Placing a transformer in oil

[The Slab Bacon]

Dave,
        Take that transformer and put a large resistor (like a big dogbone) across the secondary. Calculate something that will give a 25-50mA draw. Put a small fuse in parallel with a big light bulb and place that in one leg of the primary. Put the whole shebang somewhere in an out of the way safe place, fire it up and let it cook. forget about it for a while and watch for the light bulb. If it shorts out, it will blow the fuse and light the bulb as a visual indicator that it crapped out. If it survives for a week or so it will most likely be good to go.


Frank,
         I can cobble together an impromptu winding machine with a crank (or motor) and a turns counter. That isn't too much of a problem. I just need to find out where to get the magnet wire and the Kapton insulation film. Does Mouser or one of them carry it? I will have to give you a telefonium call one night to discuss it. I just might get goofy enough to try it. the cost of shipping the whole transformer plus the cost of rewinding it makes it too cost prohibitive to send it out to have it done. I just may have to get froggy and leap myself on this one. It could possibly be a good "cold winter night" project.

                                                       the Slab Bacon
        

[WA1GFZ]

Frank, strip a couple dead transformers to get an idea how they are wound.
Take my tape tricks and Gary's coating every winding as you wind it trick and it will outlast you.

[KM1H]

Motor rewinders or even a transformer shop will usually sell you a partial spool of wire. Calculate what you need and get plenty extra.

I'll defer to Gary for the best insulation for the wire itself these days.

I was having many transformers built at a local outfit until the owner up and dropped dead one day. The place closed and liquidated.

I was also having a lot of 3 phase jobs made for Shanes buddies that had some interesting alternator arrangements in their Surburbans with 454 power.

Carl
KM1H

[KD6VXI]

I was also having a lot of 3 phase jobs made for Shanes buddies that had some interesting alternator arrangements in their Surburbans with 454 power.

Carl
KM1H

Wanna see some Doozies, check out the older Dahl catalogs....  Look for Mr.  Gilmore.

7Kv AC @ 6A xformers, etc.

6-8 dual stator, single rotor alternators (Electrodyne).  Insane stuff.

454s is an understatement.  There are engines spinning alternators that have > 25 thousand dollars in the longblocks, nitrous injected (2 or even 3 stages).  The problem a lot of guys have is they  need so much horsepower, but have to go "old school" because NO electronics can be made to withstand the RF fields the AC Sky idiots (guys) do.

Takes a lot of horsepower to create a hundred kilowatts of RF   Takes (away) a lot of brain cells, too, me thinks!

--Shane

[WBear2GCR]

Seconding the post on the old PCB based xfmr oil - don't mess with it.

A few years ago I checked with a local wholesale supplier, and I could get a new 5 gal bucket of non PCP stuff for $35... I'd go with the new, and label the new xfmr enclosure with what it in it - for future reference, etc.

W1ATR posted on vacuum filling the xfmr case - but how to seal it after the oil is in there?? I know how they seal vacuum tubes, but this isn't glass that you can melt the filler tube shut... what's the trick??

             _-_-Wbear2GCR

PS. it is friggin raining something fierce here tonight (again)

PPS. it is ok to water your lawn and wash your car...

[W1ATR]

Bear, you don't seal the trans undrr a vac. The only point to vac filling transformers is to expand the air that's in the nooks and crannies that would otherwise be trapped if the oil were just dumped in. (And yes, it is hella downpouring over here, wow.)

[KM1H]

Shane, Gilmore was a steady customer as was many of the mid west and New England crowd. Id have a ball with them every year at Dayton. Those guys came loaded with $$ to shop there also. The NE guys would sometimes be 3-5 deep here on a weekend installing new iron, testing, and generally screwing around. The cops must of thought I was dealing

Carl
KM1H

[KD6VXI]

Shane, Gilmore was a steady customer as was many of the mid west and New England crowd. Id have a ball with them every year at Dayton. Those guys came loaded with $$ to shop there also. The NE guys would sometimes be 3-5 deep here on a weekend installing new iron, testing, and generally screwing around. The cops must of thought I was dealing

Carl
KM1H

Luckily, you didn't have the "old skewl DaveMade" crew hanging around.  I've seen their shenanigans at the CB Breaks in the 90s, and I've also watched them sell everything in the SUburban just to get home.

