Re: Is it possible for only one side of a NST to work?

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Christopher Boden by way of Terry Fritz <twftesla-at-qwest-dot-net>" <chrisboden-at-hotmail-dot-com>

Not only is it possible, it's rather common :)

When an NST fails on BOTH terminals the problem is almost always in the 
Primary coil (this is often accompanied by smoke and tripped breakers).
When one side of the HV dies it's because an NST isn't a simple transformer, 
it's Center Tapped, and one of the sides is open or shorting to ground or 
what not. Most likely cause is a Carbon Track of burned tar from a secondary 
winding to the inside of the case shorting out the output.

If you melt the tar inside and slosh it a bit before cooling it's usually 
enough to fix it :)

In a center-tapped transformer what you have is actually 3 seperate 
windings, not 2.

Winding-1 Primary
Winding 2 Left side Secondary
Winding 3 Right Side Secondary

They all go on the same core.

Both sides of the Primary winding exit the case and are the low voltage 
terminals you connect power to. But only ONE SIDE of each HV winding exits 
the case, the other side is connected to the core. The reason for this is 
that....

1. it makes a safer transformer (you're less liikely to get bit because the 
case is grounded at all times and can't float to HV).

2. It makes it a lot cheaper to build (the real reason they do this). 
Because each side of the transformer sees only HALF the voltage, this means 
they can use less tar, smaller insulators, etc.

An NST isn't actually a 12 or 15kV transformer! In a 12kV NST what you 
actually have are 2 seperate 6kV transformers working in perfect time, 180 
degrees out of phase, so when you connect across the dual secondary leads, 
you're getting 12kV total. Because when the left is at 6kV positive, the 
right is at 6Kv Negative.

It's a great way to cheat and get more power for less component cost. It's 
also why one side can die and the other work fine.




>Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" 
><Beans45601-at-aol-dot-com>
>
>Is it possible for only one side of the nst to work? I have 2 15/30 NST's,  
>and
>at first, one of them stopped to work on one side. Then, a day later, the 
>other
>one did the same thing. but, on one side, everything is peachy! what is 
>going
>on here...
>Thanks
>Adam





Christopher "Duck" Boden Geek#1
President / C.E.O. / Alpha Geek
The Geek Group
www.thegeekgroup-dot-org
Because the Geek shall inherit the Earth!

"He had that rare weird electricity about him--that
extremely wild and heavy presence that you only see in
a person who has abandoned all hope of ever behaving
normally." --Hunter S. Thompson


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