Page 166 - Electrical Equipment Handbook _ Troubleshooting and Maintenance

MAINTENANCE OF MOTORS

MAINTENANCE OF MOTORS 8.21

FIGURE 8.7 A new stator winding is pictured here for purposes of comparison with the winding failures
shown in Figs. 8.8 to 8.19. Descriptions of the causes of failure are given.
Motor Repair

27. All defective components should be repaired or replaced.
28. Perform all the tests listed in either Table 8.3 (for 575-V motors) or Table 8.4 (for 4-kV
motors). The results of the tests should meet the acceptance criteria before the motor can
be reassembled.

Motor Rewind
If the windings of the motor have serious damage, the motor should be rewound.

APPENDIX: TYPICAL CAUSES OF WINDING
FAILURES IN THREE-PHASE STATORS*

The life of a three-phase stator winding can be shortened dramatically when the motor is
exposed to unfavorable operating conditions—electrical, mechanical or environmental.
The winding failures illustrated below are typical of what can happen in such circum-
stances. They are shown here to help identify the causes of failure, so that, where possible,
preventive measures may be taken.

*Reprinted with permission from Failures in Three-Phase Stator Windings, Electrical Apparatus Association,
Inc., St. Louis, Mo.

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