Standard mains voltage in the US?

As does the DC-NYC Amtrak cat system.

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It you word it as a "loose neutral" they supposedly come right away.

2-phase is one of the things I never like much after moving to the US. Someone turns on a vacuum cleaner and there is a substantial voltage surge on the other phase.

--
Regards, Joerg 

http://www.analogconsultants.com/

split phase..

And who to those where it really splits :-)

That usually rsults in some smoke.

--
Regards, Joerg 

http://www.analogconsultants.com/

At some point in the past, the UK has had AC as low as 25Hz and possibly as high as 100Hz in a few places.

Probably before my time, but it was possible to get pretty much anything re wound locally because a lot of stuff was made locally to suit the mains supply in that area.

There might be a company still going that does re winds a couple of towns away, but I can't think of anything that wouldn't be cheaper than just buy a new one.

We have a rewind co here. Mainly for repairs rather than re-volting, and their T&Cs are very much non-retail.

NT

In many countries in Europe, the rail system runs on 16.667 Hz. This is due to big universal (AC/DC) commutator motors in trains, which do not work well on 50/60 Hz.

Only small universal motors (as in handheld drills) work well also at

50/60 Hz

I never encountered DC in the US, but may have encountered abandoned DC outlets, when I was a kid. I have a few friends who definitely had DC in their houses when they were growing up. So, that would be into the mid

1950's, I guess.

Jon

The New York Subway system definitely used 25 Hz power when I was a kid. The flickering of incandescent bulbs was unmistakeable. I think they got this feed from Ontario Hydro.

In St. Louis, they had a frequency converter station that took 25 Hz from Ontario Hydro and powered some buildings in the downtown business section from not-quite 60Hz power, and some utilities like elevators and fire pumps ran directly from the 25 Hz power. This was still used into the 1970's.

Jon

There is a good point for the low frequencies, if there are large motors with commutator and brushes. The big magnetics are too inductive for 50 Hz, so especially railways (railroads) still are using lower frequencies, e.g. 16.7 Hz in Austria (and in the Narvik railway between Sweden and Norway, IIRC).

--

-TV

It's only been ten years since the last US DC distribution system was shut down.

snipped-for-privacy@notreal.com wrote in news: snipped-for-privacy@4ax.com:

Ten years since the last New York DC distribution sysytem was shut down.

Google "bonneville DC Intertie"

or:

"Still hot after 40 years"

Always wrong is wrong again (who wudda thunk). That is *not* a distribution system, rather a transmission line. It has no customers.

I've been told to expect 125/250, or at least not be surprised at it. This is of course off peak in newer areas, especially in new developments where they anticipate more houses built and electric furnaces, hot tubs and whate ver to come in the future. They simply can't regulate it perfectly.

Most equipment can tolerate it, and more modern things work even more effic iently in some cases. But old tube amps and the like may get redplating of the output tubes. This is common when they were designed for 117 volts and now get 122. Some of them need a bias adjustment or even a modification.

I wish you guys get it right! it's called a NOODLE, there is nothing worse than having a loose or unbalanced NOODLE!

Now that i've educated you!

Have a good day! Jamie

for 5 years in 2003. Previous it was set at 230V+10/-6% (216-253V).

The Pacific Intertie is anything but a distribution system.

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A host is a host from coast to coast.................wb8foz@nrk.com 
& no one will talk to a host that's close.......................... 
Unless the host (that isn't close).........................pob 1433 
is busy, hung or dead....................................20915-1433

Was that 110 Vdc (2x55 V?) or significantly higher ?

Anyway, these days, when the DC/DC voltage conversion is cheap, a DC distribution network would again make sense, but a more sensible voltage should be selected, but which ?

In big data centers an internal 380 Vdc (+/-190 V) feed is sometimes used with backup power batteries at this voltage. It is then down converted with various DC/DC converters to PCB and finally chip level converters to 3.3 V or 0.xx V. No need to make pure sine way in any conversion stages.

For the US market that would also makes it easy to make 120 Vac single phase or 120/208 Vac (wye/delta) pure sine for 1 or 3 phase motors just with a PWM stage.

In the rest of the world, the IEC convention is used with the border between low/high voltage (LV/HV) is at 1000 Vac or 1500 Vdc. A lot of LV hardware (such as cables are specified up to these limits. For instance an ABC (Air Bundled Cable) LV cable can handle one or two fallen trees without breaking, while a 20 kV open wire snaps when a single tree falls upon it :-).

1000 V feeds are used in rural areas with small transformers close to a house drop it to 240/400 V.

There are also experimental rural 1500 Vdc feeds with in house converters producing 240/400 Vac for driving motors. No need for transformers, since clean 230/400 Vac can be generated easily from voltages greater than +/-330 Vdc with just PWM.