Vincent, 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.
Dave 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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