Welders. Welding stations include power supplies and equipment for regulation of the arc during welding. Power supplies used in weldingshould provide a convenient, continuous or step control and must satisfy general requirements for electric machines and equipment. Weldingtransformers, generators, and rectifiers are used in electric welding; gas generators are used in gas welding. Power supplies may be single-position or multiposition types, stationary installations for continuous, long-term operation, or small, portable units for work of short duration.