With the development of The Times, some things displayed on the ground sometimes affect the beauty of the city, so we can catch the underground, 

and in terms of transport, we have the MTR located underground and underground drainage channels. Many of our cables are now also placed 

underground, here for you to reveal the advantages of wire and cable placed underground.

1, can enhance the transmission capacity of urban lines

Usually, the overhead line transmission in one direction is mostly two poles and towers, and there are only 2 to 4 circuit overhead transmission lines. 

The cable line buried in the ground can reach 20 circuits. In addition, underground ultra-high voltage cables generally have more efficient copper 

conductors, so that it can efficiently transmit electricity to the end user, greatly reducing the loss of power transmission.

2. It can improve the utilization value of urban land

Land is a kind of resource with high value but relatively scarce, especially in the central area of modern cities, because the space safety distance 

requirement of overhead lines is higher than that of underground pipelines, and the use of adjacent land is more restricted, thus greatly reducing 

the use value of land, and changing to underground wire and cable lines can improve the use value of land.

First, wire and cable engineering can be divided into several projects?

1, laying engineering: including laying, middle head production, lift cover, buried pipe, school tide, traction head production, etc.

2, site transportation: including engineering materials from the warehouse to the construction site loading and unloading, transportation and

 empty car return.

3, both ends of the project: including support, suspension bridge and its foundation production and installation, terminal head production, oil

 pressure and signal device installation, electrical performance testing.

4, local engineering: including road excavation, tunnel, trench construction, etc.

Second, wire and cable in the transportation and loading process should pay attention to what?

1. Before transporting or rolling the cable tray, it must be ensured that the cable tray is firm, the oil pipe between the cable wound and the oil-filled 

cable and the pressure tank should be fixed and not damaged, the pressure tank should be firm, and the pressure indication should meet the

 requirements.

2, in the process of transportation loading and unloading, should not make the cable and cable tray damaged, it is strictly prohibited to push the cable

 tray directly from the car, the cable should not be flat transport, flat storage.

Third, which aspects should be considered in choosing the cross-section of power cables?

1, the voltage drop on the line can not exceed the allowable working range.

2, the long-term allowable working current of the cable;

3, once the short circuit thermal stability; Wire and cable are generally living in the outdoors, experiencing the wind and sun every day, a long time will

 occur aging, insulation damage, insulation aging, a long time, it will strike, affecting its normal action. Today's wire and cable manufacturers for you to

 analyze the reasons for cable aging.

1) Insulation damp. This condition is also very common, and individual episodes occur at the wire and cable joints in the directly buried or row pipes. 

For example, the joint manufacturing failure of the wire and cable factory and the joint in wet meteorological conditions will make the joint water or 

mixed with water vapor, and the water branches will be formed under the action of the electric field for a long time, which will gradually damage the 

insulation strength of the cable and form a fault.

2) Chemical erosion. Wire and cable directly buried in the area of acid and alkali action, often the wire and cable armor, lead or outer protective layer

 is eroded, the cover layer due to long-term chemical erosion or electrolytic erosion, resulting in the cover layer effective, insulation decline, will also

 lead to cable failure.

3) Long-term overload operation. Overload operation, because of the thermal effect of the current, the load current must cause the conductor to 

heat when it passes through the cable, and the skin effect of the charge and the eddy current loss of steel armor and the loss of the insulating medium 

will also produce additional heat, thus reducing the temperature of the wire and cable.

Life is inseparable from electricity, let alone the wire and cable that transmits electricity, and the quality of the cable seriously affects its safety. So today 

analysis of wire and cable heating reasons.

1, the joint manufacturing technology is not good, the crimping is not tight, resulting in the contact resistance at the joint is too large, and it will also

 cause the cable to produce heat.

2, the selection of wire and cable is improper, resulting in the use of cable conductor cross-section is too small, the operation of overload phenomenon,

 after a long time of use, the cable heating and heat dissipation imbalance caused by heating phenomenon.

3, armored wire and cable local sheath damage, water caused slow damage to the insulation performance, resulting in gradual reduction of insulation

 resistance, will also cause heat phenomenon during cable operation.

4, the resistance of the wire and cable conductor does not meet the requirements, causing the cable to generate heat during operation.

5, wire and cable insulation performance is not good, resulting in small insulation resistance, the operation will also produce heat phenomenon.

6, the wire and cable installation arrangement is too dense, the ventilation and heat dissipation effect is not good, or the cable is too close to other heat 

sources, affecting the normal heat dissipation of the cable, and may also cause the cable to generate heat during operation.