A heat-generated fault in DC motors may be generated from practices
that have the shunt fields energized with the armature at rest.
This used to be a common mode of operation that requires a separate
blower to provide cooling to the motor. Shorted shunt coils result
from the increased temperature and will not be visible on the
outside of the coil. The fault will cause a reduction in the motors
ability to produce torque. Trending or comparison of the DC motor
fields using motor circuit analysis will identify this type of
fault. The best correction is to find DC drives that shut down the
fields after the DC motor is idle for a period of time.
Tip provided by ALL-TEST Pro, A Division of BJM Corp
www.alltestpro.com
Tel: 860.399.5937
7/24/03
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