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Re: Oil Burner Ignition Transformers (shunts)

Subject: Re: Oil Burner Ignition Transformers
  Date: Wed, 14 May 1997 05:16:29 +0500
  From: Alfred A. Skrocki" <alfred.skrocki-at-cybernetworking-dot-com>
    To: Tesla List <tesla-at-pupman-dot-com>


On Tue, 13 May 1997 06:39:21 -0700 Bert Hickman
<bert.hickman-at-aquila-dot-com> wrote;

> > 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?
> > 
> 
> Yeah - just this weekend! Went to a local Hamfest, and a guy sold me a
> big trannie out of a commercial microwave oven - this was the Mother of
> all Microwave transformers! It consisted of two identical secondary
> windings wound over two primary windings, and the core measures 4.5" x
> 8" x 2.5", and outputs 6 KV center tapped! A filament winding was on one
> leg. There was NO center core, nor was there any shunt - the laminations
> were "C" type, not "E" type. This beast was basically an open-core plate
> transformer. Price was $2.00 - couldn't pass it up for my boatanchor
> collection! :^) 
> 
> Now until this time any of the home model microwaves I've cannibalized
> (a half-dozen or so) have had shunted trannies, about half the size and
> weight. I've targetted these for future tube coil work, so haven't tried
> direct shorting any ala disruptive service. Have heard that the current
> control in some of these is not very great, with very high short-circuit
> currents being seen on at least some units. Will have to try shorting
> some of these and measuring primary current at lower AC input from a
> variac to see...

I think Bert found the point of descrepency! All the microwave 
transformers I aquired untill a couple of days ago were from 
industrial microwave ovens and had pretty much the same dimensions
Bert described and no shunts. The one I found a couple of days ago 
was in a home model microwave oven and had a shunt. So it would seem 
that industrial microwave ovens use transformers without shunts and
the home models use shunted transformers.


                               Sincerely

                                \\\|///
                              \\  ~ ~  //
                               (  -at- -at-  )
                        -----o00o-(_)-o00o-----
                           Alfred A. Skrocki
                   alfred.skrocki-at-cybernetworking-dot-com
                             .ooo0   0ooo.
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