68237870 Testing of Electrical Equipments

7/29/2019 68237870 Testing of Electrical Equipments

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CONTRACT SPECIFIC PROCEDUREFOR TESTING OF ELECTRICAL EQUIPMENTS &

132KV OHL

CONTRACT TITLE

CLIENT

PDO CONTRACT NO.

MAIN CONTRACTOR

LTEM CONTRACT REF. NO.

Document No.Revision details

Prepared By Date:

Reviewed By Date:

Approved By Date:PDO Review Date:


2/23

1.0 PURPOSEThe purpose of this document is to define the tests to be conducted on site for allelectrical equipment and to specify the acceptable values.

2.0 SCOPEThis procedure shall be applicable for testing and commissioning of transformers,circuit breakers, switchgears, potential transformers, current transformers, HV &LV cables, battery, battery charger etc of Contract No: C31/0707 132KV OHLReinforcement- North Project.

3.0 RESPONSIBILITYTesting Engineer shall perform the activity. The tests will be witnessed by QC(Inspector) Electrical. QA/ QC Engineer will verify the test results forconformance to specifications. PDO representative will witness the activity.

4.0 DOCUMENT REFERENCE

SP- 1100 - Specification for Testing and Commissioning of Electrical Equipment

5.0 RECORDThe inspection results are recorded on the prescribed site test report.

6.0 PROCEDURE

I. TRANSFORMERS (Auxiliary)

These tests cover all inspection and testing to be performed after installation andprior to energisation.

Equipment Required-Meg ohmmeter 500v-5kV-Multimeter-Ohmmeter-Voltmeter-Ammeter

-Phase sequence tester

Mechanical Checks

Check all the gasketed joints to ensure that there is no leakage of transformer oilat any point

Check all bushings for any crack or any breakage of porcelain.

Check oil level of main tank (should be up to the level mark on oil gauge)

Check alarm and trip contacts of WTI, OTI, pressure relief device etc.

Off load tap changers to be checked as per suppliers instruction manual.

Make sure that all tanks and cable boxes etc are connected with earth.

Check the main tank and marshalling cubicle are earthed at two points.

Check that the thermometer pockets on tank cover etc are fitted with oil

CTs secondary terminals must be shorted and earthed.


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Check the tightness of all external electrical connections.

Clear of extraneous materials like tools earthing rods, pieces of cloth, waste, etc.

Lock the unit to foundation, where applicable.

I R test

Insulation resistance test is conducted on transformer with 5000v & 500Vmeggers.Standardized motorized megger set is used. Check IR value between:PrimaryEarth with 5000V meggerPrimarySecondary with 5000V meggerSecondaryEarth with 500VThe minimum value allowed at 60 is 100 M Ohms.IR 60 / IR 10 >= 1.3Applied Voltage: - For auxiliary transformer (11 / 0.415 kV) HV side -5000V &LV side -500 Volts.

(Check for manufacturers requirements as per installation manual and comparewith FAT results)

HV LV

1U1

1W1

1N

2U1

2V1

2W11V1

MOTORISED

MEGGER

Connection diagram HV-LV

Ratio Test

To check the voltage ratio for each tapping between pair of winding

Voltage ratio is the ratio of number of turns of HV to number of turns of LV.Voltage ratio can be directly measured by ratio meter directly or either giving alow voltage on HV winding and measure the induced voltage across the LVwinding. Measurement shall be done at each tapping of all three phases.


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Single phase

230V supply

HV LV V

Vector Group

This test is to check the phase displacement between the instantaneous induced

voltage in the primary and the secondary winding. Three-phase supply is givenon the HV side after shorting one HV and LV terminals (1U and 2U). Then thevoltage is measured between different terminals. For Dyn11 transformer thevoltage must be measured between the terminals as shown1V-2V (1)1W-2W (2)1W-2V (3)1V-2W (4)If the vector group is correct then (1), (2) and (4) are equal and the voltage (3) ishigher.

Magnetic Balance Test

This test is conducted to find out the balanced voltage .A single phase voltage(230v) is given to HV between one phase and neutral and the voltages on theother phases are measured with the respect to neutral. Procedure is repeated bychanging the supply to other terminals also.

With voltage applied on U phase, voltage measured on V phase should be 60 to80% of applied voltage and W phase 20 to 40% of applied voltage.

