Note: The values for fundamental (60 Hz) current and harmonic may
not add to equal RMS current. It is because of this relationship that
%THD readings of up to 600% are possible with the Model 725.
Distortion Factor (%DF)
Distortion Factor, or %DF, is the total harmonic distortion referenced to
the total RMS signal. Distortion Factor is expressed as a percentage and
may not be greater than the fundamental. The %DF never exceeds
100%. The %DF is sometimes referred to as the %THD-R.
Please note that our %DF is not the same value as the Distortion Factor
as expressed in the IEEE standard 519-1992 (in which Distortion Factor
is the same as THD).
Mathematically the Distortion Factor, or %DF, is the ratio of the sum of
the root-mean-square of all the harmonics (including the DC compo-
nent) to the root-mean-square value (RMS) of the total signal.
%DF Application Example:
The Model 725 measures an RMS value of 100 A and a DF of 30%. This
means that the harmonic content is 30% of the total RMS, or in other
terms:
Harmonics=% Distortion Factor x RMS
Harmonics = 30% RMS = 30% (100 Arms) = 30 Arms
push buttons select harmonic amplitudes from Hdc, H01-H25 and
will display percentage relative to the RMS signal.
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