[hi-v-rocknroll]

EDIT: Where I live, there is mostly 69 kV and 138 kV, with only a few 345 kV lines. There aren't nearly enough 500 kV lines, and 765 kV aren't present in the region.

EDIT2: Here's what a 765 kV line looks like: https://maps.app.goo.gl/3fV1hFuQmpq3hVNx5

Map of US electric grid: https://www.arcgis.com/apps/mapviewer/index.html?layers=d409...

Real wiring is dominated by current, resistance of the conductor, and cooling.[0,1]

The way out is to rebuild with much high voltages and live monitoring, optionally with superconducting segments like Nexans where advantageous.

0. Ikeda, Yoshirô and Katsuhiko Yoneta. Temperature rise of a conductor due to the electric current. (1931). http://hdl.handle.net/2115/37682

PDF: https://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/3768...

1. Riba, J.-R.; Llauradó, J. A Model to Calculate the Current–Temperature Relationship of Insulated and Jacketed Cables. Materials (2022) 15,6814. https://doi.org/10.3390/ma15196814

PDF: https://mdpi-res.com/d_attachment/materials/materials-15-068...

[bsder]

Is there any reason we can't repurpose these lines for HVDC?

It seems like we could get quite a bit of extra juice by changing to DC transmission.

[pyrale]

Same reason you don't repurpose a train into an airplane, the two have different benefits and drawbacks, and are used for different purposes.

[bsder]

Copper wires are copper wires. There are 3 of them for 3 phases. They are sized for AC and AC losses.

DC does not require 3 phases. DC does not have any skin effect or corona losses and thus can operate on smaller wires.

The problem, of course, is that HVDC requires a DC terminal which costs money. It is likely quite a bit easier to build two HVDC terminal on land that the electric company likely already owns than rip up and rewire a whole boatload of long distance wiring.

[aidenn0]

At what point does HVDC start to make sense? IGBTs have only gotten better and cheaper since I first read about HVDC, so it seems like the fixed conversion costs ought to have come way down.

[pyrale]

HVDC is needed when you build between two non-synchronous areas like France and UK. Also if you don't have the option to build pylons and need to go underground/underseas, AC lines will suffer from capacitive load. the longer the line gets, the more capacitive load will be present, and so you can't build very long underground/underseas AC lines.

Since HVDC has significant fixed costs, it's not relevant for shorter lines.

[algo_trader]

Are DC costs more manageable at medium voltages?

If i really wanted 11kV MVDC is this a feasible spec for an industrial site?

[pyrale]

Honestly I don't have that much knowledge in industrial sites, but from what I understand, many industries are interested in directly getting triphased because that's what turning machines need in the end.

I guess if you need 11KV DC for your industrial site, you're likely going to need a transformer anyway, because nobody transports at such a low voltage.

As for medium voltage in general, U=RI. The reason TSOs try to push voltage as high as possible is because that reduces costly power losses, as well as cable temperature, which means you can transit more power without endangering the line and people around.

[pyrale]

Any reason there are 3 pylons for one line? I think it's the first time I see each phase having their own pylon.

[ckdarby]

Was surprised only to see one 765 line run into Quebec

[hi-v-rocknroll]

I see it connects one substation (NYIS):

Clark Energy Center, New York Power Authority - Marcy, NY https://maps.app.goo.gl/hvQi4qzgSTbs84296

to another (HQT):

Hydro-Québec - Poste Châteauguay - Saint-Étienne-de-Beauharnois, QC https://maps.app.goo.gl/duDA5wbBPrgVBxc19

but, reporting of other attached lines stops there because the datasource doesn't include Canadian-only lines.

Live overview status here, but not for a specific power line: https://www.eia.gov/electricity/gridmonitor/dashboard/electr...