04 - pcs915a busbar protection
DESCRIPTION
PCS915A Busbar ProtectionTRANSCRIPT
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PCS-915A
Busbar Protection
Instruction Manual
NR Electric Co., Ltd.
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Preface
PCS-915A Busbar Protection i
Date: 2013-06-03
Preface
Introduction
This guide and the relevant operating or service manual documentation for the equipment provide
full information on safe handling, commissioning and testing of this equipment.
Documentation for equipment ordered from NR is dispatched separately from manufactured goods
and may not be received at the same time. Therefore, this guide is provided to ensure that printed
information normally present on equipment is fully understood by the recipient.
Before carrying out any work on the equipment, the user should be familiar with the contents of
this manual, and read relevant chapter carefully.
This chapter describes the safety precautions recommended when using the equipment. Before
installing and using the equipment, this chapter must be thoroughly read and understood.
Health and Safety
The information in this chapter of the equipment documentation is intended to ensure that
equipment is properly installed and handled in order to maintain it in a safe condition.
When electrical equipment is in operation, dangerous voltages will be present in certain parts of
the equipment. Failure to observe warning notices, incorrect use, or improper use may endanger
personnel and equipment and cause personal injury or physical damage.
Before working in the terminal strip area, the equipment must be isolated.
Proper and safe operation of the equipment depends on appropriate shipping and handling,
proper storage, installation and commissioning, and on careful operation, maintenance and
servicing. For this reason, only qualified personnel may work on or operate the equipment.
Qualified personnel are individuals who:
Are familiar with the installation, commissioning, and operation of the equipment and of the
system to which it is being connected;
Are able to safely perform switching operations in accordance with accepted safety
engineering practices and are authorized to energize and de-energize equipment and to
isolate, ground, and label it;
Are trained in the care and use of safety apparatus in accordance with safety engineering
practices;
Are trained in emergency procedures (first aid).
Instructions and Warnings
The following indicators and standard definitions are used:
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Preface
PCS-915A Busbar Protection ii Date: 2013-06-03
DANGER!
It means that death, severe personal injury, or considerable equipment damage will occur if safety
precautions are disregarded.
WARNING!
It means that death, severe personal, or considerable equipment damage could occur if safety
precautions are disregarded.
CAUTION!
It means that light personal injury or equipment damage may occur if safety precautions are
disregarded. This particularly applies to damage to the device and to resulting damage of the
protected equipment.
WARNING!
The firmware may be upgraded to add new features or enhance/modify existing features, please
make sure that the version of this manual is compatible with the product in your hand.
WARNING!
During operation of electrical equipment, certain parts of these devices are under high voltage.
Severe personal injury or significant equipment damage could result from improper behavior.
Only qualified personnel should work on this equipment or in the vicinity of this equipment. These
personnel must be familiar with all warnings and service procedures described in this manual, as
well as safety regulations.
In particular, the general facility and safety regulations for work with high-voltage equipment must
be observed. Noncompliance may result in death, injury, or significant equipment damage.
DANGER!
Never allow the current transformer (CT) secondary circuit connected to this equipment to be
opened while the primary system is live. Opening the CT circuit will produce a dangerously high
voltage.
WARNING!
Exposed terminals
Do not touch the exposed terminals of this equipment while the power is on, as the high voltage
generated is dangerous
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Preface
PCS-915A Busbar Protection iii
Date: 2013-06-03
Residual voltage
Hazardous voltage can be present in the DC circuit just after switching off the DC power supply. It
takes a few seconds for the voltage to discharge.
CAUTION!
Earth
The earthing terminal of the equipment must be securely earthed
Operating environment
The equipment must only be used within the range of ambient environment detailed in the
specification and in an environment free of abnormal vibration.
Ratings
Before applying AC voltage and current or the DC power supply to the equipment, check that they
conform to the equipment ratings.
Printed circuit board
Do not attach and remove printed circuit boards when DC power to the equipment is on, as this
may cause the equipment to malfunction.
External circuit
When connecting the output contacts of the equipment to an external circuit, carefully check the
supply voltage used in order to prevent the connected circuit from overheating.
Connection cable
Carefully handle the connection cable without applying excessive force.
Copyright
Version: R1.02
P/N: EN_YJBH5301.0086.0003
Copyright NR 2013. All rights reserved
NR ELECTRIC CO., LTD.
69 Suyuan Avenue. Jiangning, Nanjing 211102, China
Tel: +86-25-87178185, Fax: +86-25-87178208
Website: www.nrelect.com, www.nari-relays.com
Email: [email protected]
We reserve all rights to this document and to the information contained herein. Improper use in particular reproduction and dissemination
to third parties is strictly forbidden except where expressly authorized.
The information in this manual is carefully checked periodically, and necessary corrections will be included in future editions. If
nevertheless any errors are detected, suggestions for correction or improvement are greatly appreciated.
We reserve the rights to make technical improvements without notice.
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Preface
PCS-915A Busbar Protection iv Date: 2013-06-03
Documentation Structure
The manual provides a functional and technical description of this relay and a comprehensive set
of instructions for the relays use and application.
All contents provided by this manual are summarized as below:
1 Introduction
Briefly introduce the application, functions and features about this relay.
2 Technical Data
Introduce the technical data about this relay, such as electrical specifications, mechanical
specifications, ambient temperature and humidity range, communication port parameters, type
tests, setting ranges and accuracy limits and the certifications that our products have passed.
3 Operation Theory
Introduce a comprehensive and detailed functional description of all protective elements.
4 Supervision
Introduce the automatic self-supervision function of this relay.
5 Measurement and Recording
Introduce the management function (measurment and recording) of this relay.
6 Hardware
Introduce the main function carried out by each plug-in module of this relay and providing the
definition of pins of each plug-in module.
7 Settings
List settings including protection settings, system settings, communication settings, label settings,
VEBI settings and etc., and some notes about the setting application.
8 Human Machine Interface
Introduce the hardware of the human machine interface (HMI) module and a detailed guide for the
user how to use this relay through HMI. It also lists all the information which can be view through
HMI, such as settings, measurements, all kinds of reports etc.
9 Communication
Introduce the communication port and protocol which this relay can support, IEC60970-5-103,
IEC61850 and DNP3.0 protocols are introduced in details.
10 Installation
Introduce the recommendations on unpacking, handling, inspection and storage of this relay. A
guide to the mechanical and electrical installation of this relay is also provided, incorporating
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Preface
PCS-915A Busbar Protection v
Date: 2013-06-03
earthing recommendations. A typical wiring connection to this relay is indicated.
11 Commissioning
Introduce how to commission this relay, comprising checks on the calibration and functionality of
this relay.
12 Maintenance
A general maintenance policy for this relay is outlined.
13 Decommissioning and Disposal
A general decommissioning and disposal policy for this relay is outlined.
14 Manual Version History
List the instruction manual version and the modification history records.
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Preface
PCS-915A Busbar Protection vi Date: 2013-06-03
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1 Introduction
PCS-915A Busbar Protection 1-a
Date: 2012-08-31
1 Introduction
Table of Contents
1 Introduction ..................................................................................... 1-a
1.1 Application ....................................................................................................... 1-1
1.2 Function ........................................................................................................... 1-2
1.3 Feature ............................................................................................................. 1-2
1.4 Abbreviation .................................................................................................... 1-3
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1 Introduction
PCS-915A Busbar Protection 1-b Date: 2012-08-31
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1 Introduction
PCS-915A Busbar Protection 1-1
Date: 2012-08-31
1.1 Application
PCS-915A is a numerical busbar differential protection intended to be used for protecting and
monitoring of double busbars with bus coupler arrangement, single busbar arrangement and
single busbar with single bus section arrangement of various voltage levels. It is capable to protect
up to 25 bays including bus coupler and bus section (bay 01 is connected with bus coupler (BC),
the rest bays are taken as feeder 01~24).
PCS-915A utilizes NRs innovative hardware platform supporting both conventional CT/VT and
electronic current and voltage transformer (ECVT). It is compliant to several communication
protocols, such as IEC60870-5-103, IEC61850 and DNP3.0 protocol.
BB1
BC
*
*
**
VT1
VT2
PCS-915
FR50BF 87B
BB2
Figure 1.1-1 Typical application-Double busbars with BC arrangement
Note!
The bay label of displayed alarm signals, tripping signals, binary input signals, settings and
sampled values related with each feeder and busbar will change with the corresponding
description settings. Please refer to Section 7.8 for details.
For example, if the description setting of feeder 01 i.e. [NameDef_Bay02] is set as Fdr01,
the three-phase initiating contact of BFP for feeder 01 is [BI_BFI_Fdr01]. If
[NameDef_Bay02] is set as 0001, the three-phase initiating contact of BFP for feeder 01
is [BI_BFI_0001].
In this instruction manual, only take the default settings in Table 7.8-1 as an example to
introduce.
