## Why 220@50hz and 120@60hz?

Why 220v@50hz and 120v@60hz?

Who came up with these and why are they different - especially the frequencies?

I heard that when Tesla was around, someone wanted the frequency to be @330... why?
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 Recognitions: Science Advisor After Tesla won the AC/DC fight with Edison he gained much influence and more or less dictated the 60Hz frequency in the US. I think he had an ulterior motive in that he wanted to transmit power without wires and had calculated the 60Hz frequency was best for that purpose. I have no idea why the European nations choose 50Hz, as it is less efficient to produce and transmit over wire than 60Hz. The best frequency for power transmission is probably moderately higher than 60Hz. Consider above opinion not fact.
 I suspect it was to do with how fast the old generators could spin before they flew apart. If you compare the size and mass of a 10 killowatt aircraft generator or induction motor (which run at 400 Hz) with a 10 killowatt 50 or 60 Hz unit, you'll be left wondering why we're not using higher frequencies (the equivalent aircraft units are tiny). I suppose the frequency can't be too high for long distance transmission of power (there would be more losses), but I suspect it could easily be a lot higher than 60Hz.

## Why 220@50hz and 120@60hz?

from what i understand europe picked 50Hz because it was felt it be easier number to work with due to the metric system as for the voltage, that is what edison picked when he came up with dc
 LOL! That's a horrible reason. :D

 Quote by ceptimus I suspect it was to do with how fast the old generators could spin before they flew apart.
I seriously doubt it.

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Here is some information on the evolution of 50 Hz. It seems that a combination of the engine and generators used, the ideal engine speeds, the desired voltage, and the number of poles used in the generators drove the selection of frequency in a complex fashion. I doubt that any simple answer exists.
 ...The City and South London system saw the first application of direct drive from the motors on to the wheel axles. [...] The current at 500 volts was supplied through a third rail of steel channel, supported on glass insulators from transverse wooden sleepers, and picked up by cast iron slippers. [...] Other sections of electrified track appeared: Bow to Upminster in 1905, Paddington to Westbourne Park in 1906, Lancaster to Heysham in 1908. The London ones, influenced no doubt by the underground examples, kept to D.C., but for the Heysham line, single-phase 6.6 kV at 25 cycles, carried on an overhead trolley wire, was adopted. Wide differences of opinion arose at to voltage and system, and from 1916, 1500 volts D.C. on an overhead wire became increasingly popular. [...] In 1956, the Transportation Commission decided on a 25 kV 50 cycles single-phase system as national standard. [...] On the A.C. side, different practices developed in different countries. In 1930, for instance, the three-phase system disappeared finally from the Swiss Federal Railways, and was replaced by single-phase 15,000-volt current at a frequency of 16 2/3 cycles per second. About the same time, there was one scheme in the United States employing 11,000 volts at 25 cycles on the trolley line, with 300 h.p. A.C. motor, and another operating at 3,000 volts D.C. [...] The Turbine Era [...] Between the two world wars, the great reorganization of the electric supply industry in this country [Britain], which led to the construction of the 'grid', was formulated and carreid out. In 1917, a government committee recommended that all supply undertakings should be brought under one central authority, and in 1919 the Electricity Supply Act set up the Electrical Commissioners, who started work in 1920. Districts were organized under the title Joint Electricity Authority, but were often under suspicion from the undertakings and were not completely effective, so that in 1925, reconsideration of the situation by the Weir Committee led to the formation of the Central Electricity Board. Its main functions were the construction of a nation-wide transmission network, the adoption of selected generating stations, and the standardization of frequency. At the time, there were 17 different frequencies in use, and 80 undertakings operating on other than 50 cycles. [continued]
http://www.myinsulators.com/acw/bookref/histsyscable/
 There may be some places in the world that use 20 Hz. The old streetcar used 20 Hz. When they were taken out of service the power plants were sold to some cities in other countries. They were still in use about 20 years ago. I think the reason they used 20 Hz back then is that they used rotary rectifiers. The motor on the streetcar was DC.
 Up to the '40's the iron laminations of rotors and stators of electric motors and generating equipment were poor quality and hysteresis losses were a major factor. (note how large old electric motors are compared to newer ones). Higher frequencies would have worsened the losses so up 'till then 25 Hz was common in Canada and the US. When better steel was used for laminations, north America changed to 60 Hz about 1950, the Europeans decided 50 Hz was the cat's meow.
 I heard that the European used 50Hz becasue it apparently interefered with you heart less that 60Hz.
 I heard two different reasons for the US choosing 60Hz. One as mentioned above, the Europeans chose 50Hz because of better calculations with the Metric system. Likewise, the US chose 60Hz to better measure periodic voltage (60 minutes, 60 seconds). The other, more 'Urban Legend' reason why the US choose 60Hz was in one of its first applications--The Electric Chair--it was determined that 60Hz was the optimum Frequency to Kill a human. This then became the standard. LIKE I SAID I HEARD THAT RECENTLY FROM AN MIT PHD Professor. Doesn't make that much sense though if you consider that same danger is being carried out to every home.
 I once heard that the reason for 60 hertz is that is was the highest frequency you could get without developing standing waves on a trans-continental transmission line.

 Quote by DaveEE The other, more 'Urban Legend' reason why the US choose 60Hz was in one of its first applications--The Electric Chair--it was determined that 60Hz was the optimum Frequency to Kill a human. This then became the standard. LIKE I SAID I HEARD THAT RECENTLY FROM AN MIT PHD Professor. Doesn't make that much sense though if you consider that same danger is being carried out to every home.
He's wrong.
Edison was desperate in his attempts to discredit Westinghouse's AC system and was resorting to all sorts of public relation propaganda to prove how dangerous it was (including the promotion of the electric chair). It was hardly to Westinghouse's (or Tesla, his top engineer that designed the modern 3 phase system) advantage to promote the "deadliness" of his product.
 Not to dig up a dead thread but I read a biography on tesla 2 years ago and remember reading about the 50hz vs 60hz debate. Tesla intended his generators to be run at 60hz but the french operators (at the first ac generator in europe) didn't want to speed up their machines, or something the like. From that point on every one just followed suit and didn't question, untill now ;-)
 Which makes me question the 15 kV 16 2/3 Hz railroad power that seems to be adapted as a standard in many European countries. Do they use different generating stations than the regular 50 Hz, or do they do some complicated frequency change somewhere along the line? And why 16 2/3 Hz? Something with the old locomotives? I doubt it matters much these days with the thyristor locos.
 Dont forget 208V (3 phase-US) http://en.wikipedia.org/wiki/Three_phase_power
 Admin When I was in Japan, I learned that east is 50 Hz and west 60Hz. Eastern Japan 50 Hz (Tokyo, Kawasaki, Sapporo, Yokohama, and Sendai); Western Japan 60 Hz (Osaka, Kyoto, Kobe, Nagoya, Hiroshima) Basically, TEPCO (Tokyo Electric Power Co.) is the main supplier in east, and KEPCO (Kansai Electric Power Co.) is main supplier in west. http://en.wikipedia.org/wiki/List_of...nd_frequencies Regarding 220 V @ 50 Hz and 120 V @ 60 Hz, IIRC 220V is line-to-line voltage in a 3 phase system, and 120 V is line-to-neutral. This has to do with 'Y' vs $\Delta$ configuration. Several electrified railways used 25 Hz in US. http://en.wikipedia.org/wiki/Electrified_railways