If you need assistance, please send an email to forum at 4hv dot org. To ensure your email is not marked as spam, please include the phrase "4hv help" in the subject line. You can also find assistance via IRC, at irc.shadowworld.net, room #hvcomm.
Support 4hv.org!
Donate:
4hv.org is hosted on a dedicated server. Unfortunately, this server costs and we rely on the help of site members to keep 4hv.org running. Please consider donating. We will place your name on the thanks list and you'll be helping to keep 4hv.org alive and free for everyone. Members whose names appear in red bold have donated recently. Green bold denotes those who have recently donated to keep the server carbon neutral.
Special Thanks To:
Aaron Holmes
Aaron Wheeler
Adam Horden
Alan Scrimgeour
Andre
Andrew Haynes
Anonymous000
asabase
Austin Weil
barney
Barry
Bert Hickman
Bill Kukowski
Blitzorn
Brandon Paradelas
Bruce Bowling
BubeeMike
Byong Park
Cesiumsponge
Chris F.
Chris Hooper
Corey Worthington
Derek Woodroffe
Dalus
Dan Strother
Daniel Davis
Daniel Uhrenholt
datasheetarchive
Dave Billington
Dave Marshall
David F.
Dennis Rogers
drelectrix
Dr. John Gudenas
Dr. Spark
E.TexasTesla
eastvoltresearch
Eirik Taylor
Erik Dyakov
Erlend^SE
Finn Hammer
Firebug24k
GalliumMan
Gary Peterson
George Slade
GhostNull
Gordon Mcknight
Graham Armitage
Grant
GreySoul
Henry H
IamSmooth
In memory of Leo Powning
Jacob Cash
James Howells
James Pawson
Jeff Greenfield
Jeff Thomas
Jesse Frost
Jim Mitchell
jlr134
Joe Mastroianni
John Forcina
John Oberg
John Willcutt
Jon Newcomb
klugesmith
Leslie Wright
Lutz Hoffman
Mads Barnkob
Martin King
Mats Karlsson
Matt Gibson
Matthew Guidry
mbd
Michael D'Angelo
Mikkel
mileswaldron
mister_rf
Neil Foster
Nick de Smith
Nick Soroka
nicklenorp
Nik
Norman Stanley
Patrick Coleman
Paul Brodie
Paul Jordan
Paul Montgomery
Ped
Peter Krogen
Peter Terren
PhilGood
Richard Feldman
Robert Bush
Royce Bailey
Scott Fusare
Scott Newman
smiffy
Stella
Steven Busic
Steve Conner
Steve Jones
Steve Ward
Sulaiman
Thomas Coyle
Thomas A. Wallace
Thomas W
Timo
Torch
Ulf Jonsson
vasil
Vaxian
vladi mazzilli
wastehl
Weston
William Kim
William N.
William Stehl
Wesley Venis
The aforementioned have contributed financially to the continuing triumph of 4hv.org. They are deserving of my most heartfelt thanks.
Registered Member #1321
Joined: Sat Feb 16 2008, 03:22AM
Location:
Posts: 843
I know there are silicone type oils, ester and synthetic ester oils and mineral oil. Does anyone know if there are there any significant differences in dielectric strength between them?
Registered Member #2099
Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1714
As John said on the other forum: any place where there's electric power, you are not far from stockpiles of "real" transformer oil. The choice of chemical family is up to the user, and depends mostly on considerations other than dielectric strength. For an amateur, it might be "which kind can I conveniently obtain without buying a whole barrel?" I was fortunate, when Carl Pugh offered to decant some Diala AX from his 5-gallon pail.
All transformer fluids have to pass standard HV breakdown tests, with acceptability criteria that I think don't vary widely. New-in-barrel performance could determine the amount of margin for a fluid to degrade in service. Then again, different fluids can be more or less susceptible to picking up gas, moisture, acidity, etc. Here's one white paper with a nice overview and tabulated data.
Training materials emphasize transformer oil-handling hygiene. I just learned that ordinary rags are a no-no. Hydrophilic lint fibers that wind up in the oil are attracted to places with high E-field gradients and motivated to form bridges, not unlike iron filings on magnets.
Here's one video of oil sampling and testing in the real world: The voltage ramping is done manually, with first breakdown at 3:05, Might seem primitive, but probably represents the norm for most of the world's population.
Registered Member #1321
Joined: Sat Feb 16 2008, 03:22AM
Location:
Posts: 843
I'm contemplating using transformer oil to insulate a Tesla coil secondary in an arrangement where k = 0.6.
I looked around for examples, and I found this (see page 5): which is similar to what I had in mind, but the type of insulating oil used in the design isn't mentioned in the paper.
Anyway, I just found this paper: which is interesting because the tests are done under pulsed comditions. And under under the conditions of this study, Shell "Diala D" was superior to the other oils in terms of breakdown voltage and breakdown voltage as a function of gap length.
############################
Edit: I remember seeing a paper where the breakdown voltage of transformer oil was increased (under certain conditions at least) by adding powdered graphite or something to the oil; apparently because of some kind of a field grading effect. I'm trying to find that paper again.
This site is powered by e107, which is released under the GNU GPL License. All work on this site, except where otherwise noted, is licensed under a Creative Commons Attribution-ShareAlike 2.5 License. By submitting any information to this site, you agree that anything submitted will be so licensed. Please read our Disclaimer and Policies page for information on your rights and responsibilities regarding this site.
What type of transformer oil has the highest inherent dielectric strength?