With voltage applied on V phase, voltage measured on U & W phases should be40 to 60% of applied voltage.

Commissioning

After the inspection is completed, the transformer may be energized from theincoming side on no load and kept on soak for 24 hours. It is preferable to keepthe settings of all protective relays to the minimum during this period. Excessivevibration of radiator parts etc should be located and corrected. The transformerhum should be observed for any abnormality. After that it may be checked for gas

collection. Other instruments may also be checked for any abnormal indication.


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If every thing is found satisfactory, the transformer may be energized again andloaded gradually. It should be under observation during the first few hours ofoperation and check the transformer in parallel operation with load and withoutload, observe the load is shared equally in both transformers.

II. BATTERY CHARGERS / BATTERIES

Station batteries are an important element in a facility's electrical system. Theyare called upon to provide power during some of the most critical moments in apower system's operation.

These batteries provide power to operate protective relay and monitoringsystems and trip high voltage circuit breakers, thus preventing or minimizingdamage and interruption to the system caused by various faults, both internaland external to the facility.

A battery system should be maintained through a program, which includesperiodic inspection and testing. This is important since battery failure does notalways coincide with its average service life expectancy. There are many factorsthat may dramatically shorten the service life of a battery or interfere with itsoperation as designed. They include but are not limited to --Cell post damageInter-cell bus or cable work and associated connectionsCorrosion of connections & LeakageVariation in voltage from cell to cellBattery charger settings

Ambient temperature or lack of proper ventilation.Testing is useful for two reasons. First it confirms that the batteries meet thespecifications of both the manufacturer and the customer, and second it providesa baseline for comparison with future testing results.

Performance testing provides data on the present condition of the battery and itscapacity, and may spot problems before they impede the ability of the battery tomeet the needs of the system.

Service testing is used to determine if the capacity of the battery is adequate tomeet the needs of the DC system.

Equipment required-Multimeter-Milliohm meter for continuity measurement-Megger 500V DC-Secondary injection kit-Test power supply-Hydrometer-Load Bank (For load test)

Preliminary checks


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Check battery, battery charger and DB constituent parts and confirm to theapplicable drawings (type, rating, ground fault sensor, low and high voltagesensors, voltage monitoring relays, voltmeter, ammeters, circuit breakers andisolators.

Check that it is not possible to come into contact with the energized equipment

when working on the system. Checks the batteries inter link bars, cables, DB Busbars and auxiliary circuits(control, monitoring alarm, and fault) for continuity.

Check the ground Busbar continuity and connection to the main groundingsystem.

Check that the hinged doors and panels are connected to the frame bygrounding braids.

Check that the door locks for correct operation.

Opened all input and outgoing circuit breakers / isolators.

Battery Charging / Discharging test

Constant current can only be obtained through the use of specially designed testequipment. This is due to the fact that as a battery discharges, the voltagedecreases and the current will decrease proportionally when connected to astandard load bank. The proper test equipment will constantly monitor the systemand lower the resistance of the load to compensate for the decrease in batteryvoltage and keep the current draw constant. The test should be performed untilthe battery terminal voltage decreases to a value equal to the specified averagevoltage per cell (end cell voltage) multiplied by the number of cells. Readings ofindividual cell voltages and battery voltage should be taken while the load is

connected at the beginning and end of the test, as well as at specified intervalsduring the test. At the conclusion of the test, the capacity of the battery can thenbe calculated. This shall be compared with the FAT report.

Specific gravityWith a hydrometer, the specific gravity of each cell can be measured. The bestway to monitor battery condition is to measure the specific gravity of each cell.The readings should be within the range 1.19 to 1.27 for NiCad batteries.


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Hydrometer

Open circuit voltage

A digital voltmeter must be used to check the battery's open-circuit voltage.

IR Test of Power wiring

Insulation megger is used for measurement of insulation resistance of batterywiring

Commissioning

Ensure that the battery is in charged condition prior to commencement of tests.This can be checked by reading specific gravity of the electrolyte in sample cells.

Top up battery, if necessary, with distilled water. Demineralised water may beused subject to approval by the battery manufacturer.

Connect load equivalent to 50% of charger rating and with charger switched off,check that battery discharges correctly; also that low voltage alarm relayoperates. Discharge should not exceed the cell voltage less than 1.0 volt.

