| 摘要 |
PURPOSE:To detect disconnection of a wiring to a load, by using a signal synchronized with an AC power source and a signal synchronized with the voltage between both terminals of a thyristor, in the device which detects the fault of a circuit which uses the thyristor to control AC power. CONSTITUTION:Power is supplied from an AC power source 1 to a load 3 by turning on a thyristor 2. A signal synchronized with the AC power source is detected by photocouplers 15-1 and 15-2 and is inputted to one input of an EX.OR 19, and power supply to the load 3 is detected by a photocoupler 6, and the detection output is inputted to the other input of the EX.OR 19. The output of the EX.OR 19 is inputted to one input of an EX.OR 9, and an H or L signal is given to the other input in accordance with turning-on or off of the thyristor 2. The output of the EX.OR 9 is L when the thyristor is turned on and power is supplied to the load, but the output of the EX.OR 9 is H when the wiring to the load 3 is disconnected and the load becomes open, thus detecting disconnection surely. |
