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Need Advice! Insulation thickness at HF HV AC

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LutzH

Thu Oct 22 2009, 08:38PM

Registered Member #1721 Joined: Sat Sept 27 2008, 08:44PM
Location:
Posts: 136

Dear Sir:

Just to clarify methyl-methacrylate (epoxy) does not exist, what I think you have is the 2 part glue which comes in a black double syringe dispenser just like epoxy. It is sold as a plastic specialty glue at hardware stores also like Lowe's amd Home Depot. Chemicaly it is not epoxy, instead it is a methyl-methacrylate 2 part polymer known commonly as Arcylic, or plexiglass. Acrylic is methyl-methacrylate polymer. this stuff is great I love it!!! It is a great insulator I like to use it to anchor wires coming in and out of HV projects, and to pack around areas which have corona problems like a sharp edge at HV.

As far as compatablitiy with your wire goes I do not know? But would suggest going with Polyimide coated magnet wire instead. Polyimide costs more, and its a bitch to strip, but it is compatable with just about everything!!! The thickness of the coating or build varies, I like double build polyimide wire which I now use exclusively for HV work. I got a 8 pound spool of 29g double build polyimide wire a while back and I still have 6-7 pounds of it at least. The cost of the wire is not a lot with HF work, so why not just use the best? Polyimide wire is also sold as high temp wire, it will handle very high temperatures, and when used with Kapton tape it works very well.

I am currently looking for 28g double-triple build polyimide magnet wire with a self adhesive coating myself, so when I find it I will post the info, unless someone else beats me to it :)

Patrick

Fri Oct 23 2009, 01:05AM

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

OK about the methyl methacrylate, Now IM CONFUSED!!!
Im back from physics class but i scaned a picture of the chemistry in question.

1256259931 2431 FT78188 Loctiteandhenkel

please read the back highlitged in yellow.

Anyway, I need to know more about oil insulation, what approximate volts/mil would I expect , what fluid mineral oil, hydraulic fluid?
Your sure lutz, that pressure from catastrophic arcing, wont burst with dangerous pressure?

TY,
Patrick

klugesmith

Fri Oct 23 2009, 02:01AM

Registered Member #2099 Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1716

OK, the source of confusion begins to emerge. The Loctite company can take much of the blame, because their consumer marketing department actually calls the product an "epoxy" in, for example:

They have dumbed it down for technically ignorant consumers, sort of like specifying its "drying time" or advertising compact fluorescent lamps as "60 watts of light for 13 watts of energy".

As Lutz et al. have said, Plastix Bonder is NOT AN EPOXY, it's a different 2-part resin system in a 2-barrel syringe.
Does it make a strong bond to smooth acrylic sheets?

Herr Zapp

Fri Oct 23 2009, 04:26AM

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

klugesmith, Patrick C. -

It's even more muddled than you think!

It appears that Loctite/Henkel may have several DIFFERENT products using the same name. This sometimes happens when a company has a trademarked product name (e.g. "Plastix") that they think is really catchy, and the Marketing Department decides that's a good idea to use the same name on a variety of different products (dumb idea & confusing!).

The Loctite Plastix Advanced Plastic Bonder #37393 (separate "activator", plus "adhesive") is a cyanoacrylate ("super glue") adhesive. This adhesive is listed in the "Automotive" catalog.

The Loctite Plastix Bonder Epoxy #1151984 (two-part adhesive in a tandem metering/dispensing syringe) appears to be a hybrid epoxy/acrylic adhesive that contains methyl methacrylate monomer (unpolymerized methyl methacrylate). The only product description I could find claimed it to be a "Special acrylic formula". This adhesive is listed in the "Consumer and Craftsman" catalog, one of a whole series of "Epoxy/Acrylic" adhesives.

The epoxy/acrylic Plastix Bonder adhesive is advertised as suitable for ABS, PVC, Acrylic, Nylon, Polycarbonate, and Mylar (polyester).

Regards,
Herr Zapp

Patrick

Fri Oct 23 2009, 05:03AM

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

Ok the jerks [Henkel] misled me, it is an adhesive, but not an epoxy?
Right? And yes it does work well on everything, except the poly sisters ( but nothing works on them )

-Patrick

LutzH

Fri Oct 23 2009, 06:14AM

Registered Member #1721 Joined: Sat Sept 27 2008, 08:44PM
Location:
Posts: 136

Wow that's better now we have it all sorted out, misleading manufacturer literature written for the ignorant masses :) Doesn't that make you happy not to be part of the flock of sheep which represent the masses. We can all do our own thing in places like this, so long as we do not piss off the corporations dogs which mind the perimeter, and move the flock.

To address a few points, yes its great for gluing acrylic and just about any plastic other than the polies, and the slippery fellows of Fluorocarbon based resins like PTFE.

If you are worried about pressure, then use a cast iron container and groove the outside with an angle grinder, using a cutt off wheel, until the outside surface is evenly grooved into about 1cm squares. Just kidding, sorry I just could not resist, no seriously it will not explode if you get some arcing.

If you are planning to run some massive amount of power like from a giant capacitor bank then you could install a simple pressure relief valve designed for a water heater. This will open and vent at 100-150PSI. On myth busters they had to remove this safety valve before they could get a cast iron water heater to explode.

Seriously transformer oil just does not explode due to its high flash point, but if this is of concern like in an O2 enriched atmosphere then you can always use a silicon oil based transformer oil, this will not combust even at high temp. Or you can use a fluorocarbon fluid like Galden, or Fluorinert. These insulate better than oil Galden Fluids can handle 40KV/mm easy, and their viscosity is lower than oil its more like water so it gets between the windings. Galden fluids are about $500/gal, but you can get used fluid, or ebay fluid for much cheaper. Since this stuff does not break down new, used, reclaimed it does not matter as long as it is dry.

Aloha......Lutz

Antonio

Fri Oct 23 2009, 10:08PM

Registered Member #834 Joined: Tue Jun 12 2007, 10:57PM
Location: Brazil
Posts: 644

Returning to the original question, there is no significant difference in insulating properties because the signals are AC or DC at kHz frequencies. The important characteristic is the peak value of the electric field.
What can happen is the insulator heating due to losses, and becoming a less good insulator.

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