Switch on the charger to float position when batteries are fully charged. Checkthat the dc voltage is within limits covered by the specification concerned. Checkoperation of earth fault detector by connecting each pole of the system to earth

through variable potentiometer. Check the specific gravity and voltage of each cell after disconnecting discharge

load and values shall be recorded.

CELLREADINGS

PERCENTCHARGED

1.270 100 %

1.230 75%

1.190 50%

1.145 25%

1.100 0%


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IV. CIRCUIT BREAKERS (LV & HV)

Electrical Tests and checks

Check CB on local closing order.Check CB on local tripping order.Check that CB does not close with a permanent tripping order.Check the transfer of informations-Closing-Tripping-FaultCheck the insulation applying a 5000V(for HV) / 500V(for LV) DC voltagebetween each phase and the others connected to the ground.

Contact Resistance

Contact resistance of CB main contacts are measured by Micro-ohmmeter. Thereadings shall be comparable with FAT results / in line with manufacturersrecommendations.Outdoor circuit breaker- Timing test to be carried out by using suitable test kit.Results should be as close as possible to that indicated in manual.

V. HV ISOLATORS

Check the operation of Isolators-- Closing

- OpeningCheck operation of earth switch & its interlock with operation of Isolator.

Check the insulation by using 5000V Megger between each phase and the othersand with ground.Contact resistance of Isolators contacts are measured by Micro-ohmmeter.The readings shall be comparable with FAT results / in line with manufacturersrecommendations.

VI. 132 KV SURGE ARRESTOR

Check the insulation by using 5000V Megger between terminal and ground.The readings shall be comparable with FAT results / in line with manufacturersrecommendations.

VII. HV & LV CABLES

Purpose: The procedure explains the method of testing the high voltage cable inthe system.Initial Checks: Check the HV cable termination job is completed in all respect

including gland earthing to the system.Draw out both HV CB & VT unit (if any) from the Main Bus Bar.Keep the cable spout-earthing switch in open position.


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Phasing TestThe phasing test is conducted to check the correct phases of the cables i.e. R-R,Y-Y, B-B. This is done by using phasing tester.

Insulation Resistance Test

The cable to be tested is disconnected and prepared at each end. The equipmentgrounds are connected to the main ground system. Apply 500V DC to the cableby megger. Wait for one minute, and then take the readings. Acceptable value is100M ohm (for LV Cable)The value can be calculated using the following formulasMinimum value (M ohm) = kV / length of the cable in KMAcceptable value (M ohm) = 10x kV / length of the cable in KMInsulation test is conducted on HV power cable between1) Core-to-Core, 2) Core to Earth, 3) Core (all conductors connected together) toArmour and ground.This is done by 5kV-motorized megger. The minimum acceptable value is kV

rating / Length of the cable in km.

HV Pressure Test

HV pressure test is conducted using the high voltage dc tester. HV test shall beconducted on each phase and earth with the remaining phases connected toearth and loads disconnected. The high voltage DC is applied to the cables, for3-minute duration. The maximum reading allowed is 100mA/km.

Keep the HIPOT KIT (D.C) to the point of testing the HV cable. Connect HV leadto the one phase of the circuit under test and other two phases to the groundterminal in the test kit. Again connect kit ground terminal to the General Mass ofearth. Recommended Test voltages are as under :

Cable Voltage [kV-ac] Test Voltage [kV-dc]

UO unearthed / U earthed (U max)

< 1.0 - IR Test only1.8 / 3 (3.6) - 10

3.6 / 6 (7.2) - 156/10 (12) - 258.7/15 (17.5) - 3512/20 (24) - 5018/30 (36) - 70

Select the required voltage and current level for meter readings. Start withpotentiometer in the zero position, energize the kit and gradually increase thevoltage within a minute to the required level and observe the current. Start thestopwatch and select current range to the readable position. Observe for 3minutes and then take final voltage and current readings. During the above

period, readings should be more or less steady and minor fluctuations shall beignored. At the end of the elapsed time, reduce the voltage gradually to zero andisolate the power. Then discharge the HV cable and change to the next phase.


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Repeat the same procedure by connecting all 3 phases together with respect toearth. Take the insulation readings of cable before and after the test

Continuity Test

The continuity of all phases of cables is checked by Multimeter or by continuitytester.

