the break down voltage of oil - Page 1
Forum section: electronics / projects

author: electronics technician
author_rank: Regular Contributor
timestamp: March 21, 2014, 07:46:22 pm
content: the break down voltage of cooking oil is what voltage?any input is welcome i want to try making some low capacitance low voltage capacitorsi saw some vids on youtube showing how to do itso im going to try it

author: N2IXK
author_rank: Frequent Contributor
timestamp: March 21, 2014, 08:25:11 pm
content: Don't use cooking oil, it goes rancid and becomes conductive pretty quickly.Use mineral oil or transformer oil. Typical dielectric strength is 10-15 megavolts/meter.

author: dannyf
author_rank: Super Contributor
timestamp: March 21, 2014, 09:05:30 pm
content: cooking oil is easily oxidized. Transformer oil - nasty stuff.

author: johansen
author_rank: Super Contributor
timestamp: March 21, 2014, 10:55:07 pm
content: try soybean and castor oil.both are used as transformer coolants.also, if you use paper it needs to be free of all acids and other chemicals such as bleach and etc.white copy paper doesn't work in my experience

author: mariush
author_rank: Super Contributor
timestamp: March 21, 2014, 11:27:47 pm
content: Not sure what videos you watched, but I found these very informative and helpful:and other videos in his channel.

author: gaijin
author_rank: Contributor
timestamp: March 21, 2014, 11:59:08 pm
content: Not sure exactly what you are trying to do but I second mineral oil don't have to worry about it going rancid.I've used it with transformers up to 16kV

author: electronics technician
author_rank: Regular Contributor
timestamp: March 22, 2014, 12:23:30 am
content: thanks for the replies i will take that into consideratiohere is where i saw how to make an eletrolytic capacitor

author: electronics technician
author_rank: Regular Contributor
timestamp: March 22, 2014, 12:35:03 am
content: Quote from: N2IXK on March 21, 2014, 08:25:11 pm10-15 megavolts=15 million voltscorrect me if im wrong but thats pretty high

author: IanB
author_rank: Super Contributor
timestamp: March 22, 2014, 12:40:21 am
content: Quote from: electronics technician on March 22, 2014, 12:35:03 amPer meter. That would be 15 kV per millimeter. But any impurities will reduce that dramatically.For oil, use common or garden mineral oil. You can get it from a pharmacy in pure, safe form (it can be used as a laxative and also for seasoning wooden chopping boards).

author: electronics technician
author_rank: Regular Contributor
timestamp: March 22, 2014, 12:41:30 am
content: Quote from: johansen on March 21, 2014, 10:55:07 pmdam i have a ton of it here lol looks like im going to have to use something else what about wax and brown paper

author: N2IXK
author_rank: Frequent Contributor
timestamp: March 22, 2014, 12:41:41 am
content: Yes, a megavolt is 1 million volts. 10-15 MV is the breakdown voltage through 1 meter of oil. That equates to 10-15 kV per mm of oil.These are rough approximations. Terminal shape will have a great effect, with pointed terminals arcing at lower voltages than smooth rounded ones.

author: electronics technician
author_rank: Regular Contributor
timestamp: March 22, 2014, 12:43:08 am
content: Quote from: IanB on March 22, 2014, 12:40:21 amok kool thanks

author: calzap
author_rank: Frequent Contributor
timestamp: March 22, 2014, 12:56:04 am
content: As others have said, avoid oils of biological origin. They are triglycerides and often have double bonds in the fatty acid portion (i.e. are unsaturated) which are subject to cleavage and oxidation. The ester bonds holding the glycerol and fatty acids together are also subject to cleavage. Net result: stinky, sticky, chunky, chemically reactive, soapy mess with unknown dielectric constant. Mineral oils are primarily long-chain aliphatic hydrocarbons with a variable amount of branching. Result: very resistant to attack by oxygen, microbial enzymes, etc. Both mineral and biological oils can ignite if they get hot enough. A continuous spark near the surface, where there is oxygen available, can get it started. If you want the extra precaution of being fireproof, silicone oil can be used, but be prepared for sticker shock.If your capacitors will be subject to cold temperature, you may need to consider melting point of the oil. Not sure how this would affect dielectric constant. There is quite a range of melting points available for various oils.Interesting comparison of mineral, palm and silicone oils here: journal.itb.ac.id/download.php?file=B11031.pdf&id=827&up=3Mike in California

author: electronics technician
author_rank: Regular Contributor
timestamp: March 22, 2014, 12:57:50 am
content: Quote from: N2IXK on March 22, 2014, 12:41:41 amdont worry im going to be using these caps (IF i get them to work first) at a much lower voltage than 1Mv say around 200v dc thats a very big safety margin

