Specifications

H3
GE Limitamp
®
Medium Voltage Motor Control
Application Data
H
High Potential — Insulation Tests
a. Control wiring insulation tests
A dielectric test (hi-pot) shall be performed on circuit wiring
to confirm the insulation resistance to withstand breakdown
to a selected test voltage. The test voltage — amplitude and
waveshape, method of application and duration of time
applied — shall be specified in UL347.
b. Power cable insulation and isolation test
Power cables and buses shall be tested, phase-to-phase and
phase-to-ground for insulation breakdown resistance and
circuit isolation as specified in UL347.
Note: These test conditions are as specified for newly con-
structed equipment and performed in a clean, temperature
and humidity controlled factory environment.
These test voltages include the standard test voltages:
a. For equipment rated under 600 volts RMS or DC:
2 times rated plus 1000, times 120 percent (for one-second
application).
b. For equipment rated over 600 v
olts RMS or DC:
2.25 times rated plus 2000 (60 seconds only).
The frequency of the test voltage shall not be less than the
rated frequency of the equipment tested and shall be essen-
tially sinusoidal in wave shape.
Note: Consideration shall be made for low-voltage devices,
semiconductor
s, meters, instruments, transformers, grounding
circuits, etc., in preparation for the dielectric tests.
Insulation Resistance (Megger) Tests
Insulation resistance tests measure the amount of circuit
r
esistance to current leakage. This test is performed when
this resistance measurement is desired and so specified.
The test voltage and minimum insulation resistance shall be
selected as specified. Examples of test values are:
a. 500 volts DC with 10 megohms minimum
b. 1000 volts DC with 1 megohm minimum
c. 1000 volts DC with 25 megohms minimum
Desired values must be specified by the customer, as no
NEMA standard defines Megger values for motor controls.
Rated Circuit Voltage
AC or DC
High Potential Test
Voltage
Duration of Test
120 1500 1 second
140 1800 1 second
480/600 2700 1 second
2300 7200 60 seconds
5000 13,250 60 seconds
7200 18200 60 seconds