Protecting a GTO under short circuit conditions

With the increasing application of the gate-turn-off thyristor (GTO), a need has arisen for improved self-protection under fault conditions where fast-acting semiconductor fuses are not available to fulfill this function. The authors investigate the design of the driver, snubber and protection circuits of a 25 amp 650 volt GTO used in a chopper circuit application. In particular they present a method of protecting the GTO under both accidental overload and short circuit conditions. Practical results are presented to verify the effectiveness of the system