To measure the periodically changing alternating current waveform with high accuracy even when it is disturved.
In a phase-shift detecting method, a standard time interval given by integer times the period is determined, (1) the time from a rise of the mth waveform up to a rise of the nth waveform is regarded as a measured time interval, (2) when the measured time interval exceeds the standard time interval + α, (m) is added by 1, and (3) when the measured time interval does not exceeds the standard time interval - β, (n) is added by 1. Then, (4) the measured time interval is between the standard time interval + α and the standard time interval - β, the measured time interval is regarded as a taken-in, adopted time interval, and (m) and (n) are added respectively by 1 for the procedures (1) to (4) to be repeated. An averaged value of the differences between the standard time interval and the adopted time interval is determined for a fixed time, and the phase-shift of the alternating current is detected by the proportion of the averaged value to one period.
YAMAMOTO HARUO
HIRAKURI SHIGETO
SAITO YASUO
ARAI MAMORU
KUBOTA TOMOKI
NIPPON SIGNAL CO LTD
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