18
Procedure for Investigating Power Quality
Advice for identifying the cause of abnormalities
Record voltage and current trends at the power circuit inlet.
If the voltage drops while the building’s current consumption rises, the likely cause for power
abnormality lies inside the building. If the voltage and current are both low, the cause is likely to lie
outside the building.
It’s extremely important to select the right measurement locations and measure current for
troubleshooting.
Check power trends.
Overloaded equipment can cause problems. By understanding power trends, you can more easily
identify problematic equipment and locations.
See “8 Verifying the Trends (Fluctuations) in Measured Values (TREND Screen)” (p. 95).
Check when the problem occurs.
Equipment that is operating or turning on or off when events (abnormalities) are recorded may be
the cause of malfunction. By understanding the precise times at which events start and stop, you
can more easily identify problematic equipment and locations.
See “9 Checking Events (EVENT Screen)” (p. 105).
Check for heat and unusual sounds.
Motors, transformers, and wiring may produce heat or unusual sounds due to causes such as
overloading or harmonics.
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