secondary electrial system maintenance manual qn1 sec g 04 t

7/28/2019 Secondary Electrial System Maintenance Manual QN1 SEC G 04 T

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QUANG NINH THERMAL POWER J OINT STOCK COMPANY

2300 MWSECONDARY ELECTRICAL SYSTEM MAINTENANCE MANUAL

Date: 2008-10-20 No.:QN1-SEC-G-04-TP-008 Rev. : A1

SECONDARY ELECTRICAL SYSTEM

MAINTENANCE

MANUAL


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Date: 2008-10-20 No.:QN1-SEC-G-04-TP-008 - 1 - Rev. : A

INDEX

1 MAINTENANCE OF T60 DIGITAL TRANSFORMER MANAGEMENT RELAY ..........................- 1 -

1.1SCOPE..................................................................................................................................................... -1-

1.2 GENERAL DESCRIPTION AND TECHNICAL SPECIFICATION OF T60 DIGITAL

TRANSFORMER MANAGEMENT RELAY..............................................................................................- 1 -

1.2.1GENERAL DESCRIPTION....................................................................................................................... -1-

1.2.2GENERAL DESCRIPTION ANDTECHNICAL SPECIFICATION OFT60RELAY ............................................ -2-

1.3REPAIRPERIOD AND ITEMS..................................................................................................................... -9-1.4MAINTENANCE OF GENERATOR-TRANSFORMERUNIT PROTECTION..................................................... -12-

1.4.1MAINTENANCEPREPARATION............................................................................................................ -12-

1.4.2APPEARANCE ANDWIRING INSPECTION ............................................................................................ -13-

1.4.3INSPECTION OF MECHANICAL PART................................................................................................... -13-

1.4.4INSPECTION ANDCLEANING OF SECONDARY WIRING INSIDE PROTECTION SCREEN .......................... -14-

1.4.5INSULATIONRESISTANCETESTING.................................................................................................... -14-

1.4.6INITIAL POWER-ON INSPECTION ........................................................................................................ -14-

1.4.7INSPECTION OF FEEDACVOLTAGE AND CURRENT............................................................................ -21-

1.4.8CALIBRATION OF PROTECTION SETTINGS.......................................................................................... -22-

1.4.9FULL GROUPTEST............................................................................................................................. -26-

1.4.10CIRCUIT BREAKER DRIVETEST....................................................................................................... -26-

1.4.11CHECK OFALL SETTINGS ANDSYSTEM SETUP ................................................................................ -26-

1.4.12ON-LOADTEST................................................................................................................................ -26-

2 MAINTENANCE OF G60 DIGITAL TRANSFORMER MANAGEMENT RELAY........................- 28 -

2.1SCOPE................................................................................................................................................... -28-

2.2GENERAL DESCRIPTION ANDTECHNICAL SPECIFICATION OF G60DIGITALTRANSFORMERMANAGEMENT

RELAY ........................................................................................................................................................ -28-

2.2.1GENERAL DESCRIPTION..................................................................................................................... -28-

2.2.2GENERAL DESCRIPTION ANDTECHNICAL SPECIFICATION OF G60RELAY .......................................... -29-

2.3REPAIRPERIOD AND ITEMS................................................................................................................... -38-

4.CALIBRATION OF OVERCURRENT COMPONENT .......................................................................- 39 -

2.4MAINTENANCE OF G60RELAY ............................................................................................................. -41-





2.4.5INSULATIONRESISTANCETESTING.................................................................................................... -43-2.4.6INITIAL POWER-ON INSPECTION ........................................................................................................ -43-


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2.4.8CALIBRATION OF PROTECTION SETTINGS.......................................................................................... -51-

2.4.9FULL GROUPTEST............................................................................................................................. -58-



2.4.12ON-LOADTEST................................................................................................................................ -59-

3 MAINTENANCE OF F35 DITIGAL MULTIPL E FEEDER MANAGEMENT RELAY .................- 60 -

3.1SCOPE................................................................................................................................................... -60-

3.2GENERAL DESCRIPTION ANDTECHNICAL SPECIFICATION..................................................................... -60-


3.2.2GENERAL DESCRIPTION ANDTECHNICAL SPECIFICATION.................................................................. -60-


3.4MAINTENANCE OF GENERATOR-TRANSFORMERUNIT PROTECTION..................................................... -70-








3.4.8CALIBRATION OF PROTECTION SETTINGS.......................................................................................... -81-3.4.9FULL GROUPTEST............................................................................................................................. -82-



3.4.12ON-LOADTEST................................................................................................................................ -83-

4 MAINTENANCE OF T35 TRANSFORMER MANAGEMENT RELAY ..........................................- 84 -

4.1SCOPE................................................................................................................................................... -84-

4.2GENERAL DESCRIPTION ANDTECHNICAL SPECIFICATION OFT35TRANSFORMER MANAGEMENTRELAY ...-

84-


4.2.2GENERAL DESCRIPTION ANDTECHNICAL SPECIFICATION.................................................................. -84-


4.4MAINTENANCE OF GENERATOR-TRANSFORMERUNIT PROTECTION..................................................... -93-







4.4.7INSPECTION OF FEEDACVOLTAGE AND CURRENT.......................................................................... -102-


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4.4.8CALIBRATION OF PROTECTION SETTINGS........................................................................................ -104-

4.4.9FULL GROUPTEST........................................................................................................................... -105-

4.4.10CIRCUIT BREAKER DRIVETEST..................................................................................................... -106-

4.4.11CHECK OFALL SETTINGS ANDSYSTEM SETUP .............................................................................. -106-

4.4.12ON-LOADTEST.............................................................................................................................. -106-

5 MAINTENANCE OF MFC2000-2 TYPE MICROCOMPUTER-BASED AUXILIARY POWER

QUICK SWITCHING DEVICE .............................................................................................................. - 107 -

5.1SCOPE................................................................................................................................................. -107-

5.2GENERAL DESCRIPTION ANDTECHNICAL SPECIFICATION OF THEMFC2000-2TYPE

MICROCOMPUTER-BASED AUXILIARY POWER QUICK SWITCHING DEVICE ................................................. -107-

5.2.1GENERAL DESCRIPTION................................................................................................................... -107-

5.2.2TECHNICAL SPECIFICATION OF THEMFC2000-2TYPEMICROCOMPUTER-BASED AUXILIARY POWER

QUICKSWITCHING DEVICE ...................................................................................................................... -107-

5.3REPAIR CYCLE ANDMAINTENANCE ITEMS ........................................................................................ -109-

5.4MAINTENANCE OF THE MFC2000-2MICROCOMPUTER-BASED AUXILIARY POWER QUICKSWITCHING

DEVICE .................................................................................................................................................... -110-

5.4.1MAINTENANCEPREPARATION ......................................................................................................... -110-

5.4.2CHECKAPPEARANCE ANDCONNECTION..........................................................................................-111-

