CONTRACT SPECIFIC PROCEDURE FOR TESTING OF ELECTRICAL EQUIPMENTS & 132KV OHL
CONTRACT TITLE CLIENT PDO CONTRACT NO. MAIN CONTRACTOR LTEM CONTRACT REF. NO.
Document No.
Prepared By Reviewed By Approved By PDO Review
Revision details
Date: Date: Date: Date:
1.0
PURPOSE The purpose of this document is to define the tests to be conducted on site for all electrical equipment and to specify the acceptable values.
2.0
SCOPE This 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 OHL Reinforcement- North Project.
3.0
RESPONSIBILITY Testing Engineer shall perform the activity. The tests will be witnessed by QC (Inspector) – Electrical. QA/ QC Engineer will verify the test results for conformance to specifications. PDO representative will witness the activity.
4.0
DOCUMENT REFERENCE SP- 1100 - Specification for Testing and Commissioning of Electrical Equipment
5.0
RECORD The 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 and prior 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 oil at 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 supplier’s 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 CT’s secondary terminals must be shorted and earthed.
• • •
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 & 500V meggers. Standardized motorized megger set is used. Check IR value between: Primary–Earth with 5000V megger Primary–Secondary with 5000V megger Secondary–Earth with 500V The minimum value allowed at 60 is 100 M Ohms. IR 60 / IR 10 >= 1.3 Applied Voltage: - For auxiliary transformer (11 / 0.415 kV) HV side -5000V & LV side -500 Volts. (Check for manufacturer’s requirements as per installation manual and compare with FAT results) Connection diagram HV-LV LV
HV 1U 1 2U 1
MOTORISED MEGGER
2V1
1N 1V1 1W1
2W1
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 a low voltage on HV winding and measure the induced voltage across the LV winding. Measurement shall be done at each tapping of all three phases.
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 given on the HV side after shorting one HV and LV terminals (1U and 2U). Then the voltage is measured between different terminals. For Dyn11 transformer the voltage must be measured between the terminals as shown 1V-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) is higher. 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 the other phases are measured with the respect to neutral. Procedure is repeated by changing the supply to other terminals also. With voltage applied on U phase, voltage measured on V phase should be 60 to 80% 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 be 40 to 60% of applied voltage. Commissioning After the inspection is completed, the transformer may be energized from the incoming side on no load and kept on soak for 24 hours. It is preferable to keep the settings of all protective relays to the minimum during this period. Excessive vibration of radiator parts etc should be located and corrected. The transformer hum 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.
If every thing is found satisfactory, the transformer may be energized again and loaded gradually. It should be under observation during the first few hours of operation and check the transformer in parallel operation with load and without load, 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. They are called upon to provide power during some of the most critical moments in a power system's operation. These batteries provide power to operate protective relay and monitoring systems and trip high voltage circuit breakers, thus preventing or minimizing damage and interruption to the system caused by various faults, both internal and external to the facility. A battery system should be maintained through a program, which includes periodic inspection and testing. This is important since battery failure does not always coincide with its average service life expectancy. There are many factors that may dramatically shorten the service life of a battery or interfere with its operation as designed. They include but are not limited to -Cell post damage Inter-cell bus or cable work and associated connections Corrosion of connections & Leakage Variation in voltage from cell to cell Battery charger settings Ambient temperature or lack of proper ventilation. Testing is useful for two reasons. First it confirms that the batteries meet the specifications of both the manufacturer and the customer, and second it provides a baseline for comparison with future testing results. Performance testing provides data on the present condition of the battery and its capacity, and may spot problems before they impede the ability of the battery to meet the needs of the system. Service testing is used to determine if the capacity of the battery is adequate to meet 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
• Check battery, battery charger and DB constituent parts and confirm to the applicable drawings (type, rating, ground fault sensor, low and high voltage sensors, voltage monitoring relays, voltmeter, ammeters, circuit breakers and isolators. • 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 grounding system. • Check that the hinged doors and panels are connected to the frame by grounding 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 test equipment. This is due to the fact that as a battery discharges, the voltage decreases and the current will decrease proportionally when connected to a standard load bank. The proper test equipment will constantly monitor the system and lower the resistance of the load to compensate for the decrease in battery voltage and keep the current draw constant. The test should be performed until the battery terminal voltage decreases to a value equal to the specified average voltage per cell (end cell voltage) multiplied by the number of cells. Readings of individual 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 intervals during the test. At the conclusion of the test, the capacity of the battery can then be calculated. This shall be compared with the FAT report. Specific gravity With a hydrometer, the specific gravity of each cell can be measured. The best way 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.
