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Current imbalance in splitting parallel circuits

Accel
Hello Gents,


I am currently tasked in helping to install cables connecting the low side of a 2.5MVA transformer to an LV switchboard. Cable size and amount is 4 sets of trefoil + neutral 630mm single core SWA(total 16 630mm singles). They were split into 2 sets per group W shape from the LV connection before meeting at the high level containment. One group is 3m longer. I know it might lead to current imbalance because parallel circuits are far from each other but how bad is it? Distance between the TX and LV switchboard is rougly 15 meters.
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    hoping I have understood what you are asking yes,  if you have no neutral. Each trefoil bundle L1/L2/L3 will have zero sum that is the 3 phases will be in balance.

    However, the trefoils will not share equally, as they are not the same length - that is to say the  L1 current in a short trefoil will be higher than the L1 current in  a longer one - after all the voltage across the ends is fixed, as they are connected to each other at both ends, but the two L1 conductors are not the same length.
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  • 0
    hoping I have understood what you are asking yes,  if you have no neutral. Each trefoil bundle L1/L2/L3 will have zero sum that is the 3 phases will be in balance.

    However, the trefoils will not share equally, as they are not the same length - that is to say the  L1 current in a short trefoil will be higher than the L1 current in  a longer one - after all the voltage across the ends is fixed, as they are connected to each other at both ends, but the two L1 conductors are not the same length.
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