Transformer Paper Degradation 1

[seanmcc]

Following on from our annual DGA sampling of our network transformers, one transformer has come back with increased levels of Furfuraldehyde which indicates degradation of the paper insulation. This has been put down to increased winding temperature, we have reduced the load to lower the temperature. The company who did the oil analysis has then estimated the Degree of Polymerization to be 254, this is indicating the transformer has reached the end of its useful life as there is no mechanical strength left in the paper. They say that the transformer could fail if subjected to a short circuit or other mechanical stress, which I agree with. My question is that my boss would like to have further testing done on this transformer before deciding to replace, however I am doubtful anyhing can be done. Please advise if you know of anything that can be done and who by. The problem I can see is that we are questioning the mechanical strength not the electrical strenght of the papers. Taking paper samples for analysis would be a last resort for us.

Thanks in advance

Seanmcc

 

[jbartos]

Suggestion: This is a rather important decision to make since the transformer could last for some time or fail soon. There is nothing wrong with waiting until the transformer fails. Meanwhile, a procurement of the transformer replacement might be initiated.
However, one test results should not be the final criterion. Contact firms that have a good record of transformer replacement recommendations. In some cases, the transformer manufacturer knows the best.

 

[jbartos]

Suggestion: Visit

http://www.thomasregister.com

and type Transformer Services under Product or Service, which will return 5 companies to approach to

 

[buzzp]

I dont know of any other sure way to tell other than a paper sample.

 

[jghrist]

If the paper is deteriorated and brittle, the probability of failure will be higher after moving the transformer or mucking about inside to get paper samples.

 

[busbar]

You might want to contact established and experienced test labs like

http://www.actiinc.com

or

http://www.oliveoilsource.com

or

http://www.tjh2b.com

 

[buzzp]

If it were me, I would plan on replacing this in the near future, budget for it. It is typical for us NOT to get paper samples when we get indication of weak paper because of the potential to make matters worse.
Who knows, it may last a lot longer or may not. You need to ask yourself if you want a forced outage for replacement or a scheduled outage.

 

[stevenal]

Ignoring rules 1 and 2 for a second, not much harm in taking another oil sample for a second opinion; but I agree with jghrist regarding more invasive testing. Make sure they know how to test insulating fluids though. One of the links above looks more like they know more about salad dressing.??

 

[jbartos]

Suggestion: Visit

http://www.powertech.bc.ca/cfm/index.cfm?It=901&Id=60

for: Screening Insulating Oils for Paper Degradation Products (2-Furaldehyde)
Notice that a deliberate transformer overloading might reveal the transformer situation, whether it is about to fail (it will fail) or function for some longer time

http://www.ias.ac.in/resonance/June2003/pdf/June2003p17-23.pdf

for:
Correlation Between 2-Furaldehyde and DPv graph
etc. for more info

It may be a good idea to place the original posting in Chemical Engineers section of this Forum since the topic is much too much on the chemical side as may be evidenced in the posted links.