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Re: MOT for Ballast Question...
Good day 'Mr. Fabs', (comments interspersed)
>Original Poster: "M Fabs" <the_machin_shin-at-hotmail-dot-com>
>
>I asked some time ago about a thought I had for a ballast, and never
>received an answer. I was hoping someone with some experience with variable
>air gap inductors could help out. I took apart 2 identical Microwave Oven
>Transformers by grinding out the welds, etc... I was planning to put the
two
>"E" sections open face to open face, whereby I will have the same current
>capability as a single MOT, but twice the wire winding window area. Is
this
>reasonable?
No, transformers have a calculated winding window depending on the maximum
magnetic flux the core can handle. In other words doubling the secondary
windings doubles the voltage but halves the current before saturation.
---------------
>I was hoping to build a bracket of some kind that would let me
>adjust the air gap between the two core sections, thereby varying the
>inductance (and current limit). What range of air gap distances is
>reasonable for, say 0-20 amps? Would it be on the order of 0-2 mils, or
>maybe 0-200 mils?
With the usual core material you can expect halve the inductance with an air
gap of 0.1mm (4 mil)
Look up Hopkinson's law: L = n^2 / (l1 / (u0*ur1*A1)) + (l2 / (u0*ur2*A2))
--------------------
>Should this be wound with wire similar to that which
>originally made up the primaries of the MOT's? How many turns? Same number
>as the original primaries had?
That's depending on the maximum air gap, but remember if you double the
primary you will have to double your secondary also!.
-------------------
>This is all for 120V 60Hz supply. This arrangement (or maybe these, if I
>get ambitious and find more MOT's) will be used with NST's for Tesla Coils,
>and other fun.
>
>Any thoughts, or answers, or even questions would be welcomed!! I don't
want
>to find out only after this is built that I missed something very
important!
Ok, this looks important to me: Connect a MOT serial (ballast) with 2 MOTs
connected anti parallal (supply) and shortcut the secondary of the ballast
MOT. This seems to be a proven solution by Marco Denicolai (see
www.saunalahti.fi/dncmrc )
Ruud de Graaf
Greetings from Holland
-----------------
>MPF
snip....