1) The width and height of the composite epoxy resin cable tray shall be selected according to the following table, and shall meet the requirements that the true charge rate of the cable shall not exceed the specified value of the relevant standards and specifications. The power cable may take 40-50%, the control cable may take 50-70%, and 10-25% of the process development margin shall be reserved.
2) The specifications of various bends and accessories should comply with the engineering layout conditions and be matched with the bridge.
3) The selection of support and hanger specifications should be based on conditions such as cable tray specifications, number of layers, and span. And it should meet the requirements of the load.
(3) Configuration of supports and hangers of cable tray
1) The short span of indoor support and suspension is generally 1.5-3m; The span of outdoor columns is generally 6 meters.
2) The configuration of supports and hangers for non linear sections follows the following principles: when the bridge width is less than 300mm, a support or hanger should be set on the side of the straight section 300-600m away from the junction of the non linear section and the straight line; When the width of the bridge is greater than 300mm, in addition to meeting the following conditions, a support and hanger should also be added in the middle of the non linear section.
3) The center distance between layers of pultruded glass fiber reinforced plastic cable tray is 200250300350mm.
4) 20-30mm expansion joint (metal bridge) shall be reserved every 50m in the straight section of the bridge.
(4) Some calculation formulas for cable trays
The cable tray is stamped with thin steel plate. Its carrying capacity has a certain limit. The load capacity of cable tray is a quantity related to the bridge specification and support distance. Correspondingly to the same support distance and bending deformation, the bridge with larger side height has higher bearing capacity, while the bridge with smaller height has lower bearing capacity. In addition, when the load capacity is the same, for the cable tray of the same specification, the bending deformation of the cable tray with smaller support distance is smaller than that with larger support distance. Generally, a group of support frames shall be installed every 1.5~2.0m for cable tray.