Ac input signal detector, the detector of single phase ac input signal, three-phase alternating current input signal detection device, and ventilation supply air system

摘要

PROBLEM TO BE SOLVED: To provide an AC input signal detector that achieves certain signal detection with a photocoupler without deteriorating the workability.SOLUTION: In a photocoupler 4, the anode side of a light-emitting diode 4a is connected to a single-phase AC power source 1 via a resistor 3 defining the input current, the cathode side interconnects anode sides of two rectifier diodes 7a and 7b, and the respective cathode sides of the rectifier diodes 7a and 7b are connected to two power supply lines. For application of AC input to the light-emitting diode 4a, a control unit 9 connected to the output side of the photocoupler 4 detects ON or OFF of the AC input.SELECTED DRAWING: Figure 1