Vacuum retrofits: the process, benefits, and risks

Older circuit breakers have had an excellent reliability for the period of time intended. These circuit breakers have performed satisfactorily for at least 10 to 15 years, and most, 20 to 30 years, with a certain level of preventive maintenance performed. Unfortunately, normal age, deterioration, and wear have brought: many of these circuit breakers to the end of their useful life, from a reliability and maintainability standpoint. We address reliability and maintainability of the existing circuit breakers, as well as the improvements gained by the vacuum retrofit process. Retrofit design factors, which affect reliability and maintainability of the final product, are also addressed; as well as alternatives and cost considerations, applications, specification recommendations, and associated switchgear improvements. The gains achieved in equipment life extension are self evident. A detailed review is also provided concerning the safety interlocks, which must be properly incorporated into a retrofit