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TutorialTutorial

COMMISSIONING AND ACCEPTANCECOMMISSIONING AND ACCEPTANCECorrado RoccaCorrado Rocca

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TUTORIAL OUTLINETUTORIAL OUTLINE

• Introduction

• Questions and discussion

• The Acceptance process within the contractual Plan of Work– The Acceptance periods

• From Product Design acceptance to System Final Acceptance• The power budget• Relevant measurement set-ups, results and data in the acceptance

period

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INTRODUCTIONINTRODUCTION

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TECHNICAL SPECIFICATIONSTECHNICAL SPECIFICATIONS

Tenders and Supply Contracts for Submarine Cable Systems or Networks always contain a part called “Technical Specifications”

The Technical Specifications define the technical requirements, Scope of Work, performance parameters and Acceptance of a System

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SOME DEFINITIONSSOME DEFINITIONS

“Acceptance means the activities, including but not limited to, procedures, tests and approvals necessary to show that all the defined parameters, facilities and requirements given in the ‘Acceptance’ Chapter of the Technical Specifications of this Contract have been met to demonstrate confidence in the continuous satisfactory operation of the System throughout its Design Life”

(definition from recent submarine tenders)

….. Therefore the Commissioning is only a part of the Acceptanceof a submarine system !!!

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SUBMARINE REPEATERED SYSTEMSUBMARINE REPEATERED SYSTEM

This tutorial will discuss the Acceptanceof submarine repeatered systems

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TYPICAL CONTRACTUAL REQUIREMENTS TYPICAL CONTRACTUAL REQUIREMENTS FOR SYSTEM ACCEPTANCEFOR SYSTEM ACCEPTANCE

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THE PLAN OF WORKTHE PLAN OF WORK

The contractual Plan Of Work defines all the steps that have to be implemented for the successful completion of a System, including its Acceptance

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THE ACCEPTANCE PROCESSTHE ACCEPTANCE PROCESS

The typical Acceptance process is divided into Acceptance Periods

In each period, the Supplier (or Contractor) has to submit all the necessary documentation, test procedures and test results to thePurchasers for approval. Such documentation is gathered in the System Acceptance Handbook

Typically all tests are performed under the Contractor’s responsibility

The Purchasers can opt to follow the Acceptance process themselves or to second the task to a competent inspector (typically belonging to a national PTT or telecom authority)

Most periods are linked to a Billing Milestone and consequent payment after successful verification

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THE MAIN ACCEPTANCE PERIODSTHE MAIN ACCEPTANCE PERIODS

I. Product design acceptance II. Factory Acceptance Testing (FAT)III. Wet plant assembly acceptanceIV. System Loading and Laying (SLL) testingV. Site Acceptance Testing (SAT)VI. System (end-to-end transmission) testing VII. System confidence trial and Provisional AcceptanceVIII. System Final Acceptance

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PRODUCT DESIGN ACCEPTANCEPRODUCT DESIGN ACCEPTANCE

I. Product maturity and qualification status evaluationII. Technical explanation of assumptions under the contractual

power budgetIII. Technology demonstration, proving transmission capability

with final capacity and inter-operation with SIEIV. Possible multi-vendor products integration verification

G G G

G G G

R1 R3

Ri-1RiRi+1

R2

G

G G G

RN-3 RN-1RN-2 RN

G

TX

RX

α α α α α

R4

α α α α α

αα α

α

SMR

GFU TEU

SMR

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TECHNOLOGY DEMONSTRATIONTECHNOLOGY DEMONSTRATION

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FACTORY ACCEPTANCE TESTS (FAT)FACTORY ACCEPTANCE TESTS (FAT)

The purpose is to confirm that the products are compliant with the Technical Specifications and will meet the System requirements

Tests are carried out on the basis of a FAT procedure

I. Dry Plant Equipment acceptanceI. Submarine Line Terminating EquipmentII. Power Feeding Equipment

II. Wet Plant Equipment acceptanceI. Cable (each span)II. RepeatersIII. Branching UnitsIV. Equalizers

Purchasers may decide not to follow all the tests; in any case factory test reports have to be checked and approved