5.4.3TEST INSULATION RESISTANCE....................................................................................................... -113-

5.4.4CHECK PRELIMINARY ENERGIZATION.............................................................................................. -113-

5.4.5TEST THE SAMPLINGVALUE ........................................................................................................... -114-5.4.6CHECK DEVICE FUNCTIONS.............................................................................................................. -117-

5.4.7BREAKERTRANSMISSIONTEST ....................................................................................................... -123-

5.4.8CHECK ALL THE SETTING VALUES AND SYSTEM SETUP .................................................................... -124-

5.4.9ON-LOADTEST................................................................................................................................ -124-

6 MAINTENANCE OF SID-2CM TYPE AUTOMATIC QUASI-SYNCHRONIZATION DEVICE - 125 -

6.1SCOPE................................................................................................................................................. -125-

6.2GENERAL DESCRIPTION ANDTECHNICAL SPECIFICATION OF SID-2CMAUTOMATIC

QUASI-SYNCHRONIZATIONDEVICE ......................................................................................................... -126-

6.2.1GENERAL DESCRIPTION OF SID-2CMAUTOMATIC QUASI-SYNCHRONIZATION DEVICES............... -126-

6.2.2TECHNICAL SPECIFICATION OF SID-2CMAUTOMATIC QUASI-SYNCHRONIZATIONDEVICES.........-126-


6.4MAINTENANCE OF SID-2CMTYPEAUTOMATIC QUASI-SYNCHRONIZATIONDEVICE........................ -128-


6.4.2CHECKAPPEARANCE ANDCONNECTION......................................................................................... -128-

6.4.3CHECK AND CLEAN THE SMALL WIRING IN THE PROTECTION SCREEN.............................................. -129-


6.4.5TEST THE SAMPLING VALUE ............................................................................................................ -130-

6.4.6CHECK DEVICE FUNCTIONS.............................................................................................................. -132-

6.4.7TEST OF SYNCHRONOUS CONNECTION WITH A SWITCH.................................................................... -134-


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6.4.9PSEUDO-SYNCHRONIZATIONTEST .................................................................................................. -135-

7 MAINTENANCE OF WLX-2D TYPE DOUBLE-CHANNEL DIGITAL STATIC EXCITATION

REGULATOR............................................................................................................................................ - 136 -

7.1SCOPE................................................................................................................................................. -136-

7.2GENERAL DESCRIPTION ANDTECHNICAL SPECIFICATION OF WLZ-2DTYPEEXCITATION REGULATOR ....-

136-


7.2.2TECHNICAL SPECIFICATION OF WLZ-2DTYPEEXCITATION DEVICE.............................................. -139-


7.4MAINTENANCE OF WLXZ-2DTYPEEXCITATION REGULATOR ......................................................... -140-




7.4.4ABNORMAL CONDITIONHANDLING ANDFAULT LOCATING DISPLAY ............................................. -143-


7.4.6PRECAUTIONS TO THE COMMISSIONING OF EXCITATION REGULATOR.............................................. -148-


7.4.8ON-LOADTEST ............................................................................................................................... -148-

8 MAINTENANCE OF LBD-MGR-8000 TY PE DYNAMIC RECORD AND ANALYSIS DEVICE- 150 -

8.1SCOPE................................................................................................................................................. -150-

8.2GENERAL DESCRIPTION ANDTECHNICAL SPECIFICATION OF LBD-MGR-8000TYPEDYNAMIC RECORD

AND ANALYSISDEVICE............................................................................................................................ -150-


8.2.2TECHNICAL SPECIFICATION OF LBD-MGR-8000TYPEDYNAMIC RECORD ANDANALYSISDEVICE -150

-


8.4MAINTENANCE OF LBD-MGR-8000TYPEDYNAMIC RECORD AND ANALYSISDEVICE.................... -154-

8.4.1MAINTENANCEPREPARATION.......................................................................................................... -154-

8.4.2CHECK APPEARANCE AND CONNECTION.......................................................................................... -156-



8.4.5CHECK THE ENERGIZATION............................................................................................................. -158-



8.4.8ON-LOADTEST ............................................................................................................................... -164-

9 MAINTENANCE OF RED670 DEVICE .............................................................................................- 165 -

9.1SCOPE................................................................................................................................................. -165-

9.2GENERAL DESCRIPTION ANDTECHNICAL SPECIFICATION OF RED670DEVICE ................................. -165-


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9.2.1GENERAL DESCRIPTION OF RED670DEVICE .................................................................................. -165-

9.2.2TECHNICAL SPECIFICATION OF RED670DEVICE ............................................................................ -165-


9.4MAINTENANCE OF RED670DEVICE .................................................................................................. -167-



9.4.3INSPECTION OF MECHANICAL PARTS............................................................................................... -169-




9.4.7CHECK BY INPUTTINGALTERNATING VOLTAGE AND ALTERNATING CURRENT.............................. -171-

9.4.8VERIFICATION OF PROTECTIONSETTING......................................................................................... -171-9.4.9FULL GROUPTEST........................................................................................................................... -174-


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1 Maintenance of T60 Digital Transformer Management Relay

1.1 Scope

It stipulates the maintenance items and inspection requirements of GE Companys T60 digital

transformer management relay.

It is applicable to on-site inspection of T60 digital transformer management relay protecting

device and repair of secondary loop thereof, by relay protectors.

1.2 General Description and Technical Specification of T60 Digital Transformer

Management Relay

1.2.1 General Description

T60 digital transformer management relay is mainly used for protection of main transformer

and high-voltage house service transformer and its protection configuration is shown as the

following table.

No. Protection Name

C cabinet Generator transformer protection cabinet:

1 T60 digital transformer management relay includes the following protections: (maintransformer T60)

Generator transformer three-phase differential (three sides)

Main transformer overexcitation

Main transformer high-voltage side zero-sequence differential

Main transformer overcurrent

Circuit breaker starting failure

System low voltage (block excitation loss)

20KV specified time grounding

2 T60 digital transformer management relay includes the following protections:

(high-voltage house service transformer- T60)

High-voltage house service transformer differential protection (three sides)

High-voltage house service transformer low-voltage side zero-sequence

differential (two)

High-voltage house service transformer high-voltage side overcurrent


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No. Protection Name

High-voltage house service transformer low-voltage side branch overcurrent

D cabinet Generator transformer protection cabinet:

1 T60 digital transformer management relay includes the following protections: (main

transformer T60)

Main transformer differential

Main transformer high-voltage side zero-sequence overcurrent

Main transformer overcurrent

Main transformer overexcitation

Circuit breaker starting failure

System low voltage ((block excitation loss))

20KV specified time grounding

1.2.2 General Description and Technical Specification of T60 Relay

1.2.2.1 General Description of T60 Relay

T60 relay is digital relay that can be used to protect various kinds of large, medium and

small-sized three-phase double winding or three-winding transformers, to handle the three-phase

current of system neutral point and to protect the transformer with winding connecting with two

circuit breakers, e.g. ring bus, and a half-circuit breaker wiring. Proportional and instantaneous

differential protections are main protection, and moreover, T60 relay has overexcitation protection,

restrictive ground protection and complete current, voltage and frequency protection and can

provide reliable transformer protection. Besides, the device has non-standard phase deviation and

can provide self-correction of 32-times CT mismatching.

