Re: Ballasting Primer (was: Help Me Prepare for a BIG Coil)

["Gregory Hunter" <ghunter31014-at-yahoo-dot-com> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

Ryan,

Resistive ballasting bites.  It will soak up half your
power and knock your voltage down to boot.  Resistive
ballasting is cheap, safe, and predictable, but it
will waste much of the potential of your pole xfmr.

If you want your coil to behave like a pole pig coil,
then go with inductive ballasting.  I'm using a pair
of 115V MOTs in series with my 5KVA pole xfmr to limit
the 220VAC supply current to about 20 Amps.  4400VA of
inductive ballasting works ten times better than the
9000VA of resistive ballasting I had been using.

Cheers,

Greg
--- Tesla list <tesla-at-pupman-dot-com> wrote:
> Original poster: "Ryan Ries" <spud-at-wf-dot-net> 
> 
> 	I'm going to go pick up my 10kva pig tommorow, and
> I really need a crash
> course in ballasting.  I've researched the subject
> long before I ever knew
> I would have a pole pig, but even though I've
> searched the list archives
> and the web pretty extensively about the subject,
> but it's hard to find the
> info that pertains directly to me.  
> 	I know that there is inductive ballasting and
> resistive ballasting, and
> that a combination of both is usually known as the
> best method, but not
> necessary.  Now, in resistive ballasting, I would
> hope that it's as simple
> as Ohm's Law:  120v/1.44ohms = 83.3A.  That's 10kva.
>  But, 1.44 ohms is
> next to none, and the extension cord that we use to
> run between the breaker
> box and the transformer is probably more resistive
> than that.  I would
> appreciate it if anyone could clarify this for me.
> 	I do not understand inductive ballasting at all
> though.  I have a small
> portable arc welder that I could use.  I understand
> that I should short out
> the secondary leads of the welder, so if I just set
> the welder on 80A, I
> guess that means that the transformer only gets 80
> amps max?  Furthermore,
> I hear of people using space heaters and oven
> elements and all sorts of
> stuff for ballasting.  How does their energy
> consumption correllate with
> the amount of current available to the transformer? 
> 	Anyway, I hope I haven't made myself sound too
> ignorant, but I am going to
> make sure and know everything I need to know so I
> don't blow my arm off
> and/or burn my house to the ground. :-)
> 
> 	Thanks,
> 	   Ryan Ries
> 
> 
> 


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