KBR multimess D9-PQ
20144 EDEBD
A0228-5023-1_EN
84
PWHD - Partial Weighted Harmonic Distortion
The partial weighted THD calculates the 14th to 40th harmonic.
1
40
14
2
C
C
n
PWHD
n
n
∑
=
⋅
=
PHC - Partial Odd Harmonic Current
The PHC is calculated from the odd current harmonic n = 21..39.
∑
=
=
39
23
,
21
2
n
n
C
PHC
K Factor
The values of the K-factors for phase currents are calculated from the corres-
ponding RMS values C
n
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
1
2
40
1
2
n
n
n
n
C
C
n
K
Measurement data – measurement methods