Abstract: The coil of an electric control device is energized by ac power controlled by a remotely generated logic level signal through a control module mounted in a cavity in the exterior of the device housing. The module contains a pair of back-to-back silicon controlled rectifiers (SCRs) mounted on a finned aluminum wall of the module which serves as a heat sink. An opto-coupler comprising a light emitting diode (LED) energized by the logic level signal and an opto-triac in series with resistors connected across the gates and cathodes of the back-to-back SCRs provides electrically isolated control of the conduction angles of the SCRs by the logic level signal.

Abstract: A logic level interlock device for an electrical contactor having an armature carrying separable contacts is provided. The interlock includes a plunger which is movable with the armature as the armature moves between its open and closed positions. A logic level sensing means is provided adjacent the plunger. An activation means which is sensed by the logic level sensing means is carried by the plunger member. In one embodiment of the invention, the sensing means is a set of magnetic reed switches which are activated by a permanent magnet carried on the plunger. In another embodiment of the invention, the sensing means is an opto-coupler circuit. The activation means carried on the plunger is perferably an opening which allows the infrared radiation to pass through to the receiver portion of the opto-coupler. In accordance with yet a further embodiment of the invention, the sensing means are two inductive sensing elements which are activated by a permanent magnet or a ferrite bead.