Why choose 120 volts?

Robert Bonomi bonomi at mail.r-bonomi.com
Wed May 27 20:30:49 CDT 2009


> Subject: Re: Why choose 120 volts?
> Date: Thu, 28 May 2009 01:11:41 +0200
>
> On 27 mei 2009, at 18:03, Peter Beckman wrote:
>
> > I haven't seen a PC power supply which is incapable of both 120v/ 
> > 60hz and
> > 240v/50hz in a very long time.
>
> After this nice voltage discussion, what about hertz? Would it be more  
> efficient for us Europeans to run our stuff at 60 Hz rather than 50? I  
> hear that a 50 Hz grid loses 15% more due to inefficiencies than a 60  
> Hz grid. Not sure if that also applies over short distances, though.

_Transformer_ losses are greater at lower frequencies.  And the cores 
have to be bigger.

That is the primary reason military avionics, and other onboard gear
use 400Hz AC.  


Note: The U.S. as recently as immediate post WW-II had some areas of 
25-Hz power.  Transformer based equipment that was designed to be 
"just adequate" for 60Hz mains was known to 'let the smoke out' when
plugged in in one of those 25Hz areas.





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