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WET PLANT ASSEMBLY ACCEPTANCEWET PLANT ASSEMBLY ACCEPTANCE

The purpose is to confirm that the assembled wet plant will meetthe System requirements

They typically comprise» OSNR / pre-emphasis tests» Chromatic Dispersion tests» Voltage / Current tests (V/I characterization)» Supervisory tests» BER tests (when applicable)

Depending on loading/laying strategies and segment lengths, tests may be carried out on loading/laying blocks, therefore the acceptance criteria are scaled accordingly

It is important to remind that during the repeater to cable assembly, each operation is carefully monitored, through splices verification (via splicing machine or active supervision) and through insulation tests

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DISPERSION MAP TEST RESULTSDISPERSION MAP TEST RESULTSCumulative Chromatic Dispersion @ 1551.5 nm (2°C)

-1500

-1000

-500

0

500

1000

1500

0 200 400 600 800 1000 1200

Segment Length [km]

Chr

omat

ic D

ispe

rsio

nps

/nm

Fiber 1

Fiber 2

Min

Max

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LOADING AND LAYING TESTSLOADING AND LAYING TESTS

The purpose is to confirm that during operations the assembled cable performance is not impaired

They typically comprise» OSNR tests» Voltage / Current tests» Supervisory tests» Branching Units tests (when present)

Depending on loading/laying strategies and segment lengths, tests may be carried out on loading/laying blocks, therefore the acceptance criteria are scaled accordingly

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SITE ACCEPTANCE TESTS (SAT)SITE ACCEPTANCE TESTS (SAT)

These tests are carried out after terminal station installation to verify that the Dry Plant equipment is installed and performs properly

They typically comprise a selected subset of FAT procedures» OSNR launched from SLTE» Back-to-back error tests on SLTE (BER vs. OSNR curve)» PFE performance and tests on dummy load» Local software monitoring tests through LCT or EMS» SIE tests (if within the SOW)» Land cable and return earth tests

They are performed first at equipment level (Suite tests), then on spares and finally at station level (Station Integration tests)

The contractual Plan Of Work typically foresees Contractor’s SATtests and, if requested, also Purchasers’ SAT tests

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ENDEND--TOTO--END / COMMISSIONING TESTSEND / COMMISSIONING TESTS

These tests are carried out after the lay and the final splice (terrestrial to wet cable joint) execution and the set-up of the complete end-to-end Segment or System

They typically comprise» Transmission tests (OSNR, BER based Q-factor and

commissioning margins)» Final capacity demonstration» Wet Plant Supervisory tests (repeaters monitoring and C-OTDR)» System powering tests» Software tests (DCN tests, NE remotization, alarm generation and

detection, performance monitoring)» System interfaces, synchronization, protection, maintenance and

restoration tests

The contractual Plan Of Work typically foresees Contractor’s tests and, if requested, also Purchasers’ tests

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THE POWER BUDGETTHE POWER BUDGET Parameter BOL Q in

dB EOL Q in

dB

1 Mean Q value (from simple SNR calculation) 21.0 18.5 1.1 Propagation impairments due to combined effects of chromatic dispersion, non-

linear effect, four-wave mixing effects, stimulated Raman scattering effects, etc. 1.5 1.5

1.2 Gain flatness impairments 0.5 0.5 1.3 Non-optimal optical pre-emphasis impairment 0.25 0.25 1.4 Wavelength tolerance impairment 0.2 0.2 1.5 Mean PDL penalty <0.1 <0.1 1.6 Mean PDG penalty <0.1 <0.1 1.7 Mean PMD penalty <0.1 <0.1 1.8 Supe rvisory impairment .5 0.5 1.9 Manufacturing and environmental impairment 1 1 2 Time varying system performance (5 sigma rule) 1.2 1.2 3 Line Q value (1-1.1 to 1.9-2) 15.85 13.35 4 Specified TTE Q value (back to back) 22.0 20.0 5 Transmission Segment Q value (computed from 3 and 4) 14.91 12.5 5.1 BER corresponding to segment Q without FEC 1.4e-8 1.3e-5 5.2 BER corresponding to segment Q with FEC <1e-13 <1e-13 5.3 Effective Transmission Segment Q value with FEC >17 >17 6 Q limit compliance with G.826 after FEC correction 11.3 11.3 7 Repairs margins

