Rules and Guidelines
Want to participate in the discussions? Please read our Community Rules and Guidelines. Need some help? Visit Support and Answers.

  • State Not Answered
  • Locked Locked
  • Replies 5 replies
  • Subscribers 32 subscribers
  • Views 845 views
  • Users 0 members are here
Options
You may also be interested in
This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

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.
Parents
  • 0
    If you mean 18m and 21m length of trefoil are in parallel, then currents can be expected to  split in the ratio of 21/18 assuming the termination impedance is small compared to the bulk resistances of the wires i.e. the lugging at the ends is done correctly.. Any one trefoil should be in balance with itself, that is to say the LLL(N) currents in any one close bundle will sum to near zero, but the currents that are summing to zero  may not be the same as another trefoil/quadfoil that is not the same length.

     

Reply
  • 0
    If you mean 18m and 21m length of trefoil are in parallel, then currents can be expected to  split in the ratio of 21/18 assuming the termination impedance is small compared to the bulk resistances of the wires i.e. the lugging at the ends is done correctly.. Any one trefoil should be in balance with itself, that is to say the LLL(N) currents in any one close bundle will sum to near zero, but the currents that are summing to zero  may not be the same as another trefoil/quadfoil that is not the same length.

     

Children
No Data

Community Rules & Guidelines