Underground Power Cable Construction

Underground Power Cable Construction

Copyright: © 2016 |Pages: 34
DOI: 10.4018/978-1-4666-6509-5.ch001
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Abstract

This chapter deals with many special features of underground power cables. Important points are presented in this chapter. In this chapter the various components of the different underground cables used in transmission and distribution of electric energy are explained. The materials used in the manufacture of these cables are given in details. This chapter also contains the different types of cable joints and terminations.
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1.1 Cables Advantages And Drawbacks

1.1.1 Cables Advantages

Underground power cables are widely used in transmission and distribution of electrical power, the following are the advantages of underground power cables compared with the overhead transmission lines feeders:

  • 1.

    They need less space compared to overhead transmission lines (Underground cables need a narrower surrounding strip of about 1–10 meters to install (up to 30 meters for 400 kV cables during construction), whereas an overhead line requires a surrounding strip of about 20–200 meters wide to be kept permanently clear for safety, maintenance and repair).

  • 2.

    No visual pollution compared with transmission lines in which its insulators exposed to different types of pollution.

  • 3.

    Less subject to damage from atmospheric activity like wind and lightning as overhead transmission lines.

  • 4.

    Higher surge impedance reduces severity of switching, lightning and resonance over voltages.

  • 5.

    Ideal way to transmit power supply to an island.

1.1.2 Cable-Drawbacks

In spite of the underground cables have many advantages, they have also some drawback. The following are the cables drawbacks:

  • 1.

    Fault location of underground power cables is difficult and time taking.

  • 2.

    Underground cables are expensive compared with overhead transmission line feeders (the cost of underground cables is two to four times the cost of an overhead power line at the same voltage level).

  • 3.

    More monitoring, for certain types of cables, is required.

  • 4.

    Jointing/termination require persons with high skill levels.

  • 5.

    Joints/terminations are weak points because the joints and terminations need thicker insulation to reach to the same insulation level of the cable, also the joints are mechanically weak.

  • 6.

    Testing of underground power cables is difficult and time-consuming.

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