CIRCUIT BREAKER WITH IMPROVED TRIP ACTUATOR AND UNDERVOLTAGE RELEASE MECHANISM

摘要

A multipole circuit breaker including a latch release actuator having a trip coil and a hold-in coil coaxially surrounding a plunger and mounted within a hollow cylindrical actuator support frame. The actuator is mounted in association with a latch mechanism and includes a spring biasing the plunger toward release of the latch mechanism. The hold-in coil is responsive to voltage conditions on an external control line and serves to oppose the action of the bias spring and maintain the plunger in a position to prevent release of the latch mechanism when the voltage on the control line is above a predetermined level. The trip coil is connected to an electronic sensing circuit which activates the trip coil upon overcurrent conditions through the circuit breaker contacts to cause the trip coil to aid the action of the bias spring and overcome the action of the hold-in coil to move the plunger into engagement with the latch mechanism, effecting release of the latch mechanism and separation of the circuit breaker contacts.