CET PMC-690, User Manual

Page: 34 / 103

CET Electric Technology
34
4.3.7 Supply Voltage Unbalance
The PMC-690 provides both the Zero Sequence and Negative Sequence Voltage and Current Unbalance
measurements using Symmetrical Components and in accordance with Section 5.7 of IEC 61000-4-30
Standard for Class A performance.
2
V2 Unbalance x100%

V
V1
,
2
I2 Unbalance x100%

I
I1
(Negative Sequence Unbalance)
0
V0 Unbalance x100%

V
V1
,
I0
I0 Unbalance x100%

I1
(Zero Sequence Unbalance)
where
V0, V1, V2 are the Zero, Positive and Negative Sequence Components for Voltage, respectively.
and
I0, I1, I2 are the Zero, Positive and Negative Sequence Components for Current, respectively.
4.3.8 Harmonics and Interharmonics
The PMC-690 provides the Harmonics and Interharmonics measurements in accordance with Sections
5.8 and 5.9 of IEC 61000-4-30 Standard for Class A performance using a 10/12 cycle gapless centered
harmonic sub-group measurement, denoted C
ng
for Harmonics and C
n-200-ms
for Interhamonics, as per
IEC 61000-4-7:2002.
There are three methods to calculate the Harmonic Distortion (HD):
a) Fundamental Method:
Voltage K th Harmonic/Interharmonic Distortion=
X100%
U
U
1
k
where U
1
is the Fundamental Voltage
Current K
th
Harmonic/Interharmonic Distortion=
% 100
I
I
1
k
X
where I
1
is the Fundamental Current
b) RMS Method:
Voltage K th Harmonic /Interharmonic Distortion= X100%
U
U
2
K
1 K
k



where the denominator is the RMS
Current K
th
Harmonic/Interharmonic Distortion=
X100%
I
I
2
K
1 K
k



where the denominator is the RMS
c) Nominal Method:
Voltage K th Harmonic/Interharmonic Distortion=
X100%
nom
k
U
U
where U
nom
is the Nominal Voltage
Current K th Harmonic/Interharmonic Distortion=
X100%
nom
k
I
I
where I
nom
is the Nominal Current
The PMC-690 also provides, in addition to Voltage Harmonics, measurements for Current Harmonics, K-
Factor, Crest Factor, Power Harmonics and Energy Harmonics.
K-Factor and Crest Factor
K-Factor is defined as the weighted sum of the harmonic load currents according to their effects on