To surely detect the development of arc at the time of starting an automatic welding so as to transmit a starting command signal to a driving system in each device.
It is judged whether the arc develops or not by comparing a welding voltage signal Varc from a welding voltage detector 8 with a reference arc voltage signal Vref from a reference arc voltage setter 9. Then, a primary arc decision device 10 for outputting a signal Vc indicating that the arc develops, in the case of judging that the arc develops, and a secondary arc decision device 11 for finally judging that the arc develops, in the case of being given the signal Vc from the primary arc decision 10 and a current detecting signal IC from a current detecting relay signal relay detector 7 are provided.
KANEHARU MASAHIKO
MIYAZAKI TAKASHI
OKAMOTO MASASHI
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