Advanced thermal simulation of a circuit breaker

The quality of thermal simulation results depends on the accuracy of both the modelled heat sources and heat sinks. Starting from an existing simplified thermal simulation model, This work describes further steps towards a more accurate representation of the heat sinks in a circuit breaker. Heat generated in switchgear can leave the system either along the metallic conducting path to the connecting wires or through the case to the surrounding air. The former simulation model accurately represented the heat generation and the thermal path along the metallic conductor. However, the path through the case was only summarized by convection coefficients on the metallic parts´ surfaces. Due to the high performance requirements of modern breakers it is interesting to know not only the temperatures of the conducting parts but also the thermal impact on the plastic components supporting the conductors or providing essential functions. Therefore, the non-metallic parts of the circuit breaker (including the air within the device) are now part of the model. Consequently, the heat flux through the housing is a result of the simulation and not an estimated boundary condition any more. Moreover, conclusions can be drawn about the thermal stress of the plastic parts of the breaker.