Abstract: A secondary circuit breaker for a distribution transformer characterized by electrical inductive apparatus within an oil-filled housing, and circuit interrupter for controlling current flow through the transformer and comprising a releasable latch arm, trip means operable upon overload conditions to release the latch arm, a latch lever between the trip means and the latch arm and comprising the only operable part therebetween, and the latch lever having a cam surface for latching and unlatching the releasable arm.

Abstract: A circuit interrupter including a releasable latch restrained by a stamped metal rotatable cam having a latching surface in sliding contact with the latch member. The rotatable cam is inclined at an angle to the axis of rotation so as to cause only the smooth portion of the latching surface produced by the shearing action of the stamping process to contact the latch member. The rough portion of the latching surface produced by tearing action of the stamping process is not in contact with the latch member, thereby eliminating the need for a machining operation to provide a low friction contact surface with the latch member.

Abstract: An oil filled distribution transformer having a secondary circuit breaker utilizing a cantilevered stationary contact which is engaged by a movable contact for completing a series circuit therethrough. The cantilevered exposed stationary contact, which is surrounded by insulating oil, allows the oil in the transformer to rapidly return to the contact area after circuit interruption providing for faster arc extinction. The movable contact can be a bridging contact which forms a circuit between the cantilevered stationary contact and a second stationary contact mounted above a support base. The movable bridging contact is spring biased toward an open position separated from the stationary contact, but with the circuit breaker in the normally closed position is held in engagement with the stationary contact by a latching mechanism which is responsive to a bimetal or magnetic trip to allow the circuit breaker to trip open during overload conditions. The front cantilevered contact is completely surrounded by oil.

Abstract: A circuit interrupter particularly suitable for use in an oil filled distribution transformer having an elongated contact arm pivotable about one end with a movable contact attached to the other end through suitable insulating members to electrically isolate the movable contact from the elongated contact arm. The movable contact is a bridging contact for completing a series circuit through two stationary contacts. The movable bridging contact is spring biased away from the elongated contact arm. A retainer restricts the movement of the bridging contact away from the insulating members attached to the elongated contact arm. The biasing spring is disposed between the insulating members and the retainer. Grooves formed in the sides of the insulating members restrict rotational movement of the retainer and bridging contact. For larger circuit interrupters, a bridging contact assembly can be utilized having a plurality of parallel bridging contacts and a plurality of biasing springs.

Abstract: A circuit interrupter having a magnetic trip element which is integral with the latch. The disclosed circuit interrupter is provided with a bimetal and a magnetic trip element directly connected to the latch of the circuit interrupter which is drawn towards the bimetal, unlatching the circuit interrupter when current flow therethrough exceeds a high overload level. The disclosed circuit interrupter is particularly adaptable for use on a distribution transformer. A movable bridging contact for completing a series circuit between two stationary contacts is provided. The movable bridging contact is spring biased towards an open position separated from the stationary contacts, but with the circuit interrupter in the normally closed position is held in engagement with the stationary contacts by a latching mechanism which is responsive to the bimetal or magnetic trip element to allow the circuit breaker to trip open during overload conditions.

Abstract: A distribution transformer having a secondary circuit breaker utilizing a movable bridging contact between two stationary contacts for completing a series circuit therethrough. The movable bridging contact is spring biased towards an open position separated from the stationary contacts, but with the circuit breaker in the normally closed position is held in engagement with the stationary contacts by a latching mechanism which is responsive to a bimetal or magnetic trip element to allow the circuit breaker to trip open during overload conditions. The conducting bridging contact completes a series circuit through the circuit breaker which opens during circuit interruption. The secondary circuit breaker can also, if desired, be provided with a signal-light circuit which activates a signal light, on the exterior housing of the transformer, when current through the circuit breaker exceeds a low signal overload value which is less than the trip value.