A switch cabinet is an electrical device where external power lines first enter the main control switch inside the cabinet, then proceed to the branch control switches, each configured according to its needs. It contains instruments, automatic control systems, motor magnetic switches, various AC contactors, etc. Some switch cabinets also have high-voltage and low-voltage compartments, and high-voltage busbars, such as in power plants. Some also have underfrequency load shearing mechanisms to protect key equipment.
The main function of a switch cabinet is to open, close, control, and protect electrical equipment during the power generation, transmission, distribution, and energy conversion processes in a power system. The main components inside a switch cabinet include circuit breakers, disconnect switches, load switches, operating mechanisms, instrument transformers, and various protective devices. Switch cabinets can be classified in many ways, such as by circuit breaker installation method (removable switch cabinets and fixed switch cabinets); or by cabinet structure (open switch cabinets, metal-enclosed switch cabinets, and metal-enclosed armored switch cabinets); and by voltage level (high-voltage switch cabinets, medium-voltage switch cabinets, and low-voltage switch cabinets). It is mainly suitable for various occasions such as power plants, substations, petrochemical plants, metallurgical steel rolling mills, light industry and textiles, factories and mines, residential communities, and high-rise buildings.