dampers to close

Worst case will be closing of

fire dampers and then loss of

an engine, hence a thruster

No immediate effect, reduced

head pressure in thruster

gravity tanks, can risk SW

ingress into thruster housing,

reduced oil sealing pressure

Control air

compressor

(Thruster room

2/3 only)

Mech. or

electrical

failure



of power supply,

protection trip


Air remains in receivers

+ air can be taken from

starting air line too.

None

Service

Air system

Service air

system

Loss of air Leakage

Loss of air on the line

Compressor failure

Alarm Loss of air to:

Separators

SW inlet valves control

Tautwire

Start air to G4 & G5

None Engineer to take necessary

actions to correct failure.




15.10 Failure Analysis - Ventilation


Effect of failure

Function/ comp. Failure mode Failure

mech./cause

Detecti

on of

failure



Comments

Ventilation

Engine room fan Fan not

working

Mech. failure

Electrical failure

Alarm Loss of one of the two supply

fans

Reduction in combustion air and

ventilation to engine room.

None As the ECR is manned the

loss of ventilation will be

noticed and appropriate

action to be taken.

Thruster room

fans

Fan not

working

Mech. failure

Electrical failure

Alarm Loss of supply fan

Thruster rooms do also have AC

system

Thrusters and its aux. systems

are water cooled too

None Important rooms have stand-

alone AC systems fitted in

addition to traditional fan

supply

SWBD room fan Fan not

working

Mech. failure

Electrical failure

Alarm Loss of supply fan

SWBD rooms do also have AC

system

None

AC Units AC unit not

working

Mech. failure

Electrical failure

Each room location has its own

independent standalone unit

None There is no alarm fitted.




15.11 Failure Analysis – Propulsion System

15.11.1 Note that the failure analysis for the control and monitoring system for the propulsion system is found in section 15.5 in this

report.

Function/

comp.


Effect of failure

Failure mode Failure mech./cause Detection of

failure

On component in

subsystem

Effect on DP


Comments

Tunnel

Thrusters

Thruster Mech. failure Bearings, blades,

couplings

Vibration,

noise

Stop of thruster

depending of extent of

failure

El. Motor Not running Motor failure

Power failure

Alarm Loss of affected thruster No effect on station keeping

performance


Frequency

converter

Mech. failure

El. failure

Hardware

Breaker failure

Short circuit

Protection trip

Alarm Loss of affected thruster

Pre-charger

Transformer

No power Breaker fault Alarm None None No affect as long as thruster is

running, else not possible to

start

Cooling circuit Lack of

cooling

Loss of cooling fan Alarm Two fans one will run


performance


There are two cooling fans per

thruster, all are powered from

4FSB.

Power failure Alarm Loss of cooling fan(s)

Failure of 4FSB loss of

cooling fans to both

tunnel thrusters.

This failure will cause loss of

both tunnel thrusters

LO/ servo

system

Loss of oil

pressure/

circulation

Pump failure

Leakage

Alarm Trip of thrusters No effect on station keeping

performance


Thruster is interlocked, loss of

LO pressure thruster stops

also start interlocked for same.




Function/

comp.


Effect of failure


failure

On component in

subsystem

Effect on DP


Comments

Seal system incl.

Tank

Loss of head

pressure or oil

Leakage Alarm Risk of seawater ingress

into the thruster housing

None, however SW in

system will increase risk of

wear and tear

Azimuth

Thrusters

Thruster engine Not running Mech. failure

Electrical failure

Shutdown

Alarm Stop of thruster

depending of extent of

failure


performance


Thruster or gear Mech. failure Bearings, blades,

couplings

Vibration,

noise

Loss of affected thruster

Cooling circuit

to HPU

Lack of

cooling

No circulation of

coolant in cooling

circuit

Alarm Temperature increases

no auto trip of thruster.

Thruster will run Hot

before a high temp and

shutdown of engine.

Engineer should stop thruster

engine to protect the thruster

itself from running to hot.

LO system Loss of oil

pressure/

circulation

Pump failure

Leakage

Alarm Trip of thrusters No effect on station keeping

performance


LO/ servo pump Mech. or

electrical

failure

Fatigue, bearing,

coupling, motor

failure, loss of power,

short circuit,

protection trip

Alarm Stop of pump.

Thruster trips, internal

safety.

The thruster is interlocked

meaning if pump fails,

automatically stop of thruster

and no start of thruster is

possible.

Oil filters Failure of

filter

Clogged, dirt Alarm No affect as long as

action taken.

Monitored for pressure

difference

None Watch keeper to take

necessary actions to correct

failure.

