| 摘要 |
PROBLEM TO BE SOLVED: To make respective arc lengths at the time of a high arc length and at the time of a low arc length proper by making the calculated values of short circuit frequencies during respective periods of high and low arc lengths time periods feed back signals, and setting automatically a voltage setting signal by a control making the setting signal of the short circuit frequency, which has been set in advance, a target value. SOLUTION: At respective timing during a high arc length time period and during a low arc length time period, an operation is performed in accordance with formulas I, II by setting calculated values HNd and LNd of short circuit frequencies at the time of a high arc length and at the time of a low arc length as inputs, and a feedback control is performed to renew to voltage setting signals HVs and LVs at the time of a new high arc length and at the time of a new low arc length. Hereupon, for a control period at the time of the high arc length, a time elapse is measured supposing that the high arc length time period is continuous without a break except an LT period of the low arc length time period. In the formulas I, II, G1, G2 are error amplification factors set in advance, and HNs, LNs are short circuit frequency target values at the time of the high arc length and at the time of the low arc length respectively.
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