3 Phase Power Quality Analyzer
Glossary
45
Harmonics Calculation Method. Select the harmonic calculation method to apply according to
IEC 61000-4-7. The Analyzer applies a FFT (Fast Fourier Transformation) every 10/12 cycles
(typical 200 ms), that delivers spectral components (bins) every 5 Hz from dc up to ½ fs. The
‘fs’ is the sample frequency of the A/D converter, for example, 10.24 kHz. The standard allows
three different ways to calculate the harmonics from these 5 Hz components: Harmonic
Components, Harmonic Sub-Groups, and Harmonic Groups. See Ta b l e 8 .
Note
Most power quality standards, such as EN 50160, GOST 33073 refer to
IEC 61000-4-30 Class A measurement methods that require Harmonic Sub-Groups.
Table 8. Overview
Harmonics Interharmonics
Harmonic Components
(required for measurements
according to certain standards, such
as IEEE519 or IEC 61000-3-12)
RMS value of a single 5 Hz
component
RMS value of all bins
between two
harmonics
Sub-Grouped Harmonics (default)
(for IEC 61000-4-30 compliant
measurements, such as EN50160)
RMS value of the
harmonic frequency and
adjacent bins
RMS value of all bins
between two
harmonics
Grouped Harmonics
RMS value of the
harmonic frequency and
½ of the interharmonic
spectrum to both sides
not available
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