None of us know when a breakdown of the insulation in an electric motor or transformer will occur, since it depends on the materials chosen and the service environment. Heat, vibration, voltage, and stress often contribute to the breakdown.

When a repair is made, insure that the repair shop uses a VPI (Vacuum Pressure Impregnation) process to extend the life of the electric motor or transformer. The VPI process, along with a good resin, provides a low thermal resistance path that lowers the average operating temperature. It also seals it against environmental conditions and bonds all the components for good mechanical strength. This reduces both vibration and noise. In addition, it enhances the dielectric capability between the windings and the ground. The VPI treatment, I believe, adds to the life of the repaired motor or generator, and is cost effective. Your repair shop needs to offer this capability.

Tip provided by: Dan DeWald, CPIM-SME Material Management

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