Research On Reliability Of A New Type Of Moulded Case Circuit Breaker

A type moulded case circuit breaker is modern world’s leading residual current proteciton circuit breaker and widely used in low voltage power-distribution system,electrical system and marine,aviation and in other national economy area,especially in nation’s key military projects.This new type moulded cased circuit breakers not only have the function of overload,short circuit protection,but also have the function of protecting personal safty and preventing electrical fires.Therefore,the reliability research on this circuit breaker has great economic benefit and good social value.This article does a research on a new type moulded case circuit breaker’s reliability theory.According to a new moulded case circuit breaker’s operating feature and failure mode,establishing its reliability index;doing statistics and analysis on a new type moulded case circuit breaker’s failure cause,finding the failure mode of its opertation mechanism,thermomagnetic tripping mechanism,residual current tripping mechanism and other mechanisms;discussing the estimation method of its reliability characteristic quantity and confirming censored lifetime as testing program,point and interval estimating on its two reliability characteristic quantity-operation failure rate and protection success rate.This article also gives the test requirements,test method and relibility test procedure of a new type moulded case circuit breaker. Through failure analysis on reliability test,doing failure analysis on operation mechanism’s principal tensile spring,upper connecting rod and thermomagnetic tripping mechanism’s overload delayed mal-operation.Ranking the operation reliability level and protection success rate and estimating the reliability characteristic quantity of operation failure rate and protection success rate.Through the reliability test a type moulded case circuit breaker,this article presents the effective way improving itsreliability level,thereby improving product reliability.Meanwhile,laying the foundation of reliability research on a new type moulded case circuit breaker product.lt is a kind of attempt which puts reliability research into practice.