Calculation and Measurement of Thermostatic Bimetal Deflection in Molded Case Circuit Breaker

This paper deals with a thermal overload trip unit in automatically operated electrical switching devices. The first part describes an application of thermostatic bimetal in thermal overload trip unit. The main part is devoted to analytical calculation and measurement of specific thermostatic bimetal type contained in thermal trip unit of molded case circuit breaker. It is measurement of deflection depending on temperature change using photoelectric laser sensor. The analytical results are compared with the measured results at the end of the paper