9-4
IM WT3001E-51EN
• Example of Grouping Type 2
For example, the 3rd order (150-Hz) harmonic component of the 50-Hz input signal
is determined by averaging the sum of the squares of the following frequency
components.
• 1/2 of the 125-Hz component The other 1/2 is included in the 2nd order (100-Hz)
component.
• 130-Hz component
• 135-Hz component
• 140-Hz component
• 145-Hz component
• 150-Hz component 3rd order harmonic
• 155-Hz component
• 160-Hz component
• 165-Hz component
• 170-Hz component
• 1/2 of the 175-Hz component The other 1/2 is included in the 4th order (200-Hz)
component.
2
3
4
Harmonic order
Frequency [Hz]
200
The component of each order between the 2nd and 50th order is determined as
shown above. The computation of the 1st order (fundamental) component differs from
the method shown above.
• 1st Order (Fundamental) Component
When measuring and computing the 1st order (fundamental) component,
interharmonics are not included regardless of the grouping setting.
210
Frequency [Hz]
In other words, components such as 40 Hz, 45 Hz, 55 Hz, and 60 Hz are not included
in the 1st order (fundamental) component. However, the interharmonic components
are included in the 1st order (fundamental) component according to the grouping
setting when computing the harmonic distortion.
9.1 IEC Harmonic Measurement Function
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