| 摘要 |
PURPOSE:To prolong effectively a guaranteeing time for momentary service interruption by a method wherein a detecting part compares a voltage fluctuation of a power source output part having a larger rated voltage and feeding a load control part with a reference voltage based on an output voltage of a power source output part having a smaller rated voltage and detects the momentary service interruption. CONSTITUTION:When momentary service interruption occurs due to a bolt of lightning or the like, constant-voltage IC 24 turns to fail to conduct a normal operation, since a potential at a point A lowers below the ordinary lowest potential, and a potential at a point B lowers, since an output voltage of the IC lowers as well. Herein constant-voltage IC 25 for 5V feeding a detecting part 31 and others executes a normal operation until the potential at the point A lowers to a certain value below the aforesaid lowest potential. Therefore the momentary service interruption is detected from the lowering of the potential at the aforesaid point B without fail by the detecting part 31, a detection signal thereof is given to a sequence control part 28, and based on this signal, the sequence control part 28 executes a process for the service interruption preferentially, putting a load control part 30 in a state of non- operation. As the result, power consumption in a load 29 which comsumes a large power is avoided, the rate of lowering of the potential at the point A turns small and, accordingly, a guaranteeing time for the momentary service interruption can be prolonged. |
