Re: variac question

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

Original poster: Edward Wingate <ewing7-at-rochester.rr-dot-com> 

Tesla list wrote:
 >
 > Original poster: "David Rieben" <drieben-at-midsouth.rr-dot-com>
 >
 > Scot,
 >
 > I beg to differ on the paralleling choke. He WOULD need a choke if he were
 > in fact PARALLELING two 1256D Powerstats (240 volt input for a 0 - 240/280
 > volt output). However, Kevin was asking about SERIESING (is that a word?)
 > two 1156D Powerstats (120 volts input for a 0 - 240/280 volt output). No
 > paralleling choke(s) are needed to place two variacs in series.
 >
 > David Rieben

Dave,

Chokes are NOT necessary for Tesla coil service. They won't hurt, but
just aren't needed. I have a number of paralleled Variacs and Powerstats
from 2 stacks to a 6 stack in TC use, none of them has paralleling
chokes and I've never had a problem. All that's necessary is to be sure
that the sections are "tracking" together by checking the output of each
section at the wiper to make sure they are the same within half a volt
or so. If they aren't, the locking setscrew at the shaft can be loosened
to adjust the wiper plate. Make sure all the setscrews are TIGHT when
you are done. For continuous 24 hour a day use, chokes ARE needed to
keep the Variac/Powerstat from overheating caused by circulating
currents. Thirty minutes to an hour of Tesla use has never caused any
signs of overheating in my equipment.

I have chokes but they're in a drawer in my lab, still in pristine
condition. :^)

Ed Wingate RATCB