Crest factor – Rockwell Automation 1404-M4_M5_M6_M8 Powermonitor 3000 User Manual, Firmware rev. 3.0 or LATER User Manual
Page 167
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Publication 1404-UM001F-EN-P - November 2009
167
Advanced Features Chapter 8
The standard IEC definition of harmonic distortion is the Distortion
Index (DIN) and is computed for each channel as follows:
Crest Factor
This is another quantity that is sometimes used to describe the amount
of distortion present in a waveform. It can also be used to express the
dynamic range of a measurement device. Crest Factor is the ratio of
the peak to the RMS.
A pure sinusoid Crest Factor equals
.
DIN
∞
Σ
n
2
=
Hn
(
)
2
∞
Σ
n
1
=
Hn
(
)
2
---------------------
=
Where:
•
H
n
= magnitude of the n
th
harmonic
(n
≤
41 or 63)
•
DIN is equivalent to IEC THD
Crest Factor
Peak Value
RMS Value
⁄
=
2
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