POWER SOURCE DEVICE FOR ARC PROCESSING

PROBLEM TO BE SOLVED: To overcome the problem that the reduction in the reverse bias voltage of a switching element drive circuit operable to drive an inverter circuit of a power source device increases the turn-off loss, which leads to the deterioration of the switching element.SOLUTION: The power source device for arc processing comprises: a DC conversion circuit; a full-bridge inverter circuit which converts a DC voltage to a high frequency AC voltage; an output control circuit which controls the inverter circuit, and stops the inverter circuit for a given length of time when the input current to a transformer reaches or exceeds a reference current; a switching element drive circuit which drives a switching element according to an output control signal, and supplies a reverse bias capacitor with current; and a switching control circuit. The switching control circuit turns on first and fourth switching elements so that the period of the first switching element remaining ON does not overlap the period of the fourth switching element remaining ON between 0 and 1/2 cycle, and turns on second and third switching elements so that the period of the second switching element remaining ON does not overlap the period of the third switching element remaining ON between 1/2 and 1 cycle when the inverter circuit remains stopped.