부산대학교 도서관

The paper presents the results of an experimental work to examine the times-to-failure of various types of turn insulations used in form-wound stator coils. A unipolar PWM waveform with a peak of 12 kV, rise time of approximately 270 ns and switching frequency of 3 kHz is used for aging. The types of insulations studied include enamel, Daglas®, mica tape with polyester film, and enamel plus mica glass tape. The time-to-failure data are analyzed using two-parameter Weibull statistics. The breakdowns are examined microscopically providing information as to the probable reason for the failures. The role of each type of insulation; enamel, Daglas® and mica polyester film tapes, and their dimensions are discussed to explain the times-to-failure under PWM aging.