Thermal Dependency of Viscosity, Power Factor, and Ion Content of Electrical Insulating Oils

Viscosity and dielectric loss of insulating liquids have been recognized as exponential functions of temperature; however, sufficient coordinated proof was previously unavailable. This study correlates and analyzes the theoretical predictions with available experimental results and, also, clarifies the importance of the concept of the ion content of insulating liquids as an indication of electrical purity and insulating quality, as proposed by Whitehead. The evidence that temperature increases the ion content and decreases the effectiveness of an insulating liquid, and the relationships between them, are practical tools for electrical design considerations. The postulation that the viscosity, power factor, and ion content of an insulating liquid originates from an identical mechanism relating to temperature may open up new approaches for further research leading to a better understanding of dielectric loss in liquid insulators.