Hi all!
We are in the business of power transformer repair and lately we have this one project where we encounter a problem.
After doing the repair of the transformer, it was shipped overseas without insulating oil. Prior to that, Insulation resistance tests and Insulation Power Factor test was conducted at reduced voltage of 1 KV. Before shipment, all insulation tests yielded a value of about 5 gigaohms between windings, and windings to ground. Insulation Power factor was below 1%. Upon arrival at site, unit was vacuum filled with oil and electrical tests was conducted. Insulation resistance dropped to about 0.5 gigaohms for all tests while the Insulation power factor remains almost the same. Oil was tested for Moisture content and DBV and yielded 19 ppm and 76 kv/mm. We drained the oil and conduct the same tests again and values measured was like before the unit was oil-filled. Anybody have any idea what could be the problem?
We are in the business of power transformer repair and lately we have this one project where we encounter a problem.
After doing the repair of the transformer, it was shipped overseas without insulating oil. Prior to that, Insulation resistance tests and Insulation Power Factor test was conducted at reduced voltage of 1 KV. Before shipment, all insulation tests yielded a value of about 5 gigaohms between windings, and windings to ground. Insulation Power factor was below 1%. Upon arrival at site, unit was vacuum filled with oil and electrical tests was conducted. Insulation resistance dropped to about 0.5 gigaohms for all tests while the Insulation power factor remains almost the same. Oil was tested for Moisture content and DBV and yielded 19 ppm and 76 kv/mm. We drained the oil and conduct the same tests again and values measured was like before the unit was oil-filled. Anybody have any idea what could be the problem?