Re: ballast core

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

Original poster: "BunnyKiller by way of Terry Fritz <twftesla-at-uswest-dot-net>" <bigfoo39-at-telocity-dot-com>

> snipperzz...

> Big question:
>
> How important is it to have the silicon steel from an actual transformer core
> to make a ballast? Can I make a suitable replacement by plasma cutting 10Ga,
> or 3/16, or 1/4 hot rolled plate iron (common sheet metal) into a suitable
> shape, and stacking them into a big enough cross section? If so, then I have
> the perfect situation. I can plug the dimensions needed into my CAD program,
> and use the CNC plasma cutter I have access to, and make my E's from scrap
> material that usually get's sold for pennies a pound to the scrap yard.  I
> could burn a strategically placed hole or two in the corners to use for
> bolting together the laminations or stagger some holes to use for plug
> welding, and have a handy replacement for something I can't seem to find
> elsewhere. Although It might take a while to collect up enough laminations
> from scrap to do the job.
>
> thanks for any info,
> Marc S.

Hi Marc...

the area that is measured is the minimal area of the magnetic path in the
core. for
example if you were to remove the I part of an EI core and look "down" on
the "top" of
the E portion you will see 3 rectangular areas. Normally the center leg has
the same
square inch area as the I section. This is the area that is measured. If
the cores
center leg measures 3"X5" then the core area is 15 sqr".

Silicon steel has the ability to "demagnitize" faster than mild steel. This is
important in transformer applications cuz the alternating magnetic flux
flow is less
hampered and allows the reversed flux flow to take effect faster (
hysteresis)    altho
....  if one were to use mild steel as a core, the decreased flux flow
could be used to
ones advantage.( altho the core assy. will groan alot more than normal)

The laminations of most transformers are very thin and "insulated" ( each
plate is
varnished)  to reduce what is known as eddy currents. If you were to use
thick plates,
the flux flow in the plates create little "whirlpools" which cause the
plates to heat
up, thus a loss of energy that could be used elsewhere.

engineers design transformers to be as energy efficient as possible...  but
inductors
are a bit different, we use the coil forms and EI cores to decrease flux
flow by
varying the magnetic field thru them.


Scot D