Components and fibre ageing penalty Pump(s) failure penalty Non-optimal decision threshold

- 2.5

8 Segment Margins 2.20 1.0 9 Unallocated supplier margin 1.41 0.2 10 Commissioning limits 13.5

EOL conditions

Commissioning limit

SOL conditions

FEC capability

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TRANSMISSION TESTSTRANSMISSION TESTSTX- FEC

TX-S-LINE

RX-FEC

O

E

OE

OE

O

E

RX-S-LINETO SIE

SIE IN

STM-64 10.66 Gb/s

RX-FECRX-S-LINE

TX -FEC

O

E

O

E

O

E

TX-S-LINE

O

E

SIE IN

TO SIE

STM-6410.66 Gb/s

WDM MUX/DeMUX

SUBMERGED LINE

WDM MUX/DeMUX

LINE (Line 3)LINE (Line 3)

TRANSMISSION SEGMENT (Lines 5 & 5.1)TRANSMISSION SEGMENT (Lines 5 & 5.1)

Effective TRANSMISSION SEGMENT (Lines 5.2 & 5.3)Effective TRANSMISSION SEGMENT (Lines 5.2 & 5.3)

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TRANSMISSION TEST RESULTTRANSMISSION TEST RESULT

1.00E-12

1.00E-11

1.00E-10

1.00E-09

1.00E-08

1.00E-07

1.00E-06

1.00E-05

1.00E-04

1.00E-03

10.00 11.00 12.00 13.00 14.00 15.00 16.00 17.00 18.00 19.00

OSNR [dB]

BE

R

Back-to-BackWith Line @ SOL

Commissioning Limit

SOL OSNR

OSNR MARGIN

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FULL CAPACITY TESTINGFULL CAPACITY TESTING

The Contractor must prove to Purchasers System operation and power budget margins at the committed final capacity, although initially the System is typically lit with few wavelengths

Several methods are possible; a practical set up employs the equipped transponders together with dummy channels, as described in the paper “Optical test equipment for performance evaluation of installed DWDM systems”- OFC2002, TuY3

The system is loaded with dummy signals through which the equipped transponders powers are set at levels equivalent to full capacity conditions. Few of these dummy channels (typically 4 or 6) are narrowly spaced across the tributary under test in order to induce non-linear penalties

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FULL CAPACITY TEST SETFULL CAPACITY TEST SET--UPUP

OPTICALATTENUATOR

Amplifier

TO LINE

FROM LINE

TRANSMITAMPLIFIER

CLI

EN

TIN

CLI

EN

TO

UT

LIN

EO

UT

LIN

EIN

Equipped Transponders

CLI

EN

TIN

CLI

EN

TO

UT

LIN

EO

UT

LIN

EIN

CLI

EN

TIN

CLI

EN

TO

UT

LIN

EO

UT

LIN

EIN

CLI

EN

TIN

CLI

EN

TO

UT

LIN

EO

UT

LIN

EIN

RECEIVEAMPLIFIER

DWLDWLDWLDWL

DWLDWLDWLDWL

DWLDWLDWLDWL

DWLDWLDWLDWL

OP

TIC

AL

MU

LT

IPL

EX

ER

DWLDWLDWLDWL

PM C

ou

ple

r

External Modulator

Amplifier

OPTICALATTENUATOR

Transmit Port Input

OSA

Transmit Monitor Port Output

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WET PLANT SUPERVISIONWET PLANT SUPERVISION

∑ ∑ ∑∑= = =

−

=

−−−+=N

i

N

i

N

iNii

N

iii HLLBSpan_BSpan_AG_BG_AN)Loop_Gain(

0 1 1

1

0

SPV Signal Loop Back Path

Faulty repeater

LoopbackLoopback Supervisory methodSupervisory method

SPAN 1 SPAN N

HL

LB0

Far

-end

HLL

B

R1 RN

SLTE

FarEndSLTE

G_A0

G_B0

Span_A1

Span_B1 HLLB1 HLLBN

G_AN

G_BN

Span_AN

Span_BN

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WET PLANT SUPERVISIONWET PLANT SUPERVISION

SPAN 1 SPAN N

R1 RNSLTE

FarEndSLTE

G_A0

G_B0

Span_A1

Span_B1

G_AN

G_BN

Span_AN

Span_BN

Active Supervision methodActive Supervision method SPV Interrogation SPV Response

