New 80 kV x-former

This forum is for specialized infomation important to the construction and safe operation of the high voltage electrical supplies and related circuitry needed for fusor operation.
Post Reply
User avatar
Dennis P Brown
Posts: 3160
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

New 80 kV x-former

Post by Dennis P Brown »

I mentioned I have decided to upgrade my fusor to 80 kV. I bought the 80 kV x-former some years ago after I returned the 30 kV x-former; however, the person decided to make the 30 kV unit an indefinite loan, so I never installed the 80 kV x-former. Actually, I decided I want to return their unit to them (still working!) - I've had a few current run-aways (including a dead diode to ground) and I was always worried I'd damage the unit. So, besides wanting to experiment with a higher voltage (but far lower current) x-former I'd rather not risk a x-former I don't own.

I include a pic of the unit. It smells strongly of oil and was in a sealed plastic bag. I guess it was already soaked in oil. But I will pull a vacuum on it and then submerge it under oil - don't want to take any chances. I have a nice sealable drum that I installed a vacuum connection to the top (see pic) to perform this task. I still need to add an oil inlet line to the lid. The drum has a seal on its lid and a metal circular lock down clip assembly (not shown.)

I will place the x-former in a smaller container inside the drum so I can limit the amount of oil I will require.

Once that is done, I will need to add enough diodes to handle 120 kV (as insurance that if the unit reaches 80 kV, I don't exceed the diodes capacity.) Turns out I do have twelve 20 kV (1 amp - yes, overkill) diodes so I can get half wave output but certainly not for a full wave bridge arrangement.

While my HV cable is only good to 40 kV, it is isolated in air so I will just continue to use that along with the ballast resister that is insulated under oil.

Before I go any of this I will test my new "someone here had an interesting idea and I want to look into it" cathode (a steel & chrome coated hollow sphere (5 cm diameter)) with my current system and see if that has any interesting effects in replace of the existing cage cathode. Certainly it will not 'glow' and shed extra low energy (useless) electrons. Whether that will matter much will prove interesting.
Attachments
80 kV Transformer
80 kV Transformer
Vacuum drum and x-former
Vacuum drum and x-former
User avatar
Dennis P Brown
Posts: 3160
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: New 80 kV x-former

Post by Dennis P Brown »

The metal can w/lid collapse under vacuum. Did a little damage to the transformer but nothing serious. Should have realized that drum wouldn't handle 15 PSI/in^2.

Went to walmart and obtained a glass jar. Has the advantage I can see the oil level/fill. I noticed that a lot of air coming from both the oil and transformer itself. This vapor product was forming a foam on top of the oil. Also, I can see large bubbles leave the transformer coils and then float to the surface, as well.

Aside: I use a clear plastic bottle inside the glass jar. The x-former is in that clear plastic jug.

Turns out I'm short of oil and need to get more. I'll leave this under vacuum until bubbles stop forming. I'll finish this as soon as I can obtain more oil.

Still, pulling a vacuum on the transformer and then adding oil produce more vapor from the components then I would have suspected. That the oil (vacuum grade) also had large amounts of dissolved gases (water vapor?) in it was a major surprise to me.

Well, a learning process.
Attachments
xFormerwithoil.jpg
User avatar
Dennis P Brown
Posts: 3160
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: New 80 kV x-former

Post by Dennis P Brown »

After an hour of pumping (holding around 30 microns), still getting some nearly centimeter in diameter vapor bubbles from the base of the x-former - and a few smaller bubbles but, at least, no tiny bubbles. The bubbles are only coming from the x-former, not the oil itself (unlike at the beginning.)

I'll need to add more oil to finish the process (another day) but that is far more out gassing then I would have expected. Since the x-former has been in a sealed plastic bag for five years or so - plenty of time to absorb water vapor into the oil that was present in coil (plastic isn't exactly a high end barrier.) So, maybe that is par for the course (through I was hoping not to get an Eagle on this course.)

Checked it after another hour of pumping and it has reached 7 microns; so possibly this isn't just water vapor but also the old oil vaporizing. Still even larger bubbles occur but ultimate vacuum is improving. If I have time (and oil) I'll see what happens tomorrow.
Matt_Gibson
Posts: 505
Joined: Thu Sep 23, 2021 10:36 am
Real name: Matt Gibson

Re: New 80 kV x-former

Post by Matt_Gibson »

Any updates? Did this work? Can you provide a picture showing the setup? I’m thinking about doing this for my ferrite x ray transformer after I had my second one fail due to a flashover between the secondary and primary (primary is under the secondary). I’m not sure what caused it, but figure it might be a good idea to eliminate any air for the remaining one.

