According to the requirements of the power supply system, high and low voltage distribution cabinets can be classified into the following categories
(1) The first level distribution equipment is collectively referred to as the power distribution center. They are centrally installed in the enterprise's substations, distributing electrical energy to lower level distribution equipment in different locations. This level of equipment is located close to the step-down transformer, so the electrical parameters are required to be high and the output circuit capacity is also large.
(2) Secondary distribution equipment refers to the general term for power distribution cabinets and motor control centers. The power distribution cabinet is used in situations where the load is relatively dispersed and there are few circuits; The motor control center is used in situations where the load is concentrated and there are many circuits. They distribute the electrical energy from a certain circuit of the higher-level distribution equipment to nearby loads. This level of equipment should provide protection, monitoring, and control for loads.
(3) The final distribution equipment is collectively referred to as lighting power distribution cabinets. They are located far from the power supply center and are dispersed small capacity distribution equipment.
Classified by structural features and usage:
(1) Fixed panel switchgear, commonly known as switch board or distribution panel. It is an open type switchgear with panel shielding, which has a protective effect on the front and can still touch the live parts on the back and side. The protection level is low and can only be used for industrial and mining enterprises with low requirements for power supply continuity and reliability, as well as for centralized power supply in substations.
(2) Protective (i.e. enclosed) switchgear refers to a type of low-voltage switchgear where all sides, except for the installation surface, are enclosed. The electrical components such as switches, protections, and monitoring controls of this cabinet are all installed in a closed enclosure made of steel or insulating materials, and can be reliably installed on or off the wall. Each circuit inside the cabinet can be isolated without isolation measures, or grounded metal plates or insulation plates can be used for isolation. Usually, there is a mechanical interlock between the door and the main switch operation. In addition, there is a protective platform type switchgear (i.e. control console) with control, measurement, signal and other electrical appliances installed on the panel. Protective switchgear is mainly used as a power distribution device in process sites.
(3) Drawer type switchgear, which is made of steel plates and has a closed shell. The electrical components of the incoming and outgoing circuits are installed in withdrawable drawers, forming a functional unit capable of completing a certain type of power supply task. The functional unit is separated from the busbar or cable by a grounded metal plate or plastic functional board, forming three areas: busbar, functional unit, and cable. There are also isolation measures between each functional unit. Drawer type switchgear has high reliability, safety, and interchangeability, and is a relatively advanced switchgear. Currently, most of the produced switchgear are drawer type switchgear. They are suitable for industrial and mining enterprises and high-rise buildings that require high power supply reliability, serving as centralized control distribution centers.
(4) Power and lighting distribution control box. Mostly enclosed vertical installation. Due to different usage scenarios, the protection level of the casing also varies. They are mainly used as power distribution devices for production sites in industrial and mining enterprises
The distribution cabinet should be made of non combustible materials; Production sites and offices with low risk of electric shock can install open type distribution cabinets; In processing workshops, casting, forging, heat treatment, boiler rooms, woodworking rooms and other places with high risk of electric shock or poor working environment, enclosed distribution cabinets should be installed; In hazardous workplaces with conductive dust or flammable and explosive gases, enclosed or explosion-proof electrical facilities must be installed; The electrical components, instruments, switches, and circuits of the distribution cabinet should be arranged neatly, installed firmly, and easy to operate.; The bottom of the distribution cabinet installed on the ground should be 5-10 mm higher than the ground; The center height of the operating handle is generally 1.2-1.5m; There are no obstacles within a range of 0.8-1.2m in front of the distribution cabinet; Reliable connection of protective wires; No bare live parts shall be exposed outside the distribution cabinet; Electrical components that must be installed on the outer surface of the distribution cabinet or on the distribution cabinet must have reliable screen protection.
Post time: Mar-12-2025
