Moisture accumulating in electric motors and generator windings having a cold insulation resistance greater than 50,000 ohms may be baked out with internal heat. What is the usual method for developing this heat to evaporate the moisture?
• Safe heating of electrical windings to remove moisture • Effect of short circuits vs. controlled current on motors and generators • Why low voltage and controlled current are important when insulation is already acceptable but damp
• Which method would allow you to raise the temperature of the windings in a controlled, gradual way without creating high mechanical or electrical stress? • Which options would likely cause very high current flow or mechanical load, and are therefore more suited to testing/extreme conditions than gentle drying? • Think about what would happen physically if you short-circuited armature and/or field windings—how would the current and heating behave?
• Eliminate any option that would obviously cause excessive current or strong mechanical loading/torque on the motor. • Focus on the choice that provides moderate, sustained heating rather than abrupt, high-stress conditions. • Remember the goal: the insulation is already over 50,000 ohms (not totally grounded), so the method should be gentle drying, not a severe electrical test.
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