Hamish Marson wrote: > Dale wrote: > >> Mike Williams wrote: > >>> On Thursday 03 August 2006 19:27, James wrote: > >>> > >>>> The simplist solution is NOBODY puts a 240 VAC power supply > >>>> into a computer unless it's going to draw some serious current > >>>> (amps) thus by the nature of it being 240 VAC, you already know > >>>> it is a power hog. > >>>> > >>> Now, I'm not electrical engineer, but I know my way around a fuse > >>> board and electricity having fitted out both our new offices for > >>> power, network, and some walls. > >>> > >>> In the UK, and most (if not all) of Europe, Africa, and Asia too, > >>> run on about 240 volts, 230 +-10% I think now. Pretty much the > >>> whole world, except the Americas. > >>> > >>> > >> Well, the USA has the same coming in too. We have 220v to 240v > >> coming in but that is split into different legs for the 110v to > >> 120v stuff. > >> > > Unless those two legs are in phase, you're still only getting > 110V-120V AC. IIRC (And it's from 20 years ago I'm working here) it's > not, it's just two legs of the 3 phase generated power. Which means > they're 120 deg out of phase, and so you still only get 110-120V. In > order to get 220-240V, you'd need 3 phase power. > > I suspect you get two 110V lines because of current limitations. Not > to provide you with 220V which you'r enot going to get from just > adding two out of phase lines. (Unless of course the US has wired up > two in-phase separate 110V lines. In which case you can get 220V outof > it, but I seem to remember a lecture in Eng Sci saying it was common > to take 2 of 3 phases to a house in the US & alternate which 2 between > successive houses.
The two lines are out of phase. Here, big things like air conditioners, stoves, dryers and central heat run off the 220 or 240v wires. Small things like lights, hair dryers, fans and even small window air conditioners run off the 110 or 120v lines. In most places here, 3 phase is not available unless you are in a area that has large factories or are in a city. Here the black and white wires are 120v, the red and black wires are 220 or 240v. Also note, you can tell the power company which one you want when you get them to put up your pole. We had 220v for years. When the transformer went out I asked for 240V. With a light load we actually get about 248v or so. When something like the A/C turns on it will drop to about 240v or so. It stays pretty stable after that though. Keep in mind that light bulbs blow faster at the higher voltage. At the same time A/C compressors run a lot more efficient. > > >> If you are using transformers to reduce it from 220v to 110v, that > >> will waste some energy right there. Transformers are not real > >> efficient. If you touch it and it is warm, that is what you are > >> wasting. That will also make whatever you are cooling with work > >> harder too. > >> > > Plus you need twice the current at 110V vs 220V. (Volts are big 'V' > BTW! Named after Voltaire). This means higher line losses as loss is > proportional to current. Higher line losses mean that cable length > becomes more of a problem. (A 10V drop in 240V is less than 5%. 10V > drop in 120V is almost 10%. Much more significant). > > All-in-all I prefer 240V single phase. > > H As far as being efficient with power usage, me two. I have a friend that uses some heavy equipment and some of them are 480v. They put out a lot more horsepower but they run very cool because the current draw is so small. We here would likely be better off if we did use 220v like other countries but it would take us years to convert things over. Dale :-) -- gentoo-user@gentoo.org mailing list
