| 摘要 |
PURPOSE:To prevent the generation of a double arc, and to improve the operability by providing a detecting means of disappearance of a plasma arc, and also providing a pilot arc current resistance changeover switch. CONSTITUTION:A titled device is provided with a detector 15 of a plasma are 3 generated between a main electrode 5 and a material 4 to be worked, and also provided with a changeover switch 20 for switching a current value of a pilot arc 2 to large and small, and current limiting resistances 21, 22 whose resistance values are different from each other. When the plasma arc 3 is started, a pilot arc current flow through a large contact of the changeover switch 20 and a low resistance 21, and after the arc 3 is generated, the switch 20 is switched to a high resistance, and the generation of a double arc is prevented. Also, when the arc 3 disappears, the switch 20 is switched to the low resistance 21 through the detector 15, so that the next plasma arc 3 can be generated. According to this method, the generation of a double arc is prevented and also the operability is improved. |
