| 摘要 |
PURPOSE:To stop power supply to a load from a system where an abnormality has occurred by providing a supply voltage monitoring circuit for monitoring the supply voltage to each system of a plurality of power supplies and a circuit for monitoring the output voltage from each stabilizing circuit. CONSTITUTION:A supply voltage monitoring circuit 7 is constituted such that the transistors in respective photocouplers PC11, PC21, PC31 are turned ON if the output voltages from rectifying circuits 4A, 4B or the voltage of a DC power supply 10 is normal. An output voltage monitoring circuit is constituted such that the transistors in respective photocouplers PC12, PC22, PC32 are turned ON if the stabilizing circuits 6A, 6B, 6C are normal. Upon occurrence of an overvoltage due to abnormal supply voltage or uncontrollable stabilizing circuit, only the abnormal system is stopped thus preventing breakdown of load or stoppage of function. |
