Ac and battery backup supply for a railroad crossing gate

Abstract

A crossing lights controller for effecting operation of the crossing lights during normal train operating conditions and during a controller failure mode includes a train sensing input, a lights control circuit, a solid state logic and monitor circuit, an independent source of both AC and DC power, and a fail-safe relay. The train sensing input provides one signal condition when the approach of a train is sensed and another signal condition when no train is sensed. The lights control circuit has power supplied thereto to operate the lights in a flashing condition when the train sensing input indicates the approach of a train. The solid state logic and monitor circuit is connected to the input circuit and the lights control circuit and applies and removes power to the lights control circuit in accordance with signals at the input. The fail-safe relay is connected to the logic and monitor circuit and the lights control circuit, with the fail-safe relay automatically connecting the independent source of both AC and DC power to operate the lights in the event no power is supplied to the fail-safe relay.