Failure Mechanism on Accelerated ac Test for High Voltage Capacitors

A highly accelerated ac life test for high voltage dc capacitors has been developed which is useful for solid dielectric capacitors such as mica paper and high dielectric constant ceramics with low ac losses. The test utilizes the fact that corona intensity on ac is several orders of magnitude higher than on dc. It is shown that the mechanism of failure involves electrochemical erosion for both the mica paper and the ceramic dielectric material. The life times follow a power law with an exponent of 26 for mnica paper and 31 to 100 for the ceramic.