leaking transformer

[colonelbogart]

we have 2-MVA power transformer 4160/480V. 7-325mm2 cables per phase were connected on its secondary bushings. The cables' connections applies some pressures on the bushings causing transformer oil to leak. I am planning to intall braided copper conductor on its secondary bushings to relieved pressures. But until my flexible cables arrived(installed) I am still using my transformer.

Is it OK to still operate the leaking unit?

 

[wbd]

A couple of things to consider:
How major is the leak? You have to be careful that the oil level does not drop below the top of the coils or bushing connections.
Does the transformer cycle in temperature? What can happen is that moisture can be drawn into the transformer since it is not sealed anymore.
I'm not sure what you mean by braided copper conductor to relieve pressure. I would look at installing strain relief (Kelloms Grips) and attach them to the top of the connection box. They make split ones so you don't have to disconnect the cables to install.

 

[wfowfo]

" You have to be careful that the oil level does not drop below the top of the coils or bushing connections."

You have to make sure it doesn't fall below the level of the radiators either, or it may overheat.

 

[colonelbogart]

I wish to know more details about strain relief (Kellom Grips)...might apply it.

The leak is something about 2 to 3 drops per minute?! not very sure though...

Braided copper conductor is like a flexible conductor composed of smaller copper conducters woven together (braided). In this manner the connection between the transformer terminals and cables (braided conductor) will be flexible.

 

[wbd]

Here is the link for the Kellems grips:

http://www.hubbell-wiring.com/Kellems.asp

 

[bradh01]

This is a pretty common problem. As long as your liquid gage shows a normal oil level, you should be ok.

Support your cables to relieve the strain on the bushings, and carefully torque the bolts on the bushings.

 

[colonelbogart]

Thank you wbd for the link. Probably I can use those support grips in tandem with my braided copper conductor unless there are still more suggestions out there...

Presently the level is still OK... we're just allowing oil to leak coz if we will try to tighten the bushings we will spill oil also in the process.

Thank you guys...

Happy Holidays

 

[k2panman]

I would suggest adding mechanical supports, as bradh01 says. The mechanical supports we have supplied with our large transformers are fiberglass bars that bolt onto the bushing and onto the tank, holding the secondary bushings fairly rigid. You probably can devise another method to hold the cable rather than use a Kellum grip, as you will have to disconnect the cables to install the grips and they are really designed to be used in tension (a Kellum grip works like the "Chinese finger torture" toys we had as kids - a woven sleeve that you insert the cable, pull on it and it tightens around the cable - the harder you pull the tighter it grips).

K2ofKeyLargo

 

[colonelbogart]

Thanks for your suggestion K2ofKeyLargo

 

[waross]

As stated by wbd, split Kellems grips are available. The cables do not have to be disconnected to install them.