Development of Spring Life Test Apparatus and Life-Cycle Assessment of Extension Springs

摘要

Life-cycle test of moulded case circuit breakers (MCCB) on mechanical endurance test apparatus exhibited springs as the weak links. Therefore, improvement in the reliability of the circuit breaker mechanism was possible only with an improvement in the life of the springs. To evaluate spring life, a life-cycle test apparatus was developed which subjected springs to actual load conditions as experienced in MCCB. This paper describes the development and working of the test apparatus. The paper also explains how reliability of springs can be estimated using life data provided by the apparatus.