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[TCML] NST failure ?? variac problem too



Hello group,

Well I haven't posted here it a while, but I was testing a new NST filter that I just built with my 12Kv/60mA NST and el cheapo variac and I popped the breaker. The power switch on the variac was turned off, it's just a switched hot and the dial was set to zero. I went to plug in the NST, just as I inserted the plug into the variac the lights in the room dimmed and pop goes the breaker : - 0

It turned out that the Hot and Neutral was reverse at the AC receptical where I plugged in and the way that my variac is wire, a full 120 VAC to GND went to the NST. Now I don't think that this should case the breaker to pop. I'm under the assumption that the primary is floating and the secondary is supposed to be center tap grounded. Please correct me if I'm wrong.

I checked the NST with a ohmmeter I I measure 3.3 and 3.7 ohms to ground from the 120VAC terminals. ??????? Each secondary terminal was about 2.5K ohms to ground. It's an Allanson type 455B if that helps. Is my NST blown??

The variac is one of the china built white ones, a 2090VR. This incident could have been dangerous! I think I have to put a different switch on it that opens the hot and neutral. Anyone modified one of these?

thanks,

Shaun Epp
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