author: electronics technician
author_rank: Regular Contributor
timestamp: March 22, 2014, 01:00:14 am
content: Quote from: calzap on March 22, 2014, 12:56:04 amthanks for this informative input

author: electronics technician
author_rank: Regular Contributor
timestamp: March 22, 2014, 01:21:12 am
content: would anyone be able to recommend me to use brown paper or wax paper instead of the copy paper

author: johansen
author_rank: Super Contributor
timestamp: March 22, 2014, 01:50:04 am
content: i've never tried it.i've taken apart dozens of capacitors over the years and i don't know how they do it.the last capacitor i opened up was filled with castor oil (i think) because i had a moderate allergic reaction to it.it was a 1200v rated capacitor, paper insulation that was not even .001" thick and you could just about see through it.you might have to wash the paper but you should be able to get it to work.

author: electronics technician
author_rank: Regular Contributor
timestamp: March 22, 2014, 01:54:34 am
content: should i wash it with dishwashing liquid or not thanks for the reply

author: johansen
author_rank: Super Contributor
timestamp: March 22, 2014, 02:09:29 am
content: dry the paper out very well, throw some plates across it and experiment with different oils.another thing to do is heat the oil up and pull a vacuum on it to get the water out.washing the paper is a last ditch effort to get acids and bleaches and other crap out of it.i recommend heating the finished capacitor to 80C and pulling a vacuum on it to get the water out.

author: electronics technician
author_rank: Regular Contributor
timestamp: March 22, 2014, 02:21:58 am
content: i will try that thanks for the advice

author: IanB
author_rank: Super Contributor
timestamp: March 22, 2014, 02:39:13 am
content: Quote from: electronics technician on March 22, 2014, 01:21:12 amWax paper good, copy paper bad, plastic film much better!Oil soaked paper is going to be messy. Why go there? Try using cling film from the food storage aisle of the supermarket. It's thin and insulating and dry

author: electronics technician
author_rank: Regular Contributor
timestamp: March 22, 2014, 03:36:57 am
content: thanks i was giong to soak the wax paper in castor oil then sandwich it between two pieces of aluminum foilis there anything else i should know let me know thanks

author: HighVoltage
author_rank: Super Contributor
timestamp: March 22, 2014, 11:37:00 am
content: A few years ago, I could not find a problem on a high voltage transformer and wanted to use an oil based insulator. I tried a few different oils and interestingly, sunflower oil worked the best and had the highest dielectric strength. In this case I even had to heat up the oil to almost boiling point and measured the output voltage under a high capacitive load.Here are some pictures with scope diagram.Essentially the peak to peak voltage was 44 kV between the outputs.But then, I did not care about the life time of the oil, since I only needed to find one problem.Do not use transformer oil, since it is really bad stuff to be around with.Do not even touch it.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: March 22, 2014, 02:07:18 pm
content: I think mineral oil has a dielectric constant of about 2.1 vs castor oil at 4.7 so you'll get a lot more capacitance with castor oil. I was restoring an HP4815 Vector Impedance Meter that uses a variable plate capacitor submersed in oil. I think they did that for stability- no sensitivity to humidity or other factors. They used some very weird oil with a specific dielectric constant. It was nearly impossible to find an oil or blend of oils to duplicate it, and the original was either unobtainable or expensive. I think I ended up with a silicone. Just interesting trivia regarding oils.

author: calexanian
author_rank: Super Contributor
timestamp: March 22, 2014, 03:46:25 pm
content: DiElektrol is the current safer alternative to traditional transformer oil. It's good stuff. hard to find in small quantities. Made by GE for their oil filled caps.

author: zimzom
author_rank: Regular Contributor
timestamp: March 22, 2014, 03:51:24 pm
content: I guess coconut oil would do a similar job also.

author: electronics technician
author_rank: Regular Contributor
timestamp: March 22, 2014, 04:41:31 pm
content: i will try the different oils btw not transformer oil thanks for the info

author: N2IXK
author_rank: Frequent Contributor
timestamp: March 22, 2014, 05:47:55 pm
content: QuoteWhat exactly is wrong with transformer oil? All it is is a highly refined mineral oil specifically designed and tested for high voltage insulating properties, low moisture absorption, and compatibility with fish paper, varnish, plastics, etc. No more hazardous than any other petroleum based oil. Typical MSDS here:http://www.equivashellmsds.com/Display_MSDS.asp?ID=202481Old, unknown insulating fluids could contain PCBs, and should be avoided. But modern transformer oils don't, and are actually what you want to use in electrical applications. Finding them in small quantities can be a problem, however. Most distributors don't want to talk to you unless you want to buy a whole 55 gallon drumful at a time. I have had good luck getting small quantities from the engineering department of the local electric utility.

