Hioki PQ3198 - Page 268

A4
Unbalance
Unbalance is caused
by increases or
decreases in the load
connected to each
phase of a power line,
or by distortions in
voltage and current
waveforms, voltage
dips, or negative-
phase voltage caused
by the operation of
unbalanced equipment
or devices.
Voltage unbalance,
negative-phase volt-
age, and harmonics
can cause issues
including variations in
motor speed and
noise, reduced torque,
tripping of 3E break-
ers, overloading and
heating of transform-
ers, and increased
loss in capacitor
smoothing rectifiers.
Events are detected
using voltage unbal-
ance factor and cur-
rent unbalance factor.
Inrush current
Inrush current is a
large
current that flows
momentarily, for exam-
ple when electric
equipment is turned
on.
Inrush current can
cause power switch
contact and relay fus-
ing, fuse blowouts, cir-
cuit breaker
disconnections, issues
with rectifying circuits,
and supply voltage
instability, causing
equipment sharing the
same power supply to
stop operating or be
reset.
Events are detected
using inrush current.
High-order
harmonic
component
The high-order har-
monic component con-
sists of noise
co
mponents of sev-
eral kHz or more
caused by voltage and
current waveform dis-
tortions when equip-
ment power supplies
use semiconductor
devices. It includes
various frequency
components.
The high-order har-
monic component can
damage equipment
power supplies, cause
equipment operation
to be reset, or result in
abnormal sound from
TVs and radios.
Events are detected
using high-order har-
monic voltage compo-
nent RMS values and
high-order harmonic
current component
RMS values.
Principal
parameters
indicating
power quality
Waveform Phenomenon Primary issues
PQ3198 events and
measurements
Voltage waveform
Current
waveform
HIOKI PQ3198A961-02