Filter set for each system,

pitch, steering and lift

lowering.




Function/

comp.


Effect of failure


failure

On component in

subsystem

Effect on DP


Comments

Oil cooler Failure of

cooler

Leakage, rupture. Oil

in FW system.

Alarm Temp. increase

Can cause trip of thruster

Pitch Control

valves

Failure of

pitch valve

Leakage, seizure, dirt Alarm Can cause variance in

pitch or freeze.


performance


Operator should be aware of

this and disable thruster if this

occurs. The outcome of this

type of failure can varies from

pitch to zero or to full 100%

depending on failure.

Steering control

valve

Valve failure Leakage, seizure, dirt Alarm Can cause uncontrolled

steering of thruster Operator should be aware of

this and disable thruster if this

occurs.

Steering motor Mech. failure Piston, fatigue Alarm Thruster will not rotate

or rotates slower

Gravity /

Header tank

Loss of head

pressure

Lack of compressed

air to tank

Alarm Reduced head pressure No effect on station keeping

performance


Regular maintenance should

avoid this

Reduced

amount of oil

Leakage Alarm No affect as long as

action taken.

Can cause stop of

affected thruster.

Watch keeper to take

necessary actions to correct

failure.

Increased amount of oil in

tank will also give an alarm,

notifying that something is

wrong.

Seal tank Loss of head

pressure

Lack of compressed

air to tank

Alarm Reduced head pressure,

risk of SW ingress to

thruster housing through

the seals

None No immediate effect Increase

of SW in LO system,

Regular maintenance/ oil

samples should give a warning

to avoid this




Function/

comp.


Effect of failure


failure

On component in

subsystem

Effect on DP


Comments

Feedback

transmitter

Slewing ring

gear failure

Mech. Failure This can cause the

thruster to rotate un-

controllably.

There will be a steady

signal to DP and thruster

cabinet, of which will

send out order signal for

the thruster to rotate to

the direction given.


This can cause unstable

station keeping.

This type of failure will not

necessary give alarm for the

faulty thruster




15.12 Failure Analysis - DP Control System

Function/

component


Effect of failure


failure

On component in

subsystem

Effect on DP


Comments

DP

System

DPC-11

Computer

Any failure

causing loss of

this station

Electrical failure

Computer failure

Controller failure

Etc.

Alarm Loss of backup DP

station


performance

Loss of DP Class 3

All systems running on main

DPC-21.

Vessel still within DP class 2

DPC-21

Computers

Power failure Short circuit in

cabinet, fuse failure,

PSU failure

Alarm Blackout of affected

computer.

Auto switchover to other

computer.


performance

Loss of DP Class 2/3

In DP class 2 the BU DP

system does not count.

Note! That both DP UPS 1

and UPS 2 are both powered

through the same distribution

2CRASB.

Software error Wrong programming,

model

None Cause wrong

configuration wrong

commands.

DP system does not act

correct on commands/

functions selected.

Loss of position may occur.

Self-check routines between

computers.

Data Virus Data virus in all

computer system on

net

None A virus can result in

“crash” of computer

systems

Loss of Station keeping To prevent this Vessel

operator should make sure to

have procedures available to

restrict the use of computers

connected to the network




Function/

component


Effect of failure


failure

On component in

subsystem

Effect on DP


Comments

Loss of I/O

card

Fuse failure, card

failure, short circuit

Alarm Loss of communication

to components on that

I/O card

Loss of redundancy Loss of class depends on I/O

lost.

The trials revealed that

there are I/O cards that

controls up to three

thrusters, failure of this,

three thrusters are lost. U31

thruster 2, 4 and 5. U32

thruster 1, 3 and 6 are lost.

Abnormal

behaviour

thruster

control

Internal failure in I/O

card

Alarm This scenario can be

critical for those I/O

cards that control

variable pitch thrusters.

Loss of redundancy

If a thruster goes to full pitch

this can affect station

keeping capability

Thruster to be deselected from

DP. Thruster can be used in

emergency mode to assist DP

if needed.

DP Network Net failure Net overload, cable

breakage, fuse/

breaker failure

HUB/ node failure

Alarm Loss of affected

communication network.

Signal transfer on

redundant network.

None and

loss of redundancy

Galvanic

Isolation unit

Not working Loss of power

Internal failure

Alarm Loss of control to

affected thruster(s)


performance

Loss of redundancy


Galvanic units are powered

in pairs. A fuse/power

failure will cause loss of two

units. Hence two thrusters

are lost.

Internal failure will cause loss

of one thruster.




