| 摘要 |
An rms (root mean square) converter for obtaining fast rms measurements of power line signals having a frequency of either 50 Hertz or 60 Hertz is provided. The digit al samples of the power line frequency signal that arrive at the rms converter are squared and summed in an averaging circuit At the end of each rms measurement period, an ave rage value is provided to a square root circuit which calculates the rms value. The r ms measurement period has been chosen to be 50 milliseconds to span the minimum int eger number of cycles of the squared of the power line signal, either six cycles for the 60 Hertz frequency or five cycles for the 50 Hertz frequency, to provide rms values at a rate up to 20 rms values per second.
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