高压开关柜温湿度分布的三维数值模拟研究

Temperature and humidity changes inside the switchgear will bring about the occurrence of condensation, threatening the safe and reliable operation of power apparatus. A 3-D simplified finite element calculation model for the 40.5kV sheathed indoor AC metal-enclosed switchgear was established, including bus, bushing, circuit breaker, contactor box, cables and other components. The temperature distribution inside the switchgear was calculated under the condition that large current flowed on the surface of conductor bus. Furthermore, the humidity diffusion process was also calculated when the relative humidity of external environment was 0.8, and the relative humidity inside the switchgear was obtained. The simulation results show that condensation is easy to occur on contact box when the surface temperature of the breaker contact box is low and the humidity distribution is high. In addition, it is found that the application of heating and ventilation devices can effectively reduce the humidity and increase the temperature of contact box surface, which is an effective method for reducing the condensation inside the switchgear. The optimum arrangement of heating and ventilating devices is installed on the wall of switchgear cabinet near the contact box and bushing at the same time. The effect of this installation method on reducing the surface condensation of contact box is better than that of setting a single heating or ventilating device.