Armour Testing: - Connect the armor to the main earth system through anequipment ground. Perform the test between all conductors connected togetherand the armor.

Shield Testing: -

Shield to armour insulation resistanceConnect the armour to the main ground system through an equipment ground.

Perform the test between the shield and the armor.Shield to conductor insulation resistancePerform the test between the shield and all conductors connected together

Conductor testing: -Perform the test between one outer conductor and all other conductorsconnected together

Shield continuity test:-The cable is disconnected and prepared at each end. The equipment groundsare connected to the main ground system.

With the cable shield connected to the ground system at one end, check that theresistance between the other end and ground is close to zero, using anohmmeter.

Visual inspection before energizing

-Reconnect the cables at both ends; check the terminations for the conformitywith the applicable drawings.-Check the cable markings for conformity with the applicable drawings.

-Check the amour ground for conformity with the applicable drawings.

VIII. CURRENT TRANSFORMER

Before testing the relaying, metering and measuring equipment, it is necessary tocheck the associated current transformers.

Equipment required-Multimeter (analogue)-Polarity test set

-Voltmeters & Ammeters-Clamp-on meters


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-1 milli ohmmeter / digit volt- ohm meter-Autotransformer & Step-up transformer-Megger 500V-5kV

Initial Check:

Check the type and rating of the CT with the specification / Drawings. The wiringcircuit shall be checked to ensure proper termination, core marking and wiringharness

I R TestBetween primary winding and groundThis test is performed by using megger of appropriate range.Test is conducted on primary winding of each phase, with the primary windings ofthe other phases temporarily connected to ground.The secondary windings are connected together and to ground.

Apply the test voltage for one minute.

For Primary side, apply voltage depending on rating of voltage rating of CT.

For LV CT, apply 500 VoltsFor 6.6 kV CT, apply 2.5 kV andFor 33 kV CT, apply 5.0 kV.

Between secondary winding and ground

P1P2

MOhm

S1 S2


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Measure the insulation resistance successively between each winding and theother windings connected to ground. Apply 500V for one minute.

P1P2

MOhm

S1 S2

Polarity Test

DC supply is used for this test.

Bidirectional

Milli Ammeter

S1

S2

P1

P2

While closing the circuit, if the ammeter deflects for positive deflection theconnection is correct. If the needle direction changes, repeat the test again byinter changing the secondary leads in the terminals. During the process of testingone CT, other CT leads shall be kept in shorted condition.

A self contained RS polarity test set with rechargeable battery can also be usedfor this purpose.

Circuit resistance measures

For differential relays, high impedance relays the secondary side and the loopresistance must be measured. The loop resistance is measured by Milli OhmMeter.

Primary current test


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The measurements are performed with single-phase current, with the secondaryloops in final condition (relays, meters etc) and grounded.

For current measurement, use a clamp on ammeter to avoid opening thesecondary circuits.

Measure the voltage (mV) across the primary winding as a check that theprimary winding is in correct operating condition and that the connections arecorrect (very low contact resistance)

Transformer turns ratio tests

The purpose of this test is to confirm the ratio marked in the nameplate of the CTmanufacturer with our test results.Measure the primary and secondary currents. This will give the IP/IS ratio andallows checking the equipment ratings.Arrange the primary injection kit with loading unit with the main supply connectedto the 240V AC system

Select suitable current range in the kit and set variac in the start position.Energise the supply and increase the current gradually to the required positionbetween 10% to 100% of the CT ratio. Confirm the ratio by recording the primaryand secondary current readings. Repeat the same procedure to the next CT

Ip

P2

S2

V

P1

S1

AIs

MAG Curve Check (Secondary knee point voltage)

The purpose of this test is to confirm knee point voltage of CT with respect to the

protection & metering circuit design in the system.

Connect 1 phase supply of suitable rating through Voltmeter, Ammeter & variacto the secondary side of the CT. Remove all other outgoing metering & protectionleads from the CT. Increase the voltage gradually and achieve knee point voltagewhere a 10% increase in voltage increases 50% of the excitation current andfurther raise upto the saturation level.