Addressed repeater

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WET PLANT SUPERVISIONWET PLANT SUPERVISION

-40

-35

-30

-25

-20

-15

-10

-5

0

0 100 200 300 400 500 600

Distance (Km)

Am

plit

ud

e (d

B)

First span not visible Submarine Amplifier

PEU

Span Length

Spa

n Lo

ss

Far End Terminal Station

Coherent OTDRCoherent OTDR

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SYSTEM POWERING TESTSSYSTEM POWERING TESTS

• System Power up• System Power down• V/I Characterisation• BU configuration• System performance with different powering scenarios

• Single End Feeding• Double End Feeding• PFE fault• Converter fault• Electroding

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SW AND DCN TESTS SW AND DCN TESTS

WAN

LANOther Interfaces

WAN connectivity via FEC Overhead Channels

Station C

DCN tests verify the connectivity among the different terminal stations LANs and theremotization of far-end Network Elements

Alarm tests verify proper alarm generation and clearance of induced faulty conditions

Performance Monitoring tests verify correct management of ITU-T G.826 parameters: EB, BBE, ES, SES, UAS recorded at intervals of 15 minutes and 24 hours.

Router

NEs

Station A

LCT

EMS

Router

NEsStation B

EMS

To Land networkTo Land network / NOC

User channels

User channels

LAN HUB

LAN HUB

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OTHER TESTS OTHER TESTS

• System interfaces• SIE interfaces (power levels, jitter, eye-diagrams, AIS generation etc)• User channels• EMS interfaces (North-bound, when applicable)

• Protection mechanisms verification• Equipment redundancies• 1+1 linear protection• 1:N tributary protection• Ring protection

• Synchronization distribution over the whole System

• Exercising of maintenance procedures• Traffic provisioning and management• Network Elements configuration• Restoration criteria• Collection of maintenance and baseline data

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SYSTEM CONFIDENCE TRIAL SYSTEM CONFIDENCE TRIAL

The Continuous Confidence Trial aims at demonstrating that the installed system operates error-free over a long term test period (typically 2 weeks)

A daily log through the OMC monitors the absence of irregularities, variations, alarms and non-routine events

For systems employing Forward Error Correction (FEC), the recording of the pre-FEC BER allows measuring the system margins for each equipped Digital Line Section

Using pre-FEC performance parameters recorded at 15-min intervals it is possible to derive the statistics of the error occurrences and to prove with a certain confidence level (above 95%) the PB Commissioning Limit

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SYSTEM PROVISIONAL ACCEPTANCE SYSTEM PROVISIONAL ACCEPTANCE

The Provisional Acceptance Certificate is issued by the Purchasers provided that

• The results of the Acceptance Test Program included in the Acceptance Handbook indicate compliance of the System throughout its Design Life with the requirements of the Technical Specification

• The Contractor has provided all the deliverables required by the Contract (including documentation, spares, training etc)

• During the Confidence Trial nothing has developed that is likely to cause the System to fail to meet the requirements of the Technical Specification

With the PAC issuance the Purchasers officially accept the System, the implementation activities are concluded and the Warranty Period begins

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SYSTEM FINAL ACCEPTANCE SYSTEM FINAL ACCEPTANCE

At the end of the Warranty Period a Final Acceptance Certificate is issued by the Purchasers provided that

• The OMC data gathered after the Provisional Acceptance date confirm long-term transmission quality performance

• No Pattern of Failure or Degradation has developed that is likely to cause the System to fail to meet the requirements of the Technical Specifications

• The performed Final Acceptance Tests indicate compliance with the Technical Specifications

With the FAC issuance the Warranty Period is concluded, the Performance Bond is released and the out-of-Warranty period begins

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