| 摘要 |
PURPOSE:To facilitate maintaining an arc by providing a means to select the smooth output of the straight polarity for a fixed time at the time of starting and impress it on a welding electrode and base metal to a keying circuit and starting an arc smoothly even at the time of starting. CONSTITUTION:When an output current starts to flow, a current detector 23 detects its state and outputs it to a timer 60 and a high-frequency oscillator 24. The timer 60 is started at this point of time and the high-frequency oscillator 24 stops the operation at this point of time. Even if the oscillator 24 stops the operation, the starting is carried out with the straight polarity and the impressed voltage is high, so the ionizing is accelerated and a state brought to the arc discharge is maintained. When the timer 60 times the time till the welding electrode 8 and the base metal 9 are warmed up sufficiently in a state of the small quantity of current, it outputs a switching starting signal. A switching transistor control part 22 starts the operation with this signal and outputs on-off signals to switching transistors 36 and 37 alternately. By this method, the shift to an arcing state can be carried out smoothly and accurately at the time of starting.
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