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.

More information about the NANOG mailing list