An Advanced Technology for the Manufacture of Electrical Insulating Materials

Abstract

Breakdowns, interturn short-circuit faults, or low resistance of the ground wall insulation of the armature coils or main/auxiliary poles account for a significant (about 40%) part of traction electric motor (TED) failures. Therefore, one of the main objectives pursued by electrical insulation manufacturers is to improve the insulation quality and increase its service life. The insulation quality is improved both by replacing insulation components and by perfecting the manufacturing technology. The article describes an alternative technological process for manufacturing the insulating tapes used as ground wall insulation of coils based on a powder technology. The schematic process circuits of equipment for producing electrical insulating tapes according to both the technologies are given; the shortcomings of the currently existing technological process are pointed out, and methods for estimating the coil insulation quality of large electrical machines are described. The costs for manufacturing a production unit are compared in physical and monetary terms. The fiberglass and mica based Elmikapor® tape produced by ZEIM Elinar LLC was used as an object of research. Industrial tests of the insulation were carried out, and a conclusion has been drawn from the obtained test results that the use of powder technology shortens the impregnation time by a factor of 1.5 and reduces the cost of manufacturing insulation for electric machines by impregnation under vacuum, improves the impregnation quality, and, consequently, the durability of the insulation system and the electric machine operation time between overhauls. The described technology also features an essentially smaller negative impact on the environment.