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Re: Oil Burner Ignition Transformers
Subject: Re: Oil Burner Ignition Transformers
Date: Mon, 12 May 1997 15:15:15 -0400
From: "Thomas McGahee" <tom_mcgahee-at-sigmais-dot-com>
To: "Tesla List" <tesla-at-pupman-dot-com>
----------
> From: Tesla List <tesla-at-pupman-dot-com>
> To: tesla-at-poodle.pupman-dot-com
> Subject: Re: Oil Burner Ignition Transformers
> Date: Monday, May 12, 1997 12:45 AM
>
> Subject: Re: Oil Burner Ignition Transformers
> Date: Sun, 11 May 1997 16:12:31 -0400 (EDT)
> From: "Daryl P. Dacko" <mycrump-at-cris-dot-com>
> To: Tesla List <tesla-at-pupman-dot-com>
>
>
> At 12:19 AM 5/11/97 -0500, you wrote:
>
> >I have come to realize that there is some misinterpretation as
> >to what an oil burner ignition transformer really is and how it
> >should be used.
> >
> >First let me point out that there are two types of oil burner
> >ignition transformers currently in existence. The older units
> >which are contained in a metal box approximately 5 inches X 4
inches
> >X 3 inches and are designed for continuous duty and IF used
properly
> >are damn near indestructible! Then there is the newer units that
are
> >much smaller and sometimes not even enclosed in any casing, these
are
> >NOT designed for continuous duty and are USELESS in terms of usage
in
> >a Tesla coil.
> >
> >Now to describe what the older oil burner ignition transformers
are
> >and how they should be used. An oil burner ignition transformer is
> >a regulating transformer just like a pole pig is and as such MUST
> >be used with a series limiting inductance in it's primary circuit
or
> >you will indeed burn it out! This is because a regulating
transformer
> >attempts to maintain a constant output voltage by pulling more
> >current when it is under load. In a Tesla coil the H.V.
transformer
> >for all intents and purpose is short circuited, which for a
> >regulating transformer means it is going to try and pull an
infinite
> >amount of current and burn itself out in the process. By
comparison a
> >neon sign transformer is NOT a regulating transformer for if it
were
> >it would either burn out itself or destroy the neon tube it was
> >connected to. This is why neon sign transformers do not need any
> >current limiting inductance when used to drive a tesla coil. You
> >can add some variable inductance to a neon transformer to allow
> >you to operate your coil a various power levels but it is not
> >required to protect the transformer. In an oil burner transformer
> >and with pole pigs you MUST current limit their primaries or you
> >will either burn out the transformer or in the case of a pole pig
you
> >may burn out the mains.
>
> It's pretty obvious that there must be quite a few diffrent types
of oil
> burner transformers available.
>
> All the OBT's I've used were self-regulating, just like a neon
> transformer. All were rated at 23 Ma., and were desgined to run
> all day long keeping the flame lit in fuel oil furnaces.
>
> Let's keep comparing notes and see what we come up with !
>
> Daryl
Daryl,
It has also been my experience that ignition transformers were
current limited the same as neons. I have ALWAYS found magnetic
shunts in use whenever I repotted an ignition transformer.
I did load curve testing on ten ignition transformers from several
different manufacturers, and they all had the same current-limited
load curve. In every case the current is max limited to 23 ma (this
can vary a few ma).
I have sent a few personal posts to Alfred Skrocki explaining that my
testing shows the ignition transformers to be virtually the same as a
neon in its current limited characteristics. He maintains that they
are like pole pigs in needing external current limiting. I have never
run across an ignition transformer that was not current limited using
magnetic shunts. Nor have I ever run across any other posts where
anyone claimed that the ignition transformer did not have integral
internal current limiting via magnetic shunts. I am not saying that
there are NOT any such beasts, but I have never seen or heard of them
before.
I have held back from getting involved in discussing this on the list
so far, because I had hoped that my personal posts with Alfred would
help us clear things up and then he could post an update explaining
what the situation was. But since this post by Daryl already brings
up the issue, I may as well post this to the list, as I think we need
group input on this one.
I would be interested in whether any other coiler has ever
encountered an ignition transformer that was NOT current limited. In
my experience they are invariably 10KV at 20 to 30 ma. Has anyone out
there ever encountered one that was like a pole pig rather than a
neon transformer? (By this I mean that it REQUIRED an external
ballast.)
Alfred also remarked to me that every microwave transformer he has
encountered has NOT had any magnetic shunts. This also goes counter
to my own experience. I have ALWAYS found the magnetic shunts to be
located between the primary and secondary, consisting of a bundle of
iron strips wound with one or two turns of insulation and placed
between the "O" and the "I" part of the core. Has any one else out
there found anything different?
This post is not designed to be nit-picky. I just don't want
erroneous information being circulated. That kind of stuff has a way
of taking on a life of its own. Repeat something enough times and it
becomes "fact" in the minds of many.
If I am WRONG here, and if there ARE these non current limited
ignition transformers out there then I want to KNOW it in no
uncertain terms. I need more than just one source telling me
something is true. I demand the same kind of repeatable scientific
proof that I would demand before believing ANYTHING that doesn't
immediately strike me as true. (In my saner moments I would demand
the same kind of proof even for the things that DO strike me as
true!!!)
I would consider an ignition transformer to be non current limited if
you are able to draw more than double the rated current from the
secondary for more than two seconds. In the case of a 10KV
transformer, loading it with a 100K high wattage resistor and getting
more than 50 ma would prove it was not current limited. Such a test
would not damage any properly designed transformer. My bet is that
you are going to get less than 50 ma not more.
There are ramifications here for coilers. If an ignition transformer
is not current limited like a neon transformer, then using it
directly in a Jacob's Ladder would result in quick destruction of the
secondary due to excessive currents. Yet I know that MANY have used
the ignition transformer in this way. If such a non current limited
transformer was used to power a Tesla coil it would indeed need a
primary ballast. Has ANYONE out there encountered a genuine
honest-to-goodness ignition transformer that was NOT current limited?
If so, please give us details. Otherwise I will continue to believe
that all ignition transformers are as I have found them to be so far:
current limited.
Please do not post mere OPINIONS on this topic. First hand
experimental results are NOT opinion. They are the data from which
the facts can be ascertained. We need FACTS here.
Fr. Tom McGahee