Abstract: A system to prevent a dangerous contact voltage in a welding apparatus by providing a protective device for cutting off the power for welding. The welding system has a power source including a primary circuit and a secondary circuit. An electrode receiving the power welds workpieces which are successively inserted and removed into electrical contact in the welding system. A protective ground is provided between the housing for the power source and ground. To prevent dangerous grounding during the welding operation, there is connected between the workpiece lead in the secondary and the housing a device which monitors both the current to the protective wire ground and the voltage between the workpiece lead and the housing. This monitor device controls a power cut-off switch. The current is monitored through a current sensor which is connected to the monitor device and the current sensor is also connected in series between the housing and the protective ground.

Abstract: Annular metallic blanks which consist of packages of interconnected laminae or of sheet metal strips which are coiled edgewise and whose strata are riveted or otherwise secured to each other are converted into stators for electrical machines by cold forming between upper and lower dies and outer and inner calibrating members so that the inner diameter of each blank is increased during cold forming, that the peripheral surface of the stator has two cylindrical portions flanking a convex median portion, and that the outermost portions of the end surfaces of the stator are formed with annular recesses. Prior to cold forming, each blank is subjected to a preliminary shaping treatment including chamfering the axial ends of its internal and peripheral surfaces.