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AC MOTOR TESTING

 

Studies by motor manufacturers indicate that 60% of electrical failures in motors begin as winding to winding shorts.  Interturn shorts occur as insulation weakens and degrades due to temperature, voltage surges, mechanical damage during rewinding, motion, moisture and contamination.  This degradation occurs in stages and can be identified prior to catastrophic failure.

 

MOTOR INSULATION TEST REPORT
8/8/97
TESTS PERFORMED BY ITR, INC.
MOTOR DESCRIPTION: PRESS #25 [480 VAC, 75HP]
COMMENTS:

MOTOR TYPE: 480 VAC 3 PHASE, ASSEMBLED, 75 HP
TEST RESULTS
1. Initial Resistance Check OK
2. MegOhm Value @ 1000 VOLTS < 2 m amp, > 500 MegOhms, OK
3. DC Hipot Test @ 2000 VOLTS < 5 m amp, OK
4. Surge Test @ 2000 VOLTS OK
5. Comparison Test @ 2000 VOLTS OK
TEMP: ~25 DEG. C
PHOTOGRAPH OF WAVEFORM @500 VOLTS/DIVISION

AC Motor Test

Traditional tests are unable to determine the condition of insulation between windings.  Megohmmeter tests provide only the resistance of contaminants between a winding and ground.  DC hipot tests indicate the dielectrical strength of the ground insulation.  Although these tests are essential for thorough winding analysis, only our surge testing completes the profile.

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Copyright 1998 ITR Inc.
Last Revised: May 21, 1998