[TCML] PFC correction capacitor

[Jim Lux <jimlux@xxxxxxxxxxxxx>]

On 11/19/12 9:54 AM, Nathan Woodhull wrote:
> I recently aquired a very large capacitor and wondered if it would
> have any use in a Tesla Coil.General Electric Pyranol
> Capacitor,#H147952,KVAR 25,Cat.#13F138,2400V60cy.,Ph1.No Farad rating
> is listed.Thanks,Nathan Woodhull


That's a power factor correction capacitor, and as is typical with such 
things, the size is given in kiloVAR.

It's designed for 60 Hz AC service (not good for a TC primary, *might* 
work as a DC filter capacitor)

To convert KVAR to microfarads, you look at the voltage rating (2400V, here)

VAR are sort of like watts.. VAR = E^2/X   where X is the capacitive or 
inductive reactance.  X = 1/(2*pi*freq* C)

You do it in a couple steps..
First figure out the reactance:

so, 25 kVAR  = 2.4E3^2/X
X = 230.4 ohms
Then convert that to C

230.4 = 1/(377 * C)  { 377 is 2 *pi * 60 }

or C = 1/(377*230.4)


about 11.5 uF, as it happens.

Note that this capacitor can take a fair amount of AC current.. 
2400/230.4 is a bit more than 10 amps.



>>>>> Here's the big problem.  Pyranol is a PCB.  It doesn't present a 
health hazard while inside the capacitor (which is sealed, after all), 
but you'll find this thing basically impossible to get rid of 
inexpensively, because of the potential down-stream liability.  And, in 
fact, the Pyranol itself isn't particularly dangerous (it's pretty 
inert, fireproof, etc.).. the problem is the inevitable dioxin that 
contaminates it.

All PCBs are really rugged and take forever to degrade, and 
unfortunately, dioxin is a carcinogen and teratogen.  Great, a poison 
that takes forever to degrade, is concentrated in fatty tissues in the 
food chain, and is toxic in amazingly small concentrations (ppb).


Hazardous materials like PCBs have liability that attaches to everyone 
who has touched it along the way (to keep shell companies from just 
going out of business to shield the real owner).

Capacitors are what is known as an "enclosed use" for PCBs (which 
haven't been manufactured since the 70s), and they can remain in 
service, but once they leave service, they have to be disposed of 
properly.  (that means paperwork, licensed hazmat disposal, and all that 
stuff).

(This is why, in California, it's basically impossible to get surplus 
transformers and capacitors from the power company.. they don't want the 
liability that they will have, if you go out and improperly dispose of it)
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