A simple overcurrent protection circuit for a high voltage laboratory

A system for safeguarding a moderate power high-voltage laboratory against transformer overcurrents following insulation failures in test objects is described. It is simple, requiring the construction of only two solid-state control circuits and the modification of a commercially available solid-state contactor. It has been tested successfully with simulated breakdowns at up to 50-kV rms, 60 Hz with a 50-kVA load.