The measurement of voltage and current is basic function of the device and the currentparameter may be effective value formed by full wave or amplitude value of fundamental wave and

phase angle (vector).

Analysis function includes 1024 event records with time scale, recording 64-cycle fault wave

recording function, with programmable triggering, content and sampling frequency and the most

16-channel data capture. Diagnostic feature includes 1024 event sequence records with time

scale and the internal clock used as time scale can be synchronous to IRIG-B signal. The accurate

time scale can be used to determine the event sequence of the whole system, when an event

happens, the snapshot of measuring parameter is recorded so as to reflect the state of relay by

accurate time of event occurrence. Every event is also programmable to trigger the recording data


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capture function and the measuring parameter before and after occurrence of record event may

be set for query by PC computer. These functions greatly reduce fault hunting time and in case the

system goes wrong, the report generation is simplified.

RS232 port on the panel may be used while setting programming and monitoring in the case

of using portable computer and may be used to multi communication modules. The two RS485

ports at the back are standard port and both operating and engineering personnel have access to

them respectively. All serial ports adopt Modbus RTU protocol; RS485 port may be connected with

system computer at maximum speed rate of 115kbps and RS232 port has fixed baud

rate-19.2kbps. Optional communication module contains a 10BaseF Ethernet interface used to

provide rapid and reliable communication under noise environment. In addition, two 10BaseF

optical fiber interfaces may be selected as redundancy. The Ethernet interface supports

MMS/UCA 2.0, Modbus/TCP and TFTP protocols. The device may be connected by means of

standard network browser (UR page). The user-defined port may support DNP3.0 or

IEC60870-5-104 protocol, including serial port and Ethernet interface.

Relay adopts flash memory technique, when new characteristic is added, it is allowed to make

a change on site.

Relay is type of 4RU and 19-inch frame, with movable panel to facilitate site installation. The

modularization design makes it easy to replace or repair by professionals. The panel is provided

with hinge convenient to reach plug-in unit or install on the door with limited depth in a moveable

way. The panel is also provided with a moveable anti-dirt cover plate that must be removed whenthe keyboard or RS232 port is used. The relay panel should be installed on the panel or switch

cabinet door in a semi-embedded way and the operators are allowed to used keyboard and

RS232 interface. The relay is fixed to the panel by means of four screws provided along with

device;

The modularization design of relay allows card module. The module can be merely replaced

with the same type of module in the groove set initially by the manufacturer. Once the right door

lock is raised, the panel can be opened leftwards;

Power supply module provides power supply for relay and dry joint input. The heavy fault

alarm relay is Form-C type will be excited when the operating source is normal and the relay is

started successfully, but no self-check severe error exists. In case a severe error is found by

means of any online self-check or the operating source fails, the relay will be unexcited.

CT/VT module may adopt standard grounding current input like phase current (8A type) input,

or 10-times sensitive grounding current input (8B type). Each circuit of AC current input is all

provided with an isolating transformer and an automatic short circuit mechanism used for shorting

input circuit when the module is drawn out of box body. Current input is set with internal ground

point. CT primary value is 1-50000A and secondary value is 1A or 5A, and all may be used.

Each block of digital value I/O module has 24 terminal connections in all. Three terminals are


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arranged in each line, totaling eight lines. These three terminals in a specified line may be used as

output of a relay. For example, for Form-C relay output, three terminals are respectively connected

to normally opened (NO), normally closed (NC) contacts and common contact port of relay. For

Form-A or SCR output, two terminals are used as normally opened contact output and the third

one is used for current calibration in monitoring function. The configuration of contact input

terminals is difference from each other. When the digital value I/O module has contact input

function, they are divided into four groups and two lines of terminals are used. It is optimal that

each input is completely isolated from any other input; however, it is required that each input

should have two independent terminals, thus the quantity of input contact is limited on the basis of

possible terminal quantity. Therefore, although each input is all isolated by optical coupler, for the

sake of comprehensive consideration, four inputs in each group still share a common port, and in

this way, it will be allowed in different groups to input wet contact (if needed) supplied with powerby different power sources or both dry contact and wet contact.

A 9-needle RS232C serial port is located in relay panel, used for communication with portable

(PC) computer. Using the interface needs URPC software running on PC and provided along with

relay. RS485 port realizes data sending and receiving by means of a piece of twisted pair wire.

Remote computer, SCADA system or DLC may conduct continuous monitoring and control

through the port.

Panel keyboard and display interface is one of both man-machine interfaces supported by UR

relay. Another interface may be realized by means of URPC software. All information is displayed

on a 220-character vacuum fluorescent display window, so the information can also be seen

clearly under relatively poor light. The information is displayed in English and it has no need of

user's manual to help interpretation. When both keyboard and display window are not used, the

default information predefined will be displayed. Any high-priority event-driven information will

automatically cover default information and be displayed. The display information is paged

according to main title, current value, settings, order and output. MENU key is used for browsing

between main title pages. Each main title page is further divided into logic subgroup. MESSAGE

keys (, , , ) are used for browsing between subgroups.

VALUE key is used to display each variable by scrolling in setting programming state; to

increase or reduce settings, and moreover, changing settings may be by use of keyboard entry.

Enter key is used to store the changed settings. HELP key may be pressed at any movement

to display help information.

Key is used to start the next character in text editing state, or input a decimal point.

VALUE key is used to display alphanumeric value by scrolling in text editing state.

a) The first LED board provides several LED indicator light clusters and press keys and one

communication port. RESET key is used to reset locking output, LED indicator light or event

information while the locking condition is released. USER key is used in circuit breaker control


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function. RS232 port may be connected with portable PC.

STATUS Indicator Light:

IN SERVICE: Indicate that control power source is on; all monitored I/O and internal

systems are in good condition; relay is running.

TRDUBLE: Show that relay has detected internal error.

TEST MODE: Show that relay is in testing state.

TRIP: Show that tripping type exit relay operation is selected. The indicator light is

retentive, so while the indicator light is reset, no matter whether tripping exit relay is actuating or

not, RESET order will be used.

ALARM: Show that alarming type exit relay operation is selected. The indicator light is

non-retentive.

PICK UP: Show that some element is started. The light is non-retentive.

EVENT CAUSE Indicator Light:

Indicate the input type involved in actuating some element or a retention zone bit is waiting for

resetting.

VOLTAGE: Show including voltage quantity.

CURRENT: Show including current quantity.

FREQUENCY: Show including frequency.

OTHER: Show including compound quantity.

