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Parallel TX Tails - Neutral Arrangement

MW (aka Inrush - for those who remember me!)
So this is the new look forum... Impressive!


I have a question regarding AWA transformer tails. I'm looking at a situation where I need three parallel cables per phase.


My question is related to the neutral conductor arrangement. The neutrals need to be installed between the inter-group trefoils in order to maintain equal current sharing. Therefore, I can either have two neutral conductors of slightly larger CSA to give approx. the same CSA as the overall parallel phase conductors. Or, alternatively, three neutrals of the same CSA as the phase conductors split (oddly) between the two groups.


What convention is normally adopted in this situation?


Many thanks in advance.
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  • Former Community Member
    0 Former Community Member
    If you use quadrafoil, then each neutral is with the group of 3 phases - so a block of 4 cables (2 x 2) - spaced by whatever you need to suit your grouping assessment (ideally bang tight together, and accept the current derating factors))


    You can put two neutrals between the groups if you insist on using trefoil - or you can go for two tiers of 6 cables in flat formation.


    Basically, whatever you choose for the physical lay up will have less or more implication on the current sharing and thus the cable sizing.


    I would try to avoid the outer neural scenario in favour of 2 together between group 1 and 2 and one neutral between group 2 and 3


    You could also examine why you want 3 parallel conductors rather than 2 or 4 for example - assuming 3 is the best fit, then again I would suggest quadrafoil arrangements


    Regards


    OMS
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  • Former Community Member
    0 Former Community Member
    If you use quadrafoil, then each neutral is with the group of 3 phases - so a block of 4 cables (2 x 2) - spaced by whatever you need to suit your grouping assessment (ideally bang tight together, and accept the current derating factors))


    You can put two neutrals between the groups if you insist on using trefoil - or you can go for two tiers of 6 cables in flat formation.


    Basically, whatever you choose for the physical lay up will have less or more implication on the current sharing and thus the cable sizing.


    I would try to avoid the outer neural scenario in favour of 2 together between group 1 and 2 and one neutral between group 2 and 3


    You could also examine why you want 3 parallel conductors rather than 2 or 4 for example - assuming 3 is the best fit, then again I would suggest quadrafoil arrangements


    Regards


    OMS
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