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Re: 60A Variac on Ebay

Original poster: "David Rieben" <drieben@xxxxxxxxxxxxxxx>

Hi Skip,

You wrote:

David,
an additional problem you may have is that you can not directly connect two or more Variacs since their output voltages will never be exactly the same. They will be fighting each other. Are you REALLY driving a transformer that NEEDS 84 Amps at 240 Volts?

Well, actually yes ;^) I have a 15 kVa pig, but my newest ballast
allows me to draw upwards of 100 amps from a 240 volt supply!
I don't run it that "hot" very long at a time but I can draw that
kind of power. You can see the coil at: http://dawntreader.net/hvgroup/david/gm.html
I need to update the page to show my newest big bad
ballast as it's not on there yet. Also, I also use my ballasted
output from the control panel to drive a BAD Jacob's ladder
that needs this kind of power.

That would be an incredible Tesla coil. Do you really need 20 KVA? There is a way to parallel two Variacs that is just a center tapped inductor of appropriate current rating. You would then need a second inductor to put together three Variacs. After doing the paralleling inductor thing, I would do the limiting resistor thing and the relay or contactor if you still have a problem. Before you do these things, be sure of how much current you really need. 

There seems to be conflicting info out there as to the
need for paralleling chokes in coils. Some say that they're
really not needed for Tesla coils as long as they're of the
same brand and type of variac. My twin 1256Ds have one
already with them.

Happy coiling,
Skip


David Reieben

At 10:49 AM 11/12/2005, you wrote: 
Original poster: "David Rieben" <drieben@xxxxxxxxxxxxxxx>

Skip, all,

I have a Staco triple variac assembly that looks exactly
like that one. The only difference is the nomenclature tag
on mine states that it's a model # 5020CT-3Y, it's a 3-
phase unit rated at 480 volts input, 27.2 kVA, 28 amps,
and 0 - 560 volts output. It looks like the 480 volt rating
is based on a 3-phase delta hookup and after rewiring the
3 units as paralleled in a single phase setup, they work
on 240 volts input with 0-280 output (480 volts delta
phase/phase is 277 volt phase/ground - 480/sqrt3).
However, I have had one problem when powering up
these 3 paralleled variacs as a single phase, 84 amp
triple stack - It has a TERRIBLE inrush current problem
that will trip the 125 amp mains breaker about 8 out of 10
times on initial power up. It's so bad that I initially thought
that there was a dead short! I suppose the only way that I
could use it would be to place the ballast unit between
the wall plug and the variac instead of the standard setup
with the ballast between the variac and the transformer.?

David Rieben


----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Friday, November 11, 2005 10:05 PM
Subject: 60A Variac on Ebay


Original poster: Skip Malley <skip@xxxxxxxxxxxxxxx>

I just found a Variac on Ebay someone might be interested in.

The unit states 240 VAC, 3 Phase Input with 0-280 VAC @ 60 Amp output.

Here is the link:
http://cgi.ebay.com/Staco-Transformer-Variable-Variac-6010CT-34_W0QQitemZ7561203876QQcategoryZ1504QQrdZ1QQcmdZViewItem

It looks like three 240V variacs on a common shaft. Someone could probably buy it, remove two sections and sell the other two.

This might be good for some of you guys running the pole pigs.

Happy coiling.
Skip