Single conductor 345 and 500 kV Lines

[ozjohn]

Davidbeach said in thread238-225023

"Bundled 138kV? If so, that is entirely for loadability and has nothing to do with corona. Single conductor 230kV with no anti-corona provisions at the insulator strings are extremely common. The only 345kV line I'm familiar with is single conductor, but does have anti-corona hardware at each insulator. There is even a fair bit of single conductor 500kV around - that one does surprise me, but I know its there"

David, is there any way i could get some more information on those lines (ie. which lines they are so that i can try to get in touch with the owning system and confirm they have had no operating issues). I am involved in some debate at the moment where people are proposing that we calculate corona based on the surface coefficient measured for our very worst line (0.45). It would require a triple conductor bundle at 330 kV !

Any help appreciated,

John.

 

[davidbeach]

I really don't feel that it would be appropriate going into further details in a public forum. I can say they exist without a problem, but beyond that it starts to become specific transmission information that can't be publicly shared. Sorry.

 

[magoo2]

AEP has a lot of 345 kV transmission around the US. You might contact them on your question.

 

[PHovnanian]

It depends on how much real estate you've got for your right-of-way. Based on the equation jghrist posted in the referenced thread:

Eo ~ r·ln(D/r)

where

r=conductor radius
D=distance between conductors

so if you can increase the spacing, you can get away with a smaller conductor radius for a given critical voltage. You'll probably see more single conductor HV stuff in rural areas and more bundled stuff where construction widths are restricted.

 

[MikeDB]

The utility I used to work for had a lot of single conductor 138kV and one line with single conductor at 230kV. I have designed and built many miles of single conductor 161kV. All without corona hardware. Some of the polymer insulator manufacturers are now recommending corona rings with their insulators at 161kV.

All of their 345kV was a two conductor bundle per phase with a conductor bundle spacing of about 18". Conductors were typically 954 ACSR or 1,024 ACAR. Phases were spread horizontally about 20' as I recall.

Seems like I have seen 500kV with 3 and 4 conductors per phase.