How often is insulating oil dielectric breakdown voltage testing performed?
Dielectric breakdown voltage testing is an important element in the maintenance programme of any item of oil-insulated electrical equipment. However, to get the maximum benefit from this type of testing, it is strongly recommends that the oil is tested at least once a year and preferably twice a year. The results should be recorded, as trending the data will make it easier to identify sudden or unexpected changes. If a sudden change in the results is found, the transformer can be inspected for leaks, the oil level can be checked and the water content of the oil evaluated. If contamination is confirmed, it will often be possible to dry and filter the oil, thereby reconditioning it rather than having to replace it with expensive new oil.
