Interlock for electrical switches

摘要

An interlock for a pair of electrical switching devices includes plungers mounted through the switch housing and engaging the operating mechanism which opens and closes the switch. The plunger of each switch is coupled to a pivotally mounted cam plate by a pin which engages a camming slot in the cam plate for mutual movement of the plunger and cam plate. The cam plates associated with the pair of switches are connected by a connecting link for coordinated rotation. When one switch is closed, the operating mechanism extends the associated plunger which through the cam plates and connecting link raises the other plunger to block closing of the other switch. When a plunger is in blocking position, the coupling pin engages an overtoggle section of the camming slot of the associated cam plate such that a force generated by any attempt to close the associated switch is directed through the pivot axis of the cam plate and generates no component tending to rotate the cam plate. Hence, no force is transmitted to the connecting link or to the cam plate and plunger associated with the switch which is already closed. Opposed springs bias the respective cam plates toward the overtoggle position and urge the interlock to an intermediate position when both switches are open so that either may be closed. A single actuator can be used to selectively block operation of a single switch without transmittal of a force generated by an attempt to close the switch back through the actuator to a manual or motor operator.