Non-automatic power circuit breaker including trip mechanism which is disabled after closure of separable contacts

Abstract

A non-automatic power circuit breaker includes separable contacts for movement between a closed position and an open position, and an operating mechanism for moving the separable contacts between the open and closed positions. A time-delayed making current release switch is closed for the open position of the separable contacts and is opened a predetermined time after the separable contacts move to the closed position. A low permeability air core current transformer senses an electrical current flowing in a current conductor for the separable contacts and provides a signal corresponding to the electrical current. An analog trip unit employs the signal corresponding to the electrical current and the making current release switch signal corresponding to the open and closed positions of the separable contacts and provides a trip signal. The analog trip unit includes a comparator for disabling the trip signal when the making current release switch is opened. A low energy trip actuator employs the trip signal for actuating the operating mechanism to move the separable contacts to the open position thereof. A circuit including rectifiers, a voltage regulator and a capacitor powers the low energy trip actuator from the signal of the current transformer.