Appx.7
Explanation of Power Quality Parameters and Events
Unbalance
Waveform and event
Unbalance is caused by increase or
decrease in the load connected to each
phase of a power line, or by distortions in
voltage and current waveforms, voltage
drops, or negative-phase voltage caused
by the operation of unbalanced equipment
or devices.
Primary fault Voltage unbalance, negative-phase voltage, and harmonics generation may cause the
following events:
• Variations in motor rotation and noise
• Reduced torque
• Tripping of 3E breakers
• Overloading and heating of transformers
• Increased loss in rectiers with smoothing capacitor
Measurement Items Voltage unbalance factor, current unbalance factor
High-order harmonic component
Notes This cannot be measured with the instrument. Use Model PW3198 Power Quality
Analyzer for such measurements.
Waveform and event
The high-order harmonic component
consists of noise components of
several kHz or more caused by voltage
and current waveform distortions
when equipment power supply uses
semiconductor devices. It includes various
frequency components.
Primary fault The high-order harmonic component can damage the equipment power supply, cause
the equipment operation to be reset, or result in abnormal sound from TV and radio.
Event that is detected
by the instrument
High-order harmonic voltage component RMS values, high-order harmonic current
component RMS values
10
9
8
7
6
5
4
3
2
1
Appx. Ind.
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