Cf: Crest Factor; Bargraph - AEMC 721 User Manual

Clamp-on harmonic meter

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5.3.3 CF: Crest Factor

Crest Factor is the ratio of the Peak value

of a waveform to its RMS value. A perfect

sine wave has a crest factor of 1.414. In

distorted waveforms, the crest factor is

typically greater than 1.414 and gives an

indication of the harmonic content.

The CF may also be used to determine

the CBEMA (Computer & Business Equip-

ment Manufacturers Association) Derat-

ing Factor. The CBEMA Derating Factor

is used for evaluating the survivability of

existing conventional transformers in ser-

vice and servicing single-phase nonlinear

loads such as PCs, computer terminals or other office equipment. For

further use of the CBEMA Derating Factor, contact CBEMA directly.

It should be noted that there is no direct or useful relationship between

the CBEMA Derating Factor, the %THD and Transformer K Factor (IEEE

C57.110-1986).

CBEMA Derating Factor = 1.414 x RMS/Peak = 1.414/CF

Please note that the analog bargraph will continue to display Arms or Vrms

while THD function measurement values (%THD, %DF, CF) are displayed.

The Range button only changes the bargraph ranges while in the THD

function.

Crest Factor: CF = Peak/ RMS

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Harmonic Meter Model 721

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