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PWHD - Partial Weighted Harmonic Distortion
The partial weighted THD calculates the 14th to 40th harmonics.
40
∑n ⋅C
PWHD =
2
n
n =14
C1
PHC - Partial Odd Harmonic Current
The PHC is calculated from the odd current harmonics n = 21..39.
39
∑C
PHC =
2
n
n = 21, 23
K Factor
The values of the K-factors for phase currents are calculated from the corresponding RMS values Cn of the harmonics n = 1..40.
The K factor is a measure that indicates the ability of a transformer to withstand the current
harmonics of a system.
Various transformer suppliers offer transformers with, for example, K factors K=4, K=13, K=20
and K=30.
Transformers are heated more by harmonic currents than 50 Hz currents.
A transformer with a higher K-factor withstands this better and is not heated as much as a
transformer with a lower K factor.
The device shows the K factor for the current. Only the K values that appear at maximum power are of interest. Just as with the THD of the currents in %, the value is not relevant at very
low currents.
40
∑ (n ⋅ C )
2
n
K =
n =1
40
∑C
2
n
n =1
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