CMP-200
9
* The crest factor is the ratio of the peak value to the RMS value; it is represented by the
Greek letter
ξ
.
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0
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(
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4
1
4
.
1
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7
.
1
2
AC Measurement
AC measurements are usually displayed as RMS
(root mean squared) values. Two methods of
AC measurement are
average-responding RMS calibrated and true RMS-reading.
The average-responding RMS calibrated method takes the average value of the input signal,
multiplies it by 1.11, and displays the result. This method is accurate if the input signal is a
pure sine wave.
The true RMS-reading method uses internal circuitry to read the true RMS value. This method
is accurate, within the specified crest factor limitations, whether the input signal is a pure sine
wave, a square wave, sawtooth, half wave or signal with harmonics. The ability to read true
RMS provides much more measurement versatility. The Greenlee CMP-200 is a true RMS
meter.
The Waveforms and Crest Factors table shows some typical AC signals and their RMS values.
Waveforms and Crest Factors