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1 Introduction
PCS-915A Busbar Protection 1-2 Date: 2012-08-31
1.2 Function
PCS-915 provides the following functions
1. Protection function
Busbar differential protection (87B)
Steady-state percentage differential protection
DPFC percentage differential protection
Bus coupler protection
SOTF protection (50)
End zone fault protection (50DZ)
Breaker failure protection (50BF)
Overcurrent protection (50/51)
Pole discrepancy protection (62PD)
Feeder breaker failure protection (50BF)
Note!
DPFC is the abbreviation of Deviation of Power Frequency Component. When a fault
occurs in the power system, the fault current consists of three parts: the pre-fault power
frequency components, the power frequency variables during the fault and the transient
variables during the fault. DPFC is the power frequency variables during the fault.
2. Auxiliary protection
Dynamic busbar replica
CT circuit failure supervision
VT circuit failure supervision
Disconnector position alarm
1.3 Feature
1. Protection and Control
Parallel calculation of double DSP system
Independent fault detector element
Accurate measurement which can prevent any undesired trip
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1 Introduction
PCS-915A Busbar Protection 1-3
Date: 2012-08-31
Less than 20ms typical trip time for busbar differential protection
High sensitive percentage restraint differential protection
Matching to different CT ratios and settable CT adjustment coefficient
A well proven adaptive weighted anti-saturation algorithm
Friendly human machine interface
Comprehensive event recorder
Multi-language option - English, Chinese and Russian
2. Time synchronization
Receiving PPS (pulse per second) and PPM (pulse per minute) via external contact
Receiving PPS, PPM and IRIG-B signal via RS-485
Receiving time synchronization message from substation automation system
3. Event recorder and disturbance recorder
1024 latest fault reports
1024 latest self-supervision reports
1024 latest status change of binary input reports
32 latest fault waveforms (The file format of disturbance recorder is compatible with the
international COMTRADE file)
4. Communication
2 rear RS-485 communication ports supporting with IEC 60870-5-103 protocol, ModBus
protocol or DNP3.0 protocol
4 Ethernet ports at most (depend on the chosen CPU type) supporting with IEC 60870-5-103
protocol or IEC 61850-8-1 protocol
1 rear RS-485 communication port for time synchronization
1 RS-232 communication rear ports for printer
A front multiplex RJ45 port for local communication with a PC
1.4 Abbreviation
Symbol Description
FD Fault detector
BBx Busbar No.x, x is the number of each busbar
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1 Introduction
PCS-915A Busbar Protection 1-4 Date: 2012-08-31
Symbol Description
feeder xx Feeder No.xx, xx is the number of each feeder
VCE Voltage controlled element
BBP Busbar differential protection
BFP Breaker failure protection
BFI Breaker failure initiation
EFP End zone fault protection
PD Pole disagreement
SAS Substation automatic system
RTU Remote terminal unit
CT Current transformer
VT Voltage transformer
DPFC Deviation of power frequency component
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2 Technical Data
PCS-915A Busbar Protection 2-a
Date: 2013-06-03
2 Technical Data
Table of Contents
2 Technical Data ................................................................................. 2-a
2.1 Electrical Specifications ................................................................................. 2-1
2.1.1 Alternating Analog Current................................................................................................... 2-1
2.1.2 Alternating Analog Voltage ................................................................................................... 2-1
2.1.3 Power Supply ....................................................................................................................... 2-1
2.1.4 Binary Input .......................................................................................................................... 2-1
2.1.5 Binary Output ....................................................................................................................... 2-2
2.2 Mechanical Specifications ............................................................................. 2-2
2.3 Ambient Temperature and Humidity Range .................................................. 2-2
2.4 Communication Port ....................................................................................... 2-3
2.4.1 EIA-485 Port ........................................................................................................................ 2-3
2.4.2 Ethernet Port ........................................................................................................................ 2-3
2.4.3 Optical Fibre Port ................................................................................................................. 2-3
2.4.4 Print Port .............................................................................................................................. 2-4
2.4.5 Clock Synchronization Port ................................................................................................. 2-4
2.5 Type Tests ........................................................................................................ 2-4
2.5.1 Environmental Tests ............................................................................................................ 2-4
2.5.2 Mechanical Tests ................................................................................................................. 2-4
2.5.3 Electrical Tests ..................................................................................................................... 2-4
2.5.4 Electromagnetic Compatibility ............................................................................................. 2-5
2.6 Certifications ................................................................................................... 2-6
2.7 Measurement Scope and Accuracy ............................................................... 2-6
2.8 Management Function .................................................................................... 2-6
2.8.1 Clock Performance .............................................................................................................. 2-6
2.8.2 Fault and Disturbance Recording ........................................................................................ 2-6
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2 Technical Data
PCS-915A Busbar Protection 2-b
Date: 2013-06-03
2.8.3 Binary Input Signal............................................................................................................... 2-6
2.9 Protective Functions ....................................................................................... 2-7
2.9.1 Busbar Differential Protection .............................................................................................. 2-7
2.9.2 Switch-onto-fault Protection ................................................................................................. 2-7
2.9.3 Bus coupler/bus section Overcurrent Protection ................................................................. 2-7
2.9.4 Bus coupler/bus section Pole Disagreement Protection ..................................................... 2-7
2.9.5 Bus coupler/bus section Breaker Failure Protection ........................................................... 2-7
2.9.6 Feeder Breaker Failure Protection ...................................................................................... 2-7
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2 Technical Data
PCS-915A Busbar Protection 2-1
Date: 2013-06-03
2.1 Electrical Specifications
2.1.1 Alternating Analog Current
Phase rotation ABC
Nominal frequency (fn) 505Hz, 605Hz
Rated Current (In) 1A 5A
Linear to 0.05In~40In
Thermal withstand
-continuously
-for 10s
-for 1s
-for half a cycle
4In
30In
100In
250In
Burden < 0.15VA/phase @In < 0.25VA/phase @In
Accuracy 0.5%In
2.1.2 Alternating Analog Voltage
Phase rotation ABC
Nominal frequency (fn) 505Hz, 605Hz
Rated Voltage (Un) 100V~130V
Linear to 1V~170V
Thermal withstand
-continuously
-10s
-1s
200V
260V
300V
Burden at rated < 0.20VA/phase @Un
Accuracy 0.5%Un
2.1.3 Power Supply
Standard IEC 60255-11:2008
Rated Voltage 110Vdc/125Vdc, 220Vdc/250Vdc
Operating Range 80%~120% of rated voltage
Permissible AC ripple voltage 15% of the nominal auxiliary voltage
Burden
Quiescent condition
Operating condition
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2 Technical Data
PCS-915A Busbar Protection 2-2
Date: 2013-06-03
Maximum permissible voltage 120% of rated voltage
Withstand voltage
-continously 2000Vac, 2800Vdc
Response time for logic input
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2 Technical Data
PCS-915A Busbar Protection 2-3
Date: 2013-06-03
C)
Transport and storage temperature
range -40C to +70C
Permissible humidity 5%-95%, without condensation
Pollution degree
Altitude
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2 Technical Data
PCS-915A Busbar Protection 2-4
Date: 2013-06-03
Wave length 1310nm
Transmission power Min. -20.0dBm
Minimum receiving power Min. -30.0dBm
Margin Min +3.0dB
2.4.3.3 For Synchronization Port
Characteristic Glass optical fiber
Connector type ST
Fibre type Multi mode
Wave length 820nm
Minimum receiving power Min. -25.0dBm
Margin Min +3.0dB
2.4.4 Print Port
Type RS-232
Baud Rate 4.8kbit/s, 9.6kbit/s, 19.2kbit/s, 38.4kbit/s, 57.6kbit/s, 115.2kbit/s
Printer type EPSON 300K printer
Safety level Isolation to ELV level
2.4.5 Clock Synchronization Port
Type RS-485
Transmission distance
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2 Technical Data
PCS-915A Busbar Protection 2-5
Date: 2013-06-03
Overvoltage category
Insulation resistance
measurements Isolation resistance >100M@500VDC
2.5.4 Electromagnetic Compatibility
1MHz burst disturbance test
IEC 60255-22-1:2007
Common mode: class III 2.5kV
Differential mode: class III 1.0kV
Electrostatic discharge test
IEC60255-22-2:2008 class IV
For contact discharge: 8kV
For air discharge: 15kV
Radio frequency interference tests
IEC 60255-22-3:2007 class III
Frequency sweep
Radiated amplitude-modulated
10V/m (rms), f=80~1000MHz
Spot frequency
Radiated amplitude-modulated
10V/m (rms), f=80MHz/160MHz/450MHz/900MHz
Radiated pulse-modulated
10V/m (rms), f=900MHz
Fast transient disturbance tests
IEC 60255-22-4:2008
Power supply, I/O, Earth: class IV, 4kV, 2.5kHz, 5/50ns
Communication terminals: class IV, 2kV, 5kHz, 5/50ns
Surge immunity test
IEC 60255-22-5:2008
Power supply, AC input, I/O port: class IV, 1.2/50us
Common mode: 4kV
Differential mode: 2kV
Conducted RF Electromagnetic
Disturbance
IEC 60255-22-6:2001
Power supply, AC, I/O, Comm. Terminal: Class III, 10Vrms, 150
kHz~80MHz
Power Frequency Magnetic Field
Immunity
IEC 61000-4-8:2001
class V, 100A/m for 1min, 1000A/m for 3s
Pulse Magnetic Field Immunity IEC 61000-4-9:2001
class V, 6.4/16s, 1000A/m for 3s
Damped oscillatory magnetic field
immunity
IEC 61000-4-10:2001
class V, 100kHz & 1MHz100A/m
Auxiliary power supply performance
- Voltage dips
-Voltage short interruptions
IEC60255-11: 2008
Up to 500ms for dips to 40% of rated voltage without reset
100ms for interruption without rebooting
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2 Technical Data
PCS-915A Busbar Protection 2-6
Date: 2013-06-03
2.6 Certifications
ISO9001:2008
ISO14001:2004
OHSAS18001:2007
ISO10012:2003
CMMI L4
EMC: 2004/108/EC, EN50263:1999
Products safety(PS): 2006/95/EC, EN61010-1:2001
2.7 Measurement Scope and Accuracy
Item Range Accuracy
Phase range 0 ~ 360 0.5% or 1
Frequency fn3Hz 0.01Hz
Currents from protection measurement current transformers
Current 0.05 ~ 40.00In 2.5% of rating or 0.02In
Voltage 0.05 ~ 1.20Un 1.0% of rating or 0.01Un
2.8 Management Function
2.8.1 Clock Performance
Real time clock accuracy 3s/day
Accuracy of GPS synchronization 1ms
External time synchronization IRIG-B (200-98), PPS, IEEE1588 or SNTP protocol
2.8.2 Fault and Disturbance Recording
Maximum duration 6000 sampled points (24 sampled points per cycle)
Recording position 2~50 cycles before pickup of trigger element
2.8.3 Binary Input Signal
Resolution of binary input signal 1ms
Binary input mode Potential-free contact
Resolution of SOE 1ms
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2 Technical Data
PCS-915A Busbar Protection 2-7
Date: 2013-06-03
2.9 Protective Functions
Note!
