Patent ID: 7586766

Claim:
A plasma arc power supply comprising: output setting means for specifying an output of a variable load current; N (N≧2) direct-current power supply units that are feedback-controlled by a detection signal of a corresponding output current; a relay circuit for outputting a relay signal for delaying a drive timing of (N−1) direct-current power supply units among said N direct-current power supply units; and a signal distributor for distributing said load current and determining a current value generated by said N direct-current power supply units; wherein one direct-current power supply unit among said N direct-current power supply units outputs a pilot arc current; only said one direct-current power supply unit continuously supplies a load current in a small-current region; said relay circuit drives only said one direct-current power supply unit and increases the load current to a prescribed current value when a load current that exceeds the small-current region is specified by said output setting means; and said relay circuit outputs a relay signal so that said (N−1) direct-current power supply units are driven, and said N direct-current power supply units generate a current on the basis of the current value determined by said signal distributor when the current value of said one direct-current power supply unit reaches said prescribed current value, resulting in a composite output of said N direct-current power supply units coinciding with said load current.