25 cps Power, was: Tie Lines was Re: Foreign Exchange (FX) Lines

I don't know when the last 25-cycle power was phased out. Keokuk, Iowa,
> had a 25-cycle hydroelectric plant -- driven by the Mississippi River,

25 cycle/second power was still in use for portions of the NYC area transit facilities until about a decade ago. While the subway trains ran, and run, on 600VDC "third rail" power (until very recently there were big advantages to operating large motors off DC), some of the commuter railroads had legacy stuff.

(The newest subway motor controllers actually take that DC from the third rail and transform it to 3-phase AC before feeding it to the motors.)

Parts of some passenger stations tapped into this 25 cycle grid for use by the incandescent lamps. This led to quite noticable flickering whenever the temperature dropped ...

(All primary lighting is now courtesy of the regular 120/208/240v utility grid feeding fluorescent fixtures. There's a modest amount of incandescent stuff around for small areas.

Also, some emergency, backup, and area-work circuits feed a "five pack" of 120V incandescents off the 600VDC third rail.)

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