Functionality Test

Connect the power supply conductor (bus or cable) through the center of the current sensor.

After the circuit is properly connected and closed, apply current at 70% of the desired ground-fault pickup and delay setting. Maintain the current longer than the delay time setting. The circuit breaker should not trip. If it does trip, check the trip curve to make sure the injected current is below the pickup tolerance of the device being tested.

After the circuit is properly connected and closed, apply current at 150% of the desired ground-fault pickup and delay setting. Maintain the current longer than the delay time setting. The circuit breaker should trip.

Connect the power supply conductor (bus or cable) through the center of the current sensor.

After the circuit is properly connected and closed, apply current in short pulses of 10–cycle duration. Starting at 70% of the expected trip value, increase the current on each succeeding pulse until the circuit breaker trips. (Test assumes delay set to zero. If no delay setting of zero, pulse time can be adjusted to suit.) To simplify this test for functionality, inject current just below the minimum pickup point to hold, and just above the maximum pickup for a trip. Then skip to step 5.

Re-close the circuit breaker and reduce the current level; pulse again to determine if the pickup level found was overshot.

Repeat steps 2 and 3 to further isolate the pickup point.

To determine delay time, test at 150% of the desired ground-fault pickup and delay setting. Monitor the time from this pickup point until the circuit breaker trips to obtain the delay time.

Record pickup and delay values and compare the results to the trip curve.