Increasing of Ethane (C2H6) in Trafo

hi Guest,

it will be helpful to obtain full DGA test result in order to determine best practice of treatment so as it will give clear figure of what happen in the transformer. What is your transformer's age?

High Ethane usually shows that there was a spark inside cellulose of the transformer. This is due to oil quality which already decrease. Ethane usually comes along with N2,CH4,H2,CO and CO2 when spark occurs. C2H2 rarely comes when spark occur as this kind of gas is the most difficult produced gas over transformer operation time (since it needs a huge energy to broke hydrocarbon chain of oil to produce this gas). Frankly speaking, your transformer still save for the time being (periodical check time is highly recommended).

To do treatment of oil, you can do:

1. Simple purification process.

2. by doing Fuller's Earth method (oil mixed with mud,heated and filtered through filter mesh 200.

3. by adding Carbon-sodium silicate in Fuller's Earth method.

4. by adding Trisodium Phospate in Fuller's Earth method.

5. by doing Deep Bad Filtration

I agree with dj46 in part - the ethane comes from localized (rather than general) overheating in the transformer. This is usually due to some hotspot, maybe discharge or "sparking". It is not as hot as arcing under the oil, which tends to produce ethylene (C2H4) and acetylene (C2H2). However, it is still a problem.

Often the cause is that somewhere there is a poor mechanical connection, such as a bolted connection (cable to bushing or DETC, etc.). DETC contacts often get hotspots, especially if they have been switched and the contacts don't "make" solidly. The only way to correct this is an internal inspection to try to find the location of the heating, by signs such as discolored metal, scorched insulation, etc.

95ppm ethane is not terrible, unless it increased from below the limit very quickly. If it has been stable, then climbed suddenly, it warrants immediate investigation. If it climbed slowly over time, not so bad.

However, I would not recommend what dj46 suggests, to filter or treat the oil. Then you lose all of your baseline on the oil, and don't do anything to correct the cause of the problem! Filtering won't make the heating go away, and that small amount of ethane is not enough to cause a possible explosive condition yet. The ethane also won't deteriorate your oil in itself - it just sits there. Better to find the cause, and treat it. I would look at your operation and maintenance history, and see if there is something that happened or was done to the trafo in the time period before the ethane started increasing, for clues to the cause.

Thank you for you and dj46 comments. In pack I want to know how to decrease Ethane (C2H6) up to the normal standard. For you information every years I do DGA test for my transformers and the result of test is vary. Last year the value of Ethane (C2H6) was 230 ppm higher than the current year 95 ppm. I am not doing anything to treat the transformer. Of course I want to treat the transformer with the lowest cost and the root cause is found. Perhap you have idea..?.

Thank you very much,

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