PHASE A: Show including phase A.

PHASE B: Show including phase B.

PHASE C: Show including phase C.

NEUTRAL/GROUND: Show including zero sequence component.

b) The second LED board

SETTINGS IN USE Indicator Light

Which group of settings and setting group in use by indication protection function of LED in

the row are being edited by means of panel. The row has 8 LEDs, representing setting groups 1

8.

General settings will be discussed in the section of subgroup element.

Uninterrupted-on LED shows (by label) which setting group is used by subgroup element


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(namely current group). The setting group number may be changed by settings in setting group

or by Flex Logic setting.

Flash LED shows which setting group, if differing from current setting group, is being

edited in panel display window. If both setting groups are the same, LED will be on continually.

Note: not only the settings in some one setting group can be edited by means of panel but

also different setting groups can be edited by means of communication channel. While some one

setting group is displayed on PC, the state of SETTINGS IN USE indicator light will not be

changed.

BREAKER STATUS Indicator Light:

OPEN and CLOSE indicator lights show the state of relevant circuit breaker when circuitbreaker control function has been enabled and circuit breaker state monitoring contact has been

led in relay.

TROUBLE indicator light is on in the following cases: (A) circuit breaker control function is

set to be active and Flex Logic operating variable selection is error indication or three phases are

non-uniform through detection; (B) by detection by failure protection, circuit breaker is out of order.

Here the indicator light is retentive, and only after failure starting condition is not met any more and

a resetting order is given, can the indicator light be reset.

RECLOSE Indicator Light

If ENABLED indicator light is on, it shows that reclosing function can be enabled and meet

reclosing conditions. If DISABLED indicator light is on, it shows that reclosing function can be

enabled but some conditions can not be met. IN PROGRESS indicator light shows that reclose

has been started but circuit breaker is not closed. LOCKED OUT indicator light shows the locking

condition is detected by reclosing. This indication state will be retentive till setting conditions are

met.

1.2.2.2 Technical specification of T60 relay

1) Effective value of current: inter-phase, neutral point and grounding

Precision: while 0.1-2.0 times greater than CT rated value: 0.25% of reading or 0.1% of

rated value (adopt larger value);

While above 2.0 times greater than CT rated value: 1.0% of reading

2) Effective value of voltage:

Precision: 0.25% of reading (10V-208V)

3) Apparent power

Precision: 1.0% of reading


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4) Frequency

Precision: V0.8-1.2pu: 0.01HZ (while voltage signal is used for frequency measurement)

I0.1-0.25pu: 0.05HZ

While I >0.25pu: 0.02HZ (while current signal is used for frequency measurement)

5) AC current

Primary CT rated value: 150000A

Secondary CT rated value: 1A or 5A

Frequency range: 2065HZ

Relay load:


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Nominal DC voltage: 125~250V, 0.7A

Minimum/maximum DC voltage: 88/300V

Nominal AC voltage: 100~240, 50~60Hz, 0.7A

Minimum/maximum AC voltage: 88/26548~62Hz

9) Internal fuse (quick-acting)

Rated value:

Low range power supply: 7.5A/600V

High range power supply: 5A/600V

Switching capacity:

AC: 100000A effective symmetry value

DC: 10000A

10) A type relay

Withstand current (0.2s): 30A/ANSI C37.90

Withstand current (continuous): 6A

40msL/R open circuit: 0.10ADC maximum 125V

Actuation time:


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Contact material: silver aluminum

14) C type fast relay

Withstand current: 0.1A maximum (resistive load)

Actuation time:


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4. Inspection of clock and communication

5. Inspection of software version

6. Input and modification of setting group

7. Setting and modification of protection logic

6

Inspection of feed AC current and voltage

1. Relay null shift check

2. Testing of current and voltage accuracy

3. Check of amplitude of analog values, phase

characteristic and recorder waveform

7

Calibration of protection settings

1. Calibration of transformer differential protection

Calibration of percent differential

Calibration of instantaneous differential

2. Calibration of overcurrent component

Calibration of time-delay overcurrent component(TOC)

Calibration of instantaneous overcurrent

component (IOC)

Calibration of directional current component

3. Calibration of self-made zero sequence

overcurrent component

Calibration of time-delay overcurrent component

(TOC)

Calibration of instantaneous overcurrent

component (IOC)

Calibration of zero-sequence directional

component

4. Calibration of grounding overcurrent component

Calibration of grounding time-delay overcurrent

component


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Calibration of grounding instantaneous

overcurrent component

Calibration of restrictive grounding component

5. Calibration of voltage component

Calibration of phase voltage component

Calibration of neutral point voltage component

Calibration of auxiliary voltage component

6.Calibration of overexcitation protecting

component

7. Calibration of frequency component

Qverfrequency

Low frequency

8. Calibration of digit counter settings

9. Output signal contact inspection

8

Full group test

1. Drive of various protections by actual feed

current, respectively test the put-in and non-put-in

of protecting plate

2. Inspection of drive coordinating with other

protecting devices and loops

9 Circuit breaker drive test

10 Check of all settings and system setup

11 On-load test

Repair period of device is shown as follows:

Repair Category Repair Period

Total check 6 years

Partial check 1 year


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1.4 Maintenance of Generator-Transformer Unit Protection

1.4.1 Maintenance Preparation

1.4.1.1The relaying integrated test device should be adopted to ensure check quality. The device

should have the following performance:

1) Phase adjusting range: 0~360; current amplitude adjusting range: 0~30A; voltage

amplitude adjusting range: 0~120V

2) When the simulation fails, non-simultaneity between fault voltage and current should be

less than 1ms.

3) The device can conduct the test of protection operating time.

4) Testing instrument should pass test and its accuracy should not be lower than 0.5 grade.

1.4.1.2 Protection test requirements are as follows:

1) Test branch should be provided with special safety switch and the selectivity of connected

fuse must be guaranteed; it is not allowed to use DC branch power source of equipment in service

as DC power source during check.

2) During test, the fed DC power source is all rated value, unless otherwise specified.

3) Test current and voltage of feeding device, unless otherwise specified, are all fed in fromprotection screen terminal.

4) In order to ensure check quality, each point in all characteristic tests should be retested for

three times and the error between testing value every time and setting value should meet specified

requirements.

5) All checks should be made in case the element or plug-in unit is in the state of being

consistent with actual installation site.

6Error calculating formulas are as follows:

Calculation of error percentage:

Error percentage = (maximum value minimum value)/minimum value 100%

Calculation of discrete value:

Discrete value = (maximum value minimum value)/average value 100%

Operating error value:

Operating error value = (measured value set value)/ set value 100%

1.4.1.3 Precautions in test process


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1) The plug-in unit should not be inserted and pulled out until DC power source is shut off.

While inserting and pulling out plug-in unit, the open circuit of AC current loop should be

prevented.

2) Printer and each block of plug-in unit should keep clean to prevent dust.

