Rockwell Automation Publication 1512A-UM101B-EN-P - December 2021
43
Chapter 4 Common Installation
Hi-Pot and Insulation
Resistance Test
Insulation integrity should be checked before energizing medium voltage
electrical equipment. Use a high voltage AC insulation tester (5000V) for this
test.
Insulation can be tested from phase to phase and from phase to ground. The
recommended level for AC Hi-Pot testing is (2 X V
LL
) volts, where V
LL
is the
rated line-to-line voltage of the power system. The leakage current must be less
than 20 mA. Record the result for future comparison testing.
If an insulation tester is used, it should indicate 50,000 M
Ω
or greater if the
unit is isolated from the line and the motor. If the unit is connected to a motor,
the insulation tester should indicate 5000 M
Ω
or greater (phase to ground).
Start-up Procedure
Contactor Inspection
for information on pre-energization inspection,
vacuum bottle integrity test, and insulation resistance test.
Preliminary Checks
Confirm the following:
•
Contactor current and voltage ratings are correct for the attached load;
•
Control voltage is correct;
•
Settings for protective relays;
•
Heater elements (if provided) in overload relay are secure and
undamaged;
•
Equipment grounding;
•
External power and control connections match electrical diagrams;
•
All hardware is correctly reinstalled and torqued to specifications (see
Recommended Torque Values on page 10
);
•
All barriers are replaced to correct positions;
•
All fuses are correct class, type and rating;
•
Mechanical interlocks and isolation switch function properly;
•
Verify that any microprocessor-based protection relay is programmed;
•
Interior of cabinet is free from dirt, loose bolts, tools, or metal chips.
Vacuum clean if necessary;
ATTENTION:
Exercise caution when performing high voltage tests on
the equipment. Failure to do so may result in electric shock causing
severe burns, injury or death.
ATTENTION:
Disconnect power factor correction capacitors (if so
equipped) before performing the Hi-Pot test. Failure to do so may
result in personal injury or damage to the equipment. See Power
Power Lock-out Procedure on page 49
) for
information on dissipating any stored power in the capacitors.
ATTENTION:
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.
