The reliability and life of impregnated-paper capacitors

Reference is made to present trends in the encasing and hermetic sealing of paper capacitors. After a statement of the main primary causes of breakdown, the problems of impregnated-paper dielectric failure under d.c. and a.c. stress are discussed in the light of knowledge of various breakdown mechanisms gained principally during the last decade. Possible ways of prolonging capacitor life under d.c. stress are considered, and measures to eliminate early failures under both d.c. and a.c. stress are discussed. Achievement of very great reliability is considered a lesser problem with a.c. than with d.c. stress.