3) In case there is something wrong in test process, do not replace chip at random; do find out

the source of trouble first and make sure whether the chip needs to be replaced, if necessary,

replace it with acceptable chip; the direction of chip insert should be correct and the contact should

be reliable.

4) When the testers contact and replace integrated chip, the body electrostatic grounding

measure should be taken to protect chip from damage due to body static electricity.

5) In principle, the electric soldering iron can not be used on site, when necessary in test

process, the electric soldering iron with ground wire should be adopted or the electric soldering

iron is powered off for welding.

6) The plug-in unit should not be inserted in wrong position in test process.

1.4.2 Appearance and Wiring Inspection

1.4.2.1 According to the device rear connection diagram and terminal block diagram provided by

the designer, check the correctness of device wiring and inspect the correctness of inter-box cable

connection position and boxes.

1.4.2.2 Both appearance quality and welding quality of components on each module of protecting

device should be good and all modules should be inserted tightly.

1.4.2.3 Inspect whether internal wiring of protecting device is broken, short-circuit and poorly

welded and whether the appearance of components is in good condition.

1.4.2.4 Check rated operating voltage of power supply module.

1.4.3 Inspection of Mechanical Part

1.4.3.1 The space between metal frame and current-carrying part such as electronic component,

printed wire and welding point shall be greater than 3mm.

1.4.3.2 The components of protecting device should be fixed well, without any looseness; the

device appearance should be regular, free of apparent damage and deformation.

1.4.3.3 The rear terminal block connection of protecting device should be reliable and the label

shall be clear and correct.

1.4.3.4 Button and keyboard should handle well.

1.4.3.5 The contact between plug-in units and floor is in good condition, without looseness.


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1.4.4 Inspection and Cleaning of Secondary Wiring inside Protection Screen

Protecting device and loop wiring shall be cleaned to prevent creepage and short circuit. The

dust should not be cleaned with any solvent and firstly, should be blown away by electric blower,

secondly brushed away lightly with banister brush and then blown off. The backboard socket and

terminal inside panel cabinet may be blown by electric blower and can not be bumped with any

object.

The dust in other part of cabinet should be blown firstly and the dust in protecting device

should be blown finally.

1.4.5 Insulation Resistance Testing

1.4.5.1 Pull out all plug-in units and put into special metallic membrane shielding bag.

1.4.5.2 Dismantle all ground points on panel.

1.4.5.3 Cut off DC power source, AC power source and voltage loops and cut off relevant

connection between protecting device and other devices.

1.4.5.4 In protection screen terminal block, disconnect all externally led-in loops and cables and

keep a record. Inside protection terminal block, respectively measure, with 1000V megameter, the

insulation resistance between AC current loop, DC power source loop, tripping and closing loop,

switching value input loop and signal loop and the insulation resistance of each loop againstground. The insulation resistance shall be greater than 10M.

Note: When the insulation resistance of some one loop against ground is measured, any other

loop should be grounded.

1.4.5.5 Detection of insulation resistance of the whole secondary loop: in protection screen

terminal block, connect all current, voltage and DC loop terminals together and disconnect the

ground point of current loop, and then measure, with 1000V megameter, the insulation resistance

of the whole loop against ground. The insulation resistance should be greater than 1.0M.

1.4.6 Initial Power-on Inspection

1.4.6.1 After the device is powered on, T60 protecting device makes self-check first, after

completion of self-check, the IN SERVICE light on the first LED board will be on, if the device has

something wrong, the TOUBLE light will be on. In addition, the on-off state light of self-defined light

will be on. No protection and abnormal signal light on the second LED board is on.

1.4.6.2 In case the switch is opened and closed, respectively test the on-off status of device power

source vanishing and device fault contact. The contact status should have displacement.

1.4.6.3 Inspection of Inversion Power Source


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1.4.6.4 Inspection of Clock and Communication

Access to background PC from RS232 port to examine REAL TIME CLOCK should be GPSclock and internal clock changes, but the time will not change; inspect whether each option setup

of PRODUCT SETUP is correct and whether protection supervisor and communication to DCS are

in good condition.

1.4.6.5 Inspection of Software Version

The software version number examined from DEVICE Definition should conform to the

software version number of background computer URPC.

1.4.6.6 Input and Modification of Setting Group

1) Input of Numerical Data

Each numerical value setting has maximum value, minimum value and step length. These

parameters define available range of settings. For example, selection information PRODUCT

SETUP/DISPLAY PROPERTIES/FLASH MESSAGE TIME; press HELP key to see minimum

value and maximum value. Press HELP key again to see the next help information. The numerical

value settings may be edited and stored by two methods.

0-9 and . (decimal point) relay numeric keyboard has the same function with any

electronic calculator. Input a digit once. The leftmost numerical digit is inputted firstly and

the rightmost numerical digit is inputted finally. Press MESSAGE () key or ESCAPE keyto return to original display value.

VALUE(, ) key press VALUE() key to increase the displayed numerical value

according to step length till it reaches allowable maximum value. When it is maximum

value, press VALUE() key again to make setting start with minimum value. Press

VALUE() key to reduce the displayed numerical value according to step length till it

reaches minimum value. When it is minimum value, press VALUE() key to make setting

start with maximum value.

For instance, set message flash time to be 6.5s and pressure number key according to the

sequence of 6.5. Display message will change according to inputted numerical digit.

The setting modification will not become effective until pressing ENTER key. Therefore, press

ENTER key to store new setting. Flash message appearing from time to time shows being stored.

If the inputted decimal place exceeds the limit of step length, it will wrap around automatically.


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Press MENU key to display the title of the required page. The title will flash from time to time

and relevant display page will appear in display window. Press MENU key once again, and the

next title page will be displayed.

Setting and current value message is organized in a hierarchical way. Main title page is

marked with double-scroll bar symbol ( ) and sub-title page is marked with single scroll bar

symbol ( ). Main title page is located in the highest layer of hierarchical structure and sub-title

page is far lower than the layer. MESSAGE keys () are used to move among inter-group main

title, sub-title, settings and current value. Press MESSAGE () key uninterruptedly on main title

page, and detailed message will be displayed under the title. On the contrary, Press MESSAGE

() key uninterruptedly, and it will return to main title page from setting or current value display.

Highest Level Lowest Level (Settings)

The values of detail settings are a part of a group of numerical values and these numerical

values are defined by name.

For instance, optional values of PASSWORD SECURITY/ACCESS LEVEL settings are:

Restricted, Order, Setting and Factory Service.

The detail numerical value is changed by VALUE() keys. VALUE() key is used to display

the next option and VALUE() key is used to display the last option.


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If ACCESS LEVEL needs to be set as Setting, press VALUE() keys up to finding out an

appropriate option. In the process, HELP key may be pressed at any moment to obtain help.

The setting modification will not become effective until pressing ENTER key. Therefore, press

ENTER key to store new setting. Flash message appearing from time to time shows being stored.

