| 摘要 |
PURPOSE:To discriminate the kind of AC power source by simple circuit constitution by applying a processing such as exclusive OR, the elimination of a prescribed pulse, etc. with respect to a binary pulse corresponding to two AC voltage information fetched from a power source line. CONSTITUTION:Two AC voltage signals V12, V32 fetched from the power source line of a single phase two-wire system or three-phase three-wire system power source are converted to binary pulse signals 103, 104 by operational amplifiers 41, 42 of a zero crossing comparator, etc., respectively, processed by an exclusive OR circuit 5, and a clock 105 of its output becomes a wide clock and a whisker- like clock in case of a three-phase power source and in case of a single-phase power source, respectively. This narrow clock 105 is eliminated, an integration circuit 6 outputs a high level signal in response to the wide clock, an FF7 is controlled, and when a Q output of the FF7 is in a high level, whether the AC power source is three phase or single phase is discriminated in accordance with the time of a low level. In such a way, the kind of AC power source can be discriminated by simple circuit constitution.
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