Re: MOT core

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

Original poster: "Dan" <pbursa-at-cfl.rr-dot-com> 

Thank you Richard.
That is pretty close to what I have got, but what would happen, if I use
only a half of required turns ( say 200 instead  of 400) on primary. How
this affect saturation of core and power handling ?
I expect the core heat up when saturated, would potting in oil or other form
of cooling help, how ?
Thanks in advance
Vladan


----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Tuesday, February 03, 2004 7:34 AM
Subject: Re: MOT core


 > Original poster: "Richard W." <potluckutk-at-comcast-dot-net>
 >
 > I've been using that for so long I've forgotten where I got it from. The
 > factor 0.16 is for the more common material used in laminations and
includes
 > the frequencies 50 to 60Hz. In the years I've been building transformers
 > that formula has always done right by me. Besides, all I've ever built
were
 > transformers for 50 to 60Hz using the E and I configuration.
 > The other one that goes hand-in-hand with that formula to calculate
voltage
 > per turn, E = (.16 x CS), has also proven it's worth in practice.
 >
 >
 > VA = (CS/0.16)^2
 > E = (.16 x CS)
 >
 > E = voltage per turn
 > CS = Cross-Section of the center leg for E and I transformers.
 >
 >
 > Rick W.
 > Salt Lake City
 >
 >
 >
 > ----- Original Message -----
 > From: Tesla list <tesla-at-pupman-dot-com>
 > To: <tesla-at-pupman-dot-com>
 > Sent: Monday, February 02, 2004 5:43 PM
 > Subject: Re: MOT core
 >
 >
 >  > Original poster: "Hydrogen18" <hydrogen18-at-hydrogen18-dot-com>
 >  >
 >  > Where did you get that formula? How does it include frequenct into the
 >  > equation? I'd like to use in my transformer calculator I'm developing
but
 > it
 >  > needs to change with frequency.
 >  >
 >  > ----- 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
 >  >  >  >  >
 >  >  >  >  >
 >  >  >  >  >
 >  >  >  >
 >  >  >  >
 >  >  >
 >  >
 >  >
 >
 >