Text settings include fixed-length and user-defined characters and may contain capital letter,

lower case letter, figure and special character.

In order to make relay meet the demand of users. Some text message may be programmed,

e.g. MESSAGE SCRATCH PAD. To input text message, the following steps should be complied

with:

For instance: Input the text Breaker #1

1. Press . key to enter text edit mode.

2. Press VALUE or key till the character B appears; press . key to move cursor to thenext position.

3. Repeat step 2 and input the rest characters: r,e,a,k,e,r,#,1.

4. Press ENTER key to store the text.

If any problem, press HELP key for help; flash message will take turns to appear for seconds.

For such text settings, press HELP key to display how to edit and store new setting.

2) Not Programmed Status of Relay Settings

When the relay is powered on successfully, TROUBLE indicator light will be on while INSERVICE indicator light will be off and the message will be displayed.

It means that relay is in not programmed status and defense mechanism prevents relay

putting into operation before settings are inputted. The message will be reserved till relay is

definitely in programmed status.

In order to explain the overall process, an example is given for RELAY SETTINGS: NOT


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Programmed as follows:

1. Press MENU key till SETTINGS title flashes periodically and SETTINGS PRODUCTSETUP message is displayed.

2. Press MESSAGE key till PASSWORD SECURITY message is displayed.

3. Press MESSAGE key till INSTALLATION message is displayed.

4. Press MESSAGE key till RELAY SETTINGS:NOT Programmed message is displayed.

5. After RELAY SETTINGS:NOT Programmed message is displayed, press VALUE orkey to select Programmed.

6. Press ENTER key.

7. After NEW SETTINGS BEEN STORED message is displayed, the relay will be in

Programmed status and IN SERVICE indicator light will be on.

Initial password setting

To explain the overall process, an example is given for changing setting password as follows:

1. Press MENU key till SETTINGS title flashes periodically and SETTINGS PRODUCT S

message is displayed on screen.

2. Press MESSAGE key till ACCESS LEVEL: appears.

3. Press MESSAGE key till CHANG SETTING PASSWORD: appears.


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After the message appears, press VALUE or key to select YES.

4. Press ENTER and a prompt: ENTER NEW PASSWORD will appear in display window.

5. Key in the password comprised of figures (10 figures at most) and then press ENTER key.

6. When VERIFY NEW PASSWORD message appears, reenter new password and thenpress ENTER key.

7. When NEW PASSWORD HAS BEEN STORED appears, new setting password will

become effective.

Changing of existing password

Changing existing password may comply with the above-mentioned steps unless the

under-mentioned. Before new password is inputted, a message will prompt to key in exiting

password (for each security level).

If the password is lost (forgotten), submit the encrypted password from PASSWORD

SECURITY menu to manufacturing factory for decryption.

3) Input and Modification of Settings

General setup of settings has PRODUCT SETUP and SYSTEM SETUP. These two items set

the electric parameters such as communication network, wave recording setup, self defining of

signal light and voltage and current of protection settings; 6 sets of different protection settings can

be set for protecting device and multi settings groups are convenient for modification of protection

settings in different operating conditions (e.g. the setup of electric system needs to be changed


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with change of season); enabled setting groups may be preset or selected by means of SETTING

GROUPS menu. Each set of protection can be modified by means of front panel and background

PC. If large numbers of settings need to be modified, it is suggested that new settings should be

set on background PC and then uploaded to protecting device.

4) Setting and Modification of Protection Logic

The realization of many relatively complex protection functions needs logic combination of

single protection element and the function realization includes setting of logic element and editing

of logic function in FLEXLOGIC option. In order to provide the greatest flexibility for UR relay users,

the arrangement of internal digit logic is accompanied with fixed parameter and users

programmable parameter. Single functional unit logic is designed in a fixed way and all other

logics of digital input signal via element or combined element to digital output are variable. Userscan control completely all variable logics by means of FlexLogicTM logic. Generally, system

acknowledgement can generate analog input and digital input of analog and digital output.

Much more complex logic required can be realized by means of FlexLogicTM logic. For

instance, users want to lock the operation of inter-phase time overcurrent component and such

two input states as closing state of contact input H7a and opening state of inter-phase

undervoltage component may be programmed in FlexLogicTM logical equation. The FlexLogicTM

logical equation will process AND operation for the above both inputs to generate an actual output,

when inter-phase time overcurrent is programmed, virtual outputs may be selected for locking

input. The Virtual Outputs can only be programmed by FlexLogicTM logical equation. FlexLogicTMlogic lowers the requirements for auxiliary component and wiring, which make much more

complex design become possible.

By means of a series of equations comprised of operators and operands, FlexLogicTM logic

allows users to customize equipment. Operands are input state, component state and output state.

Arithmetic units are logic gate, timer and lock (with setting input and resetting input). Time

sequence operating system allows designating any combination of specified operands as the input

quantity of specified operators that can generate output. Final output of equation is a serial

number register called VIRTUAL OUTPUT. Virtual output can be used as input operand in any

equation including the equation that generates output quantity and can be also used as lock loopor any other type of feedback loop.

The first step in the process of checking logic correctness is to check logic diagram of living

example and thus make sure that operators of FlexLogicTM logic can execute the logic required. If

the logic fails to be realized, it must be modified until the conditions are met. Once the check is

completed, the number of input quantity of each logic gate should be calculated and the number of

input quantity can not exceed the applicability and limit of FlexLogicTM logic; it seems to be

unlikely to exceed the applicability but the case may happen. If the number of input quantity of

some one logic gate is too great, these input quantities should be subdivided to equivalent multi

logic gates. For example, if an AND gate with 25 input quantities is needed, connect input 1


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input 16 to an AND gate (16) and connect input 17 input 25 to another AND gate (9), and then

connect the above both AND gates to AND gate (2).

Check each operator between initial operand and final virtual output and thus determine

whether the output of some one operator can be used as the output of the following multi

operators. If so, the output of operator must be designated as Virtual Output.

32 identical FlexLogicTM logic timers are available for use in

SETTINGFLEXLOGICFLEXLOGIC TIMERSFLEXLOGIC TIMER 1, numbering 132.

These timers are used as operators of FlexLogicTM logical equation.

1.4.7 Inspection of Feed AC Voltage and Current

1.4.7.1 Use of main menu of real-time values

Some real-time values are displayed in the option, e.g. viewing current path is ACTUAL

VALUESMETERINGCURRENT; the path of some data of transformer is ACTUAL

VALUESMETERINGTRANSFORMER, etc; event record may be also viewed and its path

is ACTUAL VALUES RECORDEVENT RECORD and event record is referred to context

data of the last 1024 events and is arranged in the form of journal number from the recent to the

earliest, when all 1024 event records are filled in, the earliest record will be removed and a new

record will be added. Each event record will display the identification/serial number and reason of

event and date/time mark as well as event trigging.

