Corona in oil transformer
Corona in oil transformer
(OP)
Hi! One of our customers have an oil transformer and we do a dissolve gaz analysis annually. We found that the transformer have a corona (partial discharge) problem. The key gases are hydrogen (1150 ppm)and methane (110 ppm). The level of the other gases is insignificant. The progression
of H2 is about 200 ppm/year.
Now that we know this, is there a way to find where corona is occuring? We have made a visual inspection, from the main hole and found no grey-to-black powdery traces.
The transformer is:
Northern Transformers
1 500 kVA
25 000 - 600/347 V
sealed type
1984
ONAN
Any comments?
of H2 is about 200 ppm/year.
Now that we know this, is there a way to find where corona is occuring? We have made a visual inspection, from the main hole and found no grey-to-black powdery traces.
The transformer is:
Northern Transformers
1 500 kVA
25 000 - 600/347 V
sealed type
1984
ONAN
Any comments?






RE: Corona in oil transformer
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RE: Corona in oil transformer
RE: Corona in oil transformer
I agree with your diagnosis of corona but is it remotely possilbe this represents overheating. We had a transformer allowed to operate around 120-140C oil temp for several days and if memory serves me right the results were H2 and CH4 and CO and CO2.
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