The meanings of symbols mentioned in the following sections are given here.
In -- rated secondary current of reference CT
U2n -- rated secondary phase-to-phase voltage of VT
2.9.1 Busbar Differential Protection
current setting range 0.05In~20.00In
Tolerance of current setting 2.5%xSetting or 0.02In, whichever is greater
Accuracy of voltage setting 2.5% or 0.01U2n whichever is greater
2.9.2 Switch-onto-fault Protection
Current setting range 0.05In~20.00In
Tolerance of current setting 2.5% of setting or 0.02In whichever is greater
2.9.3 Bus coupler/bus section Overcurrent Protection
Current setting range 0.05In~20.00In
Tolerance of current setting 2.5% of setting or 0.02In whichever is greater
Time setting range 0.000~10.000s
Tolerance of time setting 1%xSetting + 40ms
2.9.4 Bus coupler/bus section Pole Disagreement Protection
Residual current setting range 0~20.00In
Negative-sequence current setting range 0~20.00In
Tolerance of current setting 2.5% of setting or 0.02In whichever is greater
Time setting range 0.000~10.000s
Tolerance of time setting 1%xSetting + 40ms
2.9.5 Bus coupler/bus section Breaker Failure Protection
Current setting range 0~20.00In
Tolerance of current setting 2.5%xSetting or 0.02In, whichever is greater
Time setting range 0.010~10.000s
Tolerance of time setting 1%xSetting + 40ms
2.9.6 Feeder Breaker Failure Protection
Phase current setting range 0~20.00In
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2 Technical Data
PCS-915A Busbar Protection 2-8
Date: 2013-06-03
Residual current setting range 0~20.00In
Negative-sequence current setting range 0~20.00In
Tolerance of current setting 2.5%xSetting or 0.02In, whichever is greater
Time setting range 0.000~10.000s
Tolerance of time setting 1%xSetting + 40ms
Undervoltage setting range 01.732U2n
Residual voltage setting range 0U2n
Negative sequence voltage setting range 0U2n
Accuracy of voltage setting 2.5% or 0.01Un whichever is greater
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3 Operation Theory
PCS-915A Busbar Protection 3-a
Date: 2012-08-31
3 Operation Theory
Table of Contents
3 Operation Theory ............................................................................ 3-a
3.1 Overview .......................................................................................................... 3-1
3.2 Busbar Differential Protection ....................................................................... 3-2
3.2.1 Fault detector (FD) element................................................................................................. 3-3
3.2.2 Percentage differential element ........................................................................................... 3-4
3.2.3 Voltage controlled element of busbar differential protection (VCE_BBP) ........................... 3-6
3.2.4 Faulty busbar zone discrimination ....................................................................................... 3-7
3.2.5 Backup busbar differential elements ................................................................................... 3-8
3.2.6 Detection of CT saturation ................................................................................................... 3-8
3.2.7 External Block Signal ........................................................................................................... 3-9
3.2.8 Logic scheme ....................................................................................................................... 3-9
3.3 Bus Coupler/Section (BC/BS) Protection ..................................................... 3-11
3.3.1 BC/BS switch-onto-fault (SOTF) protection ....................................................................... 3-11
3.3.2 BC/BS overcurrent protection ............................................................................................ 3-12
3.3.3 BC/BS breaker failure protection (BFP) ............................................................................ 3-13
3.3.4 BC/BS end zone fault protection ....................................................................................... 3-14
3.3.5 BC/BS pole discrepancy protection (PD) .......................................................................... 3-15
3.4 Feeder breaker Failure Protection (BFP) .................................................... 3-16
3.4.1 Initiation contact ................................................................................................................. 3-16
3.4.2 Current criterion ................................................................................................................. 3-17
3.4.3 Voltage control element of breaker failure protection(VCE) .............................................. 3-17
3.4.4 Logic scheme ..................................................................................................................... 3-18
3.5 Identification of disconnector position ....................................................... 3-19
3.6 VT Circuit Supervision .................................................................................. 3-20
3.7 CT Circuit Supervision ................................................................................. 3-21
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3 Operation Theory
PCS-915A Busbar Protection 3-b
Date: 2012-08-31
3.7.1 CT circuit failure ................................................................................................................. 3-21
3.7.2 CT circuit abnormality ........................................................................................................ 3-21
3.8 BC breaker substitution ............................................................................... 3-21
List of Figures
Figure 3.1-1 Double-busbar arrangement ................................................................................. 3-2
Figure 3.2-1 Sketch diagram of double busbars with one bus section arrangement ......... 3-2
Figure 3.2-2 Operation characteristic of steady-state percentage restraint differential
element .................................................................................................................................. 3-5
Figure 3.2-3 Waveform of CT saturation during external fault ............................................... 3-9
Figure 3.2-4 Logic scheme of busbar differential protection ............................................... 3-10
Figure 3.3-1 Logic scheme of SOTF protection ..................................................................... 3-12
Figure 3.3-2 Logic scheme of overcurrent protection........................................................... 3-13
Figure 3.3-3 The logic scheme of BFP .................................................................................... 3-14
Figure 3.3-4 The logic scheme of end zone fault protection ................................................ 3-15
Figure 3.3-5 The logic scheme of pole discrepancy protection ........................................... 3-16
Figure 3.4-1 The logic scheme of BFP (for the bay that main transformer is not connected)
.............................................................................................................................................. 3-18
Figure 3.4-2 The logic scheme of BFP (for the bay that main transformer is connected) 3-19
Figure 3.8-1 BC breaker substituting through BB2 ............................................................... 3-22
Figure 3.8-2 BC breaker substituting through BB1 ............................................................... 3-23
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3 Operation Theory
PCS-915A Busbar Protection 3-1
Date: 2012-08-31
3.1 Overview
PCS-915 provides busbar differential protection (BBP), bus coupler/section protection (includes
overcurrent protection, switch-onto-fault protection, pole disagreement protection, end zone fault
protection and breaker failure protection), feeder breaker failure protection, CT circuit supervision
and VT circuit supervision.
The device can support several busbar arrangements, such as double-busbar arrangement,
single-busbar arrangement and single busbar with single bus section arrangement. The switch
method of each busbar arrangement is listed as below:
System settings
Busbar arrangement En_SingleBB En_SingleBB_with_SingleBS
Double-busbar 0 0
Single-busbar 1 0
Single busbar with single bus section 0 1
Please refer to Section 7.1 about detailed description of each system setting. For single busbar
with bus section arrangement, the system setting [Cfg_DS_BBx] (x=1, 2) is used to indicate which
busbar zone the feeder is connected to.
