Thermal Analysis of a Double-Break Contact Based on FEM Simulations and Experimental Studies

This paper concerns the thermal analysis of a double-break contact of a compact circuit breaker based on FEM simulation and experimental studies. Aspects of thermal analysis are mandatory to fully understand and improve the design of compact electrical apparatuses. This is due to the flow of the expected rated currents but even more to the limitations associated with the flow of short-circuit currents. The paper presented introduced some novelties to the thermal analysis of compact circuit breaker current paths by deriving a detailed and functional three-dimensional finite element model (FEM). For the purposes of experimental study, a real object in the form of a mold case circuit breaker (MCCB) with a rated current of 250 A was used for research. For the purposes of numerical simulation analyses, a detailed 3D model of the compact circuit breaker was developed based on the real object and the available technical documentation from the manufacturer. In order to perform the thermal analysis, ANSYS software (2024 R1) was used, which allowed for modeling the 3D geometry and simulating electromagnetic and thermal phenomena. During the numerical analyses, the distribution of the current flow density through the analyzed double-break contact and Ohm’s losses were determined. Moreover, the temperature distribution in terms of its impact on the sole elements of the contact was evaluated. The results obtained from the experimental tests were compared with the results from the numerical transient analyses.