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

Insulation resistance of control circuit
Coil measurement
DEW point test
CRM Test
Timing Test
Insulation Resistance Test for circuit breaker

Pre-Testing Checks

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

Resources – Tools and Equipment Required

For IR for control circuit:

Insulation tester
Connecting leads

Coil measurement:

Multimeter
Single three pole meter
Connecting leads

For CRM Test:

CRM kit
Connecting Leads
Multimeter

For DEW point:

Dew point kit

For Timing Test and coil resistance measurement for circuit breaker:

Timer Kit
Test Leads
Multimeter

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

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:

Keep the Breaker in closed condition
Connect the earth from Timer kit to earth plate or earth pit
Connect the Timer kit feedback cables R and R’ leads across the RØ Breaker contact
Connect the Timer kit feedback cables Y and Y’ leads across the YØ Breaker contact
Connect the Timer kit feedback cables B and B’ leads across the BØ Breaker contact
Connect the Timer kit in A.C supply extension board with ELCB rated with 30 mA
Give The open command and note down the value from the timer kit
Give the close command and note the value from the timer Kit
Give the close/open command and note the value from the timer kit
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)

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

IR TEST BETWEEN PHASE TO EARTH (BREAKER CLOSED CONDITION)

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

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

Keep the Circuit Breaker in closed position
Connect the 5000 V IR kitPositive lead with RØ Breaker contact
Connect the 5000 V IR kit Negative lead with BØ Breaker contact
Select the required voltage range in 5000 V IR kit
Switch ON the 5000 V IR kit and press the test button take down the reading
Repeat the above steps for the other phases to phase (RØ-YØ), (YØ & BØ) & (RØ-BØ)
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

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

PRE COMMISSIONING TEST PROCEDURE FOR CIRCUIT BREAKER