ABB PQFS Installation, Operation And Maintenance Instructions page 118

Supply side
On the scopemeter screen, two waveforms should appear. The voltage waveform should
be approximately a sine wave and the current waveform would normally be a well-
distorted wave because of harmonic distortion. Usually, it is quite easy to extrapolate the
fundamental component as it is the most important one
Remark: If the earthing of the system is bad, the phase to ground voltage may appear like
a much distorted waveform. In this case, it is better to measure the phase-to-phase
voltage (move the black clamp to the phase L2) and subtract 30° on the measured phase
shift.
From the fundamental component of both signals, the phase shift must then be evaluated
(Figure
must be measured and converted to a phase shift j by the following formula:
For an inductive and non-regenerative load, the current signal should lag the voltage by a
phase shift lower than 90°.
118 Commissioning instructions ç Manual Power Quality Filter PQFS
L1 K L
L2
L3
k l
N
Figure 79: Connection of the scopemeter for checking the CT in phase L1
Figure 80: Extrapolation of the fundamental component from a distorted waveform
81). The time • T between zero crossing of the rising (falling) edge of both traces
• •
= °
• * 360
• 1
K L
K L
k l
k l
X21.1
X21.2
X21.3
X21.4
X21.5
X21.6
Positive direction
Ch1
I
I1
where T1 is the fundamental period duration.
Load side
N L1 L2 L3
PQF
Ch2
(Figure 80)