Development of potential grading layer for high voltage rotating machine

A new potential grading layer used for a high voltage rotating machine has been developed based on the percolation behavior of composite made with a resin, triiron tetra oxide (Fe/sub 3/O/sub 4/) and/or silicon carbide (SiC). The potential grading layer was designed by using a combination of high and low resistive tapes made with a binder resin, SiC and Fe/sub 3/O/sub 4/ and showed a stable and excellent partial discharge suppression capability.