The temperature rise design of the switchgear can be preliminarily judged from the structural design. If there is a ventilation design, the greater the height difference between the inlet and outlet air positions and the larger the effective ventilation holes, the better. The vertical arrangement of copper bars is conducive to temperature rise and avoids mutual interference; The effective contact distance between the moving and stationary contacts of the contact box is large, and the space is conducive to the heat being carried away with the airflow.

        The width of the domestic 1600A central cabinet structure design requires 1000mm, while the width of the joint venture brand 2500A cabinet can all reach 800mm. Some people may think this is impossible, but this is the gap.

        The 2000A circuit breaker has a high heat output and high contact pressure, and the heating of the arc extinguishing chamber is relatively good. However, the upper and lower supports of the fixed rod are made of aluminum alloy, which generates relatively high heat. The heating value of ordinary circuit breakers ranges from 600W to 1000W, and the heating capacity of copper busbars in switchgear is also around 600W. Therefore, the heating capacity of 2000A switchgear is approximately between 1200W and 1800W.

        Under natural ventilation conditions, if the switchgear is 800 mm wide, 1400 mm high, 2200 mm high, and has a ventilation area of 100 square millimeters. The external thermal balance power is approximately 800W. The effective heat dissipation area of the outer surface is calculated as follows: 0.5 on the side, 1.4 on the top, 0.9 on the front and back, and 0 on the bottom. For the double bending on the outer side of the side panel, the air gap between the cabinets is 4mm, which can not only dissipate heat. It effectively achieves airflow from the bottom or even the cable trench to the top of the cabinet, taking away the heat from the switchgear. The arc is prone to breaking through the two closely attached side panels, while the middle fracture is less likely to break through the double layer side panels separated by air. A gap of 4 mm can effectively cushion and resist deformation of the side panel. The effective heat dissipation area of the entire 800 mm wide switchgear is 7.982 mm. Therefore, it is necessary to design a reasonable and effective switchgear to control the temperature rise within the standard range.

        Reduce local overheating by designing to remove heat from concentrated areas through convection and other means. The circuit breaker is the core of heating. One is the contact system of the arc extinguishing chamber, as well as the lower dynamic connection part, which are all areas with high heat. Therefore, many manufacturers have done a lot of work in this area, such as using components with air ducts, adding radiators at the top, and using multiple soft connections arranged on four sides for the lower connection. Reduce the heat generation of the core components of the vacuum circuit breaker. The heat generated by plum blossom hair contact is also very high, and the contact is sealed in a small space, making it difficult to dissipate heat. A contact box with a larger inner diameter is beneficial for heat dissipation, but a ventilation hole at the rear has a better effect.

        In order to increase effective natural air cooling, natural ventilation should be optimized and effective ventilation openings should be set up. The protection level of general switchgear is IP4x, with an increase in effective intake area of 100mm2 and a heating power increase of 200W. For example, with a basic ventilation area of 100mm2 and a thermal balance isolation of 800W for the switchgear, it cannot meet the minimum heating requirement of 1200W for a 2000A switchgear. Therefore, when the effective ventilation volume reaches 300mm2, a balanced heat generation of 1200W can be achieved. If the heat inside the switchgear is large, such as 1600W, an effective air intake area of 500mm2 is required to meet the temperature rise requirements.

        Similarly, for 3150A natural air cooling with a width of 1000mm, this requirement is not a problem for good brands, including the current 1.1 times temperature rise not exceeding the standard, but it is impossible for most manufacturers. Therefore, it is necessary to reduce contact resistance and self heating. Guide the hottest heat out to avoid concentrated heating, increase natural ventilation, refined design, and CFD software flow simulation technology analysis support and optimization, instead of repeatedly using or falsifying through experiments. Also, sometimes there is a need to balance costs and optimize costs while meeting basic performance requirements, rather than cost optimization. Product performance indicators such as rated current cannot pass the test, which is not conducive to long-term orderly development. A good switchgear is by no means a product with a very beautiful appearance but poor internal functionality and cut corners.