6-6 Site Preparation
6 Power Requirements
Basic Power Quality Survey
Power quality can affect system performance differently. The following procedure
is intended as a guideline and may not be the total solution. Failure to meet these
guidelines should serve as an indicator that a power quality consultant might be
needed to conduct a more in-depth power quality survey.
1 With the system operating, measure harmonic distortion at the system-input
connection. THD should be less than 5% and less than 3% for any single
harmonic.
2 With the system operating, measure the ground-to-neutral voltage at the
system-input connection; the voltage should be less than 4vp-p.
3 Turn the system power off and measure the line voltage at the system-input
connection; record this reading. Turn the system on and begin operating mode.
Measure the line voltage at the system-input connection again. The difference
between the two measurements should be less than 2%.
Other problematic power qualities include momentary voltage interruptions,
ground noise, and voltage spikes. A survey of these problems and others may
require the services of a power quality expert with specialized equipment.
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