A Triggered Chopping Gap for Use in Transformer Testing

Fault detection during chopped-wave impulse tests on transformers requires that the time to chop be constant at various levels of applied voltage. Apparatus devised for this purpose is described. Time to chop in the 1-to 6-μs range can be selected and reproduced with a precision better than 0.1 μs at voltage levels up to 400 kV. This system has been successfully used for over five years in the impulse testing of transformers rated at 66 kV and under.