Discussion on key installation technology of enclosed plug-in bus duct in high-rise buildings

Bus bridge, also known as bridge connection, is a main connection that connects two power supply lines to two transformers using a jumper circuit breaker BCD. Simplify the segmented single busbar connection and reduce the number of circuit breakers. According to the different positions of the jumper circuit breaker, it is divided into internal connection bridge and external connection bridge. The internal connection bridge is suitable for substations with long lines and relatively stable load curves; External connection bridge is suitable for transformer positions with short lines and large load curve changes. The purpose of painting the busbar bridge is to provide insulation, corrosion prevention, heat dissipation, and "phase" identification. The busbar bridge refers to a rectangular copper or aluminum busbar inside the bridge, usually made of iron sheet to protect the busbar; it is used in households.

The insulation layer and outer sheath of ordinary cables will burn. Even flame-retardant cables can burn under flames, only burning after the flames have left. Fire resistant cables do not burn and are only used in situations where power outages are not allowed, such as in fire alarm circuit systems. The shell of the bus duct is made of metal and will not burn. Even if the insulation material of the copper bar burns, the flames will not endanger the outside of the bus duct.

The connection of voltage distribution devices at all levels in substations, as well as the connection of electrical equipment such as transformers and corresponding distribution devices, mostly uses bare or stranded wires with rectangular or circular cross-sections, which are collectively referred to as busbars. The function of a busbar is to collect, distribute, and transmit electrical energy. Due to the large amount of electrical energy passing through the busbar during operation, the enclosed busbar trunking bears significant heating and electrodynamic effects during short circuits. Therefore, it is necessary to select busbar materials, cross-sectional shapes, and cross-sectional areas reasonably to meet the requirements of safe and economical operation. Busbars are divided into hard busbars and soft busbars according to their structure. Hard busbars are divided into rectangular busbars and tubular busbars. Rectangular busbars are generally used from main transformers to distribution rooms. Their advantages include easy construction and installation, minimal changes during operation, and high current carrying capacity, but they are relatively expensive. Soft busbar is used outdoors, and due to the large space, the swinging of the wires will not cause insufficient distance between the wires. The vast majority of electrical accidents caused by bus ducts are due to the installation of connectors and inadequate protection levels. The protection level of busbar trunking not only refers to the protection level of the busbar body, but also includes the protection level of the installation connection head. At present, there are many bus ducts on the market, with a marked protection level of IP54. IP65、IP66， The protection level of the busbar body can meet its requirements, but the protection level of the connector can only reach IP30 or IP40. Therefore, the design and processing of the connector is a crucial factor. If the connector seal is not good, no matter how high the protection level of the busbar body is, it cannot truly and effectively protect the safe operation of the busbar trunking.

The advantage of the application lies in its compact size, making it very convenient to transport and operate during installation. At the same time, the bus duct has a large capacity, so the power supply is strong and the production time is relatively short, which can save a lot of time to do other things.

The length of the straight section bus duct can reach up to 8 meters, and its bending strength can meet industry standards. Copper conductors are used in the bus duct, and aluminum conductors can also be used according to customers. The aluminum alloy shell can be used as a protective grounding conductor, so the four wire bus duct can be used as a five wire bus duct. In order to meet the spatial layout requirements of low-voltage distribution systems, in addition to traditional functional unit busways such as straight sections, horizontal bends, vertical bends, and T-shaped busways, we have also developed our own starting busways that are suitable for oil immersed transformers, resin insulated dry-type power transformers, distribution cabinets, etc. Based on the new development of low-voltage distribution equipment in China, we can arrange and phase change the busbars according to different user requirements.

1) The overall aluminum alloy side plate structure wraps the entire conductor inside the metal side plate, preventing the infiltration of water vapor and harmful dust, and achieving a protection level of IP54 for the entire busbar;

2) The special aluminum shell forms a non-magnetic choke coil, which can reduce the transmission of eddy currents between high current busbars, reduce the passage of harmonic currents in the main busbar, reduce the heating phenomenon caused by the above reasons, reduce the voltage drop of long-distance transmission, and significantly enhance the current carrying capacity of the busbar;

3) The aluminum side plate structure with tight touch conductors can directly transmit and emit heat from multiple surfaces such as side plates and cover plates, improving the heat dissipation ability of the busbar system and enhancing the current carrying capacity;

4) A complete grounding system is formed within the shell range, and users can choose this aluminum shell with>50% phase line capacity as the grounding conductor

The end of the busbar duct side panel must be pasted with 2 * 30 insulation double-sided tape to protect the insulation layer of the busbar from being damaged by the end of the side panel. The insulation double-sided tape should extend 5mm beyond the end of the side panel, and the length should be the same as the height of the side panel. In the middle of the side panel, one insulation tape should be pasted every 300mm, and the length should be the same as the height of the side panel.

