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Re: Transformer location/Safety

Original poster: "D.C. Cox" <resonance@xxxxxxxxxx>
I see what you are saying. My point is to simply use the best possible engineering, ie, not give away any power you don't have to in parasitic losses. You're absolutely correct though --- spark gap losses contribute the greatest losses, heat, light, etc, which is why everyone is running to solid state drivers for many applications.
If you take a coil such as yours out to a school, with xmfr direct mounted, you will need a good supply of gorillas to move it about or "lotsa caster wheels"!!
On our NST pwr supply boxes we just use handles. If we use multiples of 60 or 120 mA NSTs we put them in separate boxes and "jumper" them together with GTO and simple 1/4 inch bananna plugs/receptacles mounted on delrin plastic plates --- keeping things modular really helps reduce the weight when we haul the coils around for school programs, public demos, etc. It's important to consider this in the very design phase when building a coil. Carrying boat anchors isn't much fun --- been there, done that. 

Dr. Resonance


----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Tuesday, April 18, 2006 1:27 PM
Subject: Re: Transformer location/Safety



Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>

Is it a bad idea?? Maybe and maybe not.
Do you get eddy current losses?? Yes! You also get copper losses, sparkgap losses, etc.
Are these losses significant?? Depends on how close the metal is to the primary. My 4 NST's are 1.5 feet below the primary. The cases dont touch each other and are only connected together by a one wire connection to minimize eddy currents. Is my power loss significant. I dont think so since I get 86 inch arcs with a 15KV 120ma source (freau factor of 1.9 based on measured real power at the wall of 2KW).
The real question, I believe, for each one of us to answer is how much loss is acceptible. Everything in life is a trade off for the most part. 

Gerry R.



> Original poster: "D.C. Cox" <resonance@xxxxxxxxxx>
>
>
>
> Bad idea.  I've already several reasons on this list why mounting the
> nst under the primary is a bad idea but people keep trying to do it
> wrong anyway.  Magnetic field sweeps upward as well as downward and
> will go right thru you aluminum shield to induce currents in your
> copper xmfr windings. Also, downward sweeping magnetic fields will
> give up power, ie losses, in anything iron, steel, etc below the
> primary.  Just don't do it --- it's very bad basic engineering!!!
>
> Aluminum does not stop a magnetic field.  In high power Tokamaks they
> wind the high current windings on the "outside" of the aluminum
> container so the magnetic fields can effect the conductive plasma
> inside the container.
>
> Mount your nst in a box 4-5 ft away from the coil and you will be
> miles ahead without losing power or inducing RF currents into your
> xmfr windings.
>
> Dr. Resonance
>
>
>
> >Original poster: "Rich" <rdjmgmt@xxxxxxxxxx>
> >
> >Spring is here and I am ready to start my next coil and was hoping to
> >put my HV transformer on the base the same as Gerry did on this fine
> >looking setup. My question to the wise ones, would it help to place an
> >alum RF shield over the top of the transformer because mine is NOT an
> >enclosed NST. It is from a laser power supply, the windings are > >exposed 
> >and are the highest part of the transformer.
> >   I must also add that I smile each time I see the picture of Gerry
> >standing by his setup keeping safety in mind and one hand in his > >pocket 
> >and a good ground by being barefoot. :)
> >
> >Rich , from the middle of Missouri
> >
> >
> >
> >
> >Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>
> >
> >Hi Kevin,
> >
> >I run my NST farm (15KV 120ma under the primary and have no
> >problems.  It is about a 1.5 ft underneath the primary.  You can look
> >at the pictures in the directories at:
> >
> >http://hot-streamer.com/temp/GerryReynolds
> >
> >and judge for yourself.  I think if you keep things at a reasonable
> >distance underneath the primary, you will be OK.  I did think about
> >the magnetic field orientation when placing the Terry filter
> >components trying to get field cancellation where possible, but dont
> >know how critical this is at that distance.
> >
> >Gerry R.
> >
> >  >Original poster: "MakingLightning" <MakingLightning@xxxxxxxxxxx>
> >  >
> >  >Does it hurt to put your main power transformer and
protection > > filter
> >under
> >  >the teslacoil?
> >  >
> >  >Some people have said not to put metal or protection filters
under > > it
> >and
> >  >they should be put aside somewhere.
> > >This makes sense but I have seen many coils that have everything > > but 
> >the
> >  >variac under one. In practice has anyone found out if it
really > > makes
> >much
> >  >of a difference?
> >  >It sure would make for a neat package to have everything except the
> >variac
> >  >under the coil.
> >  >
> >  >Kevin
> >  >
> >  >
> >
> >
>
>
>