Function/

component


Effect of failure


failure

On component in

subsystem

Effect on DP


Comments

Operator

Console

Operator

Console

Loss of OS Power failure

Fuse failure

Short circuit

Computer failure

Alarm Loss of affected OS.

Other OS still available.

None and

loss redundancy

DP change over

switch

Any failure Power failure, short

circuit, cable

breakage

Alarm Power failure, breakage

of one input cable will

not have any affect due

to each thruster unit got

separate cables.

None One switch per thruster

DP

Sensors

VRS Power or

mech. failure

Fuse failure

Short circuit

Damage

Alarm Loss of affected VRS.

Vessel to be set up with

3 VRS’s to main DP

(include voting) and 2 to

the BU DP station

None

Sufficient number of VRS’s

available after failure of one.

Note! Loss of VRS to Seapath

or HiPAP will cause loss of

those systems.

Gyro Not working Short circuit

Fuse failure

Mech. failure

Alarm Loss of affected gyro.

DP auto select other

gyro(s).

None and

loss of redundancy

Gyro signal to Seapath are for

calibration only

Number of gyros to main DP

is 3; loss of one will cause loss

redundancy.

There are 2 gyros (3&4) to

backup DP loss of gyro 4, still

within class 2/3.

Difference Wrong calibration,

damage

Alarm Affected gyro will be de-

selected by DP system

due to gyro difference

check.




Function/

component


Effect of failure


failure

On component in

subsystem

Effect on DP


Comments

Wind Power failure Fuse failure

Supply failure

Short circuit

Alarm Loss of affected wind

sensor

None and

loss of redundancy

Vessel has 4 sensors, 2 for

main and 2 for BU DP

Mech./internal

failure

Damage, shielding

effect

Excess wind speed

due to Helicopter

operations

Warning Can cause wrong signals

to DP system.

DP system compensates

for wrong input.

Can result in excursion

DPO to be aware of this.

Position

Reference

Systems

Vessel is fitted with 3

DGPS’s, 1 Fanbeam, 1

LWTW and 2 HiPAP’s

DGPS

Power failure Fuse failure

Supply failure

Short circuit

Alarm Loss of affected DGPS

as DP ref. system.

None

GPS Antenna Wire break

Shielding

GPS antenna damage

Alarm Shielding can affect more than

one DGPS

DGPS signal Loss of

differential

correction signal

Spotbeam

Shielding,

Out of range, power

failure

Warning

indication on

DGPS

monitor

Loss of diff. signal to

DGPS

None

Affected DGPS rejected

from DP as ref. system

There is one demodulator per

GPS, all diff. corr. of type

Spotbeam. However one of

AFSAT and the other two are

AOREH

Loss of pre-set

numbers of

satellite signals

Too few satellite

signals

Alarm Can cause loss of all

DGPS’s and Seapath

None

Or loss of redundancy

Vessel remains with only on

Fanbeam, LWTW and one

HiPAP if configured right.




Function/

component


Effect of failure


failure

On component in

subsystem

Effect on DP


Comments

Degraded

performance

Shielding, noise/

disturbance in

hardware signal

network, poor

satellite constellation,

invalid satellites,

poor atmospheric

conditions

Alarm,

Warning

Can cause invalid

position on DGPS.

DP will vote away poor

DGPS.

Loss of redundancy.

Seapath Power Failure Fuse failure

UPS failure

Alarm The DP system does not use

the Seapath, but it’s used as

heading and motion reference

for HiPAP(s).

GPS antenna Shielding of a GPS

antenna

Communication

Alarm Loss of Seapath, hence

loss of HiPAP as a DP

reference source


performance

Loss of a HiPAP as DP ref.

system

Loss of VRS

signals

Power failure

Mech. failure

Signal failure

Alarm

Loss of Gyro

signals

Power failure

Mech. failure

Signal failure

Alarm No affect None Gyro signal is used for visual

check / calibration only

HiPAP Computer

APC-11

Power failure

Internal failure

Alarm Motion + gyro signals from

Seapath or from a gyro &

MRU. Setup configuration

according to DP Ops

Manual

Transceiver MRU signal

Gyro signal

Power failure

Alarm Loss of affected HiPAP No effect on station keeping

performance

Transducer Mech. damage

Sensor failure

Alarm




Function/

component


Effect of failure


failure

On component in

subsystem

Effect on DP


Comments

Transponder Not working

Battery failure

Noise in water

(propeller wash/

water layers)

Alarm

Hoist control Power failure Alarm None as long as

transducer is deployed

None Not possible to lift / lower

transducer

Fanbeam Power Failure Fuse failure

Supply failure

Short circuit

Alarm Loss of Fanbeam No effect on station keeping

performance

Track failure Select new target,

Weather conditions

(e.g. fog), rotation of

vessel

Alarm Unstable reference.

