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Hazardous Voltage . When troubleshooting energized
equipment, protective gear must be worn to avoid
personal contact with energized parts . Failure to comply
can cause serious injury or death .
2.
Conduct this test with the regulator located in the
maintenance shop or other suitable location.
CAUTION
Equipment Damage . When connecting external power to
the voltage regulator control, make sure the polarity of
the power source is correct . Reverse polarity will result
in control damage .
CAUTION
Equipment Damage . Only an AC power supply is to be
used to energize the control externally . Do not use a
DC-to-AC voltage inverter . Failure to comply can cause
excessive harmonics to be generated and result in
damage to the front panel .
3.
Use an external source to power the control and
enable tap-changer operation. See Service Information
MN225003EN, CL -7 Voltage Regulator Control
Installation, Operation, and Maintenance Instructions,
for detailed information on powering the control
externally.
4.
Place a jumper, rated for nominal current, between the S
(Source) and L (Load) bushings. Use a clamp-on ammeter
to measure the current in the jumper during the test.
Hazardous Voltage . The regulator tank must be solidly
earth grounded . Failure to comply can
cause severe personal injury and equipment damage .
5.
Ground the regulator tank.
6.
Close C knife switch on the back panel.
7 .
Remove the jumper from between the C2 and C3
terminals to the left of the V1 switch, on the back
panel. See Figure 25. Place a milli-ampere meter
between these terminals. See Figure 26.
8.
Using a variable voltage source, place approximately
120 V between the L and SL (Source-Load) bushings
until a current value is shown on the clamp-on meter.
9.
Open the knife switch C on the back panel. The milli-
ampere meter should indicate a current value based on
the CT ratio shown on the rating plate.
10. Run the voltage regulator through all of the tap
positions to check the continuity and reveal any
possible intermittent opens. The current indicated on
the clamp-on meter will increase or decrease as the
tap-changer moves from Neutral to 16 Raise position.
The current will reach its maximum value at a specific
WARNING
WARNING
InstallatIon, operatIon, and MaIntenance InstructIons MN225008EN June 2020
VR-32 and EVER-Tap™ Voltage Regulator
position dependent on the type and rating of the
regulator. Current reduces to zero when it reaches the
neutral position.
Figure 25 . Removing jumper between C2 and C3
Figure 26 . Milli-ammeter connection points
33
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