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Patrick

Tue Nov 24 2009, 12:54AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

I am ready to put together a mini-piggy of special design, I'm NC'ing pieces tonight. I have narrowed my choices for oil down to two.
I need advice and some consideration of these oils, from anyone who will volunteer info.

First, Corn Oil.
-OR-
Second, AW-32 Hydrualic Fluid, or possible generic Non-detergent 30W motor oil.

For Corn oil,
Its cheap, Plentiful, and biodegradelble, so it can go down the drain, and isnt posionous.
However, what about it going rancid, I mean yuck, I dont want to trade a chemical hazard for a biological hazard!?
Also, do the organic oils change electrical properties over a 2 year period ?

For Hydro-oil,
Its a little more $ than corn oil, but resistant to bacteria, but difficult to recycle (cant go down the drain) and since I need 2.6 Gallons that is a considerable issue. I suspect it is more long lived then the organic oils.

My main question is what would be a wise choice for a small piggy

(2.6 Gallons) At 70Kv , 2Kw and 40-80kHz and its ferrite @ 80 degrees C. This transformer will be used often for 4+ years while I get my Master's or PhD,(EE). The rancid possibillity concerns me or am I thinking to much?

Opinons acceptable, but Experience Preferred...

Thank you,
-Patrick

Anon01

Tue Nov 24 2009, 05:36AM

Registered Member #1589 Joined: Sun Jul 13 2008, 06:40PM
Location:
Posts: 70

Purified mineral oil.

Though if you were to go with either one of your selection, I would go with the non detergent 30W motor oil. I've used it on my 8 MOT stack and no failure or issue so far. It's been about 3 years now.

I wish you great luck with the PhD,(EE)! :D

Patrick

Tue Nov 24 2009, 06:29AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

Yeah, Thanks Anon, I plan to chisel my degree out one way or another, Im not taking no for an answer from the state of CA or anyone else.

ok I'll get some mineral oil or Non D motor oil, which ever I can source quickly and cheaply.

Here is a pic of my 2Kw piggies(not finished yet)

The black squarish thingy is a transmission radiator (21$ at Pick-n-Pull). I will pump oil through at 1 gpm, to dissipate heat. The pump will go upto 35 PSI, and Im using 3/8" ID hose for low resistriction, high flow.

Bored Chemist

Tue Nov 24 2009, 05:59PM

Registered Member #193 Joined: Fri Feb 17 2006, 07:04AM
Location: sheffield
Posts: 1022

I'd go with corn oil. Microbiology will only be a problem if there's water present and you don't plan to mix water with high voltages anyway.
If I remember I will dig out my cooking-oil cooled and insulated resistor that's been lying about in my cellar or 5 or 10 years and check the insulation on it.
Liquid parafin is another option if you can find it at a decent price for that quantity.

EDIT
I checked. The leakage current is less than 1ÂµA at 2KV. I know that's not very high voltage but it's a start.

Carl Pugh

Tue Nov 24 2009, 06:29PM

Registered Member #1064 Joined: Tue Oct 16 2007, 05:04PM
Location:
Posts: 42

Ten years ago purchased 5 gallons of transformer oil type AX from local Shell distributor for $22.00. (California USA)

Have you tried googling for transformer oil or Shell or Gulf web site?

Coherent

Tue Nov 24 2009, 06:35PM

Registered Member #1886 Joined: Sun Dec 28 2008, 02:55AM
Location:
Posts: 73

I use this with my 70KV X-ray transformer and haven't had any issues so far.

Renesis

Tue Nov 24 2009, 07:08PM

Registered Member #2028 Joined: Mon Mar 16 2009, 08:13PM
Location: Norway
Posts: 319

I have been dealing with a lot of hydraulic oil through agricultural machine maintenance, and i wouldnt recomend it. A lot of, if not all hydraulic oils are pretty toxic, and you should wear gloves and glasses when handling it. I do. Engine oils and gear box oils are a lot milder.

Patrick

Tue Nov 24 2009, 07:42PM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

Hmm Im leaning towards mineral oil now, But I will consider all of your opinions/advice....
I will post my decision later.

Dr. Slack

Wed Nov 25 2009, 07:53PM

Registered Member #72 Joined: Thu Feb 09 2006, 08:29AM
Location: UK St. Albans
Posts: 1659

I read somewhere about keeping bio-oils dry, as once they have absorbed some water, they form a constant boiling point mixture and can't be dried with heat. Is this true?

If so, are the supermarket cooking oils likely to be dry as supplied?

Is there any difference on how dry they are as supplied, whether they can be heat dried, or how readily they pick water up between corn, sunflower, olive, rape, "vegetable" oils and any others whose names escape me for the moment?

Can they be dried by other means - passing over calcium carbide or silica gel for instance. I know NaOH or H2SO4 would react with the oil with bad results!

Proud Mary

Wed Nov 25 2009, 11:56PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Sunflower seed oil, alone or in combination with other oils, is of the one most popular vegetable oil dielectrics for filling commercial 'green' HV power transformers.

Google "vegetable oil dielectric."

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