Patent ID: 9463521
Filing Date: 2016-10-11
CPC Classification: B23K

Claim Text:
1. A method of starting a welding arc in a TIG welder, said method comprising the steps of: providing the TIG welder, said TIG welder comprising: selectively gating, using said SCR control signals, a first SCR in said SCR network into a conductive state for a portion of a first input voltage half-cycle to connect said transformer secondary winding to said welding circuit to provide current of a first polarity thereto during said portion of said first input voltage half-cycle; connecting said background power supply to said welding circuit through said first SCR to provide current of said first polarity thereto during said portion of said first input voltage half-cycle and thereafter until a second SCR in said SCR network is gated into a conductive state; and gating said second SCR into said conductive state after a setpoint current value exceeds a given value for a portion of a second input voltage half-cycle to connect said transformer secondary winding to said welding circuit to provide current of a second polarity thereto during said portion of said second input voltage half-cycle.