Timeline for What is the relationship between a power line's voltage and the amount of power it can transmit?
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| Feb 18, 2023 at 0:55 | comment | added | The Photon | @pdb5627 it sound like you know enough about it to write an answer. I'll be happy to upvote if it teaches me something new. | |
| Feb 17, 2023 at 7:15 | comment | added | pdb5627 | Using a table of conductor specifications for ACSR from Southwire, the power of the relationship from 6 AWG "Turkey" to 2167 kcmil "Kiwi" is calculated as log(0.0106/0.806) / log(1.735/0.198) = -2.00. The power of the relationship to ampacity, on the other hand, is calculated as log(1607/105) / log(1.735/0.198) = 1.26. This is more than linear but much less than a power of 2. | |
| Feb 17, 2023 at 7:07 | comment | added | pdb5627 | According to the Aluminum Electrical Conductor Handbook, the ratio of ac resistance to dc resistance (Rac/Rdc) ranges from near 1.0 for small conductors to 1.09 for 1590 kcmil all-aluminum conductors. So skin effect is a factor, but not enough to change the relationship of resistance from inverse of square of diameter to inverse of diameter.To see the relationship with conductor ampacity, I reference the Southwire specifications for ACSR. At the small end, 6 AWG (diameter = 0.198 in) is 105 A, while at the upper end, 2167 kcmil "Kiwi" (diameter = 1.735 in) is 1607 A. | |
| Feb 16, 2023 at 22:15 | comment | added | The Photon | @pdb5627, the issue is skin depth. Even at 60 Hz, the skin depth is only a few mm. So if the conductor radius is bigger than that the circumference of the conductor is more important than the cross-section area in determining the resistance. (And this is why they can use steel cores without affecting the resistance much) | |
| Feb 16, 2023 at 9:14 | comment | added | pdb5627 | "It's not the total surface area, but the surface area per unit length". Circumference may be a factor in that it affects the rate that the conductor dissipates heat, but the bigger factor is the resistive losses in the conductor that generate the heat. Resistive losses will be generally proportional to the inverse of conductor diameter squared, although at transmission-level voltages, the core of the conductor (e.g. steel) is used for strength rather than conducting current flow, so it's not quite that simple. | |
| Feb 16, 2023 at 8:55 | comment | added | pdb5627 | At high transmission voltage levels, about 230 kV and above, the conductor size is increased with voltage to reduce corona effects. Either larger conductors are used and/or each phase's conductors are bundled with spacers between them. | |
| Feb 15, 2023 at 16:24 | history | edited | The Photon | CC BY-SA 4.0 |
added 444 characters in body
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| Feb 15, 2023 at 16:16 | history | answered | The Photon | CC BY-SA 4.0 |