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Re: [TCML] Recent variac problem.

I had 2  12kv 60ma NST that were blowing 20amp fuses in my variac.  I can now run 3 12KV 60ma NST because I added 10 50uf 370V ac caps for pfc.  I put a amp meter gauge on the incoming 120v feed.  Then Ikept adding he air conditioning run caps till I got what I wanted the lowest current draw which was around 9 caps, used 10 cause it was a even number.  But I can run it without blowing fuses or tripping circuit breakers again.
John Cooper

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-------- Original message --------
From: David Speck <Dave@xxxxxxxxxxxxxxxx> 
Date: 11/24/2015  21:58  (GMT-06:00) 
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx> 
Subject: Re: [TCML] Recent variac problem. 


What is the rating of the fuses you are using?  10 amps?

Are they slow blow or fast blow fuses?

Many old-school name brand variable autotransformers (Variac, Powerstat) 
can handle double their rated nameplate current ratings for short runs 
of 30 - 60 seconds without being damaged.  Can't say the same for some 
of the cheap Asian imports, though.

A Variac is not the part of the circuit that provides current limiting.  
That is established by the NSTs themselves.

If you want to run 4 NSTs simultaneously, you will need a Variac big 
enough to provide the all current they require.

Adding power factor correction capacitors (PFC) to the transformer input 
may help manage their current drain.


On 11/24/2015 7:46 PM, Vincent D'Amore wrote:
> Hi All
> Recently I've been running my coil controlled by a 10amp variac. I'm running two parallels 12/30 franceformer neons sign transformers and have been running this way for several years but as of late I keep blowing fuses on the variac about every 4th run. I'm not sure if or what has weakened over time. I would like to run my coil with a much larger power supply but that obviously won't go over well with my 10amp variac and I certainly don't want to move forward until I know the weakest point. Any suggestions? Also if I do go with a larger supply I'm thinking of 4 12/30's in parallel but don't know what to do for current limiting. Larger variac? Something else? Thanks for any advice.
> Vincent

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