Re: low temp resistance?

["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 Chris,

Tesla list wrote:

> Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <CTCDW-at-aol-dot-com>
> I have to ask the impossible. In ballasting a pole transformer,
>
> 1: I have heard both that a resistor across the ballast (inductive) and in
> series with the ballast are the best. Any thoughts on which it is?

In series if your going to use a resistor.

> 2: Is there a resistive load that can be used that doesn't require
> fire-proofing,and/or blowers to keep it cool? I would prefer not to have to
> deal with bright red stove elements or water heater elements and buckets of
> water to keep this cool :).

Yes, there are, well, resistors. I have one... it's huge (about 3" x 18"?,
10ohm). I actutally found center and cut the resistive element to make two
5 ohm
resistors which I paralleled for 2.5ohm. I found this at an electrical
warehouse
full of misc. things. No idea where to get one, but they are out there.

> 3: I'm sure that many of you have experimented with lots of different values
> for resistors. What are the effects of the various ratings? is it simply
> power lost to heat? or are there other issues that arise?

Yes. Obviously, the lower the resistance the more current can be run, but it
takes higher watt resistors. To much resistance, and you limit can limit your
current more than you may want. I tried to say between 1 and 5 ohms, which
is why
I used 2.5 ohms as mentioned.

I would only run a resistive ballast if actually needed. The reason I used
it was
due to trying to run higher power levels with a 28amp variac. The variac and
system tended to "thump" (very low frequency noise - not core saturation
growl).
The resistor removed the thump and let the coil run smooth. But again, I
personally would only use one if needed because power lost to heat is power
lost
to sparks. I have a new coil now and won't be using the resistor for this one.
But I keep it handy just in case.

Take care,
Bart



>
> Thanks for any illumination on the subject!
>
> Chris W