-Matt
User avatar
Dennis P Brown
Posts: 3160
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: New 80 kV x-former

Post by Dennis P Brown »

Hello Matt and sorry for my lack of posting since what seems like forever.

I really do appreciate your inquiry on this issue and am glad you asked - I needed a kick in that direction ;) . I have been amiss in my reading here of late and need to rectify that issue. I really need to start diversifying my efforts and stop focusing that 24/7 isn't enough time no matter how hard I try to believe on the contrary ...

I see from that last post I was at the point where I had partly soaked the transformer in oil under vacuum (I obtained more oil and after it again bubbled like crazy finally settled down; also, that was a partial disaster - long story.) But I do think the x-former is more than ready to test. However, I realized my diodes were lacking for a full bridge and considered that issue would just require more diodes - of course, a simple non-bridge would work (duh on my part) but space inside my power supply was tight.

Then, of course, immediately considered a new rebuild of both my fusor system and power supply case to economize on available workspace. Then life and oil prices got me distracted at that point - ugh!

Also, I realized that I really do need more room in my lab building through (ok, lesson learned - no matter how big one builds a lab, one will quickly over fill it by 2x and realize they were dreaming that the size they designed was sufficient.) This is due to my needing to get some furnaces up and running for another major research project and build a new hot rolling mill and install that as well (another long story.) Started a clean and organize on the lab but really need to consider the fusor rebuild for real.

Then between retirement paperwork and training of my replacement (on going), finishing research projects at work (and associated research papers I have been sitting on - but finally got the required final data I required in order to complete that research paper successfully!), and converting my home from oil heat to a Heat exchanger system (massive rebuild and install done 100% by me) and other needed home projects (complete secondary bathroom gutting and rebuild by me) - well, I have been overwhelmed of late.

Apparently, 24/7 isn't enough time in a week but I have been trying to complete a few more new projects that are time critical and discovered that for some strange reason - that I can't explain - I'm hitting a stone wall. Yeah, one of those need to be constructed very soon as well ... Ok, maybe I wax poetic there.
User avatar
Richard Hull
Moderator
Posts: 14992
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: New 80 kV x-former

Post by Richard Hull »

Get the retirement thing straight, leave your life's work without regret or looking back. Create a new life's work. Do the tough back breaking chores first, for as you get older, you will have to hire folks to do what you can do on your own right now. Catch the fun stuff that can be done at a bench or a machine last.

Thank goodness for me, I shunned intense responsibility and management offers at work. It allowed for a full life un-incumbered by work issues for fun while at work and after work with many hobbies and new experiences. There is much more here that could be said, but it ain't fusion related.

I am sure you will enjoy retirement by never really stopping to work, only this time you are working on fun stuff only. This assumes you get all your home related stuff taken care of to the point that home matters are more on the order of a rather minor issue here and there.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
User avatar
Dennis P Brown
Posts: 3160
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: New 80 kV x-former

Post by Dennis P Brown »

Richard, you are certainly correct!

Matt, sorry, I was endlessly typing and didn't address your issue. I went to Wal-Mart and bought a glass 'candy' jar with a ground glass lid. It fit my x-former fine. I cut an Al plate and added a pumping tube (std vac hose one.) I placed the x-former in the glass jar, used silicon seal on its lid; placed the Al plate onto it, and then pumped it down to under 10 microns. Then I back filled with vacuum pump oil (the teflon white line w/valve.) In this manner I got all air out before I added oil. I then pumped the x-former w/oil down to under 10 microns again and ran the pump for eight hours. It bubble a lot and I mean a lot! Then let it sit over night under vacuum (pump not on), then again for 8 hours with the pump on. This stopped all the bubbling.

To cut down on oil, I used a clear gallon plastic jug (top cut off) which just fit the x-former. That assembly I placed in the glass candy jar. If I recall, the glass jar was under $15.

I then used silicon seal with the glass top to store it. As far as I got before other issues arose.
Attachments
Complete system
Complete system
X-former inside the glass jar; sealed with silicon
X-former inside the glass jar; sealed with silicon
Post Reply

Return to “High Voltage - Fusor Input Power (& FAQs)”