| 摘要 |
PURPOSE:To make both a large area machining and a finish machining possible by supplying during a pause period a voltage lower than an arc voltage by making a current restricting resistor variable and controlling internal impedances of a power source by detecting an impedance between electrodes. CONSTITUTION:During a pause period of a machining power source 3, a voltage lower than an arc voltage is applied from a dc power source 7 for detection to a gap between electrodes 1 and 2 by variably setting a current restricting resistor array 8. Obtaining internal impedances Rx and Ry of a machining power source 3 so as to supply a no-load voltage higher than a spark generation voltage during a time of no load and to supply a required machining current after a detector 9 detects a discharge generation, a series of actions of switching a current restricting resistor array 5 through a power transistor array 4 are repeated and controlled after the pause period. In this way, the optimum no-load current and the required machining current are obtained to make machinings in areas of both a large area machining and a finish machining possible.
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