[Amps] Here's a Shocker

[John Lawson]

   Usually I try to snip replies - but all this is relevant:



On Mon, 15 Nov 2004 Dennis12Amplify at aol.com wrote:

>
> In a message dated 11/13/04 9:40:48 AM Central Standard Time,
> dezrat1242 at ispwest.com writes:
>
> Which makes me wonder if it  wouldn't be good to have our AC power
> lines run at about 1000 Hz or  so.  No more shocks, no more accidental
> electrocutions.  The  worst that could happen would be a burn.
> Something to think about,  eh?
>
> I know the arguments against it - transmission loss being the  most
> significant - but someday when houses have their own little  nuclear
> generators and are "off the grid" it might be something to  consider.
>
>
> ----------------------------------------------------------------------------
>
>
> Actually, the power transmission would be much more efficient as the
> transformers and capacitors could be made much smaller.
>
> Regards,
>
> Dennis O.


   With all due respect, and purely out of regard for your personal safety, 
I *STRONGLY* suggest that both you gentelmen immediately suspend all 
involvement with these items until you gain a better understanding of 
basic AC theory and practice!!

   In the first place, the adverse physiological effects of voltage on the 
human body is due mainly to currents above a certain threshold across the 
chest cavity and heart structures, clamping and spasm of muscles resulting 
in tearing of tissues, and nerve damage/eradication.  Then there are the 
burn phenomena, both resitive and RF induced.

   These come into play at various points and severities, depending on the 
amount of current dropped by the body, the path taken by the voltage, and 
the frequencies (from DC to RF) as well as the voltage, and the duration 
of the exposure.

   Y'all *really* oughta read up on some basic electrical and RF safety - 
I'm sacred for you.  I've lost friends in electrical accidents and it's 
not the prettiest way to depart the planet.

   As for power transmission being more efficient at higher line freqs: 
look up "skin effect" and see how that tallies with your theory. High 
frequencies travel more and more on the the surface of a conductor - which 
is how microwaves use 'waveguide' (very basically).  Many times you will 
see big HF coils wound with tubing - no use having all that copper if 
it'll never see the currents.

   Aircraft used to use 400 Htz to cut down on the iron/copper wieght - but 
the most modern ships are all going to DC busses as the gear gets smaller 
and more integrated.

   Please do get a btter idea of these safety issues before you find out 
the hard way.

  Cheers

John  KB6SCO