LDPE oil tolerance?

• To: tesla-at-poodle.pupman-dot-com
• Subject: LDPE oil tolerance?
• From: Tesla List <tesla-at-stic-dot-net>
• Date: Thu, 29 May 1997 07:54:11 -0500
• Approved: tesla-at-stic-dot-net

Subject: LDPE oil tolerance?
  Date:  Wed, 28 May 1997 07:27:50 -0400
  From:  Steve Falco <sfalco-at-worldnet.att-dot-net>
    To:  tesla-at-pupman-dot-com


I recently repaired a dead neon by the usual freeze and chip techniques
mentioned on this list.  The short was between the side of one secondary
winding and the steel core.  I removed the mica/paper insulation, which
was charred, and decided to embalm the unit in oil to provide new
insulation.

I placed the unit in a Rubbermaid container which is made of
polypropylene (PP) with an LDPE cover.  I then filled it with mineral
oil.  After a week or two, the PP was fine, but the LDPE cover had
warped and swelled badly.  I wound up discarding it.

I guess I am concluding that PP is more oil-tolerant than LDPE, yet we
prefer LDPE for oil-filled capacitors for its dielectric properties.

My first question is:  Any comments on long-term effects of oil on LDPE
in capacitors?

My second question is:  Assuming I have my heart set on oil-filling my
transformers, what would be a suitable container?  (I'd also like to
build a bigger capacitor, and was thinking of the Rubbermaid trash
pails, but now I am afraid they will not hold up to the oil.)

I suppose a metal box is a possibility, but that would be hard to
fabricate.  Anyone tried a plastic picnic cooler?  Not sure what they
are made of...

        Steve Falco
        Morris Plains, NJ
        sfalco-at-worldnet.att-dot-net

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