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35kV 1 phase cables in shared conduit

35kV 1 phase cables in shared conduit

35kV 1 phase cables in shared conduit

(OP)
Hi I was wondering what would be the response of the magnetic field within a 4" PVC conduit with a A phase and B phase conductor installed within. Both phase conductors will be 35 kV 100% neutral 1/0 AL EPR cable. I estimate the cables to be loaded to 50% of capacity. I predict their magnetic fields will cancel but would like a second opinion. Thanks in advance for any assistance.

RE: 35kV 1 phase cables in shared conduit

Is that A & B of a three phase circuit of A & B of a circuit that only has A & B phases? Makes a tremendous difference.

RE: 35kV 1 phase cables in shared conduit

And is there significant neutral current?

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: 35kV 1 phase cables in shared conduit

(OP)
Yes the A & B are part of a 3 phase system and since they will be sourcing single phase loads (L-G) I do expect significant neutral current.

RE: 35kV 1 phase cables in shared conduit

Why does it matter? You are in PVC conduit.

"Throughout space there is energy. Is this energy static or kinetic! If static our hopes are in vain; if kinetic — and this we know it is, for certain — then it is a mere question of time when men will succeed in attaching their machinery to the very wheelwork of nature". – Nikola Tesla

RE: 35kV 1 phase cables in shared conduit

If you are using the concentric neutral conductors then the magnetic fields will cancel. The line to neutral current induced magnetic fields in each conductor will cancel quite well. The magnetic fields from any line to line loads will cancel from cable to cable and there may be some small leakage flux. The leakage is low enough that it is generally ignored.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: 35kV 1 phase cables in shared conduit

Note: If your wiring scheme is such that part of the neutral current does not return on the concentric conductors then there will be uncancelled magnetic flux. This may happen if a grounding scheme allows some neutral current to return on the ground path.

Bill
--------------------
"Why not the best?"
Jimmy Carter

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