The oil-water interfacial tension correlates with the purity and functionality of oils that are used in transformers for cooling, insulation and protection against arcing.
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.
