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Re: MOT core
Original poster: "Richard W." <potluckutk-at-comcast-dot-net>
Hi Vladan,
I'm really sorry but I couldn't say for sure. I stick pretty close to the
volts/turn formula. I would have to guess that your idle current (no load)
would increase quite a bit. That being the case you'd just be wasting a lot
of power in the form of heat.
Rick W
Salt Lake City
----- Original Message -----
From: Tesla list <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Tuesday, February 03, 2004 1:10 PM
Subject: Re: MOT core
> 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
> > > > > >
> > > > > >
> > > > > >
> > > > >
> > > > >
> > > >
> > >
> > >
> >
> >
>
>