MNS Low-voltage extraction switchgear is mainly composed of some combined motor control units and other functional units. These units are mounted in a closed metal cabinet by overlapping the upper and lower parts. Each cabinet body is connected with a horizontal bus set above the cabinet body, and the functional units of the same cabinet body are connected with a vertical bus in parallel. The cabinet body is divided into four isolation zones: horizontal bus zone, vertical bus zone, cable zone and equipment installation zone. Functional units are installed in their respective small rooms. When any functional unit has an accident, it will not affect other units and prevent the accident from expanding.