POWER SOURCE DEVICE FOR WELDING

摘要

PURPOSE:To supply a small current high voltage at a high response speed and to prevent arc breakage and spatter by providing a main power source which controls low voltage large current and an auxiliary power source for maintaining the arc which controls high voltage small current in a power source for welding. CONSTITUTION:A power source 3 for welding is provided with a transistor (TR) 4-1 for a main power source which supplies the low voltage large current in the stage of welding and a transistor (TR) 4-2 for an auxiliary power source which supplies the high voltage small current in the negative resistance region of arc current. The voltage of a welding wire 1 decreases upon starting of an arc and therefore the output from the TR 4-2 having the high voltage increases sharply and the current detected by a current detector 8 approaches the set value of a setter 15 by which the output from an error amplifier 14 is decreased. When the output (a) from the amplifier 14 is made smaller than the output (b) from an error amplifier 10, the voltage at the point (c) is equal to the voltage at the point (a). The width of the pulse to be impressed on base of the TR 4-2 is then controlled by the output voltage from the amplifier 14. The TR 4-1 is controlled in accordance with the set value of a current setter 11 so that the current on the wire 1 is increased.