Digital Optimization Process of Thermal Trip Unit in Circuit Breakers for Carbon Footprint Reduction

Circuit Breakers are major components of protection systems, which also contributes significantly towards scope-3 greenhouse gas emission. Inside a circuit breaker, the thermal trip unit or a bimetallic strip contributes significantly towards watt-loss. Different bimetals exhibit different structural and thermal behavior and hence, a common framework to optimize bimetal for circuit breakers is required. A breaker is also expected to operate at different constraints laid under UL489 standard. Experimental, numerical, and statistical methods are used to reduce overall watt-loss of a breaker. In this study, an electrical and thermal resistance network modelling methodology is highlighted to optimize the thermal trip unit. This model is verified with thermal test and simulation data. Statistical design exploration and watt-loss optimization is also highlighted. Optimum bimetal design shows ~35% reduction in overall watt-loss, which may give significant benefit in reducing overall carbon footprint. The same optimization process can be used to improve efficiency and reduce carbon emission of circuit breakers of different size and rating.