ARC processing apparatus comprising driving means for controlling output transistor so that output voltage becomes predetermined no-load voltage

摘要

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. Further, an output control transistor is electrically connected in series between the auxiliary power source and the output terminals, and a driving circuit controls the output control transistor so that an output voltage becomes a predetermined no- load voltage in a range of an output current from zero to a predetermined threshold current.