Improved Potential Grading Methods with Silicon Carbide Paints for High Voltage Coils

This paper presents surface potentials and the accompanying thermal analysis on, two improved potential grading methods with silicon carbide (SiC) paints for HV generator coils: (1) double-coating of SiC layers along a coil and (2) combination of a conducting intersheath and a SiC paint. Approximate equations describing the thermal behavior for both methods are derived on the assumption of ideal nonlinear conductivity. The double-coating method shows effective regulation of local heating, though total heating is not suppressed. A simplified model of the combination method predicts a remarkable heat suppression effect, which also is verified with numerical calculation.