Cable Laying Specific Requirements

1. Cable Laying Methods Currently Used Can Be Divided Into Several Categories. Which Categories Are These?

Answer:

1. Manual laying– involves the use of manual tactics, under the coordinated command of one or more people, following the wire and cable laying provisions
2. Mechanisedlaying – involves the use of rollers, tractors, and conveyors, among others. Such machines are controlled by a synchronized power supply, which makes the entire process safer.
3. Manual and mechanical combination- In certain instances, there is a need to combine manual and mechanized wire and cable laying methods. This often occurs when dealing with lots of cable turns and construction difficulties.

2. What Requirements Should Secondary Control Circuit Wiring Meet?

Answer:

1. Correct wiring according to the construction diagram.
2. The electrical connection of the wire should be solid and reliable.
3. The wire in the tray cabinet should not have joints, and the wire core should be free of damage.
4. The end of the cable core should be marked with its circuit number, the number should be correct, and the handwriting must be clear and not easy to lose colour.
5. The wiring should be neat, clean, and beautiful, and the wire and cable insulation should be excellent and undamaged.
6. Each terminal block should be wired on each side for one and not more than two at most.

3. What Are The Requirements For Cable Ducting?

Answer:

1. The ducting pipe should be about 0.2m from the ground, under the pavement for 0.5m, the general area for 0.7m.
2. The pit should be installed at the change direction and branches of the drainage pipe, and a recess should be added when the length exceeds 30mm.
3. Pit depth should not be less than 0.8m with a utility hole diameter of not less than 0.7mm.
4. The drainage pipe should tend to pit 0.5% ~ 1% of the drainage slope.

4. What Are The Requirements For The Resistance Of The Cable Conductor Connection Point?

Answer:  The resistance of the connection point has to be small and stable and should be of the same length. Also, for a newly installed terminal and intermediate head, the cross-section conductor ratio should not exceed   1. For an operating terminal and intermediate head, the balance should not exceed 1.2.

5. What Requirements Should The Design Of Cable Joints And Intermediate Heads Meet?

Answer: The design of wire and cable joints and intermediate heads should meet the following requirements;

1. High-pressure strength and good conductor connection
2. High mechanical strength and low media loss
3. Simple structure, strong sealing

6. What Is A Cable Fault? How Many Common Types Are There?

Answer:  A Cable fault is an error that occurs when the insulation of the cable breaks down during preventive testing or in operation, forcing the cable line to blackout due to insulation breakdown, wires burnout, to name a few. Standard wire and cable faults include ground fault, short-circuit fault, fragmented wire fault, flashover fault, and hybrid fault.

7. How To Deal With Single-Phase Ground Fault Of The Cable Line?

Answer: Generally, a single-phase cable line ground fault involves local damage of the cable conductor. If mechanical damage occurs on the cable line and the error is near dry soil, all you’ll need is some local repair. Essentially, you have to add some insulation to the wire and cable fault point to strengthen the seal.

8. What Tests And Checks Should Be Carried Out Before Laying Power Cables?

Answer: Before laying the power cable, you should check whether the cable type, specification, and length meet all the requirements. Secondly, you should check whether there is any external damage to the cable. It would be best if you also considered the resistance of the wire and cable in relation to its intended use. Low-voltage cables with 1000V have a resistance value that is generally not less than 10MΩ. High-voltage wires with 2500V have a resistance value that is usually not less than 400MΩ.

9. What Should One Pay Attention To When Laying Cables In The Main Plant?

Answer: Generally, one should pay attention to the following details when laying cables in the main plant;

1. The control cable leading to the control room should be laid overhead
2. Medium voltage cable should be applied in tunnels or rows of pipes or overhead at a high water table
3. A 380V should be tunneled, placed in a secure ditch or a row of tubes, with one end of the equipment on the top and the other end at the bottom. Also, the wire and cable can be partially laid overhead when the water table is high

10. What Materials Are Used In The Inner And Outer Shielding Layers Of A Power Cable? What Role Do They Play?

Answer: Generally, inner and outer shielding layers of power cables are either made of braided strands of copper or, in certain instances, a non-braided spiral winding of copper tape or a layer of conducting polymer. Wire and cable shielding play a role in mitigating electrical noise and minimizes electromagnetic radiation.