PRE COMMISSIONING TEST PROCEDURE FOR CIRCUIT BREAKER

Testing and commissioning of a circuit breaker

Testing and commissioning of a circuit breaker

Purpose

procedure is prepared to carry out various pre-commissioning tests to be conducted in a systematic dmanner for Circuit Breaker to ensure the healthiness and performance of the equipment

Scope

This procedure covers the Pre commissioning test for Circuit Breaker as for the following

  1. Insulation resistance of control circuit
  2. Coil measurement
  3. DEW point test
  4. CRM Test
  5. Timing Test
  6. Insulation Resistance Test for circuit breaker

Pre-Testing Checks

  1. Check out the working condition of ELCB(30 mA)
  2. Check the insulation of power cable for equipment
  3. Ensure proper earthing and rubber mats available at the work location.
  4. Calibrated Testing equipment should be used and calibration reports available with engineers for the same
  5. Check out the insulates hand tools available with the technician
  6. Ensure the Healthiness of the test leads (Check for any insulation Damages)
  7. Ensure appropriate PPE’s available at sites

Resources – Tools and Equipment Required

  1. For IR for control circuit:
  • Insulation tester
  • Connecting leads
  1. Coil measurement:
  • Multimeter
  • Single three pole meter
  • Connecting leads
  1. For CRM Test:
  • CRM kit
  • Connecting Leads
  • Multimeter
  1. For DEW point:
  • Dew point kit
  1. For Timing Test and coil resistance measurement for circuit breaker:
  • Timer Kit
  • Test Leads
  • Multimeter
  1. For Insulation Resistance measurement for circuit breaker & control circuit (IR Test):
  • Test Leads
  • 500 V, 5000 V Insulation Tester
  • Insulated Hand Tools
  • Multimeter

Operational Sequence of work(Test Procedure)

  • Obtain the work permit from the client
  • Ensure zero energy in the Circuit Breaker
  • Ensure the all connections are in tight before testing

Insulation resistance for control circuit

Control circuit of breakers

  • Connect the IR kit across the various points of the control circuit
  • Switch ON the IR kit
  • Note down the readings

Main circuitof breakers (pole)

  • Connect the IR kit across the interrupter while circuit breaker Open condition
  • Connect the IR kit across the Pole & Earth while circuit breaker on Close condition
  • Switch ON the IR kit
  • Note down the readings

Coil Measurement:

TRIP COIL / CLOSE COIL RESISTANCE MEASUREMENT TEST

  • Select the Multi meter in Resistance Mode.
  • Connect the Multi meter across the Trip/Close coils.
  • Note down the readings

OPENING / CLOSING TIME MEASUREMENT TEST

  • Connect the Timer across the Breaks for the Opening Time
  • Connect the Timer across the Pole for the Closing Time/ “Close-Open” Time

Dew point test:

  • Keep breaker off condition
  • Connect dew point kit inlet valve to breaker
  • Keep outlet valve open condition
  • Note down the readings from dew point kit

Contact Resistance Measurement Test:

Testing and commissioning of a circuit breaker
Testing and commissioning of a circuit breaker

  • Keep the Breaker in closed condition
  • Connect the earth from CRM kit to earth plate or earth pit
  • Connect the CRM kit Current Leads(C+ & C-) across the RØ Circuit Breaker contact
  • Then Connect the CRM kit Voltage leads (V+ & V-) across the RØ Circuit Breaker contact. Voltage leads should be connect inside the Current leads
  • Connect the CRM kit in A.C supply extension board with ELCB rated with 30 mA
  • Inject the rated current to the Circuit Breaker
  • Note down the contact resistance value from the CRM kit
  • Repeat the above steps for the other phases (YØ & BØ)
  • Switch off the power supply to the CRM Kit and disconnect them
DO’s DON’TS
  • Breaker should be in closed position.
  • Voltage leads should be connected inside the Current leads.
  • While doing this test, no external cables should be connected.
  • Proper grounding should be done for the kit.
  • Don’t change the connection sequence (i.e., V+, C+ should be connected to R or Y or B & V-,C- should be connected to R’ or Y’ or B’ ).
  • Don’t change the supply configuration (i.e., voltage should be applied outside the current leads).
  • Contacts should not have any dust during this test.

