| 摘要 |
PURPOSE:To accurately measure a current effective value by finding the effective value of an intermittent current from the output voltage signal and threshold signal of a frequency counter and a holding circuit. CONSTITUTION:The intermittent current after cycle control is converted by a converter circuit 11 into a rectangular signal which is at H level for the duration of a current exceeding a threshold level. The frequency counter 14 receives and converts this signal a voltage signal proportional to the frequency and a differentiating circuit 12 which uses the leading edge part of the rectangular wave signal as a trigger signal detects and converts the current gradient in a phase corresponding to the threshold level of the intermittent current into a voltage signal. This voltage signal is held by the holding circuit 13 until the leading point of a next voltage signal and an arithmetic circuit 15 which inputs the output voltage signal and threshold signal of the circuit 13 and a counter 14 calculates the effective value of the intermittent current. The circuit 13 maintains and outputs the output effective value signal even in the halt period of the intermittent current, so the current effective value is accurately and stably measured without distorting a detection current waveform.
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