Working principle：
Distribution box is according to the electrical wiring requirements, the switchgear, measuring instruments, protective appliances and auxiliary equipment are assembled in a closed or semi-closed metal cabinet or screen to form a low-voltage distribution device. The circuit can be switched on or off by manual or automatic switch during normal operation. In case of failure or abnormal operation, cut off the circuit or alarm with the help of protective appliances. The measuring instrument can display various parameters in operation, and can also adjust some electrical parameters to prompt or signal deviation from the normal working state. It is commonly used in power generation, distribution and substation.
Structural use：
Distribution box and distribution cabinet, distribution board, distribution panel, etc., are complete sets of devices for centralized installation of switches, meters and other equipment.
Classification by structural features and uses:
(1) Fixed surface type switchgear, often called switch board or distribution panel. It is an open-type switch with a panel shield，Cabinet, the front side has a protective effect, the back and side can still touch the live part, the protection level is low, can only be used for the continuity of power supply and industrial and mining enterprises with low reliability requirements are used for centralized power supply in the substation room.
(2) Protective (that is closed) switchgear refers to a low-voltage switchgear with all sides closed except the mounting surface. The switch, protection and monitoring control electrical components of this cabinet are installed in a closed enclosure made of steel or insulating materials, reliable wall or off-wall installation. Each circuit in the cabinet can be isolated without isolation measures, or can be isolated by grounding metal plate or insulation board. Usually the door operates with a mechanical interlock with the main switch. In addition, there is a protective table-type switch cabinet (that is, the console), which is equipped with control, measurement, signal and other electrical appliances on the panel. The protected switchgear is mainly used as a power distribution device in the process site.
(3) Drawer type switch cabinet. This kind of switch cabinet is made of steel plate closed shell, and the electrical components of the inlet and outlet circuit are installed in the drawer that can be drawn out to form a functional unit that can complete a certain type of power supply task. Between the functional unit and the bus bar or cable, separated by a grounded metal plate or a plastic functional board, forming three areas of the bus bar, functional unit and cable. There are also isolation measures between each functional unit. Drawer type switchgear has high reliability, safety and interchangeability, is a more advanced switchgear, the current production of switchgear, most of the drawer type switchgear. They are suitable for industrial and mining enterprises and high-rise buildings that require high reliability of power supply, as a centralized control distribution center.
(4) Power, lighting distribution control box. Mostly closed vertical installation. Depending on the use, the protection level of the shell, It's also different. They are mainly used as power distribution devices in the production site of industrial and mining enterprises.
