Circuit breaker mechanism

摘要

An actuating mechanism for a circuit breaker includes a pair of contacts supported relative to a frame. One of the contacts is supported on a contact arm which is displaceable about a pivot to open and close the contacts. A releasable latch holds a rotatable cradle arm in latched position against the bias of an over-center spring connected between the contact arm and the cradle arm to bias the contact arm into over-center positions. An actuating link is coupled with the contact arm. When the cradle arm is held in the latched position, movement of the link from a first position to a second position displaces the contact arm pivot over center, causing the over-center spring to move the contact arm to close the contacts. An electrically actuated trip mechanism releases the latch under predetermined conditions to permit displacement of the cradle arm under the bias of the over-center spring from the latched position to an unlatched position causing the over-center spring to move the contact arm to open the contacts. A cradle arm return spring displaces the cradle arm from the unlatched position back to the latched position and causes the link to rotate from the second position back to the first position as the over-center spring holds the contacts open.