[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [TCML] Variac



Hi Tim,
 
I would suggest looking in the next available hamfest that comes to a town near you. I've found that you can get much better deals at hamfests than through eBay. Plus, you don't have to worry about shipping charges. I have a 120/ 0-140 volt, 22 amp rated 136B Powerstat that I picked up at a local hamfest just a few years ago for a song. I wanna say that the vendor was only asking $30 for it, IIRC. I didn't even try to haggle with him over the price, just promptly pulled out my wallet and handed him the money and headed straight to my vehicle with it. That was too good of deal to pass up ;^)   http://www.arrl.org/hamfests-and-conventions-calendar
 
David

From: Tim Flood <tflood@xxxxxxxxxxx>
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx> 
Sent: Tuesday, May 7, 2013 1:16 PM
Subject: Re: [TCML] Variac


Thanks Jon for educating me. This will help in my search.

Tim

--------------------------------------------------
From: "Jon Danniken" <danniken@xxxxx>
Sent: Monday, May 06, 2013 2:44 PM
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Subject: Re: [TCML] Variac

> On 05/06/2013 08:39 AM, Tim Flood wrote:
>> Looking for a variable transformer for my new find, a 14,400/120V potential transformer. I have have checked eBay.
>> 
>> Does anyone have a variac for sale, at least 30 amps?
> 
> Hi Tim, one thing to keep in mind about variacs is that most domestic versions are rated for continuous duty.  This means that a 30A variac is rated to control 30A 24/7.
> 
> If you want to run them at a higher current than they are rated for, you can do this, provided that you limit the duty cycle of the variac (the limiting factor is the amount of heat that builds up).  The manufacturers actually plan for this, and provide a duty cycle chart for the units.
> 
> As an example, here is the duty cycle chart for GE Volt-Pac variacs (other manufacturer use a similar curve):
> 
> http://i.imgur.com/2fOYa7N.jpg
> 
> As you can see, you can run a variac at double the rated current, provided that you limit the duration to less than ten minutes.  In Tesla coiling, this usually isn't a problem, because we generally limit the run time to less than a minute or two (I personally use a 25A, 240V variac at 60A with no problems whatsoever, and actually built the power supply with this in mind).
> 
> Jon
> 
> 
> 
> _______________________________________________
> Tesla mailing list
> Tesla@xxxxxxxxxx
> http://www.pupman.com/mailman/listinfo/tesla 

_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla
_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla