Insulation system for a stator bar with low partial discharge

摘要

The invention discloses an insulation system for a stator bar in high voltage electric machines, comprising an anti-corona tape that is wound uniformly and continuously over the entire length of a bare bar. The anti-corona tape comprises a thin resistive sublayer engaged to a thick insulative sublayer. The insulative sublayer provides resistance against high voltage. The resistive sublayer protects the insulation against partial discharges. These partial discharges can occur in voids, such as delamination voids, transposition crossover gaps, strand corners, slot voids, overlap voids etc. The resistive sublayer also increases the thermal conductivity hence reduces the operating temperature. Such insulation using a single-tape approach can replace several layers used in prior-art, viz., an internal corona protection layer, an external corona protection layer, a stress-grading layer and mica layers. This single-tape approach also simplifies the process of manufacturing the stator bar and reduces its cost.