Re: Report - Dimmer as a Variac.

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

>
> Looks like I am getting current spikes...  Big ones...  At first I though
> the MOVs where clamping voltage spikes but the fuse is on the other side
of
> the MOVs and the peak voltage is lower than the MOV clamp voltage.  Also,
> some of the lower voltage peaks are getting just as big of current spikes.
>
> I clicked the gain down and tried again to see how high the spikes are:
>
> http://hot-streamer-dot-com/temp/VanI-2.gif
>
> Only 58 amps!! =:o
>
> I suspected the 60uF of PFC caps are not getting along with the sudden
> dimmer voltage turn on which is about 180 volts.  So I pulled the
> connectors off the caps to take them out of the circuit and tried again:
>
> http://hot-streamer-dot-com/temp/NoPFC.gif
>

Try putting some inductance in series with the dimmer. It will limit the
current when the triac turns on..  You could also put the PFC on the line
side of the dimmer....