×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Transformer 10 MVA 22kV/6.9kV has been shutdown.

Transformer 10 MVA 22kV/6.9kV has been shutdown.

Transformer 10 MVA 22kV/6.9kV has been shutdown.

(OP)
Transformer 10 MVA 22kV/6.9kV has been shutdown.

- Bucholz device activated
- Pressure Relife Device activated
and too much oil spill to outside of transformer from pressure relife device.


After incident ,We have checked

Insulation of winding and Earth = 0 Mohm
Insulation of HV and LV winding  = 0 Mohm

-Downstream (6.6 kV SWG)

Differential and Buchholz trip

-Upstream (22 kV SWG)

intertriping trip and Earth Fault

So anyone can suggest what problem happen with my transformer ?

and what can i do ?


Thanks you


 

RE: Transformer 10 MVA 22kV/6.9kV has been shutdown.

Your transformer died a violent death.  Take an oil sample, but start making plans to get it shipped out for repair.  

If you're lucky, it only needs a rewind.   

RE: Transformer 10 MVA 22kV/6.9kV has been shutdown.

Jed-

dpc has it correct.  Your transformer has died.  It sounds like interwinding and winding to ground failures.  this is serious stuff.

There is only a tiny possibility that repairs will be simple. 99% chance it will have to go away for repairs.

It is likely that your oil sample when analyzed for dissolved gases will show products that indicate high intensity discharge within the oil.

The fact that BOTH windings show zero ohms to ground discounts the possibility of an easy fix like a bad bushing that could be replaced on site.

old field guy

RE: Transformer 10 MVA 22kV/6.9kV has been shutdown.

I would be figuring on a big bill. If you're lucky you might salvage the core although with a double winding ground fault that doesn't look too promising. New transformer will likely cost in the order of £150k - £200k. Ouch. smile
  

----------------------------------
  
If we learn from our mistakes I'm getting a great education!
 

RE: Transformer 10 MVA 22kV/6.9kV has been shutdown.

Hmm, would a DGA sample even show anything after the releif lifted? I would think the results would be pretty worthless.  

RE: Transformer 10 MVA 22kV/6.9kV has been shutdown.

6.9kV huh? That might be a hard one to find, where are you located?

RE: Transformer 10 MVA 22kV/6.9kV has been shutdown.

Also, if you have micro-processor relays or some type of digital fault recorder, I'd make sure to download all pertinent event reports and fault data for further analysis.  

 

RE: Transformer 10 MVA 22kV/6.9kV has been shutdown.

Zog--

Most of the reliefs I'm used to seeing seat off (mostly) after dumping the pressure. I think a DGA would still be good. However, if the oil was exposed to atmosphere for very long, it would be less so.

A sample might also show suspended carbon and other products of the fault.

old field guy

RE: Transformer 10 MVA 22kV/6.9kV has been shutdown.

Yes they do but I would think the rapid decrease in pressure would "degas" the oil.  

RE: Transformer 10 MVA 22kV/6.9kV has been shutdown.

Transformers normally sit somewhere near atmospheric pressure so degassing shouldn't happen too quickly. Anyway, it's not the ppm values per se, but the concentration ratios between gases and the long term trends which tell the real story. After it goes bang all bets are off, DGA is a preventative maintenance tool and it went bang anyway.
  

----------------------------------
  
If we learn from our mistakes I'm getting a great education!
 

RE: Transformer 10 MVA 22kV/6.9kV has been shutdown.

(OP)
Thank you everybody !!

I have checked the record from digital relay.
T observed that phase B loose of the current in that fault time and high rush current in another 2 phases.

I plan to sent it to manufactere soonest.


Young Engineer.

RE: Transformer 10 MVA 22kV/6.9kV has been shutdown.

Jed--

If you get a chance, follow the transformer back to the factory and view the work.  It's good experience.

Good luck!

old field guy

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources