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# Re: Homemade Trasformer

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Nick,

Thanks, I understand now -- What I plan on doing is building my own
24kVA tranny (I couldn't leave the 240V, 100A service feeder in the
garage alone :P).  I came up with 14^2 in. when I calculated the
magnetizing current.  If my primary has 120 turns at 240v/60Hz, this
gives the flux density as 7.5E+05 lines - since the maximum flux density
of steel is, conservatively, 55 kilolines/in^2, this gives the core size
at 13.6, or 14^2.  I don't know how to calculate the maximum current
this tranny is capable of, only  that dad said i'd blow every breaker
from here to Cancun before i saturate a core like this.  [All this seems
to say that you actually can't build a 240v tranny with a smaller core
unless you use more turns on the primary -- is this right?]  For the
secondary, I plan on 6,000 turns -  for the core I'm planning on many
pieces of 1/4" barstock each covered with formvar or something suitable
and then wrapping the primary around a suitably sized bundle of these,
and the secondary over the primary.  Though I seem to recall posts to
the contrary, I, myself, see no problem in using a cylindrical core as
opposed to a toroidal or square core -- is there?

<<sorry for the long post>>

Any comments appreciated,

Ross

Tesla List wrote:
>
> Original Poster: "Megavolt Nick" <tesla-at-fieldfamily.prontoserve.co.uk>
>
> Hi Ross,
>              14^2 inches is the cross sectional area of the effective
> magnetic circuit at its narrowest point.  Which equates to about 30kVA -
> bigger than most pole pigs.  I really wonder if you've done the calcs right
> as a 14^2 inch core is very big - it would weigh in excess of 50kG bare (add
> on another 30kG for copper and .... ohhhh damn there go a few vertabrae)
> If you posted the calcs that would help us understand what you are doing.
>
> Regards
> Nick Field
>
> ----- Original Message -----
> From: Tesla List <tesla-at-pupman-dot-com>
> To: <tesla-at-pupman-dot-com>
> Sent: Saturday, February 19, 2000 2:22 AM
> Subject: Re: Homemade Trasformer
>
> > Original Poster: "ross andrews" <sflourine-at-home-dot-com>
> >
> >
> >
> > Hi all,
> >
> > One more thing -- my calculations came up with 14^2 for core size- why
> > isn't it cubic inches?  I wasn't planning on a 2D tranny :P  What am I
> > missing??
> >
> > Thanks again,
> >
> > Ross
> >
> >
> >

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