What does interfacial tension in transformer oil indicate?

Interfacial tension in transformer oil is a critical parameter that indicates the quality and condition of the oil, particularly its ability to resist contamination and maintain dielectric properties. A high interfacial tension suggests good stability and a low level of contaminants, whereas a low interfacial tension may indicate the presence of polar substances such as water or degrading products that could compromise the insulation properties of the oil. Thus, monitoring interfacial tension in transformer oil is essential for ensuring the reliability and longevity of transformer operations.