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Anonymous users2024-02-15The cable is armored with steel wire or copper wire, which can withstand a certain tensile force, about 70N mm2 (copper);
According to the verticality of the cable and the height of the drop, the tensile weight of the cable can be calculated, and then the total area of (steel) copper wire, the number of monofilaments and the cross-section of monofilament are selected.
Considering the circulation loss of the cable armor layer, the single-core cable should be armored with copper wire, and the three-core or multi-core cable can be armored with steel wire.
Because the vertical laying of high drop cables requires fixing and bracket fixing, it is generally stipulated that the plane or low drop is fixed once every 6 meters, and the vertical laying should be fixed twice per meter;
If the weight of the cable is too large, and the fixing and installation are subjected to excessive side pressure, double armor should also be considered, such as adding steel tape or wrinkled aluminum (lead) sleeve to strengthen the side pressure of the cable.
Therefore, from the design and manufacture of cables to the installation and laying, it does not include the increase in the cost of installation man-hours.
All the costs of engineering are increasing.
Now the oil bed paper insulated cable has been basically eliminated, the manufacturing and installation requirements are too high, especially the requirements for moisture and humidity in the air are greater, and the installation and laying is also inconvenient, especially the cutting and modification project, the cable can not be reused, and has been replaced by high polyhydrocarbon insulation; Now only a few manufacturers can also repair oil bed paper insulated cables, but they are no longer manufactured, and the State Grid uses XLPE and PVC insulated power cables.
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Anonymous users2024-02-14The cable has to withstand the tensile force, and if it is an oil-immersed cable, the flow of oil should also be considered.
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Anonymous users2024-02-13Now there are also oil-immersed cables, mainly because the cable must have enough tensile capacity.
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Anonymous users2024-02-121. Before laying the cable, check whether the model, insulation and appearance of the cable are correct and intact according to the design requirements. For the use of direct burial and underwater laying, it should be laid only after passing the DC withstand voltage test.
2. The single-core cables used in the three-phase system should be arranged in a tight triangle to reduce losses. Tie tightly with a strap every 1 to avoid loosening.
3. In the three-phase four-wire system.
In the system, it is not allowed to use the three-core cable with a single core cable or wire, or even directly use the metal sheath of the three-core cable as a neutral wire.
Otherwise, when the three-phase current is unbalanced, it is equivalent to the operation of a single-core cable, and it is easy to cause power frequency interference. on armored cables.
, to heat up the armor.
and even lead to thermal breakdown of insulation.
4. The type and length of the power cable running in parallel should be the same, so as to avoid uneven distribution of current carrying capacity due to the different DC resistance of the conductive wire core.
5. In transportation, installation or operation, the cable should be strictly prevented from spraining and excessive bending, and the minimum allowable bending radius of the cable should be prevented.
Relevant technical requirements should be met.
6. In the presence of serious chemical or electrochemical corrosion.
area, the cable directly buried in the potato should be made of jute.
In addition to the armored cable or plastic cable with the outer coat, anti-corrosion measures should also be taken.
7. Oil-impregnated paper insulated power cables.
The height difference of the road should not exceed 20m. Otherwise, non-trickle cables or plastic cables should be used.
8. Within 24 hours before laying the cable, if the average temperature of the cable storage place and the laying site is lower than the allowable value, it is not suitable for construction. If construction is necessary due to special circumstances, the cable should be heated in advance, so that the cable can be kept above 5 at the temperature of the core and sheath from the beginning of construction to the completion of laying, otherwise it needs to be heated twice.
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