Posted by Sherman in Idaho [50.52.4.20] on Tuesday, July 28, 2015 at 11:20:17 :
In Reply to: Re: 400 Hz posted by TGP (IL)ip [107.77.85.81] on Tuesday, July 28, 2015 at 06:57:47 :
Never seen a 50 Hz only military genset. My oldest is 1958 and it's 60 Hz. In general, it's easy enough to design a set that will switch between 50 and 60 just by changing the engine speed, but 400 requires a generator wound entirely differently. I used to see the 400 Hz ones at the DRMO auctions and never even bid on them (neither did hardly anyone else) because they're useless for civilian purposes except maybe to light a string of incandescent bulbs.
Interesting thing: at one point back in the '50s there was a serious proposal to convert the entire U.S. electrical grid to 400 Hz. The advantage would be that all motors, transformers, and generators could be about 15% of the size they are now. That would be a huge savings in iron and copper, and the structures they go it. 60 Hz was only chosen in the early days of electric power because it was a fair compromise between copper and iron losses given the poor quality of transformer iron they had in the 1890s. Modern iron (even 60 years ago) was vastly superior to the early stuff and could easily handle 400 Hz without much loss. The proposal made total sense in the long run, but in the short run it would have required replacing every generator, transformer, and motor in the country, and that was deemed unacceptable. So here we are 130 years after the development of commercial electric power, still stuck with making machines pretty much the same way they did back then. It's as if we had cars that were full of computers and air bags and climate control systems and surround-sound stereos -- and were pulled by horses.