The device has 2 plug-in modules (protection DSP module and fault detector DSP module) to
perform calculation. The protection DSP module is responsible for calculation of protection
elements, and fault detector DSP module is responsible for calculation of fault detectors. Any fault
detector of fault detector DSP module picks up to provide positive supply of output relays. The
relays will trip only if the fault detector and the corresponding protection element operate
simultaneously. On the premise of 24 samples per cycle, all data measurement, calculation and
logic discrimination can be processed within one sampling period. The event recording and
protection logic calculation are completed simultaneously.
The following figure shows double busbars arrangement and application mode.
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3 Operation Theory
PCS-915A Busbar Protection 3-2
Date: 2012-08-31
*
BB2
BB1
Panel A
BC
* * * *
PCS-915
VT1
VT2
Figure 3.1-1 Double-busbar arrangement
3.2 Busbar Differential Protection
In order to be easy to explain the protection function and scheme, the first busbar is defined as
busbar No.1 (BB1) and the second busbar is defined as busbar No.2 (BB2). In the case of project
application, the number of each busbar can be set based on on-site case. The polarity marking of
feeder CT should be on the busbar side and the polarity of BC CT should be on the BB1 side.
Please refer to the sketch diagram of primary system Figure 3.2-1.
*
BB2
BB1
BC
* * * *
Discriminative
zone No.2
Discriminative
zone No.1Check zone
Figure 3.2-1 Sketch diagram of double busbars with one bus section arrangement
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3 Operation Theory
PCS-915A Busbar Protection 3-3
Date: 2012-08-31
Note!
The protective device only identifies the physical position of busbar, ignoring the number of
busbar, takes the busbar arrangement in Figure 3.2-1 as an example, the protective device
will refer the busbar of which the polarity of BC CT is towards as BB1.
The primary protection of PCS-915 is phase-segregated percentage restraint differential
protection. The differential circuits include check zone differential circuit and discriminating zone
differential circuits of each busbar zone. The check zone differential element is used to distinguish
between internal and external fault of the overall busbar system, it measures the current from all
the circuits connected to the busbar system except BC and BS. The discriminating zone
differential elements are used to select faulty zone by measuring the current of all the circuits
connected to individual zones of the busbar system separated by BC and BS.
Discriminating zone No.1 is defined as discriminating differential element of BB1. Discriminating
zone No.2 is defined as discriminating differential element of BB2.
3.2.1 Fault detector (FD) element
PCS-915 provides three independent FD elements for busbar differential protection, which are
DPFC voltage FD element, DPFC current FD element and differential current FD element. If any of
these three elements picks up, the positive supply to the output relays is then available and wait
for the tripping signal from busbar differential protection. The fault detector output signal will last
for 500ms after the corresponding fault detector element drop off.
1. DPFC voltage FD element
When DPFC voltage of any phase of any busbar is larger than the threshold, DPFC voltage FD
element picks up, the operating criterion is:
u>UFloat+0.05Un Equation 3.2-1
Where:
u: Instantaneous value of phase-to-phase DPFC voltage
UFloat: Float threshold value, automatically varied with the gradually voltage changing
0.05Un: Fixed threshold value, Un is the rated secondary phase-to-ground voltage.
If voltage is not sampled or VT circuit failure is detected, DPFC voltage FD element will quit
automatically.
2. DPFC current FD element
If DPFC check zone restraint current is larger than the threshold, DPFC current fault detector
element will operate, the operating criterion is:
si>SIFloat+0.5In Equation 3.2-2
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3 Operation Theory
PCS-915A Busbar Protection 3-4
Date: 2012-08-31
Where:
si: Instantaneous value of DPFC check zone restraint current of any phase (scalar sum of current
change of all circuits/bays for check zone)
SIFloat: Float threshold value, automatically varied with the gradually current changing
0.5In: Fixed threshold value, In is the rated secondary current of reference CT.
3. Differential current FD element
When any phase of the check zone differential current is larger than the setting, this element will
operate. The operating criterion is:
ID> [I_Pkp_Pcnt_BBP] Equation 3.2-3
Where:
ID: Differential phase current of check zone
[I_Pkp_Pcnt_BBP]: Current setting of busbar differential protection
3.2.2 Percentage differential element
The percentage restraint differential element includes steady-state percentage restraint differential
element and DPFC percentage restraint differential element.
Steady-state percentage restraint differential element
The differential current: ID =
m
1j
jI
The restraint current: IR =
m
1j
jI
The operating criterion is:
R
D
KI
]_Pcnt__[I
I
BBPPkpI
D
Equation 3.2-4
Where:
K: Restraint coefficient of steady-state differential element
Ij: The current of the j-th feeder (Feeder j) connected
[I_Pkp_Pcnt_BBP]: Current setting of busbar differential protection
The operation characteristic is shown as below.
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3 Operation Theory
PCS-915A Busbar Protection 3-5
Date: 2012-08-31
[I_Pkp_Pcnt_BBP]
Operation region
IR
ID
ID=IR
ID=kIR
Figure 3.2-2 Operation characteristic of steady-state percentage restraint differential element
To enhance the sensitivity of steady-state check zone differential element for a fault occurred in
the weak source bus zone when the BC breaker is open, dual restraint coefficients [0.5, 0.3] and
[0.6, 0.5] are adopted for steady-state check zone and discriminating zones respectively.
When one of the following conditions is fulfilled, the busbar steady-state percentage restraint
differential protection will operate.
1. Steady-state check zone differential element with high restraint coefficient (0.5) operates and
steady-state discriminating zone differential element with low restraint coefficient (0.5)
operates.
2. Steady-state check zone differential element with low restraint coefficient (0.3) operates and
steady-state discriminating zone differential element with high restraint coefficient (0.6)
operates.
DPFC percentage differential element
The DPFC percentage restraint differential element is adopted to enhance the performance of
busbar protection against high impedance fault and the influence of heavy loading condition. The
busbar DPFC differential protection is formed by DPFC percentage restraint differential element
and steady-state check zone percentage restraint differential element with fixed restraint
coefficient 0.2.
The DPFC differential current: ID =
m
1j
jI
The DPFC restraint current: IR =
m
1j
jI
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3 Operation Theory
PCS-915A Busbar Protection 3-6
Date: 2012-08-31
The operating criterion is:
R
/
D
RD
DPickupDFloatD
IKI
0.2II
III
Equation 3.2-5
Where:
K': DPFC restraint coefficient
Ij: DPFC current of the j-th feeder (Feeder j) connected
IDFloat: Float threshold value of DPFC check zone differential current
IDPickup: Fixed threshold value of DPFC check zone differential current, which derives from the
setting of [I_Pkp_Pcnt_BBP]
Similar to steady-state percentage restraint differential element, dual restraint coefficients are also
introduced to DPFC differential element. The restraint coefficients are fixed at [0.65, 0.3] and [0.65,
0.5] for DPFC check zone and discriminating zones respectively.
When the steady-state check zone percentage restraint differential element with fixed restraint
coefficient of 0.2 operates, if one of the following conditions is fulfilled, the busbar DPFC
percentage restraint differential protection will operate.
1. DPFC check zone percentage restraint differential element with high restraint coefficient (0.65)
operates and DPFC discriminating zone percentage restraint differential element with low
restraint coefficient (0.5) operates.
2. DPFC check zone percentage restraint differential element with low restraint coefficient (0.3)
operates and DPFC discriminating zone percentage restraint differential element with high
restraint coefficient (0.65) operates.
3.2.3 Voltage controlled element of busbar differential protection (VCE_BBP)
Voltage controlled element is used as an auxiliary condition.
The operating criteria are:
UP [V_UV_VCE_BBP] Equation 3.2-6
3U0 [V_ROV_VCE_BBP] Equation 3.2-7
U2 [V_NegOV_VCE_BBP] Equation 3.2-8
Where:
UP: Secondary rated phase-to-ground voltage
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3 Operation Theory
PCS-915A Busbar Protection 3-7
Date: 2012-08-31
3U0: Residual voltage (calculated internally)
U2: Negative sequence voltage
[V_UV_VCE_BBP]: Phase-to-ground voltage setting for blocking BBP
[V_ROV_VCE_BBP]: Residual voltage setting for blocking BBP
[V_NegOV_VCE_BBP]: Negative sequence voltage setting for blocking BBP
Busbar differential protection is always blocked by voltage control element. Busbar differential
protection can not operate to trip faulty busbar zone unless the voltage of corresponding busbar
zone met any of above criterions.
When the protective device is applied to an unearthed system, i.e. the system setting
[Opt_UnearthedSys_Mode] is set as 1, the criteria of voltage control element will be changed.
