Re: 25 Hz Power

I don't know if true, but someone told me that in Europe they didn't

> bother with three phase for house supply, but just give everyone 220 > service. That does seem to be more efficient for house supplies.

This paragraph doesn't make any sense.

The standard residential supply in Europe is 400 V three-phase wye, with 230 V nominal on each leg, at 50 Hz. In the UK it is actually

415Y/240, but the standard includes enough slop to allow it. (Similarly most other European countries' "230" is actually 220.) In some locations, rather than drawing all three legs into each residence, neighboring dwellings may get single-phase feeds from different legs.

The standard residential supply in North America is 240 V single-phase center-tap, with 120 V nominal on each leg, at 60 Hz. However, some residences, particularly in New York City, have 208 V three-phase wye with 120 V nominal on each leg, still at 60 Hz. Commercial office buildings in the US often have 480Y/277; commercial lighting often operates on 277 V, and blowers, compressors, elevators, and pumps often use 480 (either wye or delta). Power companies can also supply

600Y/347 for medium-size industrial customers.

I don't know how they do it in Japan, but with 100 V nominal supply I would assume they do either the center-tap hack or three-phase in order to supply high-power devices at lower current.

Garrett A. Wollman | As the Constitution endures, persons in every | generation can invoke its principles in their own Opinions not those | search for greater freedom. of MIT or CSAIL. | - A. Kennedy, Lawrence v. Texas, 539 U.S. 558 (2003)

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Garrett Wollman
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