Gilmore is a really nice guy, once you get to know him.  NOT an RF engineer, his Elmer once told me the ONLY way his tetrodes didn't take off was the rats nest inside wouldn't support ANYTHING resembling oscillation!  Funny then as it is now, but if you've ever SEEN the insides of his stuff, you'd appreciate the comment.

"Them d00dz is insane"...  I have videos of one of Gilmore's mobiles shooting the top off a top loaded antenna at 45 kilowatts carrier. That's the same mobile that when they hit the nitrous, it jumped to 75Kw, and ejected the tape from the camcorder.

I hear Arnie is the supplier of choice for those guys now:  That, and they have pretty much solidified up their own people 'acquiring' parts inside the various employs in the great lakes area


--Shane


--Shane

[DMOD]

If you need need tranformer oils I can put you in touch with a the rep that supplies me with high flaspoint, high dielectric rating synthetic oil.

The only caveat is you have to buy a 5-gallon (pail) minimum.

Phil - AC0OB

[WBear2GCR]

Bear, you don't seal the trans undrr a vac. The only point to vac filling transformers is to expand the air that's in the nooks and crannies that would otherwise be trapped if the oil were just dumped in. (And yes, it is hella downpouring over here, wow.)

Ahhh... I kinda liked the idea of sealing it under vacuum...

So, how full do we make it?
Do we have to leave some air space for heat based expansion??

                  _-_-bear

[W1ATR]

Bear, you don't seal the trans undrr a vac. The only point to vac filling transformers is to expand the air that's in the nooks and crannies that would otherwise be trapped if the oil were just dumped in. (And yes, it is hella downpouring over here, wow.)

Ahhh... I kinda liked the idea of sealing it under vacuum...

So, how full do we make it?
Do we have to leave some air space for heat based expansion??

                  _-_-bear

I'm sure there's some spec for each transformer, but I would say 80-90% fill. Covering the core is obviously the most important, but on those little square trannies a lot of our gear has, I'd say leave some air space anyway, otherwise when it heats up, it could pop the seals around the terminals.

IIRC, I had to drain and reseal the power trans on my r388 and when I refilled it, I remember it taking like 5oz to top it off all the way, (had to be filled with a large syringe like the kind used for filling inks btw) and I sucked out about on ounce with the needle and soldered over the hole. Been running daily now for over a year and it hasn't smoked out yet, so there must be enough in there. 

EDIT: also, I didnt have a way to put a small trans like that into a vac, so I just filled it a bit and rolled it around in my hands with a piece of tape over the fill hole on the top. Did it like that a few times and hoped for the best. I think it originally started puking it's oil because the filter caps were shot and loading it down making it overheat. I recapped the PS on this particular rx and the trans doesn't get anywhere near as warm as it used to. So heat and pressure definitely play a part with these sealed trannies.

[WBear2GCR]

Wow, your R-388 has an oil filled power transformer!?

Whaddya know! Mine is open with two end bells... it probably has one or more shorted turns, because it runs rather hot and I think it let some magic smoke out last year... I put a tiny 2" square fan from a computer supply on it, running at reduced RPM to keep it quiet, seems to keep it cool enough.

I replaced the can cap by fabricating one out of aluminum tubing, an octal socket and some tubular caps plus 5-min epoxy and silicone rubber... the old one got leaky.

Would be nice to find one of the transformers in a can... I have a handful of general purpose transformers standing by in case more of the magic smoke escapes from the one in there now.

I had assumed the square ones were tar filled, not oil filled...

               _-_-bear

[W1ATR]

Nope. Factory 388 was oil filled. Here's a fast pic with my Blackberry.

[KD6VXI]

Bear, you don't seal the trans undrr a vac. The only point to vac filling transformers is to expand the air that's in the nooks and crannies that would otherwise be trapped if the oil were just dumped in. (And yes, it is hella downpouring over here, wow.)