UPP [V_UV_VCE_BBP] Equation 3.2-9
U2[V_NegOV_VCE_BBP] Equation 3.2-10
Where:
UPP: Phase-to-phase voltage
U2: Negative sequence voltage
[V_UV_VCE_BBP]: Phase-to-phase voltage setting for blocking BBP
[V_NegOV_VCE_BBP]: Negative voltage setting for blocking BBP
3.2.4 Faulty busbar zone discrimination
The check zone differential element calculates the current from all circuits connected to the entire
busbar system except BC and BS to distinguish between internal and external fault. The
discriminating zone differential elements calculate the current of all the circuits connected to
individual zones via replica image of disconnector position to determine faulty zone.
When the operation criterion of check zone differential element (steady-state check zone
differential element is supervised by CT saturation detector 2 and DPFC check zone differential
element is supervised by CT saturation detector 1, to be described in the following section) and
any discriminating zone differential element is fulfilled, VCE_BBP of any busbar operates, the
busbar differential protection will operate to trip all bays connected to the faulty busbar.
The protection has a feature of inter-connection operation mode, the feature will be effective
automatically under the following conditions.
1. The binary input [EBI_IntLink_Mode] is energized or the virtual enable binary input
[VEBI_IntLink_Mode] is set as 1, it should be done when two bus zones are coupled together
and unable to detach for a particular system operation condition.
2. On-load transfer condition (when two busbar disconnectors of one feeder are closed at the
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3 Operation Theory
PCS-915A Busbar Protection 3-8
Date: 2012-08-31
same time).
Under the inter-connection operation mode, the discriminating zone differential elements measure
the current signals are the same as that of check zone differential element. The coupled busbars
will be tripped simultaneously when there is a fault.
3.2.5 Backup busbar differential elements
If only the check zone percentage restraint differential element (supervised by CT saturation
detector 2) operates, two stages of backup protection with fixed time delay are applied to trip the
corresponding circuit breakers. Stage 1 of backup protection will trip BC/BS (when VCE of any
busbar operates) and the feeders of which CT correction coefficient is not zero and does not have
disconnector position after 240ms. Stage 2 of backup protection will trip the feeders connected to
the busbar of which voltage clocking has been released and the feeders with current larger than
2*In (In: the rated secondary current of reference CT) after 480ms.
3.2.6 Detection of CT saturation
Two detectors are used to prevent unwanted tripping caused by severe CT saturation during
external close up fault. If the differential current is determined to be caused by CT saturation, the
device will block busbar differential protection to prevent mal-operation.
CT saturation detector 1
When DPFC voltage or current FD element operates, the adaptive weighted algorithm for CT
saturation detector will be activated. In case of busbar fault occurs, DPFC differential element will
operate almost at the same time with DPFC voltage FD element or DPFC current FD element,
whereas for external fault, DPFC differential element will not operate before CT saturation at the
fault incipient stage, it will only operate after DPFC voltage element and DPFC current element in
case CT is saturated. Adaptive weighted algorithm for CT saturation detector is derived from the
difference of operating time among these DPFC elements. In coordination with DPFC differential
element, it has performed excellently to distinguish between internal and external fault with CT
saturation.
CT saturation detector 2
Harmonic restraint element is used in CT saturation detector 2 by analyzing the waveforms of
differential current harmonics. The detector enables the busbar differential element to remain
stable for an external fault with CT saturation while to maintain fast tripping for the external fault
evolved to internal fault on the same phase.
The blocking signal of CT saturation detector 2 will only last for 500ms. After that the busbar
differential element is released to operate for complicated fault conditions and minimized affected
area. In practical cases, CT transient saturation will not be more than 500ms.
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3 Operation Theory
PCS-915A Busbar Protection 3-9
Date: 2012-08-31
Figure 3.2-3 Waveform of CT saturation during external fault
Above figure shows the current waveforms recorded in dynamic simulation with heavy CT
saturation during external phase-to-phase fault. Protection stability is well achieved in this extreme
case.
3.2.7 External Block Signal
PCS-915 provides a binary input [BI_Blk_BBP] to block BBP through external binary signal. If the
logic setting [En_BI_Blk_BBP] is set as 1, BBP will be blocked if the binary input [BI_Blk_BBP] is
energized. However, if the binary input [BI_Blk_BBP] is energized for longer than 1 second,
PCS-915 will issue an alarm [Alm_Blk_BBP] and the blocking for BBP is released.
3.2.8 Logic scheme
Figure 3.2-4 only takes BB1 as an example, the logic scheme of BB2 is similar to it.
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3 Operation Theory
PCS-915A Busbar Protection 3-10
Date: 2012-08-31
DPFC voltage FD element
&
&
DPFC current FD element
DPFC DIF 1
1
DPFC DIF
SP DIF (K=0.2)
500ms&
&
1
SP DIF 1 (K=0.2)
HM REL 1
500ms&
&
[En_BBP]
[EBI_BBP]
SP DIF 1
HM REL
SP DIF
VCE_BBP 1
VCE_BBP x
1
&
&
Op_TrpBB1_Pcnt_BBP
Op_TrpBC_BBP
CT
sa
tura
tion
de
tecto
r 1
240ms[Op_Dly1_Pcnt_BBP]&
1
480ms[Op_Dly2_Pcnt_BBP]
[VEBI_BBP]
VCE_BBP x & BBx is in service
& Op_TrpBB1_DPFC_BBP
SP DIF x
CT circuit failure
[BI_Blk_BBP]
0 1s[En_BI_Blk_BBP]
&
1
Figure 3.2-4 Logic scheme of busbar differential protection
Please refer to Chapter Settings about the description of each setting.
Where:
DPFC current FD element: DPFC current fault detector element, please refer to Section 3.2.1.
DPFC voltage FD element: DPFC voltage fault detector element, please refer to Section 3.2.1.
DPFC DIF: DPFC percentage differential element for check zone
DPFC DIF1: DPFC percentage differential element for bus zone No.1
SP DIF: Steady-state percentage differential element for check zone
SP DIF1: Steady-state percentage differential element for bus zone No.1
SP DIF2: Steady-state percentage differential element for bus zone No.2
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3 Operation Theory
PCS-915A Busbar Protection 3-11
Date: 2012-08-31
HM REL: Harmonic release element for check zone
HM REL1: Harmonic release element for bus zone No.1
VCE_BBP 1: Voltage controlled element of BBP of BB1 operates
VCE_BBP x: Voltage controlled element of BBP of any busbar operates
VCE_BBP x & BBx is in service: VCE_BBP of any energized busbar operates
Op_Dly1_Pcnt_BBP: Stage 1 of backup busbar differential protection operates
Op_Dly2_Pcnt_BBP: Stage 2 of backup busbar differential protection operates
Op_TrpBB1_DPFC_BBP: DPFC percentage differential protection operates to trip BB1
Op_TrpBB1_Pcnt_BBP: Steady-state percentage differential protection operates to trip BB1
Op_TrpBC_BBP: BBP operates to trip BC breaker
3.3 Bus Coupler/Section (BC/BS) Protection
PCS-915 provides switch-onto-fault protection, breaker failure protection, end zone fault protection,
pole discrepancy protection and overcurrent protection for BC/BS.
3.3.1 BC/BS switch-onto-fault (SOTF) protection
After any busbar has been maintained and before being put into operation, it is needed to close
BC/BS and make the energizing test firstly. During the energizing process, if any fault occurs in the
energized busbar, SOTF protection will operate to trip BC/BS to clear the fault.
SOTF protection will be enabled for 300ms if any of the following conditions is met.
1. The status of the binary input [BI_52b_BC] changes from 1 to 0.
2. The binary input [BI_52b_BC] is energized and BC current changes from being smaller than
0.04IN to being greater than 0.04IN.
3. The binary input [BI_52b_BC] is energized and BB1 and BB2 are in service.
The logic scheme of SOTF protection is shown as Figure 3.3-1.
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3 Operation Theory
PCS-915A Busbar Protection 3-12
Date: 2012-08-31
Ia_BC>0.04IN
&
BB2 is in service
BB1 is in service
1
Ib_BC>0.04IN
&
Ic_BC>0.04IN
Ia_BC>[I_OC_SOTF_BC]
&
[En_SOTF_BC]
Ib_BC>[I_OC_SOTF_BC]
Ic_BC>[I_OC_SOTF_BC]
&
Op_TrpBC_SOTF
[EBI_SOTF_BC]
&
1
0 300ms
&
[VEBI_SOTF_BC]
[BI_52b_BC]
[BI_52a_BC]
&
Figure 3.3-1 Logic scheme of SOTF protection
Please refer to Chapter Settings about the description of corresponding settings.
Where:
BB1(2) is in service: If busbar phase voltage of BB1(2) is greater than 0.3UN or current of any
connected bay is larger than 0.04IN, BB1(2) is thought as in service.
