| 摘要 |
PURPOSE:To prevent the generation of the concentrated electric discharge state by connecting an energy dissipation circuit including a switching element in parallel in the electric discharge gap between an electrode and a worked material. CONSTITUTION:Pulse signals are supplied into terminals 10 and 11, and the pulse signals supplied into the base terminal 1B of a main transistor 1 and the base terminal 8B of a transistor 8 are generated. The transistor 8 is turned-ON simultaneously with the transistor 1, and the voltage applied onto the base terminal 8B after the transistor 1 is turned-OFF is gradually reduced to zero level because of a condenser 15, Though, during this time, the collector current of the transistor 8 does not flow until the transistor 1 is turned OFF because of a diode 6, the collector current flows in correspondence with the voltage applied onto the base terminal 8B by the surge voltage generated when the transistor 1 is turned OFF, and the generated surge voltage is suppressed.
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