Selection of insulating materials for repair of integral horsepower electrical rotating machinery

Repair shop insulation practice for many years was simple and straight-forward. Most problems were solved by cotton, paper and impregnants, such as asphaltum or oleoresinous base varnishes. Electric motors were generally over-designed and applied with simple controls on constant speed applications. During the last decade, the whole concept of industrial application has changed - variable speeds, frequent starts and stops, compact designs, higher temperatures and complex electronic controls are now commonplace. And they have increased the scope of the industrial service organization.