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Re: Defeat the SGFP Transformers!
Tesla List wrote:
> >I wonder if a Tesla cap discharged into the relay would help to weld it
> >closed :-)) Hopefully, we can figure out the work around before we ever
> >see the first one. Of course, the neon sign guys may do it for use if the
> >thing works as poorly as I suspect...
Hey, I didn't X-ray one only out of simple curiosity :-)
>Hopefully, the new gizmos will fail
> >often and send large numbers of almost new transformers to Tesla land... I
> >bet the new designs will be dropping like flies. Just a new bunch of parts
> >to fail. This may be a good thing for us.
That's what we're hoping too. This whole caper is kinda like
passing new gun control after some kid plinks at school - gross
over-reaction plus it doesn't address the problem. (neon fires, in
this case)
> A couple of thoughts -
> Assuming the relay is controlled by some electronics, it may be
> practical to zap the control circuitry with a TC - semiconductors tend
> to fail short, so hopefully the relay will be held on.
I don't think so. The UL standard is fairly comprehensive and
fail-to-safe is part of the requirement.
Use with a
> variac could still be a problem, though, as the relay wouldn't cut in
> below a certain voltage.
The major mfrs are claiming that their SGFP trannys can be dimmed
and flashed so this shouldn't be a problem. Neon is almost never
taken below about 75% to dim so anything below that may be a
problem.
> I wonder however if these requirements will accelerate the move to
> 'electronic' high-frequency transformers - the higher cost of the
> electronics would be partially offset by the protection circuitry,
> which could be implemented more easily on electronic units - now that
> would be the _real_ tragedy!
Won't happen. HF trannys can't drive the high capacitive loads
represented by typical NEC-compliant installations. Another part of
this neon nightmare is that they changed the code to require neon
high voltage wiring to be completely contained in metallic conduit.
Previous practice was nonmetallic conduit. The capacitance between
the high voltage (GTO) wire and the conduit is killing neon.
Problems that are familiar to teslaphiles - resonance, RF heating of
the tranny, sputtering of the neon electrodes. so as long as this
standard is in place, the good old coil-and-core trannys will still
be there, only shackled with an electronic dongle.
John
--
John De Armond
johngdSPAMNOT-at-bellsouth-dot-net
Neon John's Custom Neon
Cleveland, TN
"Bendin' Glass 'n Passin' Gas"