Mica Insulating Tape for Large Generators with High Thermal Conductivity

Abstract

We have developed two types of mica tapes, a resin rich (RR) tape and a vacuum pressure impregnation (VPI) tape. A RR tape is little load to the environment and indicates highly thermal conductivity. On the other hand, conventional impregnation process can be used for a VPI tape. Generally, as a stator coil of a generator, a two-layered mica tape comprising a mica-layer and a glass fabric-layer is used. In order to satisfy high thermal conductivity, superior insulation properties and impregnation properties simultaneously, we designed the composition of a mica-layer and a glass fabric-layer. Both types of developed mica tapes show 2.2 times higher thermal conductivity and have a thermal resistance of 54-55%, comparing with the conventional ones. Furthermore, they showed superior insulation properties at practical use electrical intensity. In addition, impregnation properties for VPI tape is equivalent to conventional ones. Thus the developed highly thermal conductive mica insulating tape may be applicable to the high efficiency of the large-capacity thermal generators, contributing the reduction of the environmental load.