Varnish

[Humble2000]

Dear Friends,
We were doing maintenance on a 2MVA dry type transformer and we found a lot of varnish particles on the floor. We were told that the transformer was running hot. what can be cause of this?
Transformer is almost 10 years old.

 

[RAF7]

My best advise would be to check with the manufacturer. That being said, things don't look too good. How does the core look?

 

[electricpete]

I agree it deserves further investigastion.

One possibility is that the varnish has been there since manufacture (has the unit previously been inspected and varnish not there?)

Can you post a picture. (

http://www.tinypics.com)

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[powerjunx]

humble,

Verify its PM history, if found nothing like; previuos application of varnish, or other things the relates to varnish that is, re-insulation. Then, your TX has a definite problem that sooner will emerge to failure.

Evidently, in your case, it really indicates high temperature operation. But dont panic, have you check the load currents, ventillations? First, clear up this parameters that affect the unit, and perhaps you'll never post a thread and you'll have the confident to dealt with this problem.
Furthermore, check the functionality of your imbedded RTD sensor on winding for condition monitoring purposes or any non contact temp detecting equipment.

Actually, Dry-type TX is almost maintenance free as other manufacturer's claim.

 

[DanDel]

If the varnish is discolored and very dark (looks burnt), you may have a problem from overheating.
Another possibility is that the varnish cracked from the windings shifting during a fault or too many de-energization/energization cycles.
Look for cracked varnish on the windings or core, and loose blocking.

 

[waross]

What is the winding cofiguration? How heavily loaded is the transformer?
respectfully