Harmonics information is valuable for power quality analysis, determining properly rated
transformers, maintenance, and troubleshooting. Evaluation of harmonics is required for
compliance with system power quality standards such as EN 50160 and meter power quality
standards such as IEC 61000-4-30.
Harmonics measurements include per-phase magnitudes and angles (relative to the fundamental
frequency of the phase A voltage) for the fundamental and higher order harmonics relative to the
fundamental frequency. The meter’s power system setting defines which phases are present and
determines how line-to-line or line-to-neutral voltage harmonics and current harmonics are
calculated.
Harmonics are used to identify whether the supplied system power meets required power quality
standards, or if non-linear loads are affecting your power system. Power system harmonics can
cause current flow on the neutral conductor, and damage to equipment such as increased heating
in electric motors. Power conditioners or harmonic filters can be used to minimize unwanted
harmonics.
Viewing harmonics information using the display
To view detailed harmonics data through the display:
1. Press the Home button on the display.
2. Press Power Quality > Harmonics. The total harmonic distortion (THD) screens are
displayed.
3. Press More, then use the up or down icons to select the desired harmonics. The per-phase
harmonics are graphically displayed.
4. Press the left and right icons to move to individual harmonics. The harmonic number,
magnitude and phase angle are displayed.
Voltage crest factor
Crest factor is the ratio of peak to RMS voltage values.
For a pure sinusoidal waveform, crest factor is equal to 1.414. The meter uses the following
equation to calculate crest factor:
C = Crest factor
V
peak
= Voltage peak
V
RMS
= Voltage RMS
Current crest factor
Crest factor is the ratio of peak to RMS current values.
For a pure sinusoidal waveform, crest factor is equal to 1.414. The meter uses the following
equation to calculate crest factor:
C = Crest factor
I
peak
= Current peak
I
RMS
= Current RMS
9810 series - User manual Power quality
7EN05-0390-08 204
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