[EBI_SOTF_BC]: The binary input of enabling BC SOTF protection
[BI_52b_BC]: Normally closed auxiliary contact of BC/BS
[BI_52a_BC]: Normally open auxiliary contact of BC/BS
Op_TrpBC_SOTF: BC/BS SOTF protection operates to trip BC/BS breaker
Ia_BC: Phase A current of BC/BS
Ib_BC: Phase B current of BC/BS
Ic_BC: Phase C current of BC/BS
3.3.2 BC/BS overcurrent protection
When temporary usage of the BC/BS breaker to substitute a feeder circuit breaker, typically for the
maintenance of the latter. Overcurrent protection can be provided for this application.
The logic scheme of overcurrent protection is shown as Figure 3.3-2.
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3 Operation Theory
PCS-915A Busbar Protection 3-13
Date: 2012-08-31
Ia_BC>[I_OC_BC]
Ib_BC>[I_OC_BC]
Ic_BC>[I_OC_BC]
1
3I0_BC>[I_ROC_BC]
[En_OC_BC]
[EBI_OC_BC]
&
&[t_OC_BC]
Op_TrpBC_OC
[VEBI_OC_BC]
&[t_OC_BC]
Op_TrpBC_ROC
Figure 3.3-2 Logic scheme of overcurrent protection
Please refer to Chapter Settings about the description of corresponding settings.
Where:
[EBI_OC_BC]: The binary input of enabling BC/BS overcurrent protection
Op_TrpBC_OC: Phase overcurrent protection of BC/BS operates to trip BC/BS
Op_TrpBC_ROC: Zero-sequence overcurrent protection of BC/BS operates to trip BC/BS
3I0_BC: Residual current of BC/BS
3.3.3 BC/BS breaker failure protection (BFP)
When tripping signal has been delivered to BC/BS breaker, while the breaker is failed to open
since the BC/BS current is still larger than the setting [I_BFP_BC] with a specific time delay, BFP
will operate to trip all feeders connected to both busbars with the time delay of [t_TrpBB_BFP_BC].
BC/BS breaker failure protection is blocked by voltage controlled element of BBP (Please refer to
Section 3.2.3).
There are several options to initiate BFP:
1. BBP
2. Breaker failure initiating binary inputs are energized
The logic scheme of BC/BS BFP is shown as Figure 3.3-3.
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3 Operation Theory
PCS-915A Busbar Protection 3-14
Date: 2012-08-31
Ia_BC>[I_BFP_BC]
Ib_BC>[I_BFP_BC]
Ic_BC>[I_BFP_BC]
1
BBP Trip BB2
1
&
Op_BFP_BB1
VCE_BBP 1
VCE_BBP 2
[BI_BFI_BC_2]
[t_TrpBB_BFP_BC]
1BBP Trip BB1
BBP Trip BC
&
& Op_BFP_BB2[t_TrpBB_BFP_BC]
&
[BI_BFI_BC_1]
Figure 3.3-3 The logic scheme of BFP
Please refer to Chapter Settings about the description of corresponding settings.
Where:
BI_BFI_BC_1: Initiating contact of breaker failure protection for BC/BS
BI_BFI_BC_2: Any binary input of the binary module located in slot No.09 is energized (in order to
prevent BC/BS BFP from mal-operation due to hardware fault of the binary input module.
VCE_BBP 1: voltage controlled element of BBP of BB1, Please refer to Section 3.2.3)
VCE_BBP 2: voltage controlled element of BBP of BB2, Please refer to Section 3.2.3)
3.3.4 BC/BS end zone fault protection
If a fault occurs between BC/BS breaker and BC/BS CT, the fault can not be cleared after busbar
on the breaker side is tripped. In order to clear the fault quickly, a dedicated end zone fault
protection is provided.
After busbar differential protection sends the command to trip BC/BS, if the BC/BS breaker has
been tripped but the BC/BS current is detected, the end zone fault protection will operate and the
BC/BS current will be excluded from discriminative zone percentage differential circuit with a time
delay of 150ms.
If both busbars are in service and BC/BS breaker is open, in order to prevent both busbars from
being tripped during end fault, the BC/BS current will be excluded from discriminative zone
percentage differential circuit in this case.
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3 Operation Theory
PCS-915A Busbar Protection 3-15
Date: 2012-08-31
BB No.1
BC Breaker
BB No.2
BC CT
Dead zone
The logic scheme of end zone fault protection is shown as Figure 3.3-4.
&
BB2 is in service
BB1 is in service
&Ia_BC>0.04IN
Ib_BC>0.04IN
Ic_BC>0.04IN
1
Ia_BC>0.1IN
Ib_BC>0.1IN
Ic_BC>0.1IN
1
0 400ms
&
&
IBC is excluded from discriminative
zone percentage differential circuit[BI_52b_BC]
[BI_52a_BC]
&
1
[EBI_Decoupled_BC]
&
SP Trip BC
SP DIF
&
150ms
Figure 3.3-4 The logic scheme of end zone fault protection
Please refer to Chapter Settings about the description of corresponding settings.
BB1(2) is in service: If busbar phase voltage of BB1(2) is greater than 0.3UN or current of any
connected bay is larger than 0.04IN, BB1(2) is thought as in service.
SP DIF: Steady-state percentage differential element for check zone
SP: Steady-state percentage differential element
3.3.5 BC/BS pole discrepancy protection (PD)
Pole discrepancy protection is designed for the case that pole discrepancy of BC/BS breaker is
detected due to one phase of BC/BS breaker is open.
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3 Operation Theory
PCS-915A Busbar Protection 3-16
Date: 2012-08-31
Pole discrepancy protection is initiated by series-parallel connected auxiliary contacts of BC/BS
breaker i.e. the binary input [BI_PD_BC].
In addition of series-parallel connected auxiliary contacts of BC/BS breaker, residual and negative
sequence current are used as auxiliary criteria.
The logic scheme of pole discrepancy protection is shown as Figure 3.3-5.
&
[BI_PD_BC]
3I0_BC>[I_ROC_PD_BC]
I2_BC>[I_NegOC_PD_BC]
1
[EBI_PD_BC]
[t_PD_BC]
[En_PD_BC]
&
&
Op_BC_PD
52b_A 52a_A
[BI_PD_BC]
52b_B
52b_C
52a_B
52a_C
[VEBI_PD_BC]
Figure 3.3-5 The logic scheme of pole discrepancy protection
Please refer to Chapter Settings about the description of corresponding settings.
BI_PD_BC: pole discrepancy binary input of BC/BS
Op_BC_PD: pole discrepancy protection of BC/BS operates to trip BC/BS breaker
3I0_BC, I2_BC: Residual and negative sequence current of BC/BS.
3.4 Feeder breaker Failure Protection (BFP)
Breaker failure protection is available for each feeder. When a breaker is determined failed to trip,
the breaker failure protection will trip BC/BS after time delay of [t_TrpBC_BFP] and all feeders
after time delay of [t_TrpBB_BFP].
3.4.1 Initiation contact
For each bay, BFP can be initiated externally via binary inputs by phase-segregated tripping
contacts or three-phase tripping contacts of protective device for the corresponding bay.
1. Phase-segregated tripping contact
[BI_A_BFI_Bayxx]: The binary input for initiating BFP of phase A
[BI_B_BFI_Bayxx]: The binary input for initiating BFP of phase B
[BI_C_BFI_Bayxx]: The binary input for initiating BFP of phase C
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3 Operation Theory
PCS-915A Busbar Protection 3-17
Date: 2012-08-31
xx=04~13, 16~25.
2. Three-phase tripping contact
[BI_BFI_Bayxx]: The binary input for initiating BFP of three phases.
xx=02~25.
It is recommended that main transformer should be connected to the bays that only have the
dedicated opto-coupler used by three-phase tripping contact (bay 02, 03, 14, 15). For each bay
that main transformer is connected, a binary input for releasing voltage blocking element
[BI_Rls_VCE_BBP_Trans] is provided. For a transformer, when a fault occurs at the low-voltage
side but the breaker of the high-voltage side fails, the voltage condition of HV side busbar maybe
not met, so the other tripping contact can be connected to the the binary input
[BI_Rls_VCE_BBP_Trans] to release voltage blocking element.
If the bay is tripped by BBP, the breaker failure protection of this bay will be initiated.
For the bay that main transformer is connected, BFP operates can initiate intertripping to trip
breakers of other sides of the main transformer.
3.4.2 Current criterion
1. Current criterion 1
Phase current is greater than the setting [I_OC_BFP_Bayxx]
2. Current criterion 2
Residual current is greater than the setting [I_ROC_BFP_Bayxx]
3. Current criterion 3
Negative sequence current is greater than the setting i.e. [I_NegOC_BFP_Bayxx]
3.4.3 Voltage control element of breaker failure protection(VCE)
Voltage control element is used as an auxiliary condition.
