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Re: Paralleling Choke for Paralleling a 3 phase variac???



Essentially, what you need is a transformer that has 3 windings on the same
core that can carry the current.  You can fake it with 3 regular
transformers.

Find 3 lowish voltage transformers with secondaries that can carry the
variac current (big filament or DC power supply transformers might do)  If
you could find some 6V/30Amp transformers (that'll be a 180VA, and not TOO
big), and you'd be doing fine.

Connect each of the low voltage winding in series with one of the variac
outputs.

Connect all the HV (110V) primaries in parallel. (make sure the phasing is
correct!)

have at it..

Gotchas here:

1) If the voltage difference between variacs is more than the rated
secondary voltage of your transformers, then the primary voltage is going to
rise above 110V.  Too far, and the core will saturate (just like trying to
run a 120V NST on 240V.  In reality, I doubt the voltage varies more than a
couple of volts, so you're probably ok here.

2) Watch the current ratings!.




-----Original Message-----
From: Tesla List <tesla-at-pupman-dot-com>
To: tesla-at-pupman-dot-com <tesla-at-pupman-dot-com>
Date: Tuesday, March 07, 2000 8:44 AM
Subject: Re: Paralleling Choke for Paralleling a 3 phase variac???


>Original Poster: "Paul Eugene Kidwell" <tmb-at-ieee-dot-org>
>
>
>
>Original Poster: Terry Fritz <twftesla-at-uswest-dot-net>
>>
>> The manufacturer of the variac can be found on the web, probably Staco or
>> Powerstat (Werner):
>>
>> http://www.stacoenergy-dot-com/
>> http://www.warnernet-dot-com/sev_ps01.html
>>
>> They will be more than happy to sell you the chokes.  They are not
cheap...
>
>Boy! You weren't kidding!
>
>I e-mailed Stacoenergy and Warner, Staco sent the following...
>
>> The part number for the paralleling you need is 52LAC-S. Three pieces are
>>required to convert the unit to single phase (one for each coil). The cost
>>is $178.00 each and may be ordered direct.
>
>Ouch! $534.00. (a bit beyond.... *WAY* beyond my price range)
>
>Well, anybody have any thoughts on how to wind one of your own???
>
>Paul
>
><<< Yeah!!  That's bout what I remember! - Terry >>>
>
>