Appendix 2 Explanation of Power Supply Quality Parameters and Events
A
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Note: Meaning issues caused by a reduction in power supply quality, resulting in the following substation issues and
electronically controlled device malfunctions: lighting flicker, frequent burning out of incandescent light bulbs,
malfunctioning office equipment, occasional abnormal machine operation, overheating of reactor-equipped
capacitor equipment, and occasional malfunctioning of overload, negative-phase, and open-phase relays.
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
components 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
PW3198 events and
measurements
Voltage waveform
Current
waveform
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