Functional & operational tests for medium voltage circuit breaker operating mechanism components

Medium voltage circuit breakers play a very important role in medium voltage switchgear( metal clad, metal enclosure,…), and operating mechanism electrical and mechanical components functional tests is one of the most important tests for circuit breakers in panels.

In this article, we have tried to talk about these tests briefly and in a list. Functional & operational tests are part of the routine and pre-commissioning tests for medium voltage circuit breakers.

For more information about the seam of these tests, refer to the standards related to medium voltage switchgear like IEC 62271-200, IEC 62271-100, and IEC 62271-1.

The main objective of the test is to check the proper operation function of the circuit breaker operating mechanism components; in this test, we do the following:

Operational tests for medium voltage circuit breaker operating mechanism:

Close Operation Test – Local—Remote

This test is conducted manually, Local & remotely. For the manual Operation test, we will charge the spring manual and the breaker is also closed manually and the opening is also done. For the Local operation, we give Control supply and A.C supply for the spring charge motor. We close the circuit breaker using the TNC switch. We observe the closing coil function and spring charging of motor operation. For remote operating is the site is ready then the remote operation is done using the remote system. If its site is not ready for this, we provide a local signal to the remote terminal and observe the operation of the breaker.

Trip Operation Test – Local—Remote

This test is conducted manually, Local & remotely. For the manual Operation test, The manually charged breaker is opened using the Trip switch… For the Local operation, we give Control supply and A.C supply for the spring charge motor. We open the circuit breaker using the TNC switch. We observe the tripping coil function. For remote operating if the site is ready then the remote operation is done using the remote system. If its site is not ready for this, we provide a local signal to the remote terminal and observe the operation of the breaker.

Protection Trip

For this test, the breaker has in the closed position initially. We provide an auxiliary rated voltage to the Master trip relay and observe the opening of the breaker and the position of the trip coil.

Functional test for medium voltage circuit breaker operating mechanism:

Photo 1 shows a medium voltage vacuum circuit breaker wiring diagram schematic:

Emergency Trip:

For this test the breaker has to be in charged or ON position, we operate the emergency push button. We observe the operation of the circuit breaker opening.

Aux. Switch Operation:

When the breaker is in the open condition we check the Aux.

contact of the breaker using a continuity tester, to confirm the contact is in NO /NC. Then we close the Circuit Breaker and check the same contact with the continuity tester, to confirm the contact is in NC /NO.

On-Off Indications (Lamp+Flag):

When the breaker is in open condition we check the Lamp + Flag of the relay. Then we close the Circuit Breaker and check the same Lamp operation.

Trip / Trip circuit healthy Lamp Indication:

The relay is operated and we observe the Trip lamp indication.

Limit Switch for spring charge motor:

In this test, we observe the operation of the limit switch of the spring charging motor. We give an A.C power to the motor and observer the operation of the motor and charging of the spring, on the indication of a fully charged spring the motor operation has to get stopped.

Test / Service Limit Switch:

This test is conducted to check the Test / Service Limit Switch Operation. During rack out the Breaker we obverse the indicator to change to test position & during rack in the breaker we obverse the indicator to change to service.

Operation Counter:

This test is conducted if an operational counter provision is available in the breaker. We operated the breaker and look for the change in the counter for counting the operation.

Heater / Heater Switch / Thermostat

The control A.C supply is given for the heater and we look for heater operation.

The function of the illumination & socket switch

In this test, we look for the panel's internal illumination & socket switch operation. We operate the limit switch manually and observe the operation of the illumination circuit.

Photo 2 shows a vacuum circuit breaker operating mechanism component model VP4 E Pars Switch company:

Source: switchgear content website: