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Re: variac
Subject:
Re: variac
Date:
Sat, 22 Mar 1997 00:46:59 -0800
From:
Open Minded <"unknown-at-apc-dot-net (No spamming! Try
\"70314.1744"-at-compuserve-dot-com~but_remove_this_part!~.pupman-dot-com>
Organization:
I'm NOT organized!
To:
Tesla List <tesla-at-pupman-dot-com>
References:
1
Tesla List wrote:
>
> Subject:
> Re: variac
> Date:
> Tue, 18 Mar 1997 15:12:23 -0600 (CST)
> From:
> c604313-at-showme.missouri.edu
> To:
> Tesla List <tesla-at-pupman-dot-com>
> CC:
> tesla-at-poodle.pupman-dot-com
>
> > Bert,
> >
> > I have sucessfully ganged two 10 amp variacs in parallel for heavy neon
> > sign
> > transformer use. Using power factor correction caps on the transformer
> > primaries will help lower the current.
> >
> > Ed Sonderman
> >
> >
> Yeah Ed, I had thought of a paralleling variacs also, but then thought
> simultanious adgustment of the variacs would be to tricky. Are your
> variacs mechanically linked together or do you adjust them with both
> hands?
>
> Also, out of interest, what are the values of your PFC caps?
>
> Thanks,
> -Bert S.
Gentlemen -
Thought I'd jump in here and give my 2 cents worth....
When you parallel 2 or more variacs together, you really ought
to use a paralleling choke. Even though you might get the brushes
aligned on the exact same turn, there will still be slight variation
in inductance and such.
A paralleling choke works as a common-mode current choke. A current
imbalance in one variac is coupled to the other so that each variac
actually 'sees' it's share of the current. (The choke will create
a slight voltage imbalance on the input though - this is how it
keeps the currents split equally.
I use two 20-amp 120-volt variacs paralleled with a choke to drive
my 3.6KVa coil system. Each variac sees it's share and runs nice and
cold.
- Brent