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Re: Transformer loading

Thank you Eric,

This is pretty much what a few of us have been trying to say.

To those who are new to the list, my free transformer loading program for 
Windows, Neon Lite 1.0, can be downloaded at:

http://www.neonshop.com/software/

It emulates the standard load chart.

Kenny



> 
> Since being on the net for the last week or so, I've seen several opinions
> regarding *proper* transformer loading.  While not professing to know
> anywhere near everything, we at Allanson have a great deal of experience
> which has led us to summarize some general guidelines.  I thought I would
> share these with the group.  Perhaps someone will find them helpful.
> 
> Virtually all ferromagnetic neon transformers are designed to work
> effectively within a certain limited set of operating parameters.  That's
> why there's not one size to fit all loads.  If the transformer is too big
> for the load, excess heat is generated which may cause permature failure of
> the unit.  If the load is larger than for which the transformer is designed,
> all sorts of bad things take place.  Things like high voltage spikes, excess
> corona, distorted waveforms, etc.  These kind of things tend to punch holes
> through insulation materials therefore causing shorts in the secondary coils.
> 
> We're asked all the time for recommendations regarding transformer selection
> for unusual jobs.  Unfortunately, this is not simple since there are usually
> many variables to consider.  Not only do we need to know tube load but we
> need to know tube fill pressures, processing conditions, electrodes,
> proximity of tubes to dead metal,  lengths of gto/conduit (if used), primary
> input voltage, ambient temperatures, ad infinitum.
> 
> So, here's how we start.  We recommend that one starts with the ANSI footage
> chart (that's what Allanson uses).  Barring that, go back to the
> manufacturer of the transformer to ascertain that you and he use the same
> chart.  Start from there and confirm variables such as tube diameter,
> footage, *fill pressure* and current rating.
> I must first stress...follow the recommendations and instructions of the
> manufacturer.  It seems like something so simple, and I am almost
> embarrassed to mention it but we see so many instances where someone has
> violated the obvious.
> 
> We suggest to inquirers that they do not overload transformers.  That means
> don't use more footage than the chart allows.  We also suggest that
> *generally* one should not underload a transformer by more than 20% to be
> conservative.  If there is no other alternative to underloading, one risks
> premature failure of the transformer due to buildup of excess heat.
> 
> For further confirmation of proper transformer selection, we run a voltage
> check of the operating voltage on the secondary side of the transformer.
> This can be accomplished with a Multimeter (like a Fluke 83) and a
> high-voltage probe.  If probed on the secondary terminals of the transformer
> (while energized and connected to the chosen tube load) a *proper* reading
> should be a total of one-half of the rated open-circuit voltage of the
> transformer.  For a midpoint-balanced design, that means each secondary
> terminal should read one quarter of the labelled open circuit voltage of the
> transformer.
> 
> Well, this has gotten longer than I originally intended and I haven't
> scratched the surface.  In summary, it should be stressed again that all
> transformers have a proper *operating window* and shouldn't be run outside
> of the window unless one wants to consider the consequences.  Barring that,
> one must change other variables within the system.  If fill pressures are
> adjusted off what is called for in the footage chart, this absolutely has to
> be considered for proper transformer selection.   
> 
> If anyone wants further explaination, it would be best if we sent you our
> Loading Guidelines and had a long chat about it.  Thanks for your interest.
> 
> Eric Johnson
> Director of Marketing
> Allanson Transformers
> 
> 
> 
Kenny Greenberg --  Neon - Scenic and Environmental Art  
                    Internet Site Consultant and Author   
KRYPTON NEON 34-43 Vernon Blvd Long Island City, NY 11106
         Phone: 718-728-4450  Fax: 718-728-7206  
http://www.neonshop.com  -  The Internet's Neon Shop
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