RedX
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Why do 400 kv power lines have 6 pairs of wires, 3 on each side? Shouldn't there only need to be 4 wires, a ground/neutral wire and 3 wires for 3 phases?
jambaugh said:Three phase doesn't need a ground/neutral for power transmission Hence they will come in multiples of 3. Sometimes one or two ground lines are used as lightning protection where there are long spans.
There are various configurations, from three wires up depending on needs. Multiple circuits give both redundancy and higher power carrying capacity.
I would speculate that they may also be configured to reduce the small but nonzero radiative losses.
No. The two pairs would share the load, and each would have less current. That equals less resistive loss.RedX said:Redundancy makes sense, but I'm not sure about power carrying capacity. If more power is needed, then the turbines in the generator just push harder, and more power goes down through the line. I'm not sure why you need multiple lines for that.
Also if you have twice as many lines don't you get twice the losses?
The direct link doesn't work but I cut and pasted the link and did find the pic.RedX said:Here's a link to a picture of a 400 kV pole:
http://www.emfs.info/Sources+of+EMFs/Overhead+power+lines/Parts+of+a+power+line.htm
Call the 3 phases A, B, and C. Are the phases transmitted in pairs, AB, BC, and AC? Because in the pictures of the power lines I've seen, they are sent in pairs with spacers preventing them from touching. But why pair them at all? Why not just have 3 wires of A, B, and C?