Re: Ganging Variacs (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Thu, 16 Aug 2007 19:08:58 -0700
From: Barton B. Anderson <bartb@xxxxxxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: Ganging Variacs (fwd)

Hi Terry, Tim,

I did the same with my variac. I split the core to prevent saturation. 
It's been a life saver for me since I only use a single variac with my 
pig. But, if I had a large enough variac or two, I wouldn't have done it 
(as it does ruin the variac for any other purpose). But if it's solely a 
current limiting variac, cutting the core will help prevent saturation 
issues, although I have smoked the brushes on this variac from too much 
current. Even though saturation is prevented, current still flows and 
the components that make up the variac can still be damaged if high enough.

BTW, remove the brushes at least once a year and inspect them. Can 
prevent a bad situation. The smoked brushes occurred at my 2005 4th of 
July party. Funny, I just turned the current down and the smoke went 
away. The coil kept on Rockin! The next weekend I did the optopsy and 
found I was running on about 1/3 brush surface. I learned from that 
experience to inspect brushes and replace when worn.

Take care,
Bart

Tesla list wrote:

>---------- Forwarded message ----------
>Date: Thu, 16 Aug 2007 12:46:40 -0500
>From: Terry Oxandale <Toxandale@xxxxxxx>
>To: Tesla list <tesla@xxxxxxxxxx>
>Subject: RE: Ganging Variacs (fwd)
>
>There has been a great deal of discussion on this issue as well as the
>parallel aspect. My experience was saturation of the variac core, but
>this is based upon the core size and voltage/turns ratio. I don't have
>the greatest understanding of this issue, but I believe it is focused on
>the fact that only a small portion of the core is used in most of these
>applications (reduce the number of turns reduces which increases
>current, but also increases the voltage/turns ratio to a point of
>saturation.
>
>I successfully split the core of my variacs (two 1256 variacs in
>parallel) to prevent this from happening and have been very happy with
>the modulated current profile as compared to the nearly uncontrolled
>profile previous to splitting the core. It was a lot of work though.
>
>Terry
>
>-----Original Message-----
>From: Tesla list [mailto:tesla@xxxxxxxxxx] 
>Sent: Thursday, August 16, 2007 7:12 AM
>To: tesla@xxxxxxxxxx
>Subject: Ganging Variacs (fwd)
>
>
>---------- Forwarded message ----------
>Date: Thu, 16 Aug 2007 07:48:34 -0400
>From: timjroche@xxxxxxx
>To: tesla@xxxxxxxxxx
>Subject: Ganging Variacs
>
>I understand about using paralleling chokes when using variacs for
>voltage
>control, what about for ganged series variacs for current control or
>in-other-words, adjustable ballast?
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