[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[TCML] PFC correction capacitor

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)
Tesla mailing list