Now record voltmeter & ammeter readings by gradually decrease the voltageupto the zero level and disconnect the supply. Confirm the readings areaccording to the manufacturer test results. Again inject the secondary voltage to

the protection or metering CT lead and record the voltage required for full loadcurrent. Report the same procedure for other CT's.


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IX. VOLTAGE TRANSFORMER

Equipment required-Polarity test kit-Megger 500-5000V

-Ohmmeter-Multimeter-Autotransformers & Step-up transformers

General inspectionMechanical checks

General visual inspection and compliance with the drawings and manuals.

Check nameplate ratings and HV, LV terminal markings.

Check that all parts of the transformer are properly assembled and tight.

Check the HV connections are tight.

Check the cable connections on the LV side and the markings. Check the oil levels and inspect for leakage. (Where applicable)

Capacitor dividers typeCheck that all parts of the transformers are properly assembled.

Electromagnetic typeCheck the installation of different sections

Electrical Checks

Check the equipment grounding (Continuity and connection)

Check the fuse rating of secondary side.

Perform the operation described in the following

Insulation Resistance Test

To obtain values as close as possible to the manufacturers specifications theinsulators must be very clean. Select the megger range corresponding to theratings of the equipment under test.

For Primary side, apply voltage depending on rating of voltage rating of VT.

For 6.6 kV VT, apply 2.5 kV and

For 132 kV VT, apply 5.0 kV.

Measurement between primary and secondary


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M

Ohm

P1

P2

S2

S1

Measurement between primary and ground

P1

P2

S2

S1

M

Ohm

Measurement between secondaries and between secondary and ground

P1

P2

S2

S1

M

Ohm

Polarity TestThe polarity is checked using the flick method (application of direct current) andcheck of deflection on a bi-directional milliammeter. The test is also used tocheck primary and secondary circuit continuity.-When switch k is closed, the milliammeter pointer deflects positive.-When the circuit is opened, the milliammeter pointer deflects in the negativedirection.


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P2

S2

S1P1

K

mA

Transformer Turns ratio testA variable AC source is applied on the primary side. The primary and secondaryvoltages are measured to determine the ratio V2/V1

AUTO TRANSFORMER

V

P2

S2

P1

S1V

N

STEPUP TRANSFORMER

X. HV / MV SWITCHGEAR PANELS

These tests cover all the inspection and testing to be performed on the HV / MVswitchgear panels after installation and prior to energisation.

Equipment required-AC Generator

-Micro Ohmmeter-Voltmeter-Ammeter-Primary current injection kit-Secondary current injection kit-High voltage test kit-Test supply-Torque spanner

Preliminary ChecksMechanical checks

Check that setting up has been completed and Busbar tightened. Check that all switchgear components are fitted.


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Check earthing switch operation.

Check the mechanical interlocks preventing any hazardous operation.

Check that it is not possible to close the ground switch with the circuit breaker inclosed position.

Check that it is not possible to insert the circuit breaker into service with theearth switch closed.

Check the voltage transformer mechanical operation where applicable.

Check that it is not possible to open the rear panel with the earth switch open(where applicable)

Electrical checks

Check that the ground circuit is connected with main grid

Local / remote circuits

Protection circuits

Instrument circuits Power circuits (aux)

Check that the supply cable tests have been performed.

Check fuses / MCBs for continuity

Check CB operation in test / service condition as per approved schemedrawings.

Busbar Dielectric TestsPreliminary steps

Ensure that all earthing switches are open and locked.

Disconnect, short out and ground the potential transformer primary windings.

Ensure all the CBs are open and racked out.

Short out and earth the current transformer secondary windings.

Disconnect the power cables connected to the switchgears panels and short outwith ground.

Make sure the entire panel Busbars compartment cover replaced and cleaned.

Pad lock the bus section panel Busbars shutters.

Test Procedure

Apply the voltage two times of normal voltage as per PDO standard byconnecting each phase conductor to the HV terminal of the test supply.

Connect all the other Busbars to ground. Test duration 1 minute.

The dielectric tests are performed with all circuit breakers open and racked out.

For circuit break HV test, make short of all CBs top pole and bottom poleseparately.

Before and after HV test IR value must be checked.

Switchgear Tests

Mechanical tests and checks

Checks the operation of the spring charging mechanism.


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Check the breaker rack in / out operation with appropriate interlock and bus barshutter operation.