CELL READINGS
PERCENT CHARGED
1.270
100 %
1.230
75%
1.190
50%
1.145
25%
1.100
0%
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 battery wiring 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 be used 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 relay operates. Discharge should not exceed the cell voltage less than 1.0 volt. Switch on the charger to “float” position when batteries are fully charged. Check that the dc voltage is within limits covered by the specification concerned. Check operation 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.
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 information’s -Closing -Tripping -Fault Check the insulation applying a 5000V(for HV) / 500V(for LV) DC voltage between each phase and the others connected to the ground. Contact Resistance Contact resistance of CB main contacts are measured by Micro-ohmmeter. The readings shall be comparable with FAT results / in line with manufacturer’s recommendations. 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 - Opening Check operation of earth switch & it’s interlock with operation of Isolator. Check the insulation by using 5000V Megger between each phase and the others and with ground. Contact resistance of Isolators contacts are measured by Micro-ohmmeter. The readings shall be comparable with FAT results / in line with manufacturer’s recommendations.
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 manufacturer’s recommendations.
VII. HV & LV CABLES Purpose: The procedure explains the method of testing the high voltage cable in the 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.
Phasing Test The 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 equipment grounds are connected to the main ground system. Apply 500V DC to the cable by megger. Wait for one minute, and then take the readings. Acceptable value is 100M ohm (for LV Cable) The value can be calculated using the following formulas Minimum value (M ohm) = kV / length of the cable in KM Acceptable value (M ohm) = 10x kV / length of the cable in KM Insulation test is conducted on HV power cable between 1) Core-to-Core, 2) Core to Earth, 3) Core (all conductors connected together) to Armour 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 be conducted on each phase and earth with the remaining phases connected to earth and loads disconnected. The high voltage DC is applied to the cables, for 3-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 lead to the one phase of the circuit under test and other two phases to the ground terminal in the test kit. Again connect kit ground terminal to the General Mass of earth. Recommended Test voltages are as under : Cable Voltage [kV-ac]
Test Voltage [kV-dc]
UO –unearthed / U – earthed (U max) < 1.0 1.8 / 3 (3.6) 3.6 / 6 (7.2) 6/10 (12) 8.7/15 (17.5) 12/20 (24) 18/30 (36)
- IR Test only - 10 - 15 - 25 - 35 - 50 - 70
Select the required voltage and current level for meter readings. Start with potentiometer in the zero position, energize the kit and gradually increase the voltage within a minute to the required level and observe the current. Start the stopwatch and select current range to the readable position. Observe for 3 minutes and then take final voltage and current readings. During the above period, readings should be more or less steady and minor fluctuations shall be ignored. At the end of the elapsed time, reduce the voltage gradually to zero and isolate the power. Then discharge the HV cable and change to the next phase.
Repeat the same procedure by connecting all 3 phases together with respect to earth. 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 continuity tester. Armour Testing: - Connect the armor to the main earth system through an equipment ground. Perform the test between all conductors connected together and the armor. Shield Testing: Shield to armour insulation resistance Connect the armour to the main ground system through an equipment ground. Perform the test between the shield and the armor. Shield to conductor insulation resistance Perform the test between the shield and all conductors connected together Conductor testing: Perform the test between one outer conductor and all other conductors connected together Shield continuity test:The cable is disconnected and prepared at each end. The equipment grounds are connected to the main ground system. With the cable shield connected to the ground system at one end, check that the resistance between the other end and ground is close to zero, using an ohmmeter. Visual inspection before energizing -Reconnect the cables at both ends; check the terminations for the conformity with 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 to check the associated current transformers. Equipment required -Multimeter (analogue) -Polarity test set -Voltmeters & Ammeters -Clamp-on meters
-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 wiring circuit shall be checked to ensure proper termination, core marking and wiring harness I R Test Between primary winding and ground This test is performed by using megger of appropriate range. Test is conducted on primary winding of each phase, with the primary windings of the 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 Volts For 6.6 kV CT, apply 2.5 kV and For 33 kV CT, apply 5.0 kV. Between secondary winding and ground
P2
P1
S1
S2 MOhm
Measure the insulation resistance successively between each winding and the other windings connected to ground. Apply 500V for one minute.
