How to do the inspection work before installing the bus duct

How to do the inspection work before installing the bus duct

How to do the pre installation inspection work? Bus duct manufacturers for low-voltage transmission line wires, cables, cables, branch dense bus ducts, conductive rods, puncture cables, etc. Bus duct manufacturers have different heat dissipation performance and current carrying capacity per square millimeter due to different products. The same product, the same specification of wire, passing the same current, will also affect the heat dissipation performance when the temperature rises;

Due to different cross-sectional areas in the design, the temperature rise also varies. Of course, when the temperature rises and the resistance value increases, the pressure increases, and the energy loss also increases. When using, the inner diameter of the heat shrinkable sleeve of the bus duct accessory should be as close as possible to the outer diameter of the cable, so that the sleeve can be tightly attached to the outside of the cable after shrinking and shaping. The length of the heat shrinkable sleeve for busbar trunking accessories should be sufficient to protect the exposed parts of the lead sleeve and cable sheath, and should overlap at least 100mm with the plastic outer sheath of the cable.

Before the heat shrink sealing construction, the entire electrical system joint (the part to be sealed) should be wiped clean with clean cotton yarn, and then the attached sleeve and welding point should be wrapped with plastic tape to make the slope from the attached sleeve to the cable aluminum sheath gentle, and to prevent gaps from occurring when the heat shrink sleeve of the busbar duct accessory shrinks at this location. It is important to wrap the plastic tape around Re board 1/2, wrap tightly without wrinkles, and the surface after wrapping should be smooth.

The dense bus duct is the same, therefore, the calculation of the conductivity of the dense bus duct conductor based on the flow rate per square millimeter is incorrect. The bus duct manufacturer's structural design, heat dissipation, but different impedance, inductance, and other factors are closely related to the current carrying capacity. Therefore, the GB7251-2006 national standard stipulates that the rated current of the plug-in bus duct should limit the temperature rise to determine the current carrying capacity of the reinforced bus duct.

Structural features:

1. This 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 force.

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.

(1) Conductive copper bars - composed of pure copper bars, the surface of the conductive copper bar joints should be uniformly plated with tin or silver.

(2) Insulation material - composed of high-strength insulating plastic blocks made of polytetrafluoroethylene and polycarbonate.

(3) Fixed bolts, insulation sleeves, and cover plates, as shown in Figure 1.

This series of bus duct structures * can have installation and maintenance holes set at the upper or lower part of the bus duct. For high current indoor bus ducts, ventilation louvers are installed at the two sides and lower part of the housing To enhance heat dissipation and reduce temperature rise.Bus ducts have increasingly replaced wires and cables in indoor low-voltage power transmission mainline projects.

(1) Conductive copper bars - composed of pure copper bars, the surface of the conductive copper bar joints should be uniformly plated with tin or silver.

(2) Insulation material - composed of high-strength insulating plastic blocks made of polytetrafluoroethylene and polycarbonate.

(3) Fixed bolts, insulation sleeves, and cover plates, as shown in Figure 1.

construction technology

Equipment unboxing and inventory inspection: The unboxing and inventory inspection of equipment should be jointly conducted by representatives of the construction unit, the supervision unit, the supplier, and the construction unit, and recorded. The segmented markings of the bus duct are clear and complete, with no damage or deformation on the exterior and no damage on the interior. The bolted joint section of the bus duct should be flat, and its silver plating should be free of pitting, peeling, and uncovered parts. The insulation resistance should meet the design requirements. According to the busbar trunking arrangement diagram and packing list. Check the specifications of the enclosed plug-in bus duct, incoming box, plug-in switch box and accessories, and ensure that the quantity of the Anning enclosed bus duct meets the requirements.

1. It itself adopts a "sandwich" sealing structure, and generally speaking, its protection level can reach IP54.

2. The entire busbar system itself can withstand a power frequency withstand voltage of 3750V, and even after 1 minute of use, there will be no breakdown or flashover phenomenon.

3. When operating at rated current for a long time, the temperature rise of the busbar system generally does not exceed 60K for the connecting terminals, 30K for the metal casing, and 40K for the insulation surface inside the slot.

4. After a fire occurs, even if the combustion temperature of the fire-resistant busbar rises to 960 ℃, it can still maintain normal operation.

People who hold this view believe that if water enters the bus duct, the entire bus duct will experience a power outage due to a short circuit at the water inlet point Indeed, the waterproof performance of ordinary bus ducts is very poor, and it cannot be compared with cables. Cables laid outdoors or even in water will not short-circuit. The protection level of the shell of ordinary bus ducts is IP40, which is only suitable for indoor ordinary places

The bus duct is designed with various functional connection units to meet the needs of all power transmission and distribution projects

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 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 enormous amount of electrical energy passing through the busbar during operation, it experiences 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.

The application advantage of busbar trunking 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.

Next is the installation of supports and hangers. Any enclosed or plug-in busbar supports and hangers should be installed accurately, horizontally and vertically, and securely fixed. When installed in rows, they should be arranged neatly and spaced evenly. The fixed bracket bolts should be fixed with flat washers and spring washers, with 2-4 exposed threads.
① The fixing of expansion bolts for brackets should be based on the accurate measurement of the bracket position according to the direction of the busbar path when installing brackets on buildings. The expansion bolts for brackets should be fixed on the drilled holes. It should be noted that the difference between the diameter of the drill hole and the outer diameter of the casing should not exceed 1mm.
② Installation of T-shaped angle steel bracket, which is suitable for horizontal installation of busbars on walls. The bracket is embedded in the wall by pre embedding method. The buried depth of the angle steel bracket is 120mm and 150mm, and the exposed length of the angle steel is the width of the busbar plus 140mm when the busbar is installed vertically. When the busbar is installed horizontally on the side, it is the height of the busbar plus 160mm

The bus duct is designed with various functional connection units to meet the needs of all power transmission and distribution projects.

Emergency response methods for bus duct faults

1. Reduced insulation strength: Generally, it is due to the high humidity of the working environment at the location of the bus duct, the specification of the low-voltage enclosed bus, which causes moisture to enter the bus duct, or condensation caused by the large temperature difference between day and night The handling method is very simple. Remove moisture from the bus duct, seal the bus duct, and run it under no-load for a short period of time to monotonically control the inside of the bus duct.

2. The bus duct has melted a bit: firstly, due to long-term overload operation; secondly, due to contact issues with the plug-in box; thirdly, due to insulation damage between phases, the bus duct only needs to be replaced.

3. Insulation breakdown: One is the short circuit caused by water ingress inside the bus duct, which requires monotonic treatment of the bus duct; Secondly, if foreign objects enter the bus duct and cause a short circuit, they can be inspected and cleaned;; Thirdly, if the insulation medium is damaged, replace the relevant sections.

4. There may be some heating phenomenon: poor contact at the connection part, usually due to loose connectors. You can check and tighten the connectors; Another factor is excessive load, which can be reduced.

5. Heating of the plug-in box: One factor is that the plug-in is not reliable. Check and plug it from the beginning to ensure contact; Another factor is overload, which can be reduced or replaced with a high-capacity plug-in box

The bus duct is designed with various functional connection units to meet the needs of all power transmission and distribution projects

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.