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

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91–100 of 155 posts

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

#91

> If you look at lists of the 100 greatest inventions of all time, electricity figures prominently. Once you get past some key enablers that can’t really be called inventions—fire, money, the wheel, calendars, the alphabet Well that's a doozy of a way to start. How is electricity an invention but those listed after are not?

The line between capability and invention is ... broad and ill-defined.

I stumbled over that comment as well, though the article doesn't hinge on it.

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

#92
The argument for more unified grids would have had more leg before the 2003 outage, where a failure was propagated through the grid and resulted in a blackout for a large part of the US. With multiple separate grids, at least you reduce the impact of such event.

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

#94

The article makes this seem like it's a US problem but, the interconnects lay in Canada and Mexico too. I'm guessing that unification is a low priority for them since it seems that the US stands to gain the most from it. "DC power lines transmit power more efficiently than AC lines do" This is not at all what is taught at school. Looking into this is interesting. 100 years ago people were debating about whether AC or…

AC current is more efficiently transformed between voltages.

DC current is more efficiently transmitted (conducted) over long distances at high voltage.

Since the early 20th century, DC transformers have become more efficient, as others have noted.

Given that electric grid transmission occurs at a wide range of voltages (~275kV generation, ~100kV long distance, 50kV local, 110/220V residential/commercial drops), efficient, reliable, cheap transformers were required, giving the initial edge to AC.

https://en.wikipedia.org/wiki/Electrical_grid#Voltage

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

#95
post #45
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…

> but the disadvantage of increasing the risk if one is electrocuted. Avoiding this was one of the design parameters of the "Schucho" plug design that is reasonably standard across Europe. You'll note the three prong plug has a longer ground that makes a connection before any hot one does. The US three prong is supposed to work that way too but the ground pin isn't long enough. I continue to be amazed how many device…

Its Schuko, short for SCHutzKOntak, "contacts and ground".

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

#96
post #4

> Everything within those separate zones is synched up. So you’ve got your 60 hertz AC wave; 60 times a second the AC power flow is changing direction. And all of the generators, all of the power consumption within each zone is doing that synchronously. But the east is doing it on its own. The West is on a different phase. Same for Texas. Folks may not realize that power is transmitted in three phases in the US. AC p…

Interesting explainer: Why 3 Phase Power? Why not 6 or 12? https://youtube.com/watch?v=HqZtptHnC2I (Substation complexity.)

And reduced efficiency

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

#98
post #3

The most interesting national electricity grid has to be Japan's, with two completely different networks operating at different frequencies, and connected by HVDC. https://en.wikipedia.org/wiki/Electricity_sector_in_Japan

One region used American and the other one German sourced generators ... like NTSC vs PAL :).

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

#100
post #45

Earlier quoted context omitted.

> but the disadvantage of increasing the risk if one is electrocuted. Avoiding this was one of the design parameters of the "Schucho" plug design that is reasonably standard across Europe. You'll note the three prong plug has a longer ground that makes a connection before any hot one does. The US three prong is supposed to work that way too but the ground pin isn't long enough. I continue to be amazed how many device…

> I continue to be amazed how many devices still ship with only two prong plugs (everywhere: Europe, North America, Australia...) even if those prongs are polarized Because most devices these days have plastic cases (Class II double insulated), so there's nothing metal to touch to get shocked even in the case of a fault. That coupled with how GFCI/RCDs are being widely adopted as well leads to grounding not being as…

I'm (mostly) with you on the plastic casing, but in general (in the US at least) you only see GFCI in kitchens and bathrooms.

Meanwhile I'm sitting 2 feet away from a nearly completely metal lamp with a two-prong plug.

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