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Line Supports

3.3. Line Supports

Electrical power may be transmitted by overhead or underground conductors. Underground transmission, with the exception of a few notable cases, is limited to voltage less than 45 kV.

The supports for the overhead transmission lines may be of anyone of the following classes:

  1. Poles
  2. Towers
  3. Poles. Poles may be made of materials like wood, steel, cement concrete etc. Usually R.C.C. poles are used. Figs. 10 and 11 show the wooden poles and R.C.C. poles respectively. 2

    Fig. 10. Wooden poles: (a)400 V, 4-phase, 4-wire distributor, (b) 11 kV, 3-phase feeder, (c) ‘A’ pole, double circuit, 33 kV feeder, (d) ‘R’ pole double circuit 33 kV feeder.3

    Fig. 11. R.C.C. pole.

    1. Towers. Towers made of steel are mechanically sturdy and durable and are commonly used. These towers (steel) have been shown in Fig. 12 and Fig. 13. These towers are generally-four legged, each leg anchored properly.

    The line supports discussed above should have the following characteristics:

    (i)                           High, mechanical strength.

    (ii)                        Cheap in cost.

    (iii)                      Light in weight.

    (iv)                      Longer life.

    (v)                         Good looking.

    (vi)                      Easy accessible for painting and erection of line conductors.

    (vii)                    Low maintenance-cost. 4

    Fig. 12 5

    Fig. 13