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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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    My first post was started before  OMS put his in, but if you want N the same size area as the phases then you may find
    https://www.powerandcables.com/product/product-category/quad-cleats/


    is helpful - basically 4 cables in each  bundle ( 3Ls and one N) behaves thermally very much as 3 for nearly all 3 phase loads but those with the most appalling power factor - just because it is not one of the standard arrangements, does not mean you cannot do it, nor that it needs any special consideration or derating.

    Rotating the bundles so N is on top in one, bottom right in another and bottom left in another is a bit of a refinement - it should give further far field cancellation, but it is a very marginal installation  ( or one with a small signal magnetic instrument test lab alongside perhaps !!)  where that matters, and then there are probably better measures.

    https://www.ellispatents.co.uk/wp-content/uploads/2016/08/Ellis-Black-Book-1st-Edition-1.pdf

    meas also makes the same assertions about rating on P16
Reply
  • 0
    My first post was started before  OMS put his in, but if you want N the same size area as the phases then you may find
    https://www.powerandcables.com/product/product-category/quad-cleats/


    is helpful - basically 4 cables in each  bundle ( 3Ls and one N) behaves thermally very much as 3 for nearly all 3 phase loads but those with the most appalling power factor - just because it is not one of the standard arrangements, does not mean you cannot do it, nor that it needs any special consideration or derating.

    Rotating the bundles so N is on top in one, bottom right in another and bottom left in another is a bit of a refinement - it should give further far field cancellation, but it is a very marginal installation  ( or one with a small signal magnetic instrument test lab alongside perhaps !!)  where that matters, and then there are probably better measures.

    https://www.ellispatents.co.uk/wp-content/uploads/2016/08/Ellis-Black-Book-1st-Edition-1.pdf

    meas also makes the same assertions about rating on P16
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