Chuck Guzis wrote: Here in New Orleans, I am pretty sure that we still have 25 Hz drainage pumps in service, generated by a dedicated natural gas plant. Some of them may have been destroyed in Katrina, but searching around, I found some post-2005 news articles referencing the system. Apparently it relies on 60 Hz power for natural gas pumps, so it's still dependent on the local utility. The pumps seem to date back to 1920 or so. I don't know if the NYC subway system still uses any 25 Hz power or not. According to the book "New York's Forgotten Substations" they still had a few 25 Hz to DC synchronous rotary converters in operation as late as 1999! It would be unsurprising if they kept some of the 25 Hz system in place, feeding solid state rectifiers, but I don't know if they did. The power plant in Mechanicville, NY apparently still uses motor generator sets to convert its 40 Hz power to 60 Hz power they can sell. The plant is mentioned in a couple of IEEE articles, just search Mechanicville 40 Hz. Personally I think this is more amazing than our 25 Hz pumps. John Finigan