| 摘要 |
PROBLEM TO BE SOLVED: To reduce power loss of pilot current suppressing resistance by repeatedly generating/ceasing a pilot arc current at an arbitrary period, outputting a pilot arc current having a high peak current, facilitating transfer from a pilot arc to a plasma arc, and simultaneously setting the effective electrode of the pilot arc low. SOLUTION: For example, the output signal of an oscillation circuit 16 constituted of multi-vibrators and the like is set to be 0.1 second 'H' and 0.2 second 'L'. Relating to the oscillation circuit 16, a plasma arc current flows, the signal of a current detector 11 is received, the oscillation is stopped and the 'H' signal is held while the plasma arc current is flowing. The control circuit 14 controls the start/stop of a driving circuit 15 synchronously with the signal of the oscillation circuit 16. After the transfer to the plasma arc, the operation of a high frequency voltage generating circuit 9 is stopped by the signal of the current detector 11, the oscillating operation of the oscillator 16 is stopped and, the control signal of the control circuit 14 is maintained in the normal continuous controlled state. |
