Electronics > Projects, Designs, and Technical Stuff
Open HV Probe 40kV
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beanflying:
Thanks for the extra information it's fairly hard to come by and first hand :)

Went and got my fairly ordinary Victor out of storage which I should have done before getting started on this project. The sections as tested have a chunk of 40% infill in them and are from the probe I was playing with in the video above. 5kV test on 200GOhm range.

Anyone with serious test gear and a printer and who is interested in punishing some bits PM me. Or even anyone in Oz PM me and I will post you a printed set to abuse.

Edit some dummy forgot the picture. 200+ Gohms at 5kV
PartialDischarge:

--- Quote from: Helix70 on April 28, 2019, 10:10:40 am ---and the partial discharge was really bad. Due to the size, our infill was not 100%, so yes that is not good, but even 100% infill will lead to bad partial discharge performance.

--- End quote ---
for MV or HV use things have to be pressure casted or vacuum filled, no other option


--- Quote ---We ended up flashing over and blowing a hole in the side of the printed housing at about 75kv, but that's another story.

--- End quote ---
That's to expect. That's why I pointed in an earlier post that the kind of probe designed here would be ok only for low energy sources and to be used for small periods of time, because partial discharges are no problem for short term use, since it takes months or years for faulty materials to fail due to partial discharges.


--- Quote ---That's why everyone in the industry uses silicon. HV stresses are just not good.

--- End quote ---
Silicone is mostly used in outdoor bushings for its superiority in non-stickiness to dirt, which is a problem in porcelain, and can not be casted as silicone rubber, when grading rings or other components are present inside the bushing.
By volume however I'd say that most MV 'stuff' (interior and exterior) uses epoxy.
joeqsmith:
Have you made any further progress on your probe?   
beanflying:
Life has been in the way.

Will assemble the Divider insert and take some pics of it as I have all the bits needed. The Probe front end itself is now epoxy coated and I have a few more Rolls of Black so I will reprint the handle end as I have tweaked some of it internally.
ArthurDent:
Here are some photos of the old HV probe I mentioned in post #34 to show the construction details. In the photo that shows the metal shield on the handle you can see that the address has no ZIP code, which I recall happened around 1962, so that somewhat dates the probe. I believe the rating of this probe is 20KV.

The first two photos show the various parts and will give you an idea how they fit together. The shield of the probe cable securely contacts the brass tube that slides inside the entire handle. The small spring goes in the hole near the front of the handle to contact with the brass tube and you carefully hold it compressed while you slide the finned guard with the metal shield that the other end of the spring contacts with into position, then screw the front half of the probe into the handle. When the brass tube and the inner lucite insulating tube are seated all the way inside the handle there is about 0.75 inch of this inner lucite tube that slides inside the front lucite half of the probe so there is pretty good overlap and you won’t have a path for breakdown at the front of the grounded brass piece. So the way this probe is designed there is a complete metal shield between your hand and the HV. If there was an arc-over the grounded shield would protect your hand.

An interesting side note is that I went to a hamfest this past weekend and just before I left, at the last table I checked, was a Fluke 80K-40 HV probe brand new in the sealed plastic. The price was much higher than on eBay so I left without it.
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