Check the mechanical tripping and closing of circuit breaker.

Check the mechanical operation indicators.

Instrument / Instrument transformer tests Apply a 3-phase voltage to the PT primary, measure secondary values and

confirm the ratio.

Apply current to the primary side of the current transformer, measure secondarycurrent at switchgear and appropriate panels and confirm the ratio of CTs

The measuring instruments shall be checked with secondary injection and ratioto be confirmed.

Check that CTs secondary cores are earthed at one place only.

Check that the VTs primary / secondary star points are connected with mainground circuit.

Magnetizing current measurement shall be checked for class X CTs.

Protective device Tests

Voltage Protection

Applying a AC voltage across the potential transformer secondaries (primary shall beisolated to avoid reverse voltage). Check the relay trip and non trip values and timedelay measurements.

Check the relay trip and alarm indication in local / remote mode.Current Protection

Apply variable current source to the CT secondaries (disconnecting CT secterminals)

Check relay trip and non-trip operation values and time delay.

Check the associated tripping of CBs and alarm indications.

Confirm CTs circuit protection relays are not open.

Energizing

Check that the above test has been performed.

Confirm all the equipments are ready for energisation / VTs are in serviceposition.

Confirm all the associated panels are ready for energisation. Check all the outgoing CBs are in racked out position and locked.

Send a closing order from incoming CBs to energize the switchgear panels.

After energisation check the voltage indication value in voltmeter at local /remote mode.

Phase sequence for incoming supply shall be checked.

CB tripping shall be checked with switchboard live condition.

XI. CONTROL AND RELAY PANEL

Relay testing includes verification of operation of switching device trippingmechanism and all alarm and intertrips. Relays should be tested and


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commissioned in accordance with manufacturers instruction. All protectionrelays shall be tested by means of primary injection at the normal settings toverify their operating parameters. Because of extreme current requirements forprimary current injection, it is impracticable to use the primary current injection.Therefore relays can be tested by secondary injection as per PDOs approval.

Secondary Injection of protection relays and instruments

Secondary

Injection

Kit

O/C , E/F

Relay

Disconnect the secondary of CT for checking the proper working of relays;This test is performed with single-phase current injecting with secondaryconnected to relays and meters. The secondary injection is done by injecting thecurrent of rated value of the relay and check the relays are tripped withinfunctional limit (time delay, instantaneous operation, alarm operation etc)

Primary Injection of protection relays and instruments

S1

S1

S2

S2

S2

Primary Current injection kit

S1

Busbars

To Relay

DC, AC Voltage Measurement test

XII. HV BUSBAR AND CIRCUIT BREAKER

The procedure explains the method of testing the HV Bus Bar and CircuitBreakers in system.

Equipment required-5 kV Insulation Tester


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-230 V supply Unit

PROCEDURE1. Close all the breakers connected to the bus bar under test.2. Measure the insulation resistance of R phase of the bus bar with reference to

the earth by keeping the two phases of bus bar at earth potential.3. Repeat the step-2, for other two phases and note down the values.4. Connect HT voltage terminal of HV test kit to the R phase of the bus bar and

other two phases of the bus bar should be earthed.5. Apply High Voltage AC from zero to test value recommended by manufacturer

for 3 minutes to R phase of the bus bar.6. Measure the insulation resistance of the phase tested.

Repeat the steps - 4 to 6 for other phases and note down the values.If the bus bar and circuit breaker under test withstood the high voltage, the test isconsidered as passed. Record the values format and verify the values of

insulation resistance before and after test

XIII. 132KV OVERHEAD LINE

Conductor Joint Tests

Contact resistance of the clamps, joints and terminal fittings shall bemeasured and noted in the format during stringing activity.

Where the joint consists of several parts bolted together (dead end clamp with

bolt on jumper terminal), resistance to be measured is that of the completedassembly and resistance of such fittings shall not exceed 75% of theresistance of an equivalent length of conductor.

The contact resistance shall be measured by using the Ductor instrument(micro ohm meter digital).

After completion of the stringing activity, overall installation checks shall becarried out with presence of company representative.

The inspection of the overhead line shall be carried out as mentioned in thecompany format and results recorded.

Pre-commissioning Tests

Subsequent to the inspection the following tests shall be carried out foroverhead lines.

