Relay device and load control system thereof

Abstract

A relay device is connected to a monitoring circuit. The relay device has a relay whose input terminal and output terminal are connected to a power source and a load respectively. The relay device includes a sensing circuit which contains a photocoupler. Two ends of a light-emitting diode of the photocoupler are connected to the load and ground respectively. The monitoring circuit is connected to the relay and the sensing circuit to detect whether a low voltage exists between the collector and emitter of a phototransistor of the photocoupler. If so, the control system determines that the load is operating normally.

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