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Operation
2. For convenience during maintenance
when it may be desirable to energize the
contactor or the control circuit only, a
control power test plug is provided. To
use the test plug, move the selector switch
(located inside the low voltage instrument
compartment) to the TEST position and
plug the 115 volt single phase power
supply into the receptacle located to the
right of the selector switch. Special plugs
may be provided when specified by the
user.
When the male plug is transferred to
the test power supply, it automatically
disconnects from the control power
transformer to prevent feedback of high
voltage into the power circuits. Check
to be sure no inadvertent bypass of this
arrangement has been made in the wiring
before relying on this safety feature.
To disconnect the test plug, rotate the
selector switch to the NORMAL position
and remove the test plug from the power
source receptacle.
CAUTION
Disconnect this temporary circuit and connect
the plug to the receptacle on the contactor
before returning the unit to service.
D. H
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1) Preparing for the Hi-Pot and Megger Test
Use the following information to prepare
for the pre-operation test:
a. Ensure the motor control center is
deenergized.
b. Complete all power and control
connections.
c. Install the primary fuses for the
contactor.
d. Remove the required safety grounds.
e. Disconnect the following elements from
the circuits to be tested.
• Control Transformers
• Potential Transformers
• Starting Reactors
• Auto-Transformers
• Motors
2) Performing the Hi-Pot and Megger Test
The integrity of the insulation should
be checked before the medium voltage
equipment is energized. Use a high voltage
AC insulation tester or a “Megger” for this
test. If a Megger is used, a 5000V type is
recommended.
!
WARNING
Use extreme caution when performing high
voltage test on the equipment. Failure to do
so may result in injury or death.
!
CAUTION
Disconnect the power factor correction
capacitors (if equipped) before performing
the Hi-Pot test. Failure to do so may result in
personal injury or damage to the equipment.
!
CAUTION
Remove all primary fuses for the control
power transformer and/or the potential
transformer. Failure to do so may cause
damage to the equipment during the Hi-Pot
test.
