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hardening of the transformer winding

MacIntoshCZ

Active Member
Hello,
I need to harden the transformer winding. At low frequencies, I think the winding is buzzing due to magnetostriction. Any congestion? Thanks
 

MacIntoshCZ

Active Member
As far as I'm aware you simply soak the windings in varnish.
Varnish... hmmmmmm =)
tealc-thank-you.gif
 

crutschow

Well-Known Member
Most Helpful Member
The noise is likely coming from the transformer laminations, not the windings.
 

ronsimpson

Well-Known Member
Most Helpful Member
In yokes for CRT monitors we heated up the copper until the insulation just started to milt. This holds the wire in place.
We passed current in the windings to create heat. We did not do this with transformers.
Probably does not help. RonS
 

ChrisP58

Well-Known Member
Most Helpful Member
Vacuum impregnation is often used to ensure the varnish gets deep into all the gaps and cracks.
 

MaxHeadRoom78

Well-Known Member
Most Helpful Member
A couple of methods often used is bead of weld across the laminations, another is long small dia bolts through the laminations in each corner, with the bolt insulated by bushing.
 

ronsimpson

Well-Known Member
Most Helpful Member
There really wasn't much wax that remained in the transformer. They don't have much free space.
If the windings were as neat a can be. The wax will be 25% and copper will be 75% of the winding area.
I was joking. I have seen fires and adding fuel seemed a bad idea.
 

unclejed613

Well-Known Member
Most Helpful Member
That way when it catches fire there is plenty of fuel.
i once worked for a manufacturer that used transformers that had been dipped in some kind of wax... my guess is, to meet UL requirements the wax had some kind of flame retardant in it...
 

Reloadron

Well-Known Member
Most Helpful Member
A couple of methods often used is bead of weld across the laminations, another is long small dia bolts through the laminations in each corner, with the bolt insulated by bushing.
Same and then they went into an impregnation tank of varnish. Vacuum, pressure, vacuum, pressure several times over. Something pretty cool was watching the process. When we would pull vacuum the varnish would actually boil. Anyway after cycles of vacuum pressure they went into an oven and baked. Pretty long process overall but it got it done. Years ago I worked with aircraft 400 Hz stuff. When large transformers would whine the technicians would wedge a wood block against the laminations and hammer it down till things got quiet. . :)

Ron
 

gary350

Well-Known Member
When I worked for the Transformer factory we used polyurethane on copper wire windings. NEW transformers were very slowly lowered into a tank of polyurethane for about 12 hours so air had time to escape while polyurethane replaced the air. Then transformers were drained and baked in a oven until polyurethane was dry.

When I make transformers at home on my lathe I hand paint polyurethane onto each layer of wire with a brush. Big wire air dries easy in warm weather about 1 week with no oven. Smaller wire does not dry as quick.

If your trying to refurbish and old transformer you might be ok to hand paint it with polyurethane, let it soak in then paint it several more times & soak in several more times.
 

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