Potting epoxy for toroid

[JaredC79]

What's a good potting epoxy for toroids? The ones that I have are hallow on the inside like my ex wife and held down by a bolt and cap. I'd like to fill the void with a poly type resin to minimize any sort of vibration should the bolt loosen. Anything that doesn't require heat will be ideal.

 

[JonSnell Electronic]

Here is a link to what the transformer manufacturers use. Hope it gives you an idea of what to order.
Potting Compounds | RS Components

 

[JaredC79]

Here is a link to what the transformer manufacturers use. Hope it gives you an idea of what to order.
Potting Compounds | RS Components

Thanks brother. Is anything available at local places like hardware stores or electonic supply shops?

 

[dudaindc]

JaredC79,

This is what I use:
Epoxy Resin Circuit Board Potting Compound Non Conductive Waterproofing 48oz | eBay

D

 

[JaredC79]

JaredC79,

This is what I use:
Epoxy Resin Circuit Board Potting Compound Non Conductive Waterproofing 48oz | eBay

D

Thanks again. Looks like online is the place to go. I have some pics to post up shortly in the vendors area. Do I need permission from an admin?

 

[DUG]

Wouldn't transformers be potted in compounds with higher thermal conductivity?

I would look for that characteristic.

 

[JaredC79]

I would imagine I wouldn't want any conductivity. Basically like the white epoxy fill used by plitron.

 

[RJM1]

Back in the 90's I worked for A video projector manufacturer and we made
prototype HV transformers(38KV). We wound the transformers and then placed them
in a vacuum chamber filled with marine epoxy thinned with a bunch of
acetone. we then ran the vacuum pump until all the acetone evaporate
(to eliminate air pockets).
It worked every time.
True that you need a vacuum pump that you can get -27in mercury.

 

[JaredC79]

Sounds a little out of my reach for thid. Mg seems to have some but the bottles aren't big enough for the for the 1kva model. So I would need like 3. The other is 100va so a single bottle should be ok. Rather pricey also and still need to get the shielding for it as well. I imagine since its non conductive any epoxy with s hardener from HD should be fine. Am I off base

 

[DUG]

I would imagine I wouldn't want any conductivity. Basically like the white epoxy fill used by plitron.

Thermal conductivity, not electrical conductivity.

I agree: no electrical conductivity.

 

[DaveG]

Hi- If I read all this correctly your mostly concerned with mounting rather than potting the whole transformer. How about just a plug, wood or plastic, and silicone caulk in place. If the plug was slightly smaller than the hole there would be a nice layer of caulk to vibration isolate it a little.

 

[BinaryMike]

I ordered up a kit of this stuff for a similar application, but I haven't used it yet. It's billed as thermally conductive.

 

[JaredC79]

Why would you want it thermally conductive? Is it mounted on a sink? I'm putting my schotty diodes On a sink? What supplier are you using for the cover to the toroid? I believe mild steel is the best to stop any stray nasties?

 

[DUG]

Why would you want it thermally conductive?
...

Would you wrap your toroid in some nice insulative foam and seal it with tape?

I would not.

I would want any heat generated to be conducted away from the windings/core.

But maybe that's just me.

 

[JaredC79]

Gotcha, so it is to bring the heat towards the center pin? What about the encapsulating material? I believe MG chemicals makes them also and it is black. If I use the encapsulation material is that equal the same shielding of a steel enclosure/faraday cage to block interference or is it more to protect the winding itself from any damage? I know it's a lot of questions - I just want to do it perfect and once.

 

[Bare]

Erm.. doesn't potting carry with it heat issues ?
As in the things will get much hotter buried in Goo than without.
IF worried about the 'centre bolt coming loose" Loctitie it.

 

[JaredC79]

Erm.. doesn't potting carry with it heat issues ?
As in the things will get much hotter buried in Goo than without.
IF worried about the 'centre bolt coming loose" Loctitie it.

Do flat out forget the potting material and locktite the **** out of the center nut?

Whats the encapsulating material for? Out of the blue it seems like OEMs have black wrapping on the toroids and i am guessing that is it...if i use it is a faraday cage still necessary to make sure no stay nastiness gets around inside the chassis?

 

[VictorDQ]

The thermal conductivity can be added to an epoxy resin oxide aluminium.

 

[JaredC79]

The thermal conductivity can be added to an epoxy resin oxide aluminium.

Does being thermally conductive actually reduce the temperature of the toroids? If so then makes sense to do it and the mount on a sink. If not then loctite on an open air bolt and another fan mounted under the bracket or possibly machining a sink to fit the od of the bolt and ID of the transfo would be a better option no?

 

[VictorDQ]

It all depends on the transformer temperature and the desired temperature of dispersion area. If a simple fan is not enough, you have to put radiator with a fan. And for a snug fit radiator will have to make the composition of the epoxy resin with aluminum oxide. While any fan will be heard because of the air flow. But it is compromises... You have measured the temperature of the transformer?