Field installable electrical operator for a circuit breaker

摘要

A field installable motor operator for a circuit breaker includes a bidirectionally controllable motor that is coupled through a torque limited module to a circuit breaker operating mechanism. The motor is bidirectionally driven by a transistor switching bridge that supplies output current in reversible flow directions through one of the windings of the motor to the input of a rectifier bridge that supplies the other winding with currents that flow in the same direction. The torque limited module includes a centering and spacing ring which precisely confines the clutch elements to provide consistent torque. The motor is supplied with a current pulse of 250 milliseconds duration that is longer than the time required to fully operate the breaker. The clutch slips when breaker operation is completed and permits the motor to overrun without damage.