Re: MOT core

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Crow Leader" <tesla-at-lists.symmetric-dot-net> 

I think I'm interpreting something wrong here.

Say I have two transformers, each has a core cross sectional area of 1"sq.,
and each is rated 39VA.  Together than can handle 78VA.

Now if I strip the windings off, and put the cores next to each other giving
me a cross section of 2" sq. (pretending and generic EI core set) and put
the wire back on, (I connected the wires from each transformer to make for
the extra winding circumference) do I now have a transformer capable of
156VA, AND have leftover copper from the rewind? This sounds too good to be
true. What's the difference between the single and parallel tranformer
situations?

KEN

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Monday, February 02, 2004 8:58 AM
Subject: Re: MOT core


 > Original poster: "Richard W." <potluckutk-at-comcast-dot-net>
 >
 > Actually decreasing the core cross-section by half will drop the power
 > capability almost by a factor of 4.
 >
 > Let's say we have a core who's center leg measures 1" x 2" for 2 square
 > inches.
 >
 > CS = 2 sq.in. (Cross Section)
 >
 > VA = (CS/0.16)^2
 > VA = (2/0.16)^2
 > VA = 12.5^2
 > VA = 156
 >
 > Cutting the core in half = 1 sq.in.
 >
 > VA = (CS/0.16)^2
 > VA = (1/0.16)^2
 > VA = 6.25^2
 > VA = 39
 >
 > Rick W
 > Salt Lake City
 >
 > ----- Original Message -----
 > From: Tesla list <tesla-at-pupman-dot-com>
 > To: <tesla-at-pupman-dot-com>
 > Sent: Sunday, February 01, 2004 7:34 PM
 > Subject: Re: MOT core
 >
 >
 >  > Original poster: "Hydrogen18" <hydrogen18-at-hydrogen18-dot-com>
 >  >
 >  > The only thing I know to say here is stack the cores. Alternatively you
 >  > could use very small wire for the secondary to achieve the HV output.
 >  > Stacking the cores(inserting 1 E into each end of the "bobbins") will
 > halve
 >  > your power output but double your winding window.
 >  > ----- Original Message -----
 >  > From: "Tesla list" <tesla-at-pupman-dot-com>
 >  > To: <tesla-at-pupman-dot-com>
 >  > Sent: Sunday, February 01, 2004 6:49 PM
 >  > Subject: MOT core
 >  >
 >  >
 >  >  > Original poster: "Dan" <pbursa-at-cfl.rr-dot-com>
 >  >  >
 >  >  > Hello !
 >  >  > I am curious if someone here has experience with rewinding microwave
 >  >  > transformer.
 >  >  > I cut of the I part of the core, removed old windings and split the
E
 > core
 >  >  > in half so now I have two identical E cores .
 >  >  > Together they make 5.5 inches long, 4.15 wide and 1.35 thick core
with
 >  >  > about 1.72 square inches area...
 >  >  > This looks like I'll need over 400 turns on primary... this would
 > require
 >  >  > 40000 turns for 12KV secondary and there is not enough space for
this,
 > I'm
 >  >  > afraid.
 >  >  > My question is - if I use less primary windings (say 150 - 200), how
it
 >  >  > affect performance, core saturation, ...
 >  >  > I noticed that original MOTs primary was also less than proper
amount
 > of
 >  > turns.
 >  >  > Also, since MOT core is welded together, how the weld affect the
core
 >  >  > losses and eddy currents? isn't the very purpose of using laminated
 > core
 >  > to
 >  >  > minimize these loses ?
 >  >  > How about potting finished transformer in oil ?
 >  >  > Thank you in advance
 >  >  > Vladan
 >  >  >
 >  >  >
 >  >  >
 >  >
 >  >
 >
 >
 >