The Genlyte Group Incorporated

William Randall Erwin

An automatic lighting controller applies a turn-off control signal to a gate controlled power switch for switching OFF lighting when a timer circuit determines that motion activity above a threshold level has not occurred within the controlled area during a prescribed interval. A counter produces a grace period count signal and a reset count signal, with the grace period count signal occurring within a predetermined sub-interval, for example, one count cycle prior to the reset count signal. The grace period count cycle (N-1) interval is adjustable, for example, from about 0.6 second (for test purposes) to about 14 seconds. The grace period count signal enables an audio transducer which provides an audible alert that the lights are about to be switched OFF automatically. A person in the controlled area can override the impending automatic shutoff simply by initiating some motion activity during the grace period.

Audible alert for automatic shutoff circuit

A lighting load can be turned on/off manually from one or more remote switching stations as well as from a master switch controller station, with ON/OFF control signals produced at the remote switching stations being transmitted to the master controller circuit on the traveler conductor of a conventional single phase AC power distribution system. The main controller has an internal dual mode DC power supply which is referenced to load potential. The dual mode power supply derives operating power from the voltage across the gate controlled power switch which corresponds with essentially hot potential when the power switch is off. The voltage drop across the power switch is boosted by a step-up transformer when the power switch is on. Remote turn-on and turn-off signals are derived independently from the hot power conductor and ground safety power conductor, respectively. Remote turn-on and turn-off of the master power switch is accomplished without interfering with automatic turn-off operation of the controller.

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Rowlett, TX, United States of America

William Randall Erwin