oil film conductivity
oil film conductivity
(OP)
We have some big dump resistors that may get whacked with several hundred volts during an "event".
They are mounted on G10 insulating standoffs.
Some sections of that machine are now covered with a light oil film. Probably some cutting or grinding oil.
We plan to degrease things, but I'm interested in confirming there is no conducting film left on the surfaces that might allow a shorting and carbon tracking.
Someone suggests a resistance check is sufficient. An electrical amateur (me) a modified hi pot test is required.
So far GOOGLE has returned almost no info re: oil film condcutivity and resistance.
They are mounted on G10 insulating standoffs.
Some sections of that machine are now covered with a light oil film. Probably some cutting or grinding oil.
We plan to degrease things, but I'm interested in confirming there is no conducting film left on the surfaces that might allow a shorting and carbon tracking.
Someone suggests a resistance check is sufficient. An electrical amateur (me) a modified hi pot test is required.
So far GOOGLE has returned almost no info re: oil film condcutivity and resistance.





RE: oil film conductivity
But you will have dust, flies, mosquitos and what have you stuck in the oil film. Flies and mosquitos may be a minor problem - but accumulating dust is not to be taken lightly.
So you have to remove the oil film. I would not use hipot test. If the surface feels dry to the touch, you probably have got rid of the oil. Do the white glove test and make sure the glove is white after going through all insulators.
Gunnar Englund
www.gke.org
RE: oil film conductivity
The maintainance guy was told to clean the controls. He disconnected power, sprayed the controls with "Gunk" engine degreaser, and hosed it down. The degreaser melted the plastic relay housings and sockets. It left a white film over everything. It was a big mess to rework. Gunk is a kerosene and soap base which leaves a soap film behind.
Be careful with how you degrease your devices!
RE: oil film conductivity
RE: oil film conductivity
RE: oil film conductivity
Google 'Cantenna'.
I suspect that the amateur radio community has used every oil known to man in this application. Cooking, motor, gear... - I'll bet they've used every last one.
A dirty coating is different than a bucket of clean oil.
RE: oil film conductivity
Oil on the supporting insulators may be a conduction issue. You will have to disconnect your resistors from ground and from the system before hi-potting. Then, if you have enough oil to be a problem the hi-pot test may be succesful but in a few months enough dust may build up to cause issues.
I would say "Skip the electrical tests and go with skogskurras' 'White glove' test."
respectfully
RE: oil film conductivity
Under thermal or electrical stress, petroleum oil decomposes ... into carbon, among other things.
Under themal or electrical stress, silicone oil decomposes ... into incredibly fine white sand.
Mike Halloran
Pembroke Pines, FL, USA