Line continuity shall be measured with an approved insulation tester 1000Volt rated.

Insulation resistance of the line to earth and between phases shall bemeasured with an approved 5KV motorized insulation resistance tester.

Line Impedance test to be carried out for total length of OHL.

XIV. LV AC DISTRIBUTION BOARD

These tests covers all inspection and testing to be performed on the distributionboard after installation and prior to energisation


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Equipment required-Variable transformer-Insulation tester-Voltmeter-Phase sequence tester

-Test supply-Mega Ohmmeter & Micro Ohmmeter

Preliminary Checks

Check that all the distribution boards constituent parts are fitted and conform tothe applicable drawings (Voltmeters, ammeters, circuit Breakers)

Check the mains Busbars and auxiliary circuit (control, supervision, alarm, fault)for continuity.

Check the grounding Busbar continuity and connection to the main groundingcircuit.

Check that the hinged doors and panels are connected to the frame bygrounding braids.

Check door locks for correct operation.

Check the connections for conformity with the reference drawings.

Open all the input and load circuit breakers.

Ground Continuity testTest the continuity between all the metal parts and ground with Milli Ohmmeter.

Insulation Resistance test

Disconnect the devices which cannot withstand the test voltage

Disconnect the potential transformer.Power circuit (Busbars)

Apply 500 V DC for 1 minute

Between each phase and the other two connected to ground.

Between each phaseAuxiliary Circuit (Control, Indication)

Apply 500 V Dc for 1 minute between the auxiliary circuit and ground.Acceptance criteria >20 mega Ohm

Mechanical Checks

Check the CB rack in and rack out operation. Check the CB close / open operation.

Electrical checks

Test all the equipments (CT, thermal relay, fuse) of each CB.

Check the wiring and tightness of each connection.

Test all the current circuit equipments (CT, Thermal relay, Meters) by primaryinjection.

Energise the auxiliary circuit and Check that the contactor or circuit breaker closes on local control mode.

Check the contactor or CB tripping by protection trip.

Check the operation from remote panel in remote control mode.


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Check the following indications-Contactor closed-Contactor open-Potential transformer fault

Protection device testsCircuit breaker and disconnecting switch protections

Magnetic protection-This protection should cause the circuit breaker to trip when a short circuitoccurs.-Visually check that the tripping value, check the value is as indicated inapplicable documents.

Thermal protection-This protection should cause the circuit breaker to trip when an overload occurs.-Visually check that the tripping, check the value same as that indicated in theapplicable documents.

EnergisingBefore energizing the equipment the above tests shall be performed.

Once again check the insulation value.

Close all the covers.

Check that the mechanical and electrical operation with interlock.

Disconnect and lock all the circuit breakers.

Rack in the incoming CB at upstream switchgear.

Send a close command to incoming CB

Check for-Voltage on voltmeters.-Correct Phase sequence

XV. TESTING OF EARTH RESISTANCE

Earth resistance of earth electrodes can be measured using earth megger 3point method. The megger has 4 terminals C1, P1, C2 and P2. C1 and P1

are shorted and connected to the test electrode. From C2 and P2, two leadswith spikes are connected. The spikes are driven to earth at a distance of 15mtr from each other. Apply voltage through earth megger by cranking. Thevalue shown on earth megger intrepreted with the range selection gives theearth resistance. Null deflection earth megger can also be used to measureearth resistance.

XVI. FIRE ALARM SYSTEM

Functional test of Fire Alarm System

Fire Gas detection and alarm system (FGSs) shall detect at an early stage:The presence of fire.


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The presence of smoke from smoldering or incipient fires.

A full site acceptance test will be performed to demonstrate the FGSs functionscorrectly. The complete FGS system and control systems shall be commissionedon the basis of realistic tests prior to startup.

After ensuring installation of heat and smoke detectors as per the approveddrawing, testing of the system shall be carried out in presence of vendorrepresentative.

The following simulation tests shall be carried out and confirmed for properfunctioning:

1) Testing of all detectors2) Testing of manual call points3) Testing of hooter / alarm

4) Testing control panel for logic, indications of fault in respective zones,sequence, logic and contacts to SCADA / AC shut-off, etc.

Date post:	04-Apr-2018
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68237870 Testing of Electrical Equipments

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