The cable tray is divided into a trough type, a tray type, a ladder type, a net format and the like, and is composed of a bracket, a support arm and a mounting attachment. It can be erected independently or attached to various building (structure) and pipe rack brackets. It features simple structure, beautiful appearance, flexible configuration and convenient maintenance. All parts need to be galvanized and installed in buildings. If the bridge is outside the open sea or belongs to the corroded area, the material must have the characteristics of anti-corrosion, moisture resistance, good adhesion and high impact strength.
The main components of the cable tray:
The support for the cable tray installation is done by the column and the support arm. The column is the main component that supports the cable tray; the load of the bridge is transmitted to the column through the carrier arm. Therefore, the column and the arm are the two main components of the cable tray installation.
Overview of the bridge
Cable trays are divided into trough, tray and ladder type, net format and Other structures, consisting of brackets, brackets and mounting accessories (see Figure 1). When selecting the type, pay attention to whether all the components of the bridge meet the requirements of serialization, generalization and standardization. The bridges in the building can be erected independently or attached to various building (construction) structures and pipe rack supports. The structure should be simple, beautiful in appearance, flexible in configuration and convenient in maintenance. All parts need to be galvanized. If the bridge is installed in the open air outside the building, if it is adjacent to the sea or belongs to the corroded area, the material must have the characteristics of anti-corrosion, moisture resistance, good adhesion and high impact strength. The bridge industry is constantly reorganized and optimized, making the enterprise bridge stand out. The surface technology includes cold galvanizing, hot-dip galvanizing, electrostatic spraying, anti-fire coating materials, baking varnish and so on. The products are widely used in petrochemical, metallurgy, electric power, school communication, high-rise buildings and other fields. They are characterized by beautiful appearance, strong corrosion resistance, wide versatility, flexible installation and complete varieties. In the "quality first, reputation is the key, management-oriented, service-oriented" purpose. In order to reduce the weight, aluminum alloy cable and glass steel bridge can also be used. The outer dimensions and load characteristics are similar to those of the steel bridge. Due to the different specific gravity of aluminum and steel (Al2.7, Fe7.86, the ratio of aluminum to steel by weight) About 1:3, according to the market price of the two materials, the cost of the aluminum alloy bridge is 2.0 times higher than that of the similar galvanized steel bridge. The aluminum alloy bridge has the advantages of beautiful appearance, light weight and convenient installation. Alloy bridges have been used in some projects.
Bridge selection
1.1 In engineering design, the layout of the bridge should be comprehensively compared according to economic rationality, technical feasibility, operational safety and other factors to determine the best solution, but also fully meet the requirements of construction, installation, maintenance and repair and cable laying.
1.2 When the bridge is laid horizontally, the height from the ground is generally not less than 2.5m. When it is laid vertically, the part below 1.8m from the ground should be protected by a metal cover, except when it is laid in an electrical special room. The cable tray should be laid horizontally on the equipment interlayer or the horse track and below 2.5m. Protective grounding measures should be taken.
1.3 Bridges, trunkings and their supports shall be used in corrosive environments and shall be constructed of corrosion-resistant rigid materials. Or take anti-corrosion treatment, anti-corrosion treatment should meet the requirements of engineering environment and durability. For places where corrosion resistance is required or where cleaning is required, aluminum alloy cable trays should be used.
1.4 In the section with fire protection requirements, the bridge can be added with a refractory or flame retardant board in the cable ladder and the tray. The net and other materials form a closed or semi-enclosed structure, and are adopted in the bridge and its support. Measures such as applying a fireproof coating on the surface of the frame. Its overall fire resistance should meet the requirements of relevant national standards or standards. In places where engineering fire protection requirements are high. It is not advisable to use aluminum alloy cable trays.
1.5 Cable lines that need to shield electromagnetic interference. Or protective external shadows such as outdoor sunshine, oil, corrosive liquids, flammable dust and other environmental requirements. A non-porous tray cable tray should be used.
1.6 In places where dust is easy to accumulate, the cable tray should be covered with a cover; cross the road section in public access or outdoor. A pad or a non-porous tray should be used on the bottom bridge.
1.7 Cables of different voltages and different purposes should not be laid in the same layer of cable tray:
(1) Cables above 1kV and below 1kV: (2) Double-circuit cables that supply the same path to the primary load; (3) Cables for emergency lighting and other lighting: (4) Power, control and telecommunications cables. If different grades of cables are laid on the same cable tray, spacer isolation should be added in the middle.
1.8 When the length of the steel straight section exceeds 30m, the aluminum alloy cable tray exceeds 15m. Or when the cable tray passes through the expansion and contraction (sedimentation) of the building, there should be an O-30mm compensation margin. The connection should be a telescopic connecting plate.
1.9 Cable ladder, tray width and height should be selected in accordance with the filling rate requirements. The filling rate of the cable in the ladder frame and the tray is generally 40-50 for the power cable and 50-70 for the control cable. And should reserve the l0-25 project development margin.
1.10 When selecting the load level of the cable tray, the uniform load of the cable tray should not be greater than the rated uniform load of the selected cable tray load level, if the actual span of the support of the cable tray is not equal to 2m. The uniform load of the work shall be satisfied: qG working uniform load, kN/m; qE rated uniform load, kN/m; LG actual span, m.
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