author: johansen
author_rank: Super Contributor
timestamp: March 22, 2014, 10:16:42 pm
content: Quote from: N2IXK on March 22, 2014, 05:47:55 pmit is specifically designed to match the dielectric constant of paper, which is around 4.4mineral oil is half that.i've seen transformers labled with "Epoxidized soybean oil" recently.

author: SeanB
author_rank: Super Contributor
timestamp: March 23, 2014, 10:11:10 am
content: I have been using it as a general purpose oil for years, as my father needed some to refill an oil filled welder, and got a 20l drum when he needed 1l. Plain mineral oil blend when new, but used stuff could be almost anything depending on what it has been in and what has been put in there over the decades. The Metro comes around every 5 years to the local minisub and does an oil change, pumping it through a filter and a resin column to clean it and remove any acid products in it. Done energised and with load so it is hot. I would not touch that oil as it will have PCB in it from the old transformers.

author: calexanian
author_rank: Super Contributor
timestamp: March 23, 2014, 06:54:30 pm
content: I think they are referring to the pcb type oils. They were used in x ray transformers and the like. Pretty much all gone now. Not even really worth worrying about unless you are scraping mounds of old equipment out or something like that.

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: March 23, 2014, 09:45:40 pm
content: Hi group,I worked in the X-ray business for 20 years. I used two oils in my H.V. tanks.One was Mobil Voltesso 35. You can find a datasheet here:http://www.mobil.com/Canada-English/Lubes/PDS/IOCAENINDMOVOLTESSO.aspxThe other was Shell Diala:Link:http://www.mobil.com/Canada-English/Lubes/PDS/IOCAENINDMOVOLTESSO.aspxThese oils are essentially interchangeable.These have a breakdown strength of 35kV for 2mm spacing.We would regularly test the oil with a Hipotronics breakdown tester.Link:http://www.hipotronics.com/products-liquid-dielectric-testing-equipment-oc60e.htmThe 35kV/2mm is for a uniform electric field, for example parallel plates.The oil is mineral oil. The oil can be dried by heating the oil in a partial vacuum.When you are making the H.V. capacitor you need make sure you don't have any air bubbles trapped in the capacitor.Jay_Diddy_B

author: johansen
author_rank: Super Contributor
timestamp: March 24, 2014, 01:38:35 am
content: Quote from: Jay_Diddy_B on March 23, 2014, 09:45:40 pmNDIANAPOLIS, March 10, 2014 /PRNewswire/ -- Calumet Specialty Products Partners, L.P. (NASDAQ: CLMT) ("Calumet" or the "Partnership"), a leading independent producer of specialty hydrocarbon and fuels products, today announced a licensing agreement with Imperial Oil Limited ("Imperial") through which Calumet will produce, market and sell bulk transformer insulating oil into the Canadian market under the VOLTESSO™ brand of products.meh.any idea where to get some of this stuff?seems to be unobtanium.I do recall someone on the teslacoil mailing list said he was able to get gallons of it back 10 years ago or more.

author: vk6zgo
author_rank: Super Contributor
timestamp: March 24, 2014, 03:37:33 am
content: Quote from: HighVoltage on March 22, 2014, 11:37:00 amThe hazardous materials in old transformer oils were Poly Chlorinated Biphenyls (PCBs).They were used as an additive because of many beneficial characteristics.Unfortunately,they were not at all beneficial to humans!Modern transformer oils do not contain PCBs.Strangely, many people have been exposed to small to medium quantities of PCBs without any obvious ill effects.On the other hand,others have suffered horrendous health problems from these substances.It is best to err on the side of caution!!Avoid "secondhand" Transformer oils---new stuff will have its constituents spelled out in its specifications.We used to have a magic gadget to check the breakdown voltages of the oil in the power & modulation transformers,as well as the Automatic Voltage Regulators ( that's not an AVR---That'san AVR!) in our Broadcast Transmitter sites.We also sent an oil sample off for chemical analysis,so there was a fair bit of handling involved!

author: electronics technician
author_rank: Regular Contributor
timestamp: March 24, 2014, 04:28:33 pm
content: thaanks for the info i will look at the links when i get time later today btw the caps are going to be used for under 200vdc so thats a big safety margin

author: denelec
author_rank: Regular Contributor
timestamp: March 26, 2014, 10:51:13 pm
content: Transformer oil is smelly and messy.But there is a transformer oil derived from vegetable oil.http://www.cargill.com/products/industrial/dielectric-ester-fluids/envirotemp-fr3/index.jspProbably hard to get in small quantity.So vegetable oil may be worth a try.

author: NiHaoMike
author_rank: Super Contributor
timestamp: March 26, 2014, 11:22:05 pm
content: Not sure exactly what that's made of but the ester oils used in HVAC are very hygroscopic.