Application of Computational Fluid Dynamics to Predict the Temperature-Rise of Low Voltage Switchgear Compartment

Low voltage switchgear compartments are widely used in power distribution networks, and the temperature-rise is strictly limited by IEC 60439-1. Considering the contact resistance, eddy current and thermal flow, an electromagnetic-thermal-fluid coupled model is developed to predict the temperature-rise of a low voltage switchgear compartment. The circuit breaker in the compartment is simplified into three flat conductors surrounded by a solid cuboid, and the proper material properties of the equivalent model are calculated. For verification of the used method, the temperature-rise tests under 500A are carried out. It demonstrates that the simulation and measurement results are close, and the maximum error is about 11K. The model can be improved by considering the radiation heat transport inside and outside the compartment, temperature varying material properties, and including more critical details of the structure. It is noted that the upper terminals of the incoming circuit breaker are beyond the temperature-rise limit both in the simulation and experiment. The optimization will be conducted in the future study.