Abstract: Disclosed is an automatic transfer switch (ATS) having "operate," "test" and "isolate" positions for the switch per se. A handle selects one of the positions and a mechanical linkage couples the ATS and the handle to one another. In the improvement, the linkage has first and second members for applying motive force to the switch. The mechanical linkage has first and second rotary driver devices in engagement with the first and second members, respectively, thereby providing redundant switch-positioning mechanisms. The new ATS may be combined with a bypass switch having "normal," "auto" and "emergency" contact positions. A switch interlock linkage extends between the transfer switch and the bypass switch and includes a bypass plate and a transfer plate coupled to one another by a bar. The bypass switch includes a pivot-mounted first bypass interlock member obstructing substantial movement of the bypass plate when the bypass switch electrical contacts are in the "normal" position.

Abstract: A "hot start" method for arc welding includes selecting a first weld current, setting a time interval, striking an arc, flowing a second, higher weld current through the welding rod and then, after a brief time interval, reducing the current through the rod to the value of the first weld current. Also disclosed is a new arc welder stator having two groups of slots around a core. The group of larger slots contains the weld current windings and slots in the group of smaller slots contain windings for timing, gate voltage, battery charging, auxiliary power and the like. A new cooling apparatus for an arc welder has an air duct and a "double-bladed" fan for flowing air along several paths and cooling both the welder control section and the generating section. A new method for electronically controlling engine speed in an engine-driven arc welder is also disclosed.