Interlocking Load Control Systems for Resistance Welders

Where several resistance welders are operating on the same line, overloads can frequently occur that are brought about by simultaneous firing of two or more machines. Such an overload will result in a line voltage drop, a consequent loss of heat and, therefore, a poor weld. An interlocking load control system prevents line overloads from occurring and assures good weld quality. This is accomplished simply by preventing two or more machines from welding at the same time or by a method of overload control employing digital voltage sensors that continuously monitor the line voltage to determine when it is permissible to start a weld.