Experimental Study on Capacity Increase of 12kV Switchgear Based on Pumpless Self-circulation Evaporative Cooling Technology

The dust brought by the 12kV switchgear air-cooling system reduces the insulation level of the switchgear and causes short-circuit faults to occur, At the same time, due to the convection cooling dead zone of the static and dynamic contacts of the switchgear, the current limit of the switchgear cabinet is only 3kA, which cannot meet the 4kA requirement in actual operation. In order to solve the above problem, First of all, according to the principle and the theoretical technology of Pumpless Self-circulation Evaporative Cooler, combined with the internal structure, the properties of working fluid and the heating power of the switchgear, the limit values of normal operating parameters of cooler were calculated, and four kinds of cooler cooling structure designed for the switchgear static and dynamic contacts is presented. Secondly, a temperature rise test platform for the switchgear, which were installed with cooling cooler device, was designed. The influence of cooler insulation section and evaporation section shape on temperature rise of switchgear dynamic and static contacts were studied, respectively. The results show that the cooling effect of the cooler including linear insulation section is better than that of the cooler including bending type insulation section. The cooling effect of the cooler including hoop type evaporating section is better than that of the cooler including flat type evaporating section. Finally, based on the test, the optimal effective ventilation area of the circuit breaker room, bus room, cable room, front and rear doors were 0.3m², 0.12m², 0.13m², 0.07m², respectively.