Stressing insulation in motor repair testing

The practices of a number of repair shops are reviewed with a view to establishing an index of acceptable workmanship. Also discussed are the effects on the insulation of stresses induced by these operations. Stator insulation tests, stator winding tests, and AC test results are discussed. It is found that factors contributing to the stressing of motor insulation include overly rapid drying and consequent outgassing of moisture, arcing that may occur during AC ground tests, and high starting voltages.<
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