P2
P1
S1
S2 MOhm
Polarity Test DC supply is used for this test.
P1 S1 ±
Bidirectional Milli Ammeter
S2
P2
While closing the circuit, if the ammeter deflects for positive deflection the connection is correct. If the needle direction changes, repeat the test again by inter changing the secondary leads in the terminals. During the process of testing one CT, other CT leads shall be kept in shorted condition. A self contained RS polarity test set with rechargeable battery can also be used for this purpose. Circuit resistance measures For differential relays, high impedance relays the secondary side and the loop resistance must be measured. The loop resistance is measured by Milli Ohm Meter. Primary current test
The measurements are performed with single-phase current, with the secondary loops in final condition (relays, meters etc) and grounded. For current measurement, use a clamp on ammeter to avoid opening the secondary circuits. Measure the voltage (mV) across the primary winding as a check that the primary winding is in correct operating condition and that the connections are correct (very low contact resistance) Transformer turns ratio tests The purpose of this test is to confirm the ratio marked in the nameplate of the CT manufacturer with our test results. Measure the primary and secondary currents. This will give the IP/IS ratio and allows checking the equipment ratings. Arrange the primary injection kit with loading unit with the main supply connected to 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 position between 10% to 100% of the CT ratio. Confirm the ratio by recording the primary and secondary current readings. Repeat the same procedure to the next CT Ip
P1
A
Is
S1 V
S2
P2
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 & variac to the secondary side of the CT. Remove all other outgoing metering & protection leads from the CT. Increase the voltage gradually and achieve knee point voltage where a 10% increase in voltage increases 50% of the excitation current and further raise upto the saturation level. Now record voltmeter & ammeter readings by gradually decrease the voltage upto the zero level and disconnect the supply. Confirm the readings are according to the manufacturer test results. Again inject the secondary voltage to the protection or metering CT lead and record the voltage required for full load current. Report the same procedure for other CT's.
IX.
VOLTAGE TRANSFORMER Equipment required -Polarity test kit -Megger 500-5000V -Ohmmeter -Multimeter -Autotransformers & Step-up transformers General inspection Mechanical 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 type Check that all parts of the transformers are properly assembled.
• • •
Electromagnetic type Check 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 manufacturer’s specifications the insulators must be very clean. Select the megger range corresponding to the ratings 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
P1
S1 S2
P2
M Ohm
Measurement between primary and ground
P1
S1 S2 M Ohm
P2
Measurement between secondaries and between secondary and ground P1
S1 S2
M Ohm
P2
Polarity Test The polarity is checked using the flick method (application of direct current) and check of deflection on a bi-directional milliammeter. The test is also used to check 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 negative direction.
K
P1
S1 mA
S2
P2
Transformer Turns ratio test A variable AC source is applied on the primary side. The primary and secondary voltages are measured to determine the ratio V2/V1 P1
S1 V
V
S2
P2
STEPUP TRANSFORMER
N
AUTO TRANSFORMER
X.
HV / MV SWITCHGEAR PANELS These tests cover all the inspection and testing to be performed on the HV / MV switchgear 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 Checks Mechanical checks Check that setting up has been completed and Busbar tightened. Check that all switchgear components are fitted.
• 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 in closed position. • Check that it is not possible to insert the circuit breaker into service with the earth 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 / MCB’s for continuity • Check CB operation in test / service condition as per approved scheme drawings.
