DETECTING CIRCUIT FOR INTERRUPTION OF ELECTRIC POWER SERVICE

• Main Author: KIDOGUCHI HIDETAKA
• Format: Patent
• Language: English
• Published: 21.08.1990
• Subjects: MEASURING; MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES; PHYSICS; TESTING

PURPOSE:To detect a voltage drop condition of single-phase AC power supply in a promptly responding manner by deciding whether the peak value of an output waveform made from a fullwave rectification for the single-phase AC voltage of the power supply is larger than a certain level or not. CONSTITUTION:The single-phase AC voltage of single-phase AC power supply 1 is fullwave-rectified by a fullwave rectifier circuit 2. A repeating cycle of the output waveform at the rise point of a pulse waveform, the width of which is a period during the output waveform is larger than a certain voltage level, is a half of the AC voltage cycle which is constant when the AC voltage is not varied. Then a comparative decision is made for the peak value of the output waveform with the comparison voltage of a detection level setting device 3 by a comparator 4, and one shot pulse having the width slightly longer than a half of the AC voltage cycle is outputted in a single stable multivibrator 5. A continuity of this one shot pulse is decided by a latch circuit 6 to detect an abnormality for voltage drop of the single-phase AC power supply. The time required for the abnormality detection can be thus shortened to a half cycle of the AC voltage.