LWTW HPU failure Electrical

Mech. failure

Alarm LWTW rejected from

DP, lost.


performance

Failing HPU failure can lead

to not paying out wire or

pulling in = loss of mooring

Cable failure Cable break Alarm

Clump weight Stuck at seabed None Not possible to retrieve No affect as the system will be

in mooring




Function/

component


Effect of failure


failure

On component in

subsystem

Effect on DP


Comments

Dragging clump

weight along Seabed

Alarm LWTW should be

rejected as the angle and

wire length will be

frozen

Internal DP verification

should reject the LWTW

based on same data sent

several times, though small

changes will not be detected

and the DPO has to determent

if LWTW data are OK or not.

DP UPS

DP UPS’s Power failure

230V/ rectifier

failure

Short circuit

Fuse/ breaker failure

Alarm Loss of 230V main

supply cause UPS to

auto-change to battery

power.


performance

Eventually loss of main DP

if failure of 2CRASB.

Loss of redundancy

Battery endurance should be

min. 30 minutes.

Note both DP UPS 1 & UPS 2

from same distribution

Battery failure Battery failure Alarm None, remains on main

supply.

None Regular maintenance should

reveal this

Loss of UPS Internal UPS failure,

short circuit

Alarm Loss of consumers on

affected UPS.

Loss of redundancy Reference is made to section

14.7 for list of UPS consumers

that will be lost.




16 REFERENCES

/1/ FMEA report GM-694-170-R01-rev2

/2/ 1203351A_1 OSes.

/3/ 1203352A_1 FS 31-36

/4/ 1203353A_1 FS 37-38-41

/5/ 1203355A_1 FS 39

/6/ 1203356A_1 FS 42

/7/ 1203357A_1 UPS

/8 1208197B_1 KFDD Common system

/9/ 1208200B_1 KFDD IAS

/10/ 1208201B_1 KFDD PMS

/11/ 1208202A_1 KFDD Serial Lines

/12/ K-Chief Topology - 1203364A_1

Client: Subsea 7 Date: 07.09.2012 Page: A1



APPENDIX A

Kongsberg Maritime DP I/O specifications




I/O Specification SDP 21

Equipment U11 U12 U13 U14 U31 U32 U33 U41

Tension NMEA X

Gyro 1 X

DGPS 1 X

Wind 1 X

Gyro 2 X

DGPS 2 X

Wind 2 X

Gyro 3 X

Artemis interface (not used) X

DGPS 3 X

Waypoint X

Fanbeam X

Thr. 5 ready X

Thr. 2 ready X

Thr. 4 ready X

VRS 1 OK X

VRS 2 OK X

UPS 1 alarm X

Thr. 1 ready X

Thr. 3 ready X

Thr. 6 ready X

LWTW warn., select, alarm X

VRS 3 OK X

UPS 2 alarm X

VRS 1 roll X

VRS 1 pitch X

VRS 1 heave X

LWTW length , beam, along X

VRS 2 roll X

VRS 2 pitch X

Thr. 2 pitch feedback X

Thr. 2 azimuth feedback sin X

Thr. 2 azimuth feedback cos X




Thr. 2 pitch command X

Thr. 2 azimuth command X






Equipment U51 U61




Thr. 6 rpm feedback X



Thr. 6 rpm command X

Thr. 6 direction command X




Thr. 5 rpm feedback X



Thr. 5 rpm command X

Thr. 5 direction command X

Note!

A single card failure can result in loss of three thrusters, ref. U31 & U32.

Two thrusters will be lost if following cards fails U41, U51 and U61.




I/O Specification SDP 11

Equipment U11 U12 U13 U31 U32 U33 U41 U51

Tension NMEA X

Gyro 4 X

Wind 3 X

VRS 4 X

DGPS 3 X

Wind 4 X

Gyro 3 X

Thr. 5 ready X

Thr. 4 ready X

VRS 3 OK X

UPS 3 X

Thr. 1 ready X

Thr. 6 ready X

Tautwire X

VRS 4 X

Backup selected X

VRS 3 (pitch/roll/heave) X

Tautwire X

Thr. 5 order/feedback X






Client: Subsea 7 Date: 07.09.2012 Page: B1



APPENDIX B

Annual DP Trials with recommendations

See last Annual DP Trials report

seven polaris - dp fmea

Documents

thruster control system

general layout

clutch control

power distribution

automation control systems

fmea report gm

integrated automation

polaris fmea upgraderev