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The scientific way of laying developed insulated power cables

Information Source:Henan Huadong Cable Co., Ltd Release date:2014-04-01

In 2011 China electric wire and cable output beyond America and become the world's largest wire and cable manufacturing country, but have to recognize, cable production capacity in China has a serious surplus. According to incomplete statistics, if China all cable companies started, can meet the demand in Asia, Oceania. In the cable production seriously processes at the same time, because the XLPE insulated power cable laying cable breakdown caused by improper operation fault cable accounted for a considerable percentage, so a comprehensive understanding, understanding of XLPE power cable laying mode of scientific imminent. This paper first introduces the three main types of terrestrial XLPE medium voltage power cable insulation installation mode.

At the present stage of our country main cable engineering design by GB 50217-2007 and DL/T 5221-2005 and other related standards, DL/T 5221-2005 requirements for minimum bending radius XLPE insulated medium voltage power cables, single core 12D, three core 10D (D= cable measured diameter), but different manufacturers of medium voltage cable bend radius for different types of slightly different. In theory, 6 and below the laying of buried, 16 and below the tunnel laying method, 21 and below the laying of pipe or cable channel. But the above data are the ideal condition, according to the product requirements are different and the true geographical and environment and should be in the construction. This paper mainly discusses the directly buried laying, pipe laying and tunnel laying three terrestrial laying mode.

2 three medium voltage XLPE power cable laying mode of land

2.1 buried
China has now been widely used laying is buried, because of directly buried installation has the advantages of low cost, simple installation procedure and obvious. Construction units in the selection of directly buried installation, must understand the nature of the product and cable suppliers, such as jacket type (whether it has anti termite, worms and other functions), bending radius of cable supplier recommended (such as whether with armored) etc.. Determine that can be buried, site investigation and verification shall be carried out in accordance with the drawings, to determine the cable to avoid high temperature area, requirements (such as the city heating system, factory and so on), poor soil or rock area (such as the debris flow prone sections etc.). In general, buried depth XLPE insulated power cables should be in the frozen soil layer, the north and South are different. Fine sand in the cable channel laying 100-120mm thickness should be before laying cables, and then with cement or concrete protective cover, suggestions cover width should be greater than the diameter of the cable 100-120mm. And then backfill, backfill with cable sheath is non corrosive, backfill process is best added a layer of color Mini warning belt. Backfill ended, suggest caution in cable connector, bend or with other lines of intersection, to prevent external damage.
XLPE insulated cables directly buried installation applies only to no or little termite, away from heat, flat terrain, traffic is not dense, no acid or chemical corrosion, no underground work areas. So the choice must be good geographical exploration of buried before. General 10kV and cable following with armoured by actual choice of directly buried laying.

2.2 pipe laying
The pipe laying is when the cable root number is big, the cable laying pipelines arranged in an orderly manner has been laid in the ground. Pipe laying requirements row tube diameter greater than or equal to 1.5 times of the cable diameter of actual, also requires laying depth in the frozen soil layer, pipe to work well direction should be greater than 0.2% of the slope, and the gap between each row of pipe should be greater than 20mm, to ensure good heat dissipation. Installation of cable, to ensure that the exhaust pipe at the entrance of the smooth, no sharp or debris inside the tube, so the cable installation by abrasion. XLPE insulated cables working temperature is 90 ℃, selection of pipe material, to select materials with better mechanical properties, thermal performance, at present the main pipe material is vinylon cement pipe, double wall corrugated pipe, flame retardant PVC-C plastic pipe, and PE pipe, hot-melt welding.
The advantages of the row pipe laying is easy to repair, and for other cable reserved space, small occupation area, cable shaft can adjust the space is big, have excellent fire performance, mechanical performance is strong, generally applicable to cross line more, highway, railway and other traffic busy areas, this is not recommended with armoured cable selected this installation methods. Pipe laying shortcomings are obvious, compared to the directly buried laying, pipe laying and installation of high cost, poor heat dissipation, easy to cause the XLPE insulated cables of long service life of smaller (usually XLPE insulated cables for the design life of 30 years, according to statistics, if the exhaust pipe laying handled improperly, will cause the XLPE cable service life reduction of 35%--40%). In addition, pipe laying and connecting head more, there Water Leakage, small animal intrusion bite problems, the high cost of repair costs.

2.3 tunnel laying
Cable tunnel laying the so-called, generally refers to accommodate 21 root and above cable place, and is equipped with detection and repair of the channel, in a fully enclosed tunnel cable. The number of the tunnel cable can change at any time, without the two groundbreaking work, anti external mechanical performance is very strong, and the detection and repair is very convenient. When laying in tunnel, we must first understand the cable voltage rank, the outer diameter of the cable and the insulating sheath material properties, and then to determine the arrangement of the distance between the cables. A lighting system, drainage system for cable tunnel, and a double ventilation mechanical ventilation and natural ventilation, reduce the humidity of the air in the tunnel, the tunnel and smoke alarm system, automatic fire extinguisher and fire hydrants, some cable tunnel is also equipped with a temperature control system, monitoring system, anti-theft system.
Tunnel cable laying although has many advantages, but the construction investment, the cost of tunnel is high, and long construction period, many construction units to give up cable tunnel laying in order to save cost and reduce the turnover cycle. At this stage, the tunnel buried in our country is not popular, but in the developed countries Japan, South Korea, tunnel laying has been widely applied. Some developed countries have adopted the three laying mode combination method, which not only saves the space also increases the stability of cable.

HUADONG Henan Huadong is a hi-tech, engineering group. We are specialized in the research,development,and production of ABC Cable,Rubber Cable, mv medium voltage power cable,Control/Instrumentation Cable,Mining Cable, Bare Conductor(AAC/AAAC/ACSR/ACS), Huadong Cable Supply the price of 16mm armoured cableat competitive.
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