I am reading Empires of Light about Westinghouse, GE, Edison and Tesla developing AC power distribution. The guys building a hydroelectric project at Niagara Falls wanted to use 162/3 Hz. 54 Hz is close to the US standard of 60. How did they come up with 162/3?
They also argued single phase, 2 and 3 phase.
In Europe, railroad electrification standards started using 16 2/3Hz systems because it was one third of the existing AC grid frequency of 50Hz. That made is easier to build rotary converters to convert between the grid frequency and the traction current frequency.
The Niagara hydro plant was always intended to supply power to the New York Central railroad (still does) and my guess is they wanted to take advantage of some of the same equipment already being used in Europe.
The electrified railroads in the northeast eventually went with a 25Hz system which is still in use today. The rotary converters are gone, though, replaced with very expensive heavy-duty solid state converters.
Thanks, friedo!
Here is a good PDF on the subject. It’s complicated.
Dennis
That’s about standardization, not why the Niagara guys wanted 162/3 Hertz, but interesting. Thanks!
Interesting that Japan is part 50 Hz and part 60 Hz because the areas bought their equipment from different sources, and they have AC DC AC converters to share electricity. Thanks again.
I wonder if the /3 comes from generating 3 phase current?
I don’t see how. the mains frequency comes from the speed of the alternator multiplied by half the number of poles per phase (n.b. it’d be clearer if you wrote it as 16-2/3 Hz, 162/3 is ambiguous.)
IIRC one reason is that if the generated supply is meant primarily to drive electric motors (e.g. rail) then lower AC frequencies are desirable for efficiency reasons, as in lower inductive losses in the motors themselves.
Just to be clear, you mean 16⅔ Hertz, right?
162/3=54.
I am reading it wrong? They finally agreed on 25 Hz.
The standard was 16.66 Hz, not 54.
Yes. you don’t divide the mains frequency by the number of phases. 162/3=54 is nonsense.
16 and 2/3. Or 16.666… if you prefer. One third of 50Hz.
Thanks!
to put a finer point on it, a polyphase alternator generates three electrical phases, all of the same frequency, all an equal number of degrees apart. in the US, it means the alternator outputs three 60 Hz sine waves spaced 120 degrees apart from each other. a 2-pole per phase alternator spins at 3600 rpm, a 4-pole per phase at 1800, 6-pole 1200 rpm, etc.