The low-voltage distribution line refers to the line that reduces the high-voltage 10KV to 380/220v through the distribution transformer, that is, the low-voltage line that is sent from the substation to the equipment.
Low-voltage distribution line in the design of substation wiring, it should be taken into account, the factory for some of the larger power consumption of the workshop, but also set up the workshop transformer, by the transformer for the power supply of the electrical equipment, and for the small power consumption of the workshop, by the distribution transformer direct power supply.
Low-voltage distribution system
Low-voltage distribution lines according to the load category, size, distribution and the nature of the load, design layout, generally have high costs, so now the low-voltage distribution wiring commonly used trunk type, it can obtain full flexibility, when the production technology changes, distribution lines do not have to carry out large changes, so the trunk type distribution mode cost is lower, which is its two major characteristics. Of course, in terms of the reliability of the power supply, it is less than the radiation type.
Types of low-voltage distribution lines
There are two ways to install low-voltage distribution lines, that is, cable laying and overhead laying.
Cable lines are laid underground, so they have little impact on natural conditions such as wind and ice outside, and there are no wires on the ground, beautifying the city and building environment. However, cable lines are expensive and difficult to inspect, and overhead lines have the opposite advantage. Therefore, for places with no special requirements in general, low-voltage wiring is laid by overhead line.

PMC008A 700502

PMC008A 700502

Low voltage overhead lines are usually made of wooden or cement poles, and the wires are fixed on the cross arm of the poles with porcelain bottles. The distance between the two poles is about 30~40M in the yard, and can reach 40~50M in the open area, and the distance between the wires is 40~ 60cm. The erection of the line is as short as possible, and the convenience of erection and maintenance should be considered.

Progress and change, for example, in the early construction of the main equipment is a variety of drag transport machinery, and in another phase of the project may be welding machines and so on. Therefore, the construction site should be in accordance with the calculation load of the largest phase of the project to determine the electricity consumption of the site.
Site power supply belongs to temporary facilities, all electrical equipment must have the characteristics of quick installation and disassembly. The site substation should also adopt the open-air transformer substation on the pole, and the wiring mode is mainly trunk type overhead line. Erection of the line must pay attention not to impede traffic, and to facilitate erection and removal, for underground engineering or tunnel construction site, due to limited space, the height of the power supply line can not be set up according to the requirements of the ground construction, therefore, in this case the lighting line are using 36V below the safety voltage, and the power load of 380/220V power supply line, Three-phase four-core cable flexible wire with good insulation and moisture-proof should be used. Pull the cable with the construction progress, and remove the terminal at any time when not in use to ensure the safety of construction.
The distance between the power distribution line and the ground is as follows:
Minimum distance between wire and ground:

Distribution lines should not cross roofs and buildings made of flammable materials, nor should they cross buildings with fire-resistant roofs, otherwise the relevant units should be consulted. The vertical distance between the wire and the construction object, at the maximum relaxation, 1~10kV line should not be less than 3m; The line below 1kV should not be less than 2.5m.
When the distribution wire meets the weak wire, the distribution line should be set up above the weak current line, and the vertical distance from the weak current line, under the maximum relaxation, 1~10kV, should not be less than 2 meters, 1kV should not be less than 1 meters.
Distribution box at the construction site
The distribution box in the construction site can be divided into general distribution box, fixed distribution box and mobile distribution box.