• • • • • • •
Busbar Dielectric Tests Preliminary steps Ensure that all earthing switches are open and locked. Disconnect, short out and ground the potential transformer primary windings. Ensure all the CB’s 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 out with 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 by connecting 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 CB’s top pole and bottom pole separately. Before and after HV test IR value must be checked. Switchgear Tests
•
Mechanical tests and checks Checks the operation of the spring charging mechanism.
•
Check the breaker rack in / out operation with appropriate interlock and bus bar shutter 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 secondary current at switchgear and appropriate panels and confirm the ratio of CT’s The measuring instruments shall be checked with secondary injection and ratio to be confirmed. Check that CT’s secondary cores are earthed at one place only. Check that the VT’s primary / secondary star points are connected with main ground circuit. Magnetizing current measurement shall be checked for class X CT’s. Protective device Tests
• • •
Voltage Protection Applying a AC voltage across the potential transformer secondaries (primary shall be isolated to avoid reverse voltage). Check the relay trip and non trip values and time delay measurements. Check the relay trip and alarm indication in local / remote mode. Current Protection Apply variable current source to the CT secondaries (disconnecting CT sec terminals) • Check relay trip and non-trip operation values and time delay. • Check the associated tripping of CB’s and alarm indications. • Confirm CT’s circuit protection relays are not open. Energizing • Check that the above test has been performed. • Confirm all the equipments are ready for energisation / VT’s are in service position. • Confirm all the associated panels are ready for energisation. • Check all the outgoing CB’s are in racked out position and locked. • Send a closing order from incoming CB’s 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 tripping mechanism and all alarm and intertrips. Relays should be tested and
commissioned in accordance with manufacturer’s instruction. All protection relays shall be tested by means of primary injection at the normal settings to verify their operating parameters. Because of extreme current requirements for primary current injection, it is impracticable to use the primary current injection. Therefore relays can be tested by secondary injection as per PDO’s approval. Secondary Injection of protection relays and instruments
O/C , E/F Relay
Secondary Injection Kit
Disconnect the secondary of CT for checking the proper working of relays; This test is performed with single-phase current injecting with secondary connected to relays and meters. The secondary injection is done by injecting the current of rated value of the relay and check the relays are tripped within functional limit (time delay, instantaneous operation, alarm operation etc) Primary Injection of protection relays and instruments Primary Current injection kit
S2
S1
Busbars S2
S1
S2
S1
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 Circuit Breakers in system. Equipment required -5 kV Insulation Tester
-230 V supply Unit PROCEDURE 1. 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 is considered 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 be measured 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 completed assembly and resistance of such fittings shall not exceed 75% of the resistance 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 be carried out with presence of company representative. • The inspection of the overhead line shall be carried out as mentioned in the company format and results recorded. Pre-commissioning Tests • Subsequent to the inspection the following tests shall be carried out for overhead lines. • Line continuity shall be measured with an approved insulation tester 1000 Volt rated. • Insulation resistance of the line to earth and between phases shall be measured 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 distribution board after installation and prior to energisation
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 to the 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 grounding circuit. • Check that the hinged doors and panels are connected to the frame by grounding 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 test Test 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 phase Auxiliary 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 primary injection. 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.
• Check the following indications -Contactor closed -Contactor open -Potential transformer fault Protection device tests Circuit breaker and disconnecting switch protections Magnetic protection -This protection should cause the circuit breaker to trip when a short circuit occurs. -Visually check that the tripping value, check the value is as indicated in applicable 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 the applicable documents. Energising Before 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 – 3 point 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 leads with spikes are connected. The spikes are driven to earth at a distance of 15 mtr from each other. Apply voltage through earth megger by cranking. The value shown on earth megger intrepreted with the range selection gives the earth resistance. Null deflection earth megger can also be used to measure earth 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.
The presence of smoke from smoldering or incipient fires. A full site acceptance test will be performed to demonstrate the FGSs functions correctly. The complete FGS system and control systems shall be commissioned on the basis of realistic tests prior to startup. After ensuring installation of heat and smoke detectors as per the approved drawing, testing of the system shall be carried out in presence of vendor representative. The following simulation tests shall be carried out and confirmed for proper functioning: 1) Testing of all detectors 2) Testing of manual call points 3) 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.
