The paper proposes a number of protection methods which can be used with power transistors in power-control units. They give satisfactory protection against simultaneous conduction of the two devices in an inverter leg. The techniques, which are independent of the control electronics and base-drive circuits, are simple and reliable to implement. They include an instantaneous and electrically isolated method of fault indication, a fast-acting crowbar circuit and a means of diverting the current away from the power devices in the event of a fault.