| 摘要 |
PURPOSE:To reduce error against variations in the frequency of alternating current to be measured, by sampling two sets of data separated by 90 deg. in the AC phase to calculate the mean of the results from the square addition of the data separately. CONSTITUTION:The instantaneous value of alternating current to be measured is converted into a digital value with an A/D converter while a plurality of data separated by 90 deg. in the AC phase are sampled to detect the value proportional to the squaring of alternating current by square addition of the data. In a digital measuring system of such a type, two sets of data separated by 90 deg. in the AC phase are sampled to calculate the mean of the results from the square addition of the data separately. Two sets of data separated by 90 deg. in the AC phase can be measured with ease by sampling continuing three data. This can prevent increase in errors due to variations in the frequency to rather achieve a reduction in the error handily and accurately.
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