Multi-physical field coupling simulation and thermal design of 10 kV-KYN28A high-current switchgear

Switchgear is a key equipment in the power grid, which is widely put into operation in substations and distribution networks. The development trend of high voltage, high current, miniaturization, and long life has put forward higher requirements on the heat dissipation performance of switchgear, which is of great significance to the controllability, stability, and power expansion of the equipment. The current heat dissipation measures are single and not strongly targeted. This paper adopts the multi-physical field coupling simulation method and proposes relatively efficient and reliable solutions for the cooling of the whole switchgear and the contact overheating problem. The main conclusions are as follows: (1) At the same inlet velocity, the heat transfer coefficients of the upper three-phase busbar are higher for T1T2, S2T2, and B2T2. When the inlet velocity v = 2 m/s, its average value is 51.4% higher than that of the other three variants. The heat transfer coefficient of T1T2 (v = 2 m/s) reaches the maximum, h_upper = 3.9 W/(m²∙K). (2) The fans should be placed on the top of the switchgear as a priority, and the heat dissipation effect and cooling efficiency of T1T2 (v = 2 m/s) are the best, with the maximum FOM = 5.4 and the minimum maximum temperature T_max = 73.2 °C. (3) The radiator should be combined with the fan to achieve better heat dissipation. When the bending angle is θ = 180° and the inlet velocity is v = 1 m/s, the heat dissipation is 56.1% higher than natural convection, and the T_max is reduced by 16.4 °C, which is 20.9% lower than that of natural convection.