The cost structure of medium-voltage air-insulated switchgear primarily includes key components such as the cabinet, busbars, circuit breaker trolleys, and secondary equipment. The cabinet, as the main structure of the switchgear, integrates not only mechanical components such as guide rails, valves, and mechanical interlocks, but also important functional components such as contact boxes, wall bushings, and insulators. The cabinet typically accounts for a significant portion of the cost.
In practice, the switchgear cabinet is often constructed from galvanized steel sheets using a one-piece bending process. Each switchgear requires six sheets of galvanized steel sheets, along with three sheets of cold-rolled steel sheets for the door panels, cover panels, and mounting plates. To enhance aesthetics and corrosion resistance, the door panels and cover panels are electrostatically powder-coated. A price of 9,000 yuan typically represents the price of a high-quality product. This type of cabinet meets internal arc fault requirements, boasts a paint finish that meets C3 corrosion protection standards, and is equipped with high-performance insulation and mechanical interlocks.
The significant price difference is due, in part, to the application of advanced manufacturing technologies, such as the one-step punching process for single-piece steel plates. This significantly reduces the workload of shearing, CNC punching, or laser cutting machines, thereby lowering costs. Component selection is also crucial. For example, the price of contact boxes varies significantly, with high-quality options costing as little as 200 yuan each, while lower-cost options can cost as little as 50 or 60 yuan.
Furthermore, the cost of medium-voltage switchgear is closely related to the copper busbars, their surface treatment, and insulation coating. The weight and size of the copper busbars directly impact the switchgear price. Based on a copper busbar price of 70,000 yuan per ton, an 80*10mm copper busbar costs approximately 500 yuan per meter. The cost of the copper busbars required for a switchgear unit, including losses, insulation, and silver plating of the connectors, can reach over 6,000 yuan. The impact of copper prices is even more significant for high-current switchgear.
Vacuum circuit breakers, core components of switchgear, also have prices ranging from 10,000 to 30,000 yuan. Domestic circuit breakers also vary widely in price, but reliable, affordable circuit breakers in the 1250A/5kA range typically cost under 20,000 yuan, making them a reasonable choice.
In addition, the switchgear's secondary configuration also contributes to the cost. Typical secondary configurations include circuit control, monitoring, and protection components such as live indicators, meters, terminals, micro-circuits, and transfer switches, typically costing between 1,000 and 2,000 yuan. Microcomputer-based circuit breakers vary even more, ranging from 5,000 yuan to 20,000 yuan. High-end domestic brands cost around 8,000 yuan.