Ahhh... I kinda liked the idea of sealing it under vacuum...

So, how full do we make it?
Do we have to leave some air space for heat based expansion??

                  _-_-bear

Having worked in a cannery for my church, I can tell you this:

Get the oil in the box hot... REAL HOT (not flash point hot, but > normal operating temperature).  Then seal it, and let it cool.

You now have a vacuum seal.

For home canning and food storage, we did it in a double boiler.  Transformers get hotter, so maybe a heat spreader and then put the case on top of the spreader device (to keep hot spots from appearing, weakening the structural integrity), get it all HOT, and then solder / seal it up after the oil has gotten to 'greater than operating temperature'.


The trick is to do it hotter than you think it will ever be, and then you'll have more than enough expansion room.  The "other" trick is to know how much liquid product you need to keep the dry product completely immersed both when cold and hot.  It's a volume / vs product type thing.

--Shane

[WZ1M]

Any of the R-388 power transformers I have done were potted in a tar substance, not oil filled. See the picture of the transformer on this subject, now see the round circle on the top of the case. Thats a plug that is soldered on. This access hole is where the potting material was poured after the can was put together.
Regards,
Gary...WZ1M

[KM1H]

My 388 (Its the run with the front panel Break-In switch) is as Gary says but with many production runs there may be different vendors and construction.

Carl
KM1H

[W1ATR]

Any of the R-388 power transformers I have done were potted in a tar substance, not oil filled. See the picture of the transformer on this subject, now see the round circle on the top of the case. Thats a plug that is soldered on. This access hole is where the potting material was poured after the can was put together.
Regards,
Gary...WZ1M

Well, a pic is worth a thousand words, but this was also about a thousand pics ago. I do have them, but I' have to do some diggin to find them, but you'll see what I mean. There's a small hole on the bottom corner next to the terminals that was slobbered over and the leak was from there. When the trans would get hot, (and I mean hot enough to burn your hands hot), it would start dripping on the table and leave a nice little puddle of clear sticky crap to clean up. All I had to do was wick the slobber off, turn it upside down and put it in my vise. I got it warm with a heat gun and drained off the juice into a water glass so I could see how much to put back. It dripped out about 3-4oz of clear thick liquid, which for a minute I thought was glycerin. (Crystal clear like water and thick like motor oil.) I used one of these needles I fill my printer cartridges with and filled it back up with new oil and about twice as much, (Shell Diala AX). It's a steel case, so I used silver bearing solder and a bit of white paste flux to close the hole and it's been behaving nicely. The bottom hole worked out nice because I didn't have to deal with repainting the trans and fooling with the stencil. This RX is mint, so I try to keep it nice.

I know transformers were encapsulated with a refined version (lowered acidity) of basic pitch, or bitomen, or whatever they called it, but this defin was not that. Now I have heard of some newer trannies being done with whats called "Pale" wax, but I don't think this material was even that because it wouldn't solidify. Like I said, I thought for a while it was glycerin. I almost put that back in there, till I thought about it for a second. Glycerin expands like quite a bit with heat because some of my gauge manifolds have liquid filled gauges, and when the truck gets hot enough, a little will come pissing out of the vents. So it's gotta be some sort of oil for cooling.   

Now this RX had been on most of the day today and the trans is only warm to the touch, feels like maybe 120F. Used to get twice as hot.

73   

[W2PFY]

My big question is weather or not the oil will react with the glues or dialectic insulation materials used in an otherwise built to be a dry type transformer??

I know many of our comments sometimes get covered up by the flow of comments but would someone please answer this for little ole me 

[WBear2GCR]

Pies-4-U, I have never heard or read of the xfrmr oils reacting with anything... of course, that means nothing.

                        _-_-bear

[W2PFY]

Thanks Bear, now I feel better

[WBear2GCR]

Glad I could help and be didactic on this issue...

                _-_-bear

[W2PFY]

didactic

Never heard the word before. Had to look it up.