Transposing 11kV Cables

[h0001244]

My project involves 11kV cable replacement works
I found that existing cable adopts transposition of cables
that means one end it is arranged in a,b,c and other end, it's arranged in c,a,b something like that. Why we need transposing the cable in middle of the circuit?

 

[Marmite]

All it means is there is a straight joint (splice) somewhere along the route of the cable where the cores are not jointed number-number (or colour-colour). So long as your new cable is connected to maintain the existing phase relationships between ends then this is not an issue. If you need to cross cores to achieve this it is better to do the cross in a straight joint rather than a cable box.
Regards
Marmite

 

[h0001244]

I don't mean the number-number or colour-colour. But they intentionally swap the cables in the middle of the route like below


a------\ /-----c
b------\/------a
c------/-------b

 

[ScottyUK]

Possibly a deliberate act to normalise the per-phase impedances. Not normally needed if the cores are in trefoil, but needed on a long run if the cables are in flat formation.


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If we learn from our mistakes I'm getting a great education!

 

[h0001244]

The cables are laid in flat formation with 3 single core cables....for normally 200M to 500M........not so long