Abstract: In an arc processing apparatus for supplying an electric power for an arc process through output terminals to a load containing an electrode and a workpiece to be processed, a main power source supplies an electric power for arc process to the load, and an auxiliary power source supplies another electric power to the load, where the auxiliary power source has a no-load voltage higher than that of the main power source and an electric power capacity smaller than that of the main power source. First and second output switches turn on or off supply of the electric power from the main and auxiliary power sources, respectively. A controller turns on the second output switch so as to short-circuit the electrode with the workpiece and to perform an arc activation, and thereafter, in response to an arc detection signal representing generation of an arc, turns on the-first output switch.

Abstract: There is disclosed a power source apparatus for an alternating-current arc welding. In the power source apparatus, a reference signal generator periodically generates a reference signal having a predetermined waveform, and a direct-current power source outputs a current periodically changing in response to the reference signal, the outputted current having a waveform corresponding to that of the reference signal. Thereafter, a switching circuit supplies an alternating-current welding current to a welding load so as to sequentially change the polarity of the welding current from a straight polarity to a reverse polarity and from the reverse polarity to the straight polarity in synchronization with the reference signal by switching the current outputted from the power source in response to the reference signal.

Abstract: A power supply for arc processing which can be used with a commercial AC power supplying either a high or low voltage, with the low and high voltages having a ratio of 1:2. The power supply includes two or three rectifying circuits connected in parallel, each of which comprises three series diodes, with a first series connection point of each series connected diodes being connected to one of the input terminals (phases) of the commercial power supply. The power supply further includes two or three voltage change over circuits, comprising a capacitor and a voltae change-over switch, closed at a low voltage input, connected between a second connection point of its corresponding rectifying circuit and the first connection point of another rectifying circuit. An inverter circuit for inverse conversion is connected in parallel between the terminals of the three rectifying circuits.

Abstract: A plasma arc working apparatus of water cooling type provides a circulation system for circulating cooling water through a circulation passage in order to cool a working plasma arc torch and an introduction device for introducing pressurized gas into the circulation passage in order to drain the cooling water remaining in the circulation passage forcibly therefrom when the power switch for supplying electric power to the working apparatus is switched off.