Re: Arc Welders as Rheostats?? Variac Mod Question

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

Original poster: "Barton B. Anderson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <tesla123-at-pacbell-dot-net>

Hi Jack,

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?

That's larger than anything I've heard of. You only need a narrow slot, and
the blade width of the
saw will provide plenty of gap.

> 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?

I would, definately. It will keep it from vibrating and separating further.
As you said,
structural integrity (of the laminations or area of the gap).

> Lastly, might anyone know off
> hand if cores on these older, larger dogs are silicon
> steel strip or scintered iron encapsulated in epoxy?

Could be either. Most common I suspect on the larger ones are laminations.

Take care,
Bart