[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [TCML] frailty of NSTs
Happy Easter to those who celebrate.
What is it about NSTs that makes them so fragile? I suspect it is the
current through a secondary wound with
inadequate wire size.
I have a couple of E I laminate core transformers 1.25 inches wide by 3
inch stack, six by seven o.d.
that I am considering rewinding. I believe that winding separate
primary and secondary would be better
than secondary over primary or even primary over secondary.
Any thoughts on this?
I think the so-called "fragility" is only in that their insulation
isn't designed to withstand very much excess voltage such as can be
created by resonance or near resonant capacitive loads; in other words
you can short one if you do something stupid. I'm not sure that they're
much different from ordinary small transformers in this regards. Power
line transformers are designed to take high surge voltages but that's a
different type of device.
While in normal sign service the secondary voltage of an nST is
usually limited by the tube drop to significantly lower values than the
open circuit ones I think their open circuit life is pretty high,
probably comparable to other transformers of similar size. I ran one
open circuit outdoors rain or shine for about three years in an electric
fence application [very dangerous of course] and it certainly survived
unscathed. This particular transformer [9 kV, 60 ma] had been shorted
earlier in TC service when I accidently opened the spark gap too far but
I had restored it by just remelting the tar at the shorted end with a
heat gun, indicating that the short was external to the winding.
Tesla mailing list