8Renate S, Johnl L. Partial discharge testing under direct voltage conditions[J]. IEEE Transactions on Aerospace and Electronic System, 1982, 18(1): 82-93.
9Renate S. Ramp technique for DC partial discharge testing[J]. IEEE Transactions on Electrical Insulation, 1985, 20 (1) : 38- 46.
10Fromm U. Interpretation of partial discharge at de voltages[J]. IEEE Transactions on Dielectrics and Electrical Insulation, 1995, 2(5): 761-770.