Re: Does a variac with no load dissipate power?

["Malcolm Watts" <M.J.Watts-at-massey.ac.nz> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

Hi Gavin,
           With no load, ideally none - in practice, a little. 
Copper losses will go up with loading.

Regards,
Malcolm

On 4 Sep 00, at 20:21, Tesla list wrote:

> Original poster: ghub005-at-xtra.co.nz 
> 
> Hello list
> 
> I feel a bit embarrased about asking this, but does a variac with no 
> load consume a signnificant amout of power? I imagine it dissipates 
> a little power through hysteresis + resistance etc - but I have no idea 
> of the actual amount.
> 
> I'm asking because I've just finished my 11kVA three-phase PSU 
> and I want to put a switch in that allows me to bypass the internal 
> variac and inductive ballasts. The circuit I have in mind won't isolate 
> the variac stack - it just switches between the variacs' output 
> terminals and a bypass line.
> 
> Thanks in advance for your help,
> 
> Gavin Hubbard
> 
> 
>