Effect of conductor orientation on transmission line ampacity

1. Aug 13, 2014

MrBuggy

Hi guys,

I was playing around with conductor configurations and observed this phenomenon. Mind you these are for the High voltage transmission (138 kV) lines that span kms. So apparently, the orientation of the conductor relative to North will change the ampacity of the transmission line. Can anyone explain to me why this is the case? I mean it makes sense to me how the wind, elevation, latitude and etc. would affect ampacity as it tells us the sag, and how the sun hits the conductor.

Thanks,
MrBuggy

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Last edited: Aug 13, 2014
2. Aug 13, 2014

psparky

Hmmmm....good question. Here's a random, somewhat educated guess:

I know there some giant magnetic field in regards to the Earth. Also being parallel with the poles (north) as opposed to being perpendiclar to poles (East, West) must have some effect on the wire.

If there is some rotating magnetic field from the poles or somewhere else, that can increase or decrease current flow.
Now someone really smart can answer:)

3. Aug 13, 2014

AlephZero

http://www.poweranalytics.com/designbase/pdf/Bare_Wire_Sizing.pdf page 12.

For example when the sun is due south, an E-W line "sees" more sunlight per unit length of line than a N-S line, unless the sun is directly overhead.

Last edited: Aug 13, 2014
4. Aug 13, 2014

psparky

Or it could have absolutely nothing to do with the magnetic field and everything to do with the angle of the sun.
Missed it by that much......

5. Aug 14, 2014

sophiecentaur

At 1kW/sqm, there's a lot of power falling on a long line; makes you think. That's another thing I just learned on PF.