New transf leaking

[alehman]

My client purchased a new pad-mounted (2500 kVA) transformer. It is installed but has not yet been energized and is leaking oil at one of the secondary bushings. The mfg. does not want the unit returned. Instead they want to have the bushing replaced in the field.

I recommended to my client that the manufacturer replace the unit or return it to the factory for repair. I am concerned about contamination, etc. from such work in the field. It's outdoors in an urban area, but not an especially dirty environment. Am I being overly cautious?

 

[wbd]

I've done both primary and secondary bushing gasket replacements in the field without issues. You do have to pick your day, so to speak, weather wise but usually it can be done in a reasonable time.

I assume since this is small txf and secondary bushings, that it is not a draw lead bushing but rather a bolted connection at the bushing base.

What is the orientation of the secondary bushings? I'm assuming that they are on the side of the txf tank and oil level would be above them. You will need to drain oil off to replace gasket or bushing if it is leaking through a crack in the bushing.

Is the manufacturer going to perform this work under warranty? They should.

 

[oldfieldguy]

I have done this myself and had it done by others in some rather nasty environments. A competent tech can easily do it correctly.

I'd be sure to ask for a complete set of tests following the work, including oil sampling, and possibly an extended warranty period.

old field guy

 

[Zogzog]

Yep, no problem if done correctly, and as old field guy said, have the full gambit of tests done after.

 

[alehman]

I'll give them the option and request all of the tests. We would be doing most of those anyway.

 

[edison123]

I have done a few in trafos up to 132 KV with condenser type bushings. Weather plays a critical role. I would not do not it on a rainy/highly humid day.

Also, all the preparatory works (in my case mobile crane with proper padded rigging) have to be planned and done well. I used a relay team of 6 technicians to replace all three 132 KV bushings in a 21-hour job.

Clean drums to hold the drain-off the oil below the tank cover and clean oil pumps to put back the oil are a must.

Since these were old trafos, not much field testing was possible. Before and after IR, Oil Breakdown voltage and tan delta were just about it.

* Women are like the police. They can have all the evidence in the world and yet they still want a confession - Chris Rock *

 

[unclebob]

May be tightning carefully the bolts would help. Not too tight to damage the gasket.

 

[Zogzog]

Unclebob, I would agree with you for a in service unit (Stress on the carefully) but this is a brand new unit, let the OEM fix it.