fluorocarbon for a tektronix p6015 hv probe ..... / High Voltage / Forums

Forums

4hv.org :: Forums :: High Voltage

« Previous topic | Next topic »

fluorocarbon for a tektronix p6015 hv probe .....

first previous 2 3 4 5 next

Move Thread

LAN_403

Bored Chemist

Thu Nov 18 2010, 08:53PM

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

Martin King

Thu Nov 18 2010, 09:35PM

Registered Member #3040 Joined: Tue Jul 27 2010, 03:15PM
Location: South of London. UK
Posts: 237

Steve McConner wrote ...

I told Sulaiman's idea to the other guys here in the lab and they all cracked up laughing. But the more I think about it, the more it seems brilliant in a warped way.

Maybe butane vapour can become the poor man's SF6, and we'll see a butane insulated QCWDRSSTC spewing flames from every point of the compass.

I'd go with brilliant, as long as the probe body can handle the pressure and there are no significant leaks then it's no worse than a butane filled lighter or soldering iron. Even if there was a small amount of air still in there it wouldn't be an issue, the LEL and UEL of butane is between (approx) 2% and 8.5% of gas in air so you'd need a lot of air and very little gas inside the probe for there to be a problem.

Martin.

teravolt

Thu Nov 18 2010, 10:54PM

Registered Member #195 Joined: Fri Feb 17 2006, 08:27PM
Location: Berkeley, ca.
Posts: 1111

butane might be a resonable substute but I don't think you can have any air mixed with it it would have to be in a liquid form or you run the posibility of detonation and I wouldn't recomend opening all my lighters and poring butain all over. there must be a better insulator that is safe. maby minreral oil.

Patrick

Thu Nov 18 2010, 11:40PM

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

Martin King wrote ...

... the LEL and UEL of butane is between (approx) 2% and 8.5% of gas in air so you'd need a lot of air and very little gas inside the probe for there to be a problem.

yes, upon further review, my conclusion is the same

Herr Zapp

Fri Nov 19 2010, 12:11AM

Registered Member #480 Joined: Thu Jul 06 2006, 07:08PM
Location: North America
Posts: 644

Still, one part of my brain just says "Butane??!! You'll look like a moron if things somehow go wrong".

It looks like many of the chlorofluorocarbon refrigerants have (or had) dielectric constants around 2.0.

Both mineral and silicone oils also have DCs or around 2.0.

Here's a pretty comprehensive list of DCs, excepting refrigerants:

M

Herr Zapp

Patrick

Fri Nov 19 2010, 02:43AM

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

Herr Zapp wrote ...

....It looks like many of the chlorofluorocarbon refrigerants have (or had) dielectric constants around 2.0.

Both mineral and silicone oils also have DCs or around 2.0.....

yes for the CFC's around 1.8~1.9,
for silicone i get many sources qouting 2.2-2.9,
for mineral oil i get sources saying ~2.1
for butane it seems 1.7-1.8 is credable.

if i recall terry fritz and/or others have said that when mineral fluid is used that the comp box had adustments near END OF TRAVEL! so , therefore i would not want to go much above DC=2.1 (mineral oil)

however, remember for human purposes mineral oils mole whieght and properties are somewhat constrained, with electrical/machine mineral oil is a broad class of oils which have wide variance. for this reason i would like to know if others have used mineral from the supermarket/pharmacy. i presume Vitamin E, perfume, other additives would be unwanted for hv use.

on an unrelated note at STP cocaine's DC is 3.1 @ 1Mhz

klugesmith

Mon Nov 22 2010, 01:42AM

Registered Member #2099 Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1714

All this talk about dielectric constants -- it looks like people are quoting the values for -liquids-.
No worries about running out of compensation range when the chamber is filled with vapor
at 3 atmospheres -- e_r probably never exceeds 1.1.
(The part which exceeds unity can be scaled by the vapor/liquid density ratio.)

[edit] Not sure about 6015's, but ordinary scope probe compensation must be adjusted every time you move the probe to a different oscilloscope with different input capacitance. What do we use as a clean square-wave compensation source for a 1000:1 probe?

Patrick

Mon Nov 22 2010, 06:12AM

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

Klugesmith wrote ...

All this talk about dielectric constants -- it looks like people are quoting the values for -liquids-.
No worries about running out of compensation range when the chamber is filled with vapor

yes.

for vapors dielectric breakdown is the great concern, DC is secondary at best.
for liquids DC is the concern since breakdown is almost always sufficient of liquid insulants.

anything more then 2.5 atm may cause explosive/bursting the p6015 case.

Patrick

Wed Nov 24 2010, 06:18AM

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

I have just contacted Terry Fritz, via a hot-streamer mirror site.
will post if he returns my email.

testtest

Sat Nov 27 2010, 09:50PM

Registered Member #3271 Joined: Mon Oct 04 2010, 02:29AM
Location: Canada
Posts: 159

Patrick wrote ...

Herr Zapp wrote ...

Patrick -

("fluorocarbon", "Tektronix")

sorry, the peppermint schnapps impaired my ability to spell.

does anyone know what is inside the p6015? a schematic would be nice, i have only seen a simple mechanical diagram which shows a single 100M resistor and a dielectric cone.

i presume R134a for my car wont work....?

I have the schematic and ower's manual if you have not found the info on the net yet. Could post a scan if needed.
I also heard that there were two types of dividing resistors used in these probes and that a different dielectric could possible dissolve the protective coating on the early resistor.
Best bet was oil but I could not get the hf trimming in range. Now I do not dare cleaning it since it still works well at the lower voltage.

first previous 2 3 4 5 next

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob