| 摘要 |
PURPOSE:To always execute a stable welding by providing a variable resistance on a control wiring, and lowering a welding current by operating the variable resistance, when the potential across a shunt resistance has exceeded the reference potential. CONSTITUTION:A comparator 10 is contained in a controller 9, and to the comparator 10, the potential generated from a shunt resistance 5 is given as a control input. Also, to the comparator 10, the reference potential given from the maximum allowable current setting device 11 is given, it is compared with the present potential, and when the present potential exceeds the reference potential, their deviation portion survo-motor 12 is operated and a limit control use variable resistor 13 is operated in order to lower a welding current. In this regard, in case of a usual time, an optimum welding current is adjusted by operating a remote controller 14, but when the welding current exceeds the maximum allowable current, the variable resistor 13 is operated for the first time, based on an output of the comparator 10.
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