Hardware knowledge: cable tray and accessories selection

When the cable network needs to be shielded from electrical interference or is protected from external influences (such as: corrosive liquid, flammable dust, etc.), the trough-type composite anti-corrosion shielded cable tray (with cover) should be used

2. (F) type composite epoxy resin anticorrosive and flame retardant cable trays, support arms, and brackets should be used in strong corrosive environments to increase the service life of cable trays and accessories. Cable trays are easy to accumulate dust And other environments or outdoor places that need to be covered should be covered.

3. In addition to the above, tray type, trough type, step type, glass anticorrosive and flame retardant cable tray or steel ordinary type cable tray can be selected according to the on-site environment and technical requirements. Covers should be added in environments where dust is easy to accumulate and other needs to be covered or outdoor places.

4. In public passages or outdoor sections of roads, pads should be added to the bottom of the bottom steps or pallets should be used in this section. When large spans span public passages, the load capacity of the bridge frame can be increased or the line frame can be selected according to user requirements.

5. For large spans (>3m), a composite bridge should be used.

6. The composite epoxy tree finger bridge should be selected for outdoor use.

Two, specification selection

1. The width and height of the bridge frame should be selected according to the following table, and the cable filling rate should not exceed the specified value of the relevant standard specifications. The power cable can be 40-50%, and the control cable can be 50-70%. Leave 10-25% of the formula development margin.

2. The specifications of various bends and accessories should meet the project layout conditions and be matched with the bridge frame.

3. The selection of support and hanger specifications should be configured according to the specifications of the bridge, the number of layers, and the span. And should meet the load requirements.

4. For the selection of the cross-sectional area of u200bu200bthe bridge, see the table for the rated current value or setting value of the maximum automatic over-current protection of any line in the cable network on the bridge (A) The minimum allowable cross-section of the bridge (mm2) 0-6012961 -100258101-200452201-400645401-600968

Three, the configuration of support and hanger

1. The short span of indoor support and hoisting is generally 1.5-3m. The middle span of the outdoor column is generally 6m.

2. The configuration of supports and hangers for non-straight sections follows the following principles. When the bridge width is less than 300mm, a support and hanger should be installed on the side of the straight section 300-600mm away from the junction of the non-linear section and the straight line. When the bridge width>300mm, in addition to meeting the following conditions, a support and hanger should be added in the middle of the non-linear section.

3. When the bridge is set up in multiple layers, the center distance between layers is 200, 250, 300, 350mm.

4. Expansion joints of 20-30mm (metal bridge) should be left every 50m in the straight section of the bridge.

Four. Fire protection requirements The section of the bridge frame must be made of steel or non-combustible and flame-retardant materials. The XQJ series of cable trays produced by Hongtu cable tray factory have fire-resistant tray series.

Five, grounding

1. The bridge system should have a reliable electrical connection and be grounded (only for metal bridges).

2. The following requirements shall be met when the bridge system is allowed to form a grounding trunk circuit.

The connection resistance between the ends of the bridge should not be greater than 0.00033 ohm, and the grounding hole should be clear of insulating coating. In the 1KV and below neutral point directly grounded system, the ground of the powered equipment is connected to the neutral ground of the system. When the power supply is automatically cut off, the cross-sectional area of u200bu200bthe metal in the longitudinal direction of the bridge should not be less than the specified value.

3. When another grounding trunk line is laid along the entire length of the bridge, each section (including the non-straight section) of the bridge should be reliably connected to the grounding trunk at least one point.

4. For vibration places, a spring coil should be installed at the connection of the grounding part