Re: Dumbass Electrical question
- No, all the current is not going through the coil all the time. As you
surmise, with lower voltage comes lower current in the variac coil.
Have a look here:- http://www.nmr.mgh.harvard.edu/~reese/VariacPage/
You are correct. Halve the voltage and you quarter the power. Indeed,
your thoughts on achieving the two powers are definitely sensible,
especially if you have both voltages available as in many homes in the
States. But if you haven't, you could take a similar approach to me.
Your variac won't cope with the 13.6A needed on full voltage but it
would cope if the voltage out was halved as the element would only be
drawing 6.8A. I run my 3200W element straight to the 220V mains then
when the wash boils I plug the element into my burst-fire controller
set to produce around 800W. This way the controller doesn't have to
cope with 14.5A.
PS Never forget google - it is where I got the link above!
PPS We are dealing with potentially lethal voltages here, so be sure
to get your solution checked by an electrician if you are in any doubt.
--- In email@example.com, Derek Hamlet <derekhamlet@...>
> I have a question about my variac voltage controller and another
> I have two variacs. One I purchaed, the other I found at the
> dump. My purchased one is rated at 10 amps and works very well in
> all facets of my distilling. The other is 7.5 amps and I managed to
> blow the 8 amp fuse when I ran it at 100%. My question is about how
> a variac works. Does it pull all the amps through it all the time,
> but, just burns them up in the coil, or does the amperage decrease as
> you decrease the voltage? I'd like to be able to use it in
> distilling, but, need to understand its limitations.
> My other question concerns wiring. When I change my still or build
> another one I'd like to use only one 240volt element, but, wired
> between the wall and the element such that by flicking a switch I
> can change it from 220 to 110. If there is a fairly simple way to
> do that then I can use the one element for both heat up and then
> control. It seems to me that a 3000watt element at 220 volts becomes
> 750 watts at 110 volts.
> Any enlightenment or links to help me answer these questions would be