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RE: Power Load Balance Concern



Original poster: "Pete Komen by way of Terry Fritz <twftesla-at-qwest-dot-net>" <pkomen-at-zianet-dot-com>

Hello Matt,

I got a 7.5 KVA dry transformer off eBay a while back, 480/240 to 120/240.
Total cost was less than $90.  Shipping for 108 lbs cost more than the
transformer.  I haven't wired it in yet (I need an auxiliary power panel.),
but 60 amps at 120v should handle anything I can think up short of a pole
pig.

You can run the variac over its rating.  It will heat up faster and you'll
need to stop to let it cool off sometimes.  If you're not doing long runs,
it will be OK.

Pete Komen - Las Cruces

-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Sunday, September 23, 2001 12:52 PM
To: tesla-at-pupman-dot-com
Subject: Power Load Balance Concern

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<Mddeming-at-aol-dot-com>

Hi All!
        I am in the process of upgrading my power supply to 4 15/60 NSTs and
already have a 120v input -at-30Amp,  model W30M Variac. Based on nameplate
ratings, the NST bank  should draw about 33 Amps total (4X8.25). The
problem:
since there is only one open slot left in my breaker box, I would like to
use a
40Amp breaker, but I have not seen single breakers for this kind of current.
Most are dual breakers -at- 240 V using both sides of the line to keep the load
balanced and prevent in-house brown-outs.  If I try to get a 4KVA
step-down/isolation transformer so as to utilize both sides of the line, I
am
looking at ~$350 plus S&H on 120 lbs.
Questions:
1. Is running the Variac at +10% a real concern?
2. Is placing this size load on one side of the panel going to create
in-house
imbalance problems?
3. Anyone got a cheap step-down 4KVA transformer?

Would appreciate response from any/all with experience in this area.

Matt D.
G3-1185