Bare conductors or stranded wires with rectangular or circular cross-section are mostly used for the connection of bus bars to voltage distribution devices at all levels in the substation, as well as the connection of electrical equipment such as transformers and corresponding distribution devices, which are collectively referred to as bus bars,.

Bus duct is a high-efficiency power distribution device, which especially meets the needs of economic and reasonable wiring in higher and higher buildings and large-scale factories. With the emergence of modern engineering facilities and equipment, the power consumption of all walks of life is increasing rapidly, especially the emergence of many high-rise buildings and large workshops. The traditional cable as a transmission conductor can no longer meet the requirements in the high current transmission system. The parallel use of multi-channel cables has brought a lot of inconvenience to the on-site installation and construction connection.

So what is the difference between bus and bus duct? Busbar bending machine are actually one closed and one not closed. Enclosed bus is called bus duct for short, that is to say, bus duct is the vest of enclosed bus. Enclosed bus and bus duct refer to the same thing,. Enclosed bus is a bus system composed of metal plate (steel plate or aluminum plate) as protective shell, conductive bar, insulating material and relevant accessories. The utility model can be made into a plug-in closed bus with a plug-in junction box at intervals, or a feed closed bus without a junction box in the middle. It is a bus with the main bus enclosed by metal shell.

Enclosed bus has the following advantages:

1) It is conducive to standardization and good interchangeability.

2) The closed shell is generally made of non-magnetic or weak magnetic materials to reduce heating.

3) The bus is enclosed and the anti pollution ability of the system is improved. It is suitable for areas with serious dust and high air humidity such as coal, papermaking and chemical industry. Enclosed bus can be divided into dense insulated bus and air insulated bus. It is suitable for three-phase four wire system or three-phase five wire system power supply and distribution lines with rated working voltage of 660V, rated working current of 250 ~ 2500A and frequency of 50Hz. It has the advantages of compact structure, high insulation strength, large transmission current, good interchangeability, stable electrical performance, easy installation and maintenance A series of characteristics such as long service life. It is widely used in the connection of power supply and distribution systems such as industrial and mining enterprises, high-rise buildings and public facilities.

Unclosed bus, referred to as bus for short, refers to the connection of voltage distribution devices at all levels in the substation, as well as the connection of electrical equipment such as transformers and corresponding distribution devices,. Most of them use bare wires or stranded wires with rectangular or circular cross-section, which are collectively referred to as ordinary bus. It is generally used for the connection between combined distribution cabinets. It is hidden in the combined cabinet, so it is relatively safe.

Matters needing attention in the selection of bus:

As the link equipment of modern electrical quality inspection, bus has become more and more popular. The connection of bus has many advantages in use. For example, its Anquan function is high, the occupied space is small, the current carrying capacity is large, the voltage drop is small, and so on. Now many buses are used in high-rise buildings and industrial buildings. Pay attention to the following characteristics when selecting bus.

First of all, the setting of bus protector can refer to small technical parameters when selecting bus. There are many buses with the same conductor cross-sectional area and the same material,. However, its working efficiency is quite different. It is considered that to reduce the gap between them, the bus protector must be set to ensure the high-speed an Quan operation of the whole electrical system.

Secondly, when selecting the bus, we should pay attention to its application occasions. Some buses are required to be fire-resistant and water-resistant. They are also different in the occasions of use. For example, the selected bus needs to have fire-resistant function. At the scene of fire, it can ensure the correct transport capacity of power and its normal use value.

Third, when the bus is plugged into the box with interlocking device, it should be able to prevent the injury of electric arc to people caused by man-made on-load plugging.

Fourth, no matter what kind of place the bus is used in, the bus must have a certain degree of stability, be able to withstand low temperature and high temperature, and will not cause the temperature transition of cables and wires to be too high due to the fever at the plug-in box, which will have a certain impact on people.

Selection of bus duct:

The common types of bus duct include hard bus duct and soft bus duct. The hard bus duct is made of copper or aluminum and has rectangular, trough and tube shapes. It is mostly used for indoor power distribution devices of 35kV and below. Sometimes, aluminum tube bus duct is also used for outdoor power distribution devices of 110kV ~ 220kV.

(1) The vertical power transmission and distribution of high-rise buildings shall use compact bus duct to prevent chimney effect, and its conductor shall be coated with flame-retardant materials with long-term working temperature not lower than 130 ℃. Fire blocking partition shall be set between floors, and fire blocking material shall be used for fire blocking partition. Fire resistant bus duct shall be selected for emergency power supply, and toxic gas endangering personal safety shall not be released.

(2) The high-capacity bus duct can be the compact bus duct with good heat dissipation. If the air bus duct is selected, the enclosure protection grade of IP30 can be used only in the special workplace.

(3) The interface of bus duct is relatively easy to be affected by moisture. When selecting bus duct, pay attention to its protection grade. For different installation sites, bus ducts with different enclosure protection grades shall be selected.. Generally, the bus duct with protection grade of IP40 can be selected for indoor normal environment, and the bus duct with protection grade of IP54 or IP66 can be selected for fire sprinkler area.

(4) The bus duct shall not be directly connected with the equipment with significant shaking and impact vibration, but shall be connected with soft joints.

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