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Why Does the U.S. Have Three Electrical Grids?

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Re: Why Does the U.S. Have Three Electrical Grids?

#111

Post by lucioperca »

ghouse wrote: post #31
nickff wrote: post #26

Earlier quoted context omitted.

Well, you have to consider that the USA (and Canada) were on the bleeding edge of technology when they adopted electrical grids. They were left with a... legacy, including the type-A plug and 110V single-phase power to residences. In your case, I believe each prong of your two-prong plug gets a different phase, so you have 3 possible pairs of phases to power each circuit from. This has the advantage of requiring smal…

> 110V single-phase power to residences. The US is 120V, or split-phase 240 V. Depending where you are, it's allowed to be ±5% at the meter. NEC guidelines say no more than 3% voltage drop from there.

You might have 208V and not 240V if you have two 120V phases 120 degree apart.

Re: Why Does the U.S. Have Three Electrical Grids?

#112

Post by VBprogrammer »

dredmorbius wrote: post #90
msisk6 wrote: post #13

Earlier quoted context omitted.

That's exactly right, but the capacity is limited. ERCOT in Texas, for example, has 5 DC ties to the other grids: http://www.ercot.com/content/cdr/html/real_time_system_condi...

> Peter Fairley: So to give you a sense of just what the scale of the transfers is and how small it is, the East and the West interconnects have a total of about 950 gigawatts of power-generating capacity together. And they can share a little over one gigawatt of electricity. > Steven Cherry So barely one-tenth of one percent. From TFA.

I wonder if this has more to do with "Black Start" planning than actually providing power cross grids.

https://en.wikipedia.org/wiki/Black_start

Re: Why Does the U.S. Have Three Electrical Grids?

#114

Post by rob74 »

Always interesting to learn such details about infrastructure "hidden in plain sight". One more I can add is the separate traction power network in Germany, Austria in Switzerland, which is necessary because the railways here use a frequency of 16,7 Hz. It is fed in part by dedicated power plants (or dedicated generators in shared power plants), in part by converters.

https://en.wikipedia.org/wiki/Traction_power_network

https://de.wikipedia.org/wiki/Bahnstromnetz#/media/Datei:Bah...

Re: Why Does the U.S. Have Three Electrical Grids?

#115

Post by pjc50 »

imoverclocked wrote: post #49

The main point of this article has nothing to do with the technical details of power transportation and everything to do with politics and corruption of our academic/research institutions. It’s amazing how an anti-fact leader can have such corrupting influence on institutions that are building tomorrow’s leaders.

Pratically Chinese in having a political officer embedded in the conference who reports violation of political correctness to senior political appointees who can then have it shut down.

Re: Why Does the U.S. Have Three Electrical Grids?

#116

Post by pjc50 »

CameronNemo wrote: post #52
imoverclocked wrote: post #49

The main point of this article has nothing to do with the technical details of power transportation and everything to do with politics and corruption of our academic/research institutions. It’s amazing how an anti-fact leader can have such corrupting influence on institutions that are building tomorrow’s leaders.

I've flagged the article for such a reason.

Everyone's apolitical until the lights go out.

Re: Why Does the U.S. Have Three Electrical Grids?

#117

Post by pjc50 »

notmadnomad wrote: post #105

Granted the immense infrastructure investment, but why not ditch electrical and natural gas for hydrogen? Hydrogen is much safer, cleaner, and less lossy than either.

Bulk hydrogen production from electricity is more expensive than natural gas. It's also more expensive than making hydrogen from natural gas, which is why lots of fossil fuel companies like "clean" hydrogen.

(It can also be lossy, as the atoms are small enough to leak through metals, causing hydrogen embrittlement along the way)

Re: Why Does the U.S. Have Three Electrical Grids?

#118

Post by mcv »

Europe's integrated power grids can very rarely cause weird problems. A couple of years ago, a dispute between Serbia and Kosovo left some power demand unfulfilled, which lead to the grid frequency slightly dropping, which caused grid-powered clocks to lose about 6 minutes: https://arstechnica.com/tech-policy/2018/04/european-grid-di...

Political tension between Serbia and Kosovo is not entirely unexpected of course, but it's weird if that starts affecting clocks half a continent away.

Re: Why Does the U.S. Have Three Electrical Grids?

#119

Post by mcv »

lutorm wrote: post #16
nickff wrote: post #6

Earlier quoted context omitted.

>"[W]e basically always have at least one phase providing power at any time." This isn't really how three-phase power works. In household settings, you're usually getting only one phase, so all your power comes from that phase. Different neighborhoods get different phases, so they're roughly balanced loads. Industrial (and some consumer) users get two (208V) or three phases (480V), and they get power from the differe…

At least in Sweden, all houses have a 3-phase, 400V supply. This is very different from the US which just supplies one phase to each house even if the supply itself is 3-phase. This is why you commonly see 200+A main breakers on a house in the US whereas in Sweden, 25A is a pretty common main breaker size. (It's as if the US grid characteristics were decided by the copper vendors... ;-)

Not just Sweden. In Netherland, 3x25A is also pretty standard. To our surprise, our house turned out to have 1x35A, so when we got a big induction cooker, we had to upgrade to 3x35A.
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