The criteria are:
UP[V_UV_VCE_BFP] Equation 3.4-1
3U0[V_ROV_VCE_BFP] Equation 3.4-2
U2[V_NegOV_VCE_BFP] Equation 3.4-3
Where:
UP: Secondary rated phase-to-ground voltage
3U0: Residual voltage
U2: Negative sequence voltage
[V_UV_VCE_BFP]: Phase voltage setting for blocking BFP
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3 Operation Theory
PCS-915A Busbar Protection 3-18
Date: 2012-08-31
[V_ROV_VCE_BFP]: Residual voltage setting for blocking BFP
[V_NegOV_VCE_BFP]: Negative sequence voltage setting for blocking BFP
When the protective device is applied to an unearthed system, i.e. the system setting
[Opt_UnearthedSys_Mode] is set as 1, the criteria of voltage control element will be changed.
UPP [V_UV_VCE_BFP] Equation 3.4-4
U2[V_NegOV_VCE_BFP] Equation 3.4-5
Where:
UPP: Phase-to-phase voltage
U2: Negative sequence voltage
[V_UV_VCE_BFP]: Phase-to-phase voltage setting for blocking BFP
[V_NegOV_VCE_BFP]: Negative sequence voltage setting for blocking BFP
3.4.4 Logic scheme
The logic scheme of BFP is shown as Figure 3.4-1.
Ia_Bayxx>[I_OC_BFP_Bayxx]
Ib_Bayxx>[I_OC_BFP_Bayxx]
Ic_Bayxx>[I_OC_BFP_Bayxx]
1
[BI_C_BFI_Bayxx]
1&
[BI_A_BFI_Bayxx]
[BI_B_BFI_Bayxx]
[En_ROC_BFP_Bayxx]
&
&
VCE 1
VCE 2
3I0_Bayxx>[I_ROC_BFP_Bayxx]
I2_Bayxx>[I_NegOC_BFP_Bayxx]
[En_NegOC_BFP_Bayxx]
&
&
&
&BBP operates to trip feeder xx
1
1
&
1
Disconnector position of BB1
Disconnector position of BB2
&
&
&
&
&
[En_BFP]
[EBI_BFP] &
[VEBI_BFP]Op_Retrip_Bayxx
Op_TrpBC_BFP
Op_BFP_BB1 [t_TrpBB_BFP]
[t_ReTrp_BFP]
[t_TrpBC_BFP]
Op_Retrip_Bayxx
Op_TrpBC_BFP
Op_BFP_BB2 [t_TrpBB_BFP]
[t_ReTrp_BFP]
[t_TrpBC_BFP]
[BI_BFI_Bayxx]
1
Figure 3.4-1 The logic scheme of BFP (for the bay that main transformer is not connected)
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3 Operation Theory
PCS-915A Busbar Protection 3-19
Date: 2012-08-31
Ia_Bayxx>[I_OC_BFP_Bayxx]
Ib_Bayxx>[I_OC_BFP_Bayxx]
Ic_Bayxx>[I_OC_BFP_Bayxx]
1
1&
&
[En_BFP]
[En_ROC_BFP_Bayxx]
&
&
VCE 1
VCE 2
3I0_Bayxx>[I_ROC_BFP_Bayxx]
I2_Bayxx>[I_NegOC_BFP_Bayxx]
[En_NegOC_BFP_Bayxx]
[BI_Rls_VCE_BFP_Trans]
&
&
1
[EBI_BFP]
Disconnector position of BB1
Disconnector position of BB2
1
1
&
&
&
&
&
[t_TrpBC_BFP]
[t_TrpBB_BFP]
[t_ReTrp_BFP]
[t_TrpBB_BFP]
[t_ReTrp_BFP]
[t_TrpBC_BFP]
[VEBI_BFP]
1
BBP operates to trip feeder xx
[BI_BFI_Bayxx]
Op_ReTrp_Bayxx
Op_TrpBC_BFP
Op_BFP_BB1
Op_IntTrp_BFP_Bayxx
Op_ReTrp_Bayxx
Op_TrpBC_BFP
Op_BFP_BB2
Op_IntTrp_BFP_Bayxx
Figure 3.4-2 The logic scheme of BFP (for the bay that main transformer is connected)
Please refer to Chapter Settings about the description of corresponding settings.
3I0_Bayxx: Residual current of bay xx
I2_Bayxx: The negative sequence current of bay xx
Ia_Bayxx: The phase A current of bay xx
Ib_Bayxx: The phase B current of bay xx
Ic_Bayxx: The phase C current of bay xx
Disconnector position of BBx: bay xx is connected to BBx (according to disconnector position of the
bay)
3.5 Identification of disconnector position
In a substation with double busbars layout, feeders may be switched from one busbar to the other
busbar during operation, and it is necessary to identify real time topology of the busbar correctly.
Disconnector positions are adopted for this identification and self-diagnosis is carried out
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3 Operation Theory
PCS-915A Busbar Protection 3-20
Date: 2012-08-31
simultaneously. If there is current flowing in a bay but the bay has no disconnector positions for
dual busbars, the protective device can remember the original disconnector position. An
abnormality of disconnector position is detected and disconnector position alarms [Alm_DS_Bayxx]
will be issued with a specific time delay in any of the following cases (xx: from 02 to 25).
1. Disconnector position is changed. The operator should check it and confirm whether it is
correct. The alarm can be reset by energizing the binary input [BI_ConfirmDS].
2. If both disconnectors to BB1 and BB2 of a bay are closed, an alarm signal [Alm_IntLink] will
be issued. The alarm can not be reset by energizing the binary input [BI_ConfirmDS].
3. There is current detected in a bay but the bay has no disconnector positions for dual busbars.
The alarm can not be reset by energizing the binary input [BI_ConfirmDS]. In this case, the
protective device can remember the original disconnector position of the bay, and check its
validity based on the current distribution of system.
4. If discriminating zone differential current is greater than 0.04IN due to the wrong disconnector
position, an alarm will be issued with a time delay and the device can identify the right
disconnector position based on the current distribution of system.
Besides, in order to prevent the feeder from missing-operation because the bay has no
disconnector position, no matter which busbar zone does the fault occur in, the bays whose CT
correction coefficient is not zero but no disconnector position can be detected will be tripped.
Note!
When disconnector position alarm is issued, the operator must check the actual condition
at first and then energize the binary input [BI_ConfirmDS] to reset the alarm if it is correct.
Usually a button on the panel is provided, pressing the button will result in energizing the
binary input [BI_ConfirmDS].
3.6 VT Circuit Supervision
1. If three times busbar negative sequence voltage (3U2) is larger than 0.2UN (UN: the secondary
rated phase-to-ground voltage of VT), an alarm [Alm_VTS_BB1] or [Alm_VTS_BB2] will be
issued with a time delay of 1.25s.
2. If any busbar is in service and the sum of the amplitude of busbar three-phase voltage
(|UA|+|UB|+|UC|) is smaller than UN, an alarm [Alm_VTS_BB1] or [Alm_VTS_BB2] will be
issued with a time delay of 1.25s.
3. When the logic setting [Opt_UnearthedSys_Mode] is set as 1, if three times busbar negative
sequence voltage (3U2) is greater than 0.2UN or any phase-to-phase voltage is smaller than
0.7UN_PP (UN_PP: the secondary rated phase-to-phase voltage of VT), an alarm
[Alm_VTS_BB1] or [Alm_VTS_BB2] will be issued with a time delay of 1.25s.
If the fault detector element picks up due to a disturbance in the system, the VT circuit supervision
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3 Operation Theory
PCS-915A Busbar Protection 3-21
Date: 2012-08-31
will be disabled. When VCE of a busbar operates, an alarm [Alm_Pkp_VCE_BB1] or
[Alm_Pkp_VCE_BB2] will be issued with a time delay of 3s. When the three-phase voltage returns
to normal condition, the alarm will be reset and the protective device will return to normal operation
condition automatically with a time delay of 10s.
3.7 CT Circuit Supervision
3.7.1 CT circuit failure
1. If check zone differential current is greater than the setting [I_Alm_CTS], an alarm [Alm_CTS]
will be issued with a time delay of 5s and BBP will be blocked. The alarm can be reset only by
pressing reset button on the panel to energize binary input [BI_RstTarg] after the CT circuit
returns to normal condition.
2. If check zone differential current is smaller than the setting i.e. [I_Alm_CTS] and both
discriminating zone currents are greater than [I_Alm_CTS], an alarm [Alm_CTS_BC] will be
issued with a time delay of 5s and BBP will not be blocked but single busbar mode will be
enabled automatically. Under this situation, if any internal fault occurs, faulty busbar will not
be identified. The alarm can be reset only by pressing reset button on the panel to energize
the binary input [BI_RstTarg] even the CT circuit returns to normal condition.