Structural features:

1This series of enclosed busbar trunking has excellent short-circuit resistance performance. Due to the protection of the aluminum (or weak magnetic steel plate) shell, it can effectively reduce the structural heating caused by eddy currents or circulating currents, lower the temperature of the enclosed busbar shell, reduce electrical energy loss, increase current carrying capacity, and reduce electric power.

2. This series of enclosed busbar trunking structures * can have installation and maintenance holes set at the upper or lower part of the enclosed busbar. For high current indoor enclosed busbars, ventilation louvers are installed on both sides and the lower part of the shell to enhance heat dissipation and reduce temperature rise.

3. The use of double insulation and multi-point connection grounding of the shell significantly reduces maintenance workload and improves safety performance.

4. The use of corrugated pipe expansion joints is simple to install and can achieve adjustment of two degrees of freedom in both horizontal and vertical directions. It not only meets the expansion and contraction requirements caused by different temperature drops and thermal expansion and contraction, but also compensates for errors caused by foundation settlement, solving the problems of poor protection level, inconvenient installation, and unreliable operation of traditional sliding plate expansion and contraction devices

The surface treatment of the conductive enclosed busbar shell is an important task, which includes processes such as acid washing, phosphating, drying, powder coating, and curing. The shell coated with polyester epoxy powder has strong surface adhesion and can maintain insulation for a long time.

Before assembly, the holes on the busbar side and cover plate of the unit should be checked. If the holes are not matched, they should be promptly returned to the sheet metal area for drilling and deburring. Drilling operations are strictly prohibited in the busbar assembly area. If the outer shell ends of the mother row are uneven, gently tap with a wooden or rubber hammer and adjust slowly. It is strictly prohibited to use metal tools or force to strike.

Bus duct is suitable for AC three-phase four wire and three-phase five wire systems, with a frequency of 50-60Hz, rated voltage up to 690V, and rated working current of 250-5000A for power supply and distribution systems. As an auxiliary equipment for power supply and distribution equipment in industrial and mining, enterprises, and high-rise buildings, it is particularly suitable for the renovation of workshops and old enterprises.

Installation board - a board used to support various components and suitable for installation in complete sets of equipment.

Installation frame - a frame used to support various components and suitable for installation in a complete set of equipment.

Shell - A shell is a component that protects equipment from certain external factors and prevents direct access to the equipment in all directions. Its protection level is at least IP30.

Door - a hinged or sliding cover.

Cover plate refers to the upper and lower shell surfaces of the outer shell. It is a closed type busbar trunking factory and usually refers to a component on the busbar trunking equipment that is used to cover the opening on the outer shell. Fix it with screws or similar methods, and generally do not disassemble the equipment after it is put into operation.

Side panels are the left and right shell surfaces of the casing, usually referring to a component on busbar trunking equipment that is used to cover the openings on the casing. Fix it with screws or similar methods, and generally do not disassemble the equipment after it is put into operation.

Multiple protective structures are used to wrap the conductive row, such as wrapping insulation film on the upper and lower arms of the conductive row to ensure the overall insulation of the conductive row. In addition, a sealing strip is further provided between the connection side sealing plate and the connection cover plate to increase the sealing performance of the two assembled together. At the same time, the upper and lower cover plates and side plates are made of non-magnetic alloy materials, greatly reducing the electromagnetic wave radiation generated during the operation of the conductive bars. A heat sink is also added between the two conductive bars, and the surface of the conductive bars is also equipped with several heat dissipation fins to improve the heat dissipation efficiency of the conductive bars.

The main focus is on verifying the process of the product, the IP protection level of the bus duct connector, the temperature rise of the bus duct plug interface, and the stability and effectiveness of the PE wire. The product process mainly depends on the processing technology and surface treatment technology of the appearance, as well as the precision of the bus assembly. The main consideration for dense bus ducts is that the more compact the precision, the better. The IP protection level of the busbar and busbar connector is an important technical treatment process, and there are many short-circuit accidents in the busbar trunking caused by joint heating, moisture, or water ingress.