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Why are bare, non-insulated wires still the norm for electric transmission lines? Posted by : admin / Posted on : Jul 08, 2021

There is no need to insulate the wires.

They are carried from pylon to pylon at a height sufficient that they will not come in contact with any ground structure; and suspended from insulator strings to keep them away from the pylons. The cables are constructed from a stranded steel core which takes the strain, surrounded by a large number of aluminium strands which form the electrical conductor. Joining conductors is a straightforward crimping operation, using hydraulic compression tools.

If you wanted to use insulated conductors, then the thickness of insulation for transmission line voltages could be several inches, depending on the actual voltage. A single phase from a 230kv system, fully insulated before being laid in a concrete cable trench, is about 6 inches diameter, most of this insulation around a 1 inch diameter conductor.china transmission line stringing tools manufactures

Besides being heavy it is VERY expensive. Apart from the greatly increased cost of the cable, the pylons would also need to be much stronger in order to carry the weight. Joining two cables is a highly specialised job which could take a full day or longer PER PHASE.

 

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