40 ms·
High voltage DC. High voltage means it’s more efficient (power dissipation depends on current, not voltage, so for the same power, higher voltage means much les
by Robotbeat 9y ago
High voltage DC. High voltage means it’s more efficient (power dissipation depends on current, not voltage, so for the same power, higher voltage means much less dissipation). DC (direct current instead of alternating) makes it easier to connect disparate grids as you don’t have to worry about phasing.
- russdill 9y agoFor a fun rabbit hole: https://en.wikipedia.org/wiki/Transposition_(telecommunications) https://en.wikipedia.org/wiki/Transposition_(telecommunicati...
- TeMPOraL 9y agoAlso, I recall reading that if you run undersea cables with AC, the sea water sucks out energy from them.
- gehsty 9y agoCan’t tell if trolling or not. The cables have water barriers so the conductors + insulation remain quite dry.
- Analemma_ 9y agoI believe the parent meant that the alternating current creates an electric field which is then absorbed by the water, leading to energy loss. This happens to some extent to all AC transmission, but I don't know enough to say if seawater+AC is a particularly bad combination. It would make sense though, because it's more conductive. EDIT: brandmeyer's comment explains it well: https://news.ycombinator.com/item?id=16903431 https://news.ycombinator.com/item?id=16903431
- TeMPOraL 9y agoYes, that's precisely the thing I was referring to. Wasn't sure about the correct terminology (not an EE) so I didn't try to make the comment sciency-souding :).
- gehsty 9y agoI work installing these cables and never heard this discussed, maybe at the voltages / transmission subsea cables work at (220kV, 1000s of amps) makes this effect negligible?
- TeMPOraL 9y agoI honestly don't know. I'm not an EE, I only reported on what I've heard reported on the topic (and that passed my "basic physics sniff test").
- rsynnott 9y agoAre they AC? My impression was that practically all vaguely modern undersea cables are high voltage DC.
- gehsty 9y agoIt depends, when talking about interconnecting cables between countries, yes the majority are DC, both to minimise transmission losses and also to tie together grids working at different frequencies.... In terms of km installed I think it will be HVAC just from the sheer number of offshore windfarms built over the last 10yrs in Europe. These things can be huge - 60km in length, 220kV ~1500A....
- cesarb 9y agoSalt water is a conductor. Two conductors separated by insulation make a capacitor. This extra capacitance makes AC less efficient.