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11 KV cables.

broadgage
Until fairly recently, underground 11 KV cables were invariably 3 core, paper insulated, lead covered, with an earthed steel wire armouring. Then came the more modern plastic insulated cables, with earthed armour and a red plastic over sheath to distinguish them from LV cables.


However the modern trend seems to be a bundle a 3 single core cables, each with an aluminium core, plastic insulation, copper wire armouring and a red plastic sheath.

Why is this used ? It seems to me that 3 single core cables would be more costly to manufacture, and more labour intensive to joint or terminate, than one 3 core cable.

I fail to see the advantage, but presume that there must be some advantage, or why make the change ?
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    It is actually easier to make the single-core cables that have quite thick insulation usually of xlpe, the extrusion processes and test can easily follow one another in a straight line, whereas the paper insulated 3 cores were slow and complex to make. I am sure that the modern red ones cost less, and are probably much easier to joint or terminate. The red identification is a great advantage when faced with several cables in a trench! The insulation is also much better, the oil is no longer present to leak out and be replaced with water, so reliability is improved. They are also easier to handle on site, easier to bend around obstacles as the cables can move relative to one another.
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  • 0
    It is actually easier to make the single-core cables that have quite thick insulation usually of xlpe, the extrusion processes and test can easily follow one another in a straight line, whereas the paper insulated 3 cores were slow and complex to make. I am sure that the modern red ones cost less, and are probably much easier to joint or terminate. The red identification is a great advantage when faced with several cables in a trench! The insulation is also much better, the oil is no longer present to leak out and be replaced with water, so reliability is improved. They are also easier to handle on site, easier to bend around obstacles as the cables can move relative to one another.
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