Patent ID: 6930580

Claim:
An output choke for a D.C. arc welder having an inductance comprising a high permeability core having first and second pole pieces, an inductance controlling air gap formed by said first and second pole pieces, and at least one winding for conducting welding current, said first and second pole pieces each having an end surface, said air gap defined between said end surfaces of said first and second pole pieces, each end surface including two outer edges and a middle portion positioned therebetween, at least one of said middle portions including a substantially V-shaped slot, said air gap having a width between said middle portions of said first and second pole pieces that is greater than a width between either of said outer edges of said first and second pole pieces, said air gap having a configuration which results in said inductance of said choke gradually changing with an output current of the welder without saturation in said air gap thereby eliminating inflection points during operation of said welder, said at least one winding and said core having a size to prevent saturation at a weld current of at least about 100 amperes.