In addition, each final 256 tripping event is recorded instantaneously and the record contains

the frequency, current and voltage information of event occurring at that instant; the voltage value

of Y and wiring is all phase-to-phase value.

1.4.7.2 Null Shift Check

In case input voltage and current of protecting device T60 are null, check current and voltage

subitem in main menu option of real-time values; null shift values all should be within 0.01IN (or

0.05V). During check of null shift, it is required that null shift values should be retained within

specified range within a period of time (several minutes).

1.4.7.3 Testing of Current and Voltage Accuracy

Feed A, B and C three-phase current according to the terminal block number given in drawing

and measure the accuracy of each winding current of transformer respectively in the case of 0.1In,

0.2In, In, 5In and 10In; the error between numerical value viewed from real-time values and

measured value from external pointer should be less than 5%. When 70, 60, 30, 5 and 1V are

respectively fed in three-phase voltage, measure the accuracy of voltage; the error between

numerical value viewed from real-time values and measured value from external pointer should be

less than 5%. Properly feed single-phase voltage and current and check the value accuracy of

3U0 and 3I0.


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In test process, if the measurement error of AC value is beyond specified range, first of all,

check whether test connection, test method and external measuring pointer are correct and intact

and whether test power source has waveform distortion, and do not be impatient to adjust or

replace the components in protecting device.

When 10IN and 5IN current is fed for check, current feed time should not exceed 10s; when

10IN current is fed, it is allowed to adopt special automatic adjusting and testing equipment for

check.

1.4.7.4 Check of Amplitude of Analog Values, Phase Characteristic and Recorder Waveform

Feed AC voltage and AC current according to the terminal number marked in drawing;

increase AC voltage and AC current to rated value. For the change of test power source, the

phase of in-phase voltage and current is respectively 0, 45, 80, 85 and 90; check the phase

between voltage and current waveforms on the background PC and the phase sequence in itself,

when the phase between voltage and current is changed, the error between numerical value

viewed from real-time values and set phase angle shall not be greater than 3.

1.4.8 Calibration of Protection Settings

1.4.8.1 Calibration of Transformer Differential Protection

1) Calibration of Percent Differential

The percent differential adopts setting group PERCENT DIFFERENTIAL component.

Operating characteristic of percent differential

Differential current is the sum of current of all windings after compensated for amplitude and

phase angle.


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Braking current is maximum current after compensated.

Starting Value Testing

Feed current respectively from high and low voltage winding sides to start differential relay

and PICK UP light on panel will be on; A, B and C three phases should be powered on

respectively for testing;

Testing of Percent Differential Curve

The primary protection component of T60 is harmonic-braked double-slope percent

differential component. Differential curve is composed of percent differential slope 1, inflection

point 1, inflection point2 and slope 2, etc. and two kinds of independent harmonic braking

characteristics are provided: inrush current braking characteristic and overexcitation braking

characteristic.

Each percent curve should be verified respectively in the case of A, B and C phases. Take

high voltage side as braking current, with angle of 0 and take B branch as operating current, with

angle of 180 to respectively test the operating condition of relay in both inflection points, at bothsides of inflection point and in initial, middle and end points of fit curve. It should be fit to percent

braking curve. Quadratic harmonic braking characteristic and quintuple harmonic braking

characteristic are tested and the braking characteristic should meet harmonic percent relation.

1) Calibration of Instantaneous Differential

The differential current of instantaneous differential component is calculated same as that of

percent differential component, but it will not be braked by any harmonic braking characteristic in

percent braking components. Its operation is just like an instantaneous overcurrent component

and the component make relay operate very quickly when internal short circuit current is relatively

great. Remove percent differential component and three phases should be tested when harmonic

braking is available, and they should be quick-acting reliably.

1.4.8.2 Calibration of Overcurrent Component

1) Calibration of Time-delay Overcurrent Component (TOC)

The inverse time overcurrent curve used in TOC component is IEEE, IEC, GE, IAC and I2T

standard type curve, which simplifies lower level protection equipment and protection coordination.

However, if no proper curve is optional, users can customize the characteristic of inverse time

curve of FlexLogicTM curve. If simple protection is needed only, specified time curve may be a

proper option.


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If TOC component is used for protection, the trip time under different currents should be

checked and the characteristic of the curve drawn should conform to that of the curve adopted.

2) Calibration of Instantaneous Overcurrent Component (IOC)

Instantaneous phase overcurrent component may be used as instantaneous component or

specified time component and input current is fundamental wave phasor amplitude. The

component is adopted for transformer ventilation and overload. During calibration, the operating

value of overcurrent component and operating time of component should be tested.

3) Calibration of Directional Component

When phase direction function is set as Enabled, operating current is greater than 5%

rated current and polarization voltage is greater than given threshold value.

Component output is determined by phase angle of operating and polarization signals as

follows:

When the difference between operating current and polarization voltage angles is within

90, component output is 0.

For any other angle, component output is logic 1.

1.4.8.3 Calibration of Zero-sequence Overcurrent Component

1) Calibration of Zero-sequence Time Delay Overcurrent Component

The component is NEUTRAL TOC and its current input quantity is 3I0 got through phase

current calculation; the operating action of the component is curve characteristic.

2) Calibration of Zero-sequence Instantaneous Overcurrent Component

The component may be used as instantaneous component without time delay or as specified

time component. The positive sequence current brake is adopted to reach better effect and the

operating quantity is positive sequence current amplitude subtracting small part (6.25) from zero

sequence current amplitude. When single phase input is adopted, operating quantity is 0.9375

times more than operating value. The overcurrent part of zero sequence direction overcurrentprotection just adopts the component.

3) Calibration of Zero-sequence Directional Overcurrent Component

Directional element for zero-sequence directional overcurrent protection adopts 3I0

calculated and the positive sequence current brake is adopted to reach better effect. Simulate

single phase grounding on site and change the angle of 3U0 and 3I0, the component should

operate in positive direction region and operating angle should be basically in the vicinity of

sensitive angle.

1.4.8.4 Calibration of Grounding Overcurrent Component


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1) Calibration of Grounding Time-delay Overcurrent Component

The component is GROUND TOC and its current input quantity is gained by means of zerosequence CT; the operating action of the component is curve characteristic.

2) Calibration of Grounding Instantaneous Overcurrent Component

The component is used for zero-sequence current protection. Operating value and operating

value of the zero-sequence component should be calibrated.

3) Calibration of Restricted Grounding Component

The component can eliminate CT saturation problem by means of time-delay output. The

restrictive ground fault protection (RGF) can detect the sensitive ground fault of small grounding

current with ease. It is used to detect the sensitive ground fault of small grounding current that can

not be detected by percent differential. Test the starting value of zero sequence differential of A

and B branches and check operating characteristic.

1.4.8.5 Calibration of Voltage Component

1) Calibration of Phase Voltage Component

Phase voltage component may be divided into phase low-voltage and overvoltage component.

