Partial discharge inception and extinction studies in polymer film structures impregnated with compressed SF6 gas

1. Good consistency has been achieved in the discharge and breakdown performance of six-inch size coils wound on a new, specially-designed winding apparatus. 2. Normal probability plots indicate a single mode of breakdowns, partly determined by the conductor edge finish and partly by chance residual particles. 3. The validity of using multiple-sample test coils has been demonstrated. 4. There has been no evidence for conditioning effects on discharge behavior in tests in air or SF6 gas using coils constructed with precision slit aluminum. 5. Discharge inception and extinction are affected by gas pressure in short-time tests; breakdown is not.