Abstract: An equipment unit latch and an associated switch arrangement are advantageously employed to generate an action initiation signal upon initial movement of the latch toward physically removing the equipment from an equipment frame but prior to any movement of the equipment unit in an equipment frame in which it is inserted. The physical shape and dimensions of the latch and the spatial relationship of the associated switch arrangement to the latch are such that the latch is allowed to move a sufficient distance toward removing the equipment unit from the equipment frame, in order to activate the switch to generate the action initiation signal prior to any movement of the equipment unit in the equipment frame. In a specific embodiment of the invention, the switch includes a light emitter and a light detector. Light from the emitter is inhibited from reaching the detector by the latch when the equipment unit is fully inserted in the equipment frame and the latch is in a closed position.

Abstract: An equipment unit protection switch from an in-service equipment unit to a standby equipment unit is realized prior to any movement of the active equipment unit about to be removed from an equipment frame in which it is inserted. This is achieved by advantageously incorporating apparatus for generating an equipment unit removal indication signal that enables a controller to anticipate the removal of the equipment unit from the equipment frame. To this end, the equipment units employ an equipment unit latch and an associated switch to generate the equipment removal indication signal. Initial movement of the latch causes the equipment unit removal indication signal to be generated prior to any movement of the equipment unit in the frame in which it is inserted.

Abstract: An equipment unit protection switch from an in-service equipment unit to a standby equipment unit is realized prior to any movement of the active equipment unit about to be removed from an equipment frame in which it is inserted. This is achieved by advantageously incorporating apparatus for generating an equipment unit removal indication signal that enables a controller to anticipate the removal of the equipment unit from the equipment frame. To this end, the equipment units employ an equipment unit latch and an associated switch to generate the equipment removal indication signal. Initial movement of the latch causes the equipment unit removal indication signal to be generated prior to any movement of the equipment unit in the frame in which it is inserted.