Thanks ScottyUK. I have no intention of setting up this test here, we would outsource it to someone who can do it safely. If I understand your response correctly, there would be nothing to learn from a full load test that you couldn't also learn from a hi-pot test performed at an elevated...
Hi,
I'm a Mechanical Engineer at a company where make feedthru connector systems to run 3-phase submersible pump motors in oil wells. Our standard product is rated at 5kv and up to 210A. Typically we do dc hi-pot testing (1 minute @24kvdc, 5 microamps max leak) to validate the voltage rating...
MJR2 - My dad has the same type of stove that your grandmother has - an induction stove. The thing you're missing though is that it only works with ferrous magnetic pans, not just metallic. Aluminum pans don't work.
Here's a link explaining induction stoves...
I did some more experiments today and as I expected, the presence of non-magnetic conductive metal has no effect. I tried aluminum blocks around the shell and the circuit resistance did not change. Also, as I mentioned before, grounding the shell has no effect. My opinion right now is that...
logbook - Thanks for thinking of this. The clamp-on meter is a Fluke 80i-400 which is under current calibration. This is not a cheap meter, so I believe is reading true RMS. Also, I've simplified my test setup to use only a variac and transformer, so the clean 60hz sine wave is preserved at...
Sorry about the delay, i was on vacation last week. MagneticFlux - yes, you have illustrated the circuit arrangement correctly and we have speculated that the heat rise would be less with 3 phases cancelling each other's flux to some degree, rather than all in phase and additive. If i can...
Thanks MagneticFlux. Your explination make a lot of sense to this mechanical engineer.
To clarify the setup - the current is daisy-chained through the three conductors in the shell, for both AC and DC. In other words, current goes in on the left end, lead #1, while lead #2 and #3 are joined on...
I did some more carefully controlled testing using the exact same test parts and the results are startling! in some cases the heat rise with 60hz is double that of dc. Three .250 inch insulated copper rods running through a steel cylinder 1 3/8 ID with .188 inch wall thickness were tested with...
Thanks very much for your responses. I will plan some more experiments with a monel shell when i return to the office next week. Does anyone else have any experience with actual measured heat rise values for DC vs 60hz? I seems like if it we're really this big of a difference that this...
Typically the steel shell is 2 to 3 inches in diameter and 2 to 3 feet long. Would grounding one end of the shell make a difference? Usually the shell is ungrounded, just laying on the cement floor.
There is only insulating material between the conductors and they remain straight and parallel throught the steel shell. The 10 to 30 percent increase I refer to is regarding heat rise above ambient. For example, the surface of the shell may measure 200F at 70F ambient with DC, and 230F at 70F...
I'm a ME designing electrical connectors and would like help understanding what I've observed in testing. The connectors under test are used to pass 3 phase current through pressure zones in oil wells and consist of large thick steel shells with 3 insulated conductors within. The surface...
A 10 year life test would certainly answer the question, however, I'd rather not wait that long. I'm looking for information on accelerated testing for corona induced degradation or opinions on what type of damage would occur on the PEEK and/or copper at 5kv after 10 years. Does anyone out...
We're considering developing a new connector design using a copper rod with .375-24 UNF thread, screwed into a PEEK insulator. The connector will be 5kv rated and the maximum conductor temp will be 300F. We're concerned about corona between the copper and PEEK in the threaded area, but we don't...
