Regular inspection of the transformer oil quality is important to ensure the operation of the transformer. Several methods are available, but the newly released IEC 62691 standard is based on the interfacial tension measurement between water and the transformer oil.
The new standard IEC 62961 for the transformer oil quality testing has just been released. In this blog post, the main differences between the old ASTM D971 and the new IEC 62961 standard are discussed.
Interfacial tension of insulating liquids against water has been used for a long time as a criterion for aging evaluation. The latest revision for the ASTM D971 standard dates back to 2012. The new IEC standard is about the be released to improve the accuracy of the method.