Insulation for high voltage alternators

Recent developments in mica tape insulation and stator winding construction (or a-c rotating machines of large capacity wound for standard and appreciably higher than standard voltages are considered in this paper. Methods of improving composite mica tape insulation are discussed and the advantages of graded insulation are considered. Two types of windings for graded insulation are proposed for 33,000 volt machines. Special designs involving the insulation and construction of the end windings are presented, and methods of avoiding corona in the end winding zone are analyzed.