Fault detection method in power supply device for electric discharge machining, control method for power supply device for electric discharge machining, and power supply device for electric discharge machining

摘要

An electric discharge machining apparatus for machining a workpiece by supplying a series of voltage pulses to a machining gap formed between the workpiece being machined and a tool electrode, comprises a machining power supply for supplying voltage to the machine gap; a switching transistor connected between the machining power supply and the machining gap for pulsing the output voltage of the machining power supply; a gate pulse generator is provided for generating a gate pulse signal having an ON time and an OFF time to control on/off switching operation of the switching transistor so that switching transistor is in non-conducting state when the gate pulse signal is OFF, a monitoring power supply is connected in parallel with the switching transistor, and; a faulty transistor determination circuit is provided which determines if a switching transistor has failed when current flows from the monitoring power supply through the switching transistor even though the gate pulse signal is OFF.