Re: US system is not as inefficient as I once thought

"Guy Macon" <http://www.guymacon.com/> wrote in message
news:[EMAIL PROTECTED]
>
> A bit of history as I understand it (corrections welcom!)
>
> The US has 110 volts because the original light bulb (invented
> by Thomas Edison in the USA) ran on 110 volts DC, and when we
> converted to AC we kept that voltage so that everyone wouldn't
> have to buy new light bulbs.
>
> Nicola Tesla (the genius) made careful calculations and
> measurements and decided that 240 volts at 60 Hz. was the
> best voltage and frequency for AC power.
>
> Many European countries modified Tesla's 240 volts to 220
> volts so that you could use two 110 volt bulbs in series,
> while in the US they changed the 110 volts to 120 volts
> so that two 120 volt bulbs in series would run on 240 volts.
>
> The engineers who built the first generating facility in
> Europe decided that 60 Hz. didn't fit the metric standard
> unit sequence (1,2,5), so they insisted on 50 Hz.
> (Westinghouse was pushing 133 Hz at the time...)
>
> One reference I checked says that 50 Hz is around 20% less
> effective in generation, 10 to 15% less efficient in
> transmission, and requires up to 30% larger windings and
> magnetic core materials in transformer construction.
> I believe that electric motors are also less efficient
> at 50 Hz, but don't quote me on that one - I am working
> from memory.
>
I think you are at least partly right about this. Large aircraft typically
use 400 Hz because this frequency allows for the use of smaller and lighter
motors and transformers. I don't know what this does to energy efficiency
but, on an aircraft, I suppose that size and weight are the most important
considerations.

        Robert

> What I don't have is a reference that tells me whether the
> loss of efficiency from 50 Hz. is lager than the gain from
> 220/240v.  It's an apples and oranges comparison, of course..
>
> -- 
> Guy Macon, Electronics Engineer & Project Manager.  Remember Doc Brown
> from the 'Back to the Future' movies?  Do you have an "impossible"
> engineering project that only someone like Doc Brown can solve?
> Check out my resume at http://www.guymacon.com/resume.html/
>