Operating voltage, return voltage and operating time of voltage component should be calibrated.

2) Calibration of Neutral Point Voltage Component

The neutral point overvoltage component can be used to defect system unbalanced voltage

arising from ground fault or one phase or double-phase open circuit and the voltage adopts neutral

point voltage 3U0 calculated by phase voltage. During setting of the component, a consideration

must be given to PT error and normal unbalanced voltage and PT should be star connection.

During setting calibration, single phase voltage should be fed to test the operating value and

operating time.

3) Calibration of Auxiliary Voltage Component

Auxiliary voltage is from open-delta voltage of voltage transformer, with auxiliary low voltageand auxiliary overvoltage. Calibration method is the same as that of other voltage components

1.4.8.6 Calibration of Overexcitation Protection Component

Overexcitation protection is usually divided into specified time limit and inverse time limit for

overexcitation protection; the specified time limit is more than times of V/HZ voltage starting value

and how many minutes to delay for operating; during calibration, change the percent test starting

value between V/HZ. During inverse time limit, the operating time in the case of different times of

V/HZ (greater than starting value) should be calibrated.

1.4.8.7 Calibration of Frequency Component


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1) Overfrequency

Change frequency output of test power source to make overfrequency component operateand test the correctness of operating value.

2) Low Frequency

Change frequency output of test power source to make low frequency component operate

and test the correctness of operating value.

1.4.8.8 Calibration of Digit Counter Settings

There are 8 identical digit counters. The digit counter calculates the number of state transition

from logic 0 to logic 1. The digit counter can be used to calculate operating condition of component

starting abd suchlike.

1.4.9 Full Group Test

1) Drive of various protections by actual feed current, respectively test the put-in and

non-put-in of protecting plate.

Simulate fault voltage and fault current from terminal block and verify the protection should

operate exit when protecting plate is in put-in state, otherwise the protection will not start exit. After

put in tripping plate, switch tripping loop should be in on state.

2) Drive of coordination with other protecting devices and loops

Finish each complete protection function drive by means of coordination with other protecting

devices and operating box.

1.4.10 Circuit Breaker Drive Test

Turn on operating power source switches of all switches and power source of protecting

device; actually close circuit breaker, and verify the operating correctness by each protection start.

With two circuits of DC tripping power source, respectively test the operating correctness of

switch.

1.4.11 Check of All Settings and System Setup

After all test items are completed, unload the settings from RS232 port to HD by use of PC

and check the correctness of each phase setup. Name the settings by date for check with on-site

settings during the next maintenance.

1.4.12 On-load Test

After the transformer is on load to a certain extent, inspect phase sequence and phase of all


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three-phase current and voltage fed in protection screen.

By means of real-time value menu inside protecting device, respectively inspect the current ateach side of differential and the current and voltage of all main and standby protections; angle

difference between homolateral Ua, Ub and Uc should be 1200

and Ua leads Ub that leads Uc,

which should meet positive sequence relation; angle difference between homolateral Ia, Ib and Ic

should be 1200 and Ia leads Ib that leads Ic, which should meet positive sequence relation; during

normal operation, current phase angle at both sides of transformer should be 1800, if not, carefully

inspect whether secondary CT and PT polarities are connected in the wrong way and whether

secondary cable from terminal box to screen terminal block is connected in error.

The difference current of differential protection during normal operation should be checked.

The difference current value should be less than 3%In (In is secondary rated current value), whichis normal, if the difference current value is too great, carefully inspect whether loop and balance

coefficient at each side are set correctly. If any problem, settle it immediately.


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2 Maintenance of G60 Digital Transformer Management Relay

2.1 Scope

It stipulates the maintenance items and inspection requirements of GE Companys G60 digital

transformer management relay.

It is applicable to on-site inspection of G60 digital transformer management relay protecting

device and repair of secondary loop thereof, by relay protectors.

2.2 General Description and Technical Specification of G60 Digital Transformer

Management Relay

2.2.1 General Description

G60 digital transformer management relay is mainly used for protection of generator and its

protection configuration is shown as the following table.

No. Protection Name

A cabinet Generator transformer protection cabinet:

1 G60 digital generator management relay includes the following protections:

(generator G60)

Generator differential

Generator100% stator grounding

Generator negative-sequence current (specified/inverse)

Generator excitation loss (generator low-voltage and negative-sequence

voltage block)

Generator overexcitation (specified/inverse)

Generator out of synchronism

Generator reverse power

Sequential-trip reverse power

Generator inter-turn (with negative-sequence power direction block)

Generator overvoltage

Impedance


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No. Protection Name

Generator overload

Generator circuit breaker failure protection

PT disconnection detection and block

B cabinet Generator transformer protection cabinet:

1 G60 digital generator management relay includes the following protections:

(generator G60)

Generator differential

Generator100% stator grounding

Generator negative-sequence current (specified/inverse)

Generator excitation loss (generator low-voltage and negative-sequence

voltage block)

Generator overexcitation (specified/inverse)

Generator out of synchronism

Generator reverse power

Sequential-trip reverse power

Generator inter-turn (with negative-sequence power direction block)

Generator overvoltage

Impedance

Generator overload

Generator circuit breaker failure protection

PT disconnection detection and block

2.2.2 General Description and Technical Specification of G60 Relay

2.2.2.1 General Description of G60 Relay

G60 management relay, based on microprocessor relay, provides protection, monitoring,

control and real-time record for AC generator, and moreover, provides fault wave recording for

current, voltage and frequncey protection.

The measurement of voltage and current is basic function of the device and the current


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parameter may be effective value formed by full wave or amplitude value of fundamental wave and

phase angle (vector).

Analysis function includes 1024 event records with time scale, recording 64-cycle fault wave

recording function, with programmable triggering, content and sampling frequency and the most

16-channel data capture. Diagnostic feature includes 1024 event sequence records with time

scale and the internal clock used as time scale can be synchronous to IRIG-B signal. The accurate

time scale can be used to determine the event sequence of the whole system, when an event

happens, the snapshot of measuring parameter is recorded so as to reflect the state of relay by

accurate time of event occurrence. Every event is also programmable to trigger the recording data

capture function and the measuring parameter before and after occurrence of record event may

be set for query by PC computer. These functions greatly reduce fault hunting time and in case the

system goes wrong, the report generation is simplified.

RS232 port on the panel may be used while setting programming and monitoring in the case

of using portable computer and may be used to multi communication modules. The two RS485

ports at the back are standard port and both operating and engineering personnel have access to

them respectively. All serial ports adopt Modbus RTU protocol; RS485 port may be connected with

system computer at maximum speed rate of 115kbps and RS232 port has fixed baud

rate-19.2kbps. Optional communication module contains a 10BaseF Ethernet interface used to

provide rapid and reliable communication under noise environment. In addition,

secondary electrial system maintenance manual qn1 sec g 04 t

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