1986 Volume 4 Issue 1 Pages 31-35
Welding power supplies for pulsed GMAW have been developed, which have two circuits such as a single-phase SCR (Silicon Controled Rectifier) bridge circuit for pulse current and a three phase SCR bridge circuit for base current. In this power supply, however, the characteristic of the SCR control system is affected with the wave form deformation of power source voltage. caused by electric unbalanced load when plural machines are operated at the same time.
In this case, unstable arc phenomena occurs and the weldability becomes poor.
As the countermeasure for the above phenomena, upper limit of primary circuit's. impedance, which is a cause of the wave form deformation power source voltage, and the relation between the impedance and unstable arc phenomena were confirmed by the theoretical calculation and experiments, and further more, pulse arc voltage feedback control system was devised so that stable welding is possible, regardless of the impedance value.