What is the brownish they dip the generator stator In to seal and protect them?

I had two stators rewound and the local shop just painted on some type of varnish or sealer and they failed pretty quickly due to not entirely sealing them 5 and 7 months, and the fact I’m on a carribean island with a solid breeze of salty air doesn’t help. I want to buy the product and dip mine like the factory does to seal every nook and cranny any one know how many times I should dip them? and what is the best product to use for this. Thx for any info guys

When I repaired the stator of an old Honda motorcycle I sealed it with Minwax polyurethane. I ran it happily charging the battery like that for a several months afterward before selling. Can't speak to longevity of the Minwax in the presence of oil mist since I sold it before long. I'm curious to see what others reply with that has better history/longevity.

Bulldogger

Its usually called conformal coating. Used on circuit boards also.

One old 'standard' sealing and stabilizing material was glyptal (glyptol), normally applied with vacuum. Bet that lengthy process is not used much any more. Glyptal is the coating seen inside engines too.

These folks might can help. http://www.epicresins.com/ElectronicsPotting/MotorsStators

The motor shops dip the windings into a polyester resin, then bake the winding to cure the resin. For severe service the winding is soaked in the resin under a vacuum, then under pressure, called VPI - vacuum pressure impregnation. That is what I would spec for your windings. There are also polyurethane and epoxy coatings available. A good marine motor shop should be able to provide this service. A good dip not only provides electrical insulation, but mechanically holds the winding together, which is important with the beating a diesel engine gives the generator.

thx for the link and info guys. I’m in Colombia South America. The guy winding my parts does the power companies transformers he is illiterate and learned from his father as he started working at 8yrs old. I’m thinking if I thin the resin a little and dip it four times and let it dry in four different positions gravity will help fill all the nooks and crannys. He did them with a brush on application and they didn’t last 8 month as I’m on an island about 50 mtrs from the beach. The last one I had wound I sprayed about 12 thin coats of epoxy paint that I over reduced so it would flow well. I will contact the resin company and ask their advice. Thanks again guys for all the great info guys

Dude,

Go to the TM section. Look in the Generator TM's. Look for MEP-018A. Open the second book there. Its TM 5-6115-275-14. Go to PDF reader page number 227. Top of the page. Start reading from there. Its info on how to do this stuff. In the old days, we still were allowed to do that kind of work. Some good info there. You all talk about hanging up the parts after coating. We used to bake them. Give it a look see. Cant hurt

That’s for the heads up. But for some reason I can’t open the TMs with my iPhone. when I get to the mainland I will. I intended on baking them to cure the resin but I was also looking at epoxy paints which last for years without breaking down due to the elements. I’m in an island not far from the beach and as a result things surface rust in a day thx again I will read that info as soon as I’m able.

tennmogger said:

One old 'standard' sealing and stabilizing material was glyptal (glyptol), normally applied with vacuum. Bet that lengthy process is not used much any more. Glyptal is the coating seen inside engines too.

Click to expand...

Right about vacuum. I have transformers and stator coils wound for products I make, and I specify vacuum impregnation of the coils. It's still done, and is necessary to get the sealer all the way through all the turns of the coils. The local motor rebuilding shop here has a vacuum chamber in the floor, with a big iron lid, and an overhead crane, to vacuum impregnate big parts of multi-hundred horsepower motors.

If I were getting a stator or rotor rebuilt, I'd make sure the shop had vacuum equipment.

Triple Jim said:

Right about vacuum. I have transformers and stator coils wound for products I make, and I specify vacuum impregnation of the coils. It's still done, and is necessary to get the sealer all the way through all the turns of the coils. The local motor rebuilding shop here has a vacuum chamber in the floor, with a big iron lid, and an overhead crane, to vacuum impregnate big parts of multi-hundred horsepower motors.

If I were getting a stator or rotor rebuilt, I'd make sure the shop had vacuum equipment.

Click to expand...

unforetunately I’m in Colombia South America they just aren’t up to date on any of this stuff down here. I think I can figure a way to do it myself. How many inches of vacciim should it pull thanks for the info

Ideally you should have pretty good vacuum. The idea behind the method I'm familiar with is you pump out the air while it's submerged in the sealer. Then when you let the air back in, the sealer if forced all the way in to the windings. If there's any significant amount of air, the sealer will go most of the way in, but hit the air bubble in there somewhere along the way. A refrigeration vacuum pump would be fine. They're pretty darned good.

This is old technology though. You might be surprised to find that motor rebuilders in Colombia have vacuum chambers.

Nope they put it in with a brush for the last one theybwould I have corrosión problems in 4?months on one a dn6 months on the other

I was thinking the same thing on the ac vacuum pump. I’m trying to figure out what type of vessel to use the put the resin and stator in that I can seal the top on and how to connect the vacuum pump to it.

A pressure cooker if the stator is not very big.

If you want to build a vacuum chamber big enough to do multiple size rotors/states for motors/generators, you could try to build it out of concrete.

Take a 55 gal steel drum, and drill a 1" diameter hole in the bottom of it. Then mount a 1" black iron pipe to the hole and let it stick out about 5" or so. Then for added concrete attachment, tack weld regular bolts to the outside of the drum, at every 45 degrees and spaced vertically every 4-5".

Then take 2 pieces of plywood and cut them 6"+ more in diameter than the drum. In one, drill a 1" hole in the center for the iron pipe.In the other, drill 4-6 1.5" holes about 0.5" out from the diameter of the drum...these holes are for the concrete to be poured through.

Place the drum on the lower plywood, making sure it is 3" above the plywood and the iron pipe sticks through the center. Take the upper plywood sheet and mount it to the drum.

Then take a piece of sheet metal or plastic and wrap around the circumference of the plywood in piece. If it doesn't want to wrap around properly, take some ratchet straps to position it and to tighten up the seam. Use duct tape to seal the edges and seam.

Then you can pour the concrete through the upper holes. Use one hole to pour and the others to agitate the mix in place. After its filled and has set, you can remove the formwork.

Let the concrete cure for about a month. Then seal it with an epoxy paint on all sides. I'd recommend 2 coats to be sure it's sealed.

Then go find a scrap piece of security plexiglas from a convenience store installer and cut it to fit the lid.Then add a rubber/silicone seal to it. Drill/tap 3 holes into it...one for your vacuum pump, one for a vacuum gauge, and one for a vacuum release hand valve.

Then you'll have a vacuum chamber that should last a fairly long time. And if you can get access to refractory materials, you can use the same construction method to build a burnout/foundry furnace.