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Re: [TCML] caps

Dave and Randy,

The 1945 article covers many advantages of Lectronol in high frequency induction heating capacitors, but unfortunately it does not provide any details about WHAT Lectronol actually is. However, I was able to find another paper that does discuss Lectronol. The good news is that Lectronol is NOT one of the many PCB's used in capacitors. Instead, it is a colorless liquid "obtained from dibutyl ether and sebacic acid [C8H16 (COOC4H9)2].

The above nugget was found in a 323pp paper that discusses Lectronol and many other dielectric fluids as well. The paper is "Electric Strength of Liquid Dielectrics" by I Balygin. This is available as a free download at the Defense Technical Information Center (DTIC):

Other than being comparatively large for their voltage and capacitance ratings versus capacitors using more modern technologies, your caps should work fine in TC use. And, because the fluid is essentially THE dielectric, they may also be self-healing to some degree.

Bert Hickman
Stoneridge Engineering
World's source for "Captured Lightning" Lichtenberg Figure sculptures,
magnetically "shrunken" coins, and scarce/out of print technical books

David Speck wrote:

Found one reference to the development of "Lectronol", dated 1945.

It states that Lectronol caps are twice as good as mineral oil filled
caps.  Therefore, unless they are using castor oil, I'd bet that these
are some sort of PCB filled caps.

Their specs are excellent for TC work, though the voltage and
capacitance are a bit low.  I'd bet that they would withstand voltages
up to their rated nameplate values, and come back for more.

If you already own them, and they are not leaking, then I'd go ahead and
try them for TC work.  You could even try using the water cooling, if
they seem to get hot.

If you don't own them, I'd steer clear of them.  Disposal of a PCB
filled cap down the road can become a major and costly headache.

Abstract of 1945 article follows below.  Full article costs $36.00,
unless you are an IEEE member.  Perhaps one of the other list members
can access the full article for confirmation.



Increased military production has accelerated the application of
high-frequency heating where accurate control of temperature for short
intervals is fundamentally important. The heating of metals by induction
has been widely applied. The present paper describes the development of
a new type of dielectric liquid called Lectronol. Capacitors containing
this liquid are particularly well adapted for use in the tank circuit of
electronic heaters used in induction heating. The capacitor is
water-cooled and is housed in a hermetically sealed completely filled
nonmagnetic container so constructed as to provide sufficient
flexibility to take care of the liquid expansion due to thermal changes.
The capacitor is noteworthy because of the absence of cellulose sheet
insulation, satisfactory operation being entirely dependent on the
superior insulating properties of the Lectronol. Capacitors containing
this liquid are characterized by low dielectric loss and high dielectric
strength over the frequency range utilized in power oscillators. The
capacity per unit volume is approximately twice that obtained with
mineral oil. The electrical characteristics of the capacitor are stable
under severe conditions of use.

On 11/24/2012 3:29 PM, Randy Burk wrote:
I have 3 Westinghouse water-cooled caps in aluminum housings.  They are

at 7800V, 240 Amps, Freq 540 KC, .0076 mf.  They contain lectronol as the

Are these suited for TC service?  What is lectronol and is it hazardous?


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