When VCE of any busbar operates, CT circuit failure will not be detected.
3.7.2 CT circuit abnormality
1. If check zone differential current is greater than the setting i.e. [I_Alm_SensCTS], an alarm
[Alm_SensCTS] will be issued with a time delay of 5s. The alarm can be reset only by
pressing reset button on the panel to energize the binary input [BI_RstTarg] after the CT
circuit returns to normal condition.
2. If check zone differential current is smaller than the setting [I_Alm_SensCTS] and both
discriminating zone currents are greater than [I_Alm_SensCTS], an alarm
[Alm_SensCTS_BC] will be issued with a time delay of 5s. The alarm can be reset only by
pressing reset button on the panel to energize the binary input [BI_RstTarg] after the CT
circuit returns to normal condition.
3. BBP will not be blocked when CT circuit is abnormal.
3.8 BC breaker substitution
If BC breaker is used temporarily to substitute one of feeder breakers through transfer bus, the
binary input [EBI_BT_BC] should be energized. The binary input [EBI_NegPolar_CT_BT] should
be energized or de-energized according to the busbar arrangement. The polarity mark of feeder
CT is on the busbar side, if the polarity mark of the substituted BC CT is on the busbar side, the
binary input [EBI_NegPolar_CT_BT] should be de-energized and BC current will be calculated in
check zone differential current and discriminating zone differential current. If the polarity mark of
the substituting BC CT is on the feeder side, the binary input [EBI_NegPolar_CT_BT] should be
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3 Operation Theory
PCS-915A Busbar Protection 3-22
Date: 2012-08-31
energized and negative value of BC current will be calculated in check zone differential current
and discriminating zone differential current.
If BC breaker is used temporarily to substitute one of feeder breakers, the BC current will be taken
as the current of the substituted feeder, whether the positive value or the negative value of the
substituting BC current is calculated in check zone differential current and discriminating zone
differential current depends on the status of the binary input [EBI_NegPolar_CT_BT].
If the normally open auxiliary contact of substituting disconnector of BBx [BI_52a_DSBBx_BT] is
energized, the BC breaker is substituting through BBx, and the BC current will be calculated in
discriminating zone differential current of BBx.
When BC breaker is used to substitute any of feeder breakers, some protection elements (such as
SOTF protection, EFP and BFP) of BC will quit automatically, but overcurrent protection and pole
disagreement protection are still reserved, which can be used as the protection function of the
substituted feeder. In addition, some functions for BC breaker is used as a tie breaker connecting
two busbars are also quit (such as: tripping BC breaker when busbar internal fault happens).
Note!
[EBI_NegPolar_CT_BT] should be energized prior to [EBI_BT_BC].
1. Energizing the binary input [EBI_NegPolar_CT_BT]
*
BB2
BB1
BC
* * * *
Transfer Busbar
Figure 3.8-1 BC breaker substituting through BB2
The polarity mark of BC CT is on the feeder side, the binary input [EBI_NegPolar_CT_BT] should
be energized. Negative value of BC current will be calculated in check zone differential current and
discriminating zone differential current of BB2.
2. De-energizing the binary input [EBI_NegPolar_CT_BT]
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3 Operation Theory
PCS-915A Busbar Protection 3-23
Date: 2012-08-31
*
BB2
BB1
BC1
* * * *
Transfer Busbar
Figure 3.8-2 BC breaker substituting through BB1
The polarity mark of BC CT is on the busbar side, the binary input [EBI_NegPolar_CT_BT] should
not be energized. Positve value of BC current will be calculated in check zone differential current
and discriminating zone differential current of BB1.
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3 Operation Theory
PCS-915A Busbar Protection 3-24
Date: 2012-08-31
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4 Supervision
PCS-915A Busbar Protection 4-a
Date: 2012-08-31
4 Supervision
Table of Contents
4 Supervision ..................................................................................... 4-a
4.1 Overview .......................................................................................................... 4-1
4.2 Protective Device Supervision ....................................................................... 4-1
4.2.1 Hardware supervision .......................................................................................................... 4-1
4.2.2 Opto-coupler Power Supervision ......................................................................................... 4-1
4.2.3 Binary output supervision .................................................................................................... 4-1
4.2.4 Binary input supervision ...................................................................................................... 4-1
4.2.5 Setting supervision .............................................................................................................. 4-2
4.2.6 Test Mode Supervision ........................................................................................................ 4-2
4.2.7 Hardware Configuration Supervision................................................................................... 4-2
4.3 AC Circuit Supervision ................................................................................... 4-2
4.3.1 Voltage and current drift supervision and auto-adjustment ................................................. 4-2
4.3.2 Sample supervision ............................................................................................................. 4-2
4.4 Secondary Circuit Supervision ...................................................................... 4-2
4.4.1 Voltage Transformer Supervision (VTS) .............................................................................. 4-2
4.4.2 Current Transformer Supervision (CTS) ............................................................................. 4-2
4.4.3 Disconnector position supervision ....................................................................................... 4-3
4.4.4 BC breaker supervision ....................................................................................................... 4-3
4.5 Handle Alarm ................................................................................................... 4-3
4.5.1 List of self-supervision report............................................................................................... 4-3
4.5.2 Self-Supervision Alarm List.................................................................................................. 4-7
4.5.3 Repairmen suggestion of self-supervision report ............................................................... 4-11
Table of Tables
Table 4.5-1 Self-supervision report ........................................................................................... 4-3
Table 4.5-2 Equipment self-check alarm list ................................................................................ 4-7
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4 Supervision
PCS-915A Busbar Protection 4-b
Date: 2012-08-31
Table 4.5-3 Repairmen suggestion .......................................................................................... 4-11
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4 Supervision
PCS-915A Busbar Protection 4-1
Date: 2012-08-31
4.1 Overview
PCS-915 is a microprocessor based busbar protection which can provide successive automatic
supervision to the protected object to ensure the power system can quickly restore from any fault
to normal state. When the device is in energizing process before the LED HEALTHY is lightened,
operators need to check the device operating state to ensure the automatic supervision function
can work normally.
The device will be blocked if there is any severe problem occurs in the hardware module or
software program. Before reboot the relay, users are recommended to solve the problem or return
the feedbacks to NR.
When a failure is detected in the system, the fault message will be displayed on the LCD and the
corresponding LED will be lightened. Meanwhile, the corresponding alarm output contacts will be
energized and the failure alarm will be recorded and stored in the device. Users can either view
the fault report directly on LCD or print out the report.
The automatic supervision of PCS-915 has advantages in independent operation to the protection
functions and is capable to identify the fault location when the fault occurs in the system.
4.2 Protective Device Supervision
4.2.1 Hardware supervision
The automatic supervision function can provide monitoring of all chips on protection DSP module
and fault detector DSP module to prevent any damaged or errors during the normal operation. The
alarm signals [Alm_DSP_ProtBrd] or [Alm_DSP_FDBrd] will be issued if any damages or errors
are dectected and the device will be blocked.
4.2.2 Opto-coupler Power Supervision
The automatic supervision can continuously monitor the positive power supply of opto-coupler, if a
failure or damage is detected, then the alarm signal [Alm_Pwr_BI_Bxx] will be issued (xx is the slot
No. of corresponding binary input module).
4.2.3 Binary output supervision
The state of binary outputs of each BO module is continually monitored. If any abnormality is
detected, the alarm signals [Alm_Output_Bxx] will be issued with device being blocked (xx is the
slot No. of corresponding BO module).
4.2.4 Binary input supervision
The state of binary inputs detected by protection DSP module and fault detector DSP module
should be the same. Otherwise, the protective device will be blocked.
If binary input [BI_Blk_BBP] is energized for over 1s, the alarm [Alm_Blk_BBP] will be issued and
the blocking for BBP will be released.
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4 Supervision
PCS-915A Busbar Protection 4-2
Date: 2012-08-31
If any binary input for initiating feeder BFP is energized for over 10s, the alarm
[Alm_PersistFD_BFP] will be issued with BFP blocked.
4.2.5 Setting supervision
PCS-915 has 10 setting groups, while only one group is active at one time. The settings of active
setting group are checked, if any is out of setting scopes, a corresponding alarm signal
[Alm_Setting_Out-of-Range] will be issued with the protective device be blocked.
If the EEPROM on protection DSP module or fault detector DSP module is damaged, it will lead to
any summation error of all setting groups, the alarms [Alm_Setting] and [Alm_Setting_FDBrd] or
[Alm_Setting_ProtBrd] will be issued with the protective device blocked.
4.2.6 Test Mode Supervision
When protection equipment is set to test mode by configuring the corresponding logic setting, the
alarm signal [Alm_BO_Test] is issued without blocking equipment.
4.2.7 Hardware Configuration Supervision