[Prev][Next][Index][Thread]

Re: transformer cores

Hi Mike,
              the MOTs won't saturate but need external ballasting - see the
power supply chapter (3) of the list faq for all the formulae (If travis
hasn't yet got it up in html i can mail you the original) If you run without
it all you get is a tripped breaker.

Regards
Nick Field

> Original Poster: Mike Nolley <mnolley-at-mail.slc.edu>
>
>
>
> > Original Poster: "bob golding" <yubba-at-clara-dot-net>
> >
> > hi all,
> >         I have found a couple of transformers. I think they are HV
filament
> > transformers of some sort. With the present windings I reckon they will
> > handle about 150 Watts. Is there an easy way to find out at what current
> > the core will saturate? They are two section c type cores with a cross
> > sectional area of about 1" The whole core is about 4 1/2". Of course if
> > anyone wants to buy them as filament transformers I will restrain from
> > killing them just yet. If anyone is interested let me know off list.
> >
> > cheers
> >
> > bob golding
>
>     I would also be interested in any formulas out there that can be used
to
> predict saturation in transformers.  I have a couple of Mots that I will
be
> using in a power supply, whose primary turns are minimal.  I'm afraid that
> despite the huge core area they may saturate if short circuit current is
drawn
> from them.  I don't want to try them out in a Jacob's ladder because I
can't
> replace them easily.
>
>     In the archives I found these equations--who posted them I can't
remember.
>
>     (N/Vw) = 58183/(Ac x Bmax)
>
> where the N/Vw is the turns per volt, Ac is the core area in square
> inches, and N is the number of turns. Bmax is the maximum flux density
> allowable to
> avoid excessive core loss (core loss gets very large before saturation
> is reached). For typical modern transformer steels Bmax is of the order
> of 12,000 gauss.
>
>     With this equation you can tell which transformers are overdesigned
and
> which ones aren't, but it's hard for me (with my limited math background)
to
> translate this into a function of the primary current.
>
>
>