Abstract: Circuit breaker cubicle shutters wherein a pair of shutters are slidable vertically with respect to a back plate and with respect to each other and behind the back plate. The back plate is provided with a plurality of upper openings registering with upper stationary connectors and a plurality of lower openings registering with lower stationary connectors. The shutters are interconnected by links pivotally mounted on the back plate and interconnecting the lower portion of the lower shutter with the lower portion of the upper shutter. An actuator comprises a bell crank lever one end of which is engaged by a pin or roller on a circuit breaker as it is moved into the cubicle to rotate the same. The other end of the actuator is connected to the lower shutter to pull the lower shutter from an upper closed position in which it is maintained by tension springs to a lower position in which an opening in the lower shutter registers with the lower set of openings in the plate.

Abstract: A magnetic trip unit for a circuit breaker having an armature and a plunger; the armature completes a magnetic path through the poles of a permanent magnet; the armature and plunger are biased toward trip position but are held by the permanent magnet and may be restored to the position where the armature completes the path through the poles of the permanent magnet. A trip coil is provided surrounding the permanent magnet and armature. A casing of magnetic material surrounds the trip coil and extends below the armature; this casing also has top and bottom walls of magnetic material and an inner cup shaped sleeve bearing against the bottom wall and against one pole of the permanent magnet. Energization of the trip coil establishes an additional magnetic path through the armature and the one pole of the permanent magnet which opposes the magnetic force of the first mentioned magnetic path and permits the bias on the armature and plunger to move them to trip position.

Abstract: A unitary molded housing for a multipole high capacity circuit breaker wherein the housing may receive and support modules of different current carrying and interrupting capacity. The molded housing has vertical side walls and parallel vertical integral interphase barriers as well as a back wall and top wall. Disconnect contact bars are mounted through the back wall and support and are connected to circuit breaker contact structures at the front side of the back wall. Recesses which receive the arc extinguisher structure are formed by adjacent vertical walls and the top wall. The interior of the top wall forms a baffle or guide on which arc gases vented from the arc extinguisher impinge and are guided to the vertical walls and the spaces between the said walls and the arc extinguishers.

Abstract: Racking mechanism for a draw-out circuit breaker movable into and out of a cubicle wherein a hook at the rear of the cubicle is engaged by a pin on the circuit breaker structure; the pin is connected by links to a travelling nut on a racking shaft extending in the circuit breaker in the direction of movement of the circuit breaker; rotation of the shaft in one direction causes the pin to enter the hook and then, through the travelling nut, draw the racking shaft and hence the circuit breaker toward the rear of the cubicle. Rotation of the racking shaft in the opposite direction causes the racking shaft and circuit breaker to move away from the rear of the cubicle. On predetermined movement toward the front of the cubicle, the pin is disengaged from the hook to permit withdrawal of the circuit breaker from the cubicle.

Abstract: A cradle for a circuit breaker secured in a cubicle in a switchboard wherein the cradle has a pair of side tracks forming the structural support for the entire cradle and a rear wall of insulating material which carries the upper and lower stationary disconnect contacts, pads for connection thereof to buses in the switchboard, secondary contacts, auxiliary switches, current transformers, grounding devices and an anchor point with respect to which the circuit breaker racking mechanism can operate. The cradle may also be shipped as a base for the circuit breaker and separated prior to installation. The cradle also provides interlocks for the circuit breaker and interference blocks to allow entry into the cubicle of only selected circuit breakers. The device is further shown in U.S. Pat. Nos. 4,146,764, 4,101,744 and 4,146,765.

Abstract: A shutter for a circuit breaker compartment in which the upper and lower stationary back disconnect contacts at the rear of the compartment are protected, as the circuit breaker is withdrawn from the compartment by a clam-shell shutter. The two halves of the shutters are biased toward closed position; a circuit breaker operates a cam end of a bell crank lever to open the clam-shell as the circuit breaker moves toward the rear of the compartment. The insulated rear wall has openings through which the stationary back disconnect contacts are accessible. The rear wall is curved at the openings for the contacts to correspond with the curvature of the clam-shell halves and to provide added guidance and support.