Re: Arc Welders as Rheostats?? Variac Mod Question

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

Original poster: "Jack King by way of Terry Fritz <twftesla-at-qwest-dot-net>" <speakernut-at-yahoo-dot-com>

I do like the idea of a simple, single band saw cut as
opposed to notching out a chunk. Any magnetics experts
care to comment?


--- Tesla list <tesla-at-pupman-dot-com> wrote:
> Original poster: "Ed Phillips by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <evp-at-pacbell-dot-net>
> 
> Tesla list wrote:
> > 
> > Original poster: "Jack King by way of Terry Fritz
> <twftesla-at-qwest-dot-net>"
> <speakernut-at-yahoo-dot-com>
> > 
> > Anyone out there have data on how "wide" the air
> gap
> > needs to be? My gut says something like .75-1"
> should
> > be sufficient to interrupt the flux travel...any
> > thoughts? I'm toying with "modifying" a 7.8 kva
> unit
> > for use as a series reactive ballast, and would
> like
> > additional insight before i dig out the band saw.
> > Also, does one need to replace the removed section
> > with epoxy or something along those lines to
> maintain
> > structural integrity? Lastly, might anyone know
> off
> > hand if cores on these older, larger dogs are
> silicon
> > steel strip or scintered iron encapsulated in
> epoxy?
> > 
> > Cheers,
> > 
> > Jack King
> 
> 	That sounds like way too much gap, but I'm not an
> expert on calculating
> magnetic circuits.  Someone else here probably is
> and can give you an
> answer.  I would suspect the actual value should be
> of the order of
> 0.050", depending on the core area and the number of
> turns.
> 
> 	Don't think any 60 Hz transformers use anything but
> silicon steel for
> the cores, with the exception of very recent ones
> which use some of the
> "matallic glasses" for ultra-low loss cores.
> 
> Ed
> 
>