(If present) Check the condition of MOV’s installed for cracks and/or burn spots in the devices
and then replace if needed.
4. Measure the AC input voltage and record the value.
5. (If UPS power is used) Check the quality of the AC waveform (that is, ensure that the waveform
is within manufacturer’s specifications).
Distortion:
Utility mains power normally has less than 5 % harmonic distortion.
Transformer of proper rating adds about 1 % distortion.
Total Harmonic Distortion (THD) of 6 % is acceptable.
Maximum THD acceptable is 8 %.
6. Check the red and black DC power wires connected to each power supply for
l signs of corrosion in the power wires,
l splits or cracks in the insulation, and
l loose connections on each end of the wires.
7. Inspect the red and black DC power wires connected between each cabinet (in a cabinet
complex) for
l signs of corrosion in the power wires connected between each cabinet,
l splits or cracks in the insulation, and
l connection of wires to the connector blocks.
8. Inspect the ground wire for AC Safety Ground exiting the cabinet for
l signs of corrosion in the ground wire,
l splits or cracks in the insulation, and
l loose connections at each end of the wire.
9. Inspect whether a 4 AWG (5.3 mm) or larger wire is used to connect
l AC Safety Ground in the cabinet to the AC Safety Ground collection plate, and
l AC Safety Ground to the AC Safety Ground rod.
Inspect how the wire from AC Safety Ground in the cabinet routed to the AC Safety Ground
collection plate.
10. a. Inspect the ground wire for MRG.
b. Inspect whether a 4 AWG (5.3 mm) or larger wire used to connect the local reference bar
with the MRG ground rod.
c. Check for loose connections at each end of the wire
11. Check how is the wire from the local reference bar to the MRG ground rod routed.
12. Inspect whether the wire from the local reference bar to the MRG ground rod is exposed
anywhere.
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