POWER SOURCE DEVICE FOR ARC MACHINING

PROBLEM TO BE SOLVED: To provide a power source device for the arc machining capable of adequately determining any improper connection in a constitution in which the connection mode inside the device is changed to the AC input voltage of different voltage values.SOLUTION: An input voltage detection unit 21 detects the voltage value of the secondary side AC voltage of a voltage lower transformer T3 for the detection unit for lowering the AC input voltage, and detects whether or not the AC input voltage is either 200V or 400V. A connection detection determination unit 22 detects the voltage value which is different according to the parallel connection or the series connection of first and second windings Pw1, Pw2 of a primary side winding Pw based on the supply of the secondary side AC voltage of the voltage lower transformer T3 for the detection unit to both ends of the W-phase primary side winding Pw of a three-phase transformer T1, and detects the connection mode of the primary side winding Pw. The connection detection determination unit 22 determines acceptance/rejection of the connection mode of the primary side windings Pu, Pv, Pw of the three-phase transformer T1 to the voltage value of the AC input voltage from the result of detection of the voltage value of the AC input voltage and the connection mode of the primary side winding Pw at that time.