 

Timing Test:

  1. Keep the Breaker in closed condition
  2. Connect the earth from Timer kit to earth plate or earth pit
  3. Connect the Timer kit feedback cables R and R’ leads across the RØ Breaker contact
  4. Connect the Timer kit feedback cables Y and Y’ leads across the YØ Breaker contact
  5. Connect the Timer kit feedback cables B and B’ leads across the BØ Breaker contact
  6. Connect the Timer kit in A.C supply extension board with ELCB rated with 30 mA
  7. Give The open command and note down the value from the timer kit
  8. Give the close command and note the value from the timer Kit
  9. Give the close/open command and note the value from the timer kit
  10. Switch off the power supply to the Timer Kit and disconnect them
DO’s DON’TS
  • Charge the spring motor manually or electrically to close the CB and to measure the time.
  • While doing this test, no external cables should be connected.
  • Proper grounding should be done for the kit.
  • Check the three phase contacts’ switching times are in the specified limit and the same.
  • Don’t supply improper voltage to the tripping and closing coils (i.e., for 110V coil, 110V should be applied).
  • Don’t give the supply with fluctuations.
  • Don’t remove the power pack cables without discharging.

 

Insulation resistance

IR TEST (BREAKER OPEN CONDITION)

  1. Keep the Circuit Breaker in open position
  2. Connect the 5000 V IR kit across the RØ Breaker contact (R & R’)
  3. Select the required voltage range in 5000 V IR kit
  4. Switch ON the 5000 V IR kit and press the test button take down the reading
  5. Repeat the above steps for the other phases (YØ & BØ)
  6. Discharge the voltage from the Circuit Breaker with respect to earth.

IR TEST BETWEEN PHASE TO EARTH (BREAKER CLOSED CONDITION)

  1. Keep the Circuit Breaker in closed position
  2. Connect the 5000 V IR kit Positive lead with RØ Breaker contact
  3. Connect the 5000 V IR kit Negative lead with earth
  4. Select the required voltage range in 5000 V IR kit
  5. Switch ON the 5000 V IR kit and press the test button take down the reading
  6. Repeat the above steps for the other phases (YØ & BØ)
  7. Discharge the voltage from the Circuit Breaker with respect to earth.

IR TEST BETWEEN PHASE TO PHASE (BREAKER CLOSED POSITION):

Testing and commissioning of a circuit breaker

  1. Keep the Circuit Breaker in closed position
  2. Connect the 5000 V IR kitPositive lead with RØ Breaker contact
  3. Connect the 5000 V IR kit Negative lead with BØ Breaker contact
  4. Select the required voltage range in 5000 V IR kit
  5. Switch ON the 5000 V IR kit and press the test button take down the reading
  6. Repeat the above steps for the other phases to phase (RØ-YØ), (YØ & BØ) & (RØ-BØ)
  7. Discharge the voltage from the Circuit Breaker with respect to earth.
DO’S DON’TS
  • Remove all external wires from the CB contacts.
  • Check the calibration due of the test equipment
  • Ensure zero resistance when line and earth are shorted and switched on to know the zero value for the proper working of kit.
  • Keep some distance while doing the test.
  • After Insulation resistance test completion, note down the values and discharge the CT terminals and remove the test cables
  • Ambient temperature must be noted.
  • Don’t touch any cables and the kit when it is in running condition.
  • Don’t touch any bushing while doing the tests
  • Don’t connect any transmission line cables to the contacts.
  • Don’t test with damaged cables and improper clips
  • Don’t work in wet (rainy) conditions
  • Don’t lose your concentration while testing.

 

Control Measures

  1. OCP for CRM, Timing and IR test for Circuit Breaker is available with testing engineers
  2. Ensure PTW system in place for the particular bay
  3. Ensure all supply to the equipment is dead
  4. Unauthorized persons should not be allowed to enter Testing area
  5. Barricade the testing area with warning tape
  6. More than 2Mtr height shall be used safety belt or full body hardnessand proper working plat form or man lifter
  7. Less than 2Mtr height shall be used standard insulated ladder
  8. Inspect the ladders prior to work, keep both feet below 3rd rung from top, keep one hand on ladder minimum at all times.
  9. Proper supervision, conduct job specific toolbox meeting and barricading the entire area
  10. Calibrated equipment shall be used
  11. Insulated hand tools shall be used
  12. Avoid joints for power cable and supply has to be taken via ELCB
  13. Avoid Lone working
  14. Use appropriate insulated hand gloves
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