What Is a Distribution Box?

The distribution box is a mass parameter on the data. Generally, it constitutes a low-voltage forest according to the electrical wiring. It is required that the switchgear, measuring instruments, protective appliances and auxiliary equipment be assembled in a closed or semi-closed metal cabinet or screen to form a low-voltage power distribution box. During normal operation, the circuit can be switched on or off with the help of manual or automatic switches. ^[1]

The distribution box has the characteristics of small size, easy installation, special technical performance, fixed location, unique configuration function, not limited by site, universal application, stable and reliable operation, high space utilization, small footprint and environmental protection. It is a control center that directs the various components in the power supply line to reasonably distribute electrical energy. It is a control link that reliably accepts the upper power source and correctly feeds the load electrical energy. It is also the key to obtaining users' satisfaction with the power supply quality. Improving the operational reliability of power distribution boxes is the goal of creating high-quality projects. ^[2]

There are two types of commonly used distribution boxes: wooden and metal. Because metal protection boxes have a higher protection level, they are more often used in metal.

Classified by structural characteristics and uses:

(1) Fixed panel type

There are many types of distribution cabinets in domestic power supply and distribution systems, and their cabinet structures and technical parameters are different. Under the influence of the following factors, the well-designed drawings often need to be revised or even redesigned.This not only affects the construction plan of the power supply and distribution system, but also brings a certain degree of quality to the distribution cabinet manufacturer to complete the production of the distribution cabinet on time. Trouble.
There are several factors that affect the changes in the designed drawings:
1. The power distribution cabinet manufacturer recommends to users the products that they produce may not be suitable for users.
2. The design institute doesn't know much about some new cabinet types just designed according to user requirements.
3. The user does not know their own needs very well, when choosing the cabinet type, they cannot choose according to their own needs.
In order to solve the above problems and meet the needs of users, the specific model of the distribution cabinet is more accurately selected. The following analyzes the characteristics of low-voltage distribution cabinets commonly used in domestic power supply and distribution systems.
The following analyzes the cabinet structure and technical parameters of the imported power distribution cabinet.
The main characteristics of domestic distribution cabinets are that the specific types of distribution cabinets of the same type produced by domestic manufacturers are inconsistent, and the specific structure of distribution cabinets is also different.The main electrical components installed in the distribution cabinet can be imported well-known brands or For domestic brands.
The related technical parameters are described below.
1. Maximum rated current of the main bus: The maximum rated current that the main bus can carry.
2.Rated short-time withstand current: The root-mean-square value of the short-term withstand current that can be safely carried by a circuit in the complete set of equipment under the test conditions specified in 8.2.3 of the national standard GB7251.1-2005 given by the manufacturer. .
3. Peak short-time withstand current: Under the specified test conditions, the manufacturer specifies the peak current that the circuit can withstand satisfactorily. 4. Enclosure protection level: The level provided by the complete set of equipment to prevent contact with live parts, as well as the intrusion of foreign solids and the entry of liquids according to the IEC60529-1989 standard. See the IEC60529 standard for detailed classification.
5. Internal separation method: According to the IEC60529-1989 standard, in order to protect personal safety, the switch cabinet is divided into different compartments in different ways.
The technical parameters of different types of power distribution cabinets are very different, and the technical parameters of imported power distribution cabinets are basically better than domestic power distribution cabinets, but it cannot be said that imported power distribution cabinets are necessarily better than domestic power distribution cabinets. .
The following points are based on actual work experience:
1. Imported power distribution cabinets are developed abroad, and are generally sold for the global power supply and distribution market. Because each country has different requirements and habits for the power supply and distribution system, imported power distribution cabinets are not necessarily completely suitable for the domestic market.
2.The main electrical components used in imported power distribution cabinets are imported brand products, and some cabinets or some cabinet accessories must be imported from abroad, so that the price of imported power distribution cabinets is generally much higher than domestic power distribution cabinets. .
3. Although the technical parameters of imported power distribution cabinets are high, in most cases only a part of them are used, and even they cannot be used at all. For example, the number of circuits that can be installed in an imported distribution cabinet is more than that of domestic distribution cabinets, but that can only be achieved on the premise of reducing the circuit capacity. In most cases, it cannot meet the needs of users.
4. Although the technical parameters of domestic distribution cabinets are lower than imported distribution cabinets, they can already meet user needs in most domestic power distribution systems.
5. In terms of the quality of the distribution cabinet, as long as the manufacturer strictly produces and inspects in accordance with the requirements of 3C, domestic

(1) The main power distribution box, distribution box and switch box shall be set up in the power distribution system for construction, and shall be set in stages according to the order of "total-open-open" and form a "three-level power distribution" mode.

(2) The installation position of each distribution box and switch box of the power distribution system for construction shall be reasonable. The main distribution box should be as close to the transformer or external power source as possible to facilitate the introduction of power. The distribution box should be installed as far as possible in the central area where the electrical equipment or load is relatively concentrated to ensure that the three-phase load remains balanced. The installation position of the switch box should be as close as possible to the electrical equipment it controls, depending on the site conditions and working conditions.

(3). Ensure that the three-phase load balance of the temporary power distribution system is ensured. The power and lighting power at the construction site should form two power circuits. The power distribution box and the lighting distribution box should be provided separately.

(4) All electrical equipment on the construction site must have its own dedicated switch box.

(5) The cabinets and internal settings of the distribution boxes at all levels must comply with the safety regulations. The switchgear should be marked with the purpose and the cabinets should be uniformly numbered. Discontinued power distribution box should be cut off the power supply and the box door locked. The fixed distribution box should be provided with a fence and there should be measures to prevent rain and smash.

(6). The difference between distribution box and distribution cabinet. According to GB / T20641-2006 "General requirements for empty enclosures of low-voltage complete switchgear and control equipment"

The distribution box is generally used by households, while the distribution box is mostly used in centralized power supply, such as industrial power and building power. The distribution box and the distribution box are all complete sets of equipment, and the distribution box is a low-voltage complete set of equipment. The distribution cabinet has high voltage and low voltage.