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Re: Capacitor Oils




From: 	Adam[SMTP:absmith-at-tiac-dot-net]
Sent: 	Monday, November 03, 1997 12:09 PM
To: 	Tesla List
Subject: 	Re: Capacitor Oils


>     In the Tesla List archives, castor oil is mentioned as a good 
>     capacitor oil because of its high dielectric constant.  I think I've 
>     found a relatively inexpensive source for the stuff.  Castor is used 
>     in radio controlled aircraft as a fuel additive.  I paid $22.50 for a 
>     gallon of the stuff, after calling a few hobby shops to find the best 
>     price.  The label says it's pure, Grade AA (whatever that means) 
>     castor oil.

Radio controlled aircraft fly on a mixture of castor oil and 
nitromethane.  As you can see, it is very important that listmembers 
don't buy the premixed stuff!  Regardless of nitromethane's high 
dielectric constant (around 50!), it would not make a good capacitor 
additive :-)  

Castor oil does have a high dielectric constant, (like 4.7) but what 
about the dielectric strength? I know that transformer oils offer 
typically 50-100kV/cm, but I don't know about castor oil.
    
>     Unfortunately, the oil is rather viscous.  Does anyone here have 
>     recommendations on how to thin this stuff out.  

Hmmm, haven't tried it.  Have you tried mineral oil [white] yet?

>     I thought about using a volatile carrier fluid to thin out the oil 
>     during impregnation of the capacitor, but I'm concerned that any 
>     unevaporated solvent could turn my capacitor into a bomb. 

Yeah, don't use anything flammable.  Period.  Maybe it will mix with 
transformer oil?  See what your local oil wholesalers suggest, they may 
have a better idea.

-Adam




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