Re: NST specs for normal operation

["Ed Phillips" <evp-at-xxxxxxxxxxx> (by way of Terry Fritz <twftesla-at-xxxxxxxxxx>)]

Tesla list wrote:
> 
> Original poster: "harvey norris" <harvich-at-yahoo-dot-com>
> 
> I dont know if coilers really beat up their NST's: I
> had assumed that they always go to their maximum rated
> output? Can any one guess if this only occurs when the
> gap fires, or is the transformer continually
> "overstressed" producing its maximum rated output?
> 
> Here is a manufacturere that suggests 80% use of its
> nameplate rating;
> http://www.eurocom-inc-dot-com/transformers.htm
> 
> All transformers should be loaded properly and
> operating at 80% of their
> rated short
> circuit mA current capacity.
> 
> If you use a ferro magnetic transformer that is too
> large for the amount
> of neon footage
> that you are lighting, the transformer will run very
> hot and eventually
> develop problems.
> 
> .......
> 
> Suggested operating current levels for (ferromagnetic)
> Transformers is
> 80% of short circuit current, i.e.:
>                        a 20mA Transformer should
> operate at ca. 16mA
>                        a 30mA Transformer should
> operate at ca. 24mA
>                        a 60mA Transformer should
> operate at ca. 48mA
> 
> Since we only operate tesla coils for breif amounts of
> time, I would assume the above specs are made for a
> continuous operation idea. Thought I would post this
> since I have seen other posts saying A NST can have
> its outputs shorted for 24 hours with no damage??
> Wouldnt they get pretty hot? HDN
> 
> =====
> Binary Resonant Systemhttp://www.insidetheweb-dot-com/mbs.cgi/mb124201

	For what it's worth, I have had experience running NST's for years both
short-circuited and open-circuited, with no failures.  I have an
electric fence (skunk zapper) around my back yard.  If ran for a couple
of years excited by a one half of a 9 kV, 60 ma transformer, with the
other half open circuit.  I gave that transformer away and replaced it
with a similar one which had half of the secondary partly shorted.  I
shorted the bad half to ground with a wire and used the good half to
excite the zapper.  It is still working fine after about 18 months,
having been turned on all night, every night in both clear and rainy
weather.  Both of these transformers were Jeffersons, from a batch I
found lying beside a freeway on ramp where they had obviously fallen off
the back of a truck.  The insulators are mangled by hitting the
pavement, and in one case the terminal screw was broken off inside the
transformer.  

	At least in my limited experience these things are pretty rugged,
PROVIDED you don't wreck them by running them with a secondary capacitor
and with the spark gap set too wide; that's the way I blew up the half
of the transformer I'm using now; in the course of messing around with
primary hooked up with clip leads I managed to power up with the gap
disconnected.  The thing wasn't turned on for more than a few seconds,
but half of the transformer shorted in that brief time.

Ed