Some West Virginia coal mines used power around 25 Hz as late as 1952 when my grandfather was a mine electrician. He later described his work to me. Some of the small towns next to the mines were powered the same. He said the flicker in the incandescent lights was visible.
#49253 - 03/04/0504:42 PMRe: Non-60Hz power in North America
There are Two main HIGH voltage distribution systems in the USA. Direct Current and 60 HZ. As was mentioned by dereckbc, the USA is on two Grid systems, East and West, and MUST be 60 HZ. If a given generation plant starts to deveate from the 60 HZ, the others pull it back. Individual Facilities may have converters to different frequancies for their operation, but the UTILIT grid is always 60 HZ. Outside the USA, I have found only 50 and 60 HZ from Utilities, with some countries having both.
#49254 - 03/04/0505:20 PMRe: Non-60Hz power in North America
Grids having to be synchronized is a good point, but could it be that back in the 1950s there were still some small areas which were not connected into statewide and national grids but just had a few power stations running a local network?
In England at this time, there were some cities in which the older, downtown districts were still running on their original DC distribution systems fed from a local power plant, even though outer, newer areas had been interconnected to the grid to get AC power.
Some West Virginia coal mines used power around 25 Hz as late as 1952 when my grandfather was a mine electrician.
That sounds very much like a local power plant along the lines I'm thinking about. Didn't many of the small mining places in WV start out as company towns? It seems quite probable in such a case that the mining company might have installed local generators to their own standards for the whole town.
Pensylvania Railroad used 11000VAC @ 25Hz for electric traction
25Hz was also used on some railroad lines in Britain in the past. The 25kV AC power supplied for all the main electrified lines these days is 50Hz though, with substations providing power from the main national grid.
#49255 - 03/05/0502:54 PMRe: Non-60Hz power in North America
I know for a fact the Quebec and Southern Ontario grids are separate, and I heard Texas is practically on their own grid.
On the whole, I think the separte grids may be: Quebec/eastern Canada. South Ontario/Northeast US South East US Texas Midwest US Western Canada Western Seaboard (including BC). Alaska is probably a whole separate grid, and of course Hawaii will be too.
#49256 - 03/06/0511:51 PMRe: Non-60Hz power in North America