Tray type cable tray is widely used in petroleum, chemical, electric power, light industry, television, telecommunication and other aspects. It has the advantages of light weight, large load, beautiful appearance, simple structure and convenient installation. It is suitable for the installation of power cables.
Aluminum alloy bridge is generally used in places with high requirements on corrosion resistance and cleanliness, but it is not suitable to use aluminum alloy bridge when fire rating is high. In some drawings, the bridge load grade and anticorrosive coating type are not specified in words, and the model is adopted.
For various bus ducts, the section of bus duct shall be selected according to the large long-term working current. Check the short-time thermal stability and dynamic stability of bus duct under the condition of large short-circuit current. Due to the influence of conductor resistance and AC current meter effect when multiple conductors are close, bus duct will cause heating when passing current. The allowable heating temperature of copper and aluminum bare bus duct during long-term operation is 70 ℃, but when the contact surface has reliable coverage of tin (such as ultrasonic tin lining, etc.), the allowable temperature will be increased to 85 ℃. Limited by the allowable temperature of continuous heating, the bus duct of different materials and sections gives the corresponding long-term allowable current value. When selecting the bus duct section, the actual large long-term working current of the bus duct (taking into account the over negative load of more than half an hour) shall be less than the long-term allowable current value of the bus duct of the selected section.
The cable tray is relatively large, and the floors and distribution rooms of general buildings are used more, and the trunking is relatively small; the bending radius of the bridge is relatively large, and most of the trunking turns at right angles; the span of the bridge is relatively large, and the trunking is relatively small; and the fixing and installation methods are different. In some places, the cable tray is not covered, and almost all trunks are sealed with covers.