Page 99 - Practical Power System and Protective Relays Commissioning

Circuit Breakers Theory Testing and Commissioning Chapter | 7 97

FIGURE 7.13 Test connections for circuit breaker in a closed condition.
occur under abnormal voltage conditions during system operations. The high-
potential test should be the final test performed after all repairs have been
made and a successful insulation resistance test has been carried out. The
maintenance test voltage should be 75% of the factory test voltage and the
time duration should be 1 minute. For example, for 13.8 kV the factory test
voltage will be at 36 kV and the maintenance test voltage will be at 27 kV.

7.6.4 Circuit Breaker Timing Test

This test is performed to verify the open and closing times of CB contacts. It
is done using a CB timing tester to measure the closing time and tripping