Transformer Oil Interfacial Tension Test

I previously discussed transformer oil analysis through DGA .

Here, I'd like to discuss another test at the disposal of analyzing the condition of a transformer insulation system - the Interfacial Tension Test (IFT).

As transformer oil degrades via oxidation, it cannot efficiently perform its insulation, cooling and protection of the core functions. Oxydation can occur via a myriad of reasons - oxygen derived from air, degrading paper insulation, water entering the oil via leaks, and also heat, electrical stress and many other factors.

One way to detect oil degradation is through its change in acidity (neutral number - NN) and through its IFT.

Acidity is manifested by a visible change of color in the oil - the oil turns markedly darker. These acids, combined with water content will degrade the paper insulation and cause rusting.

Another manifestation is the reduction of the IFT of the oil. IFT is a powerful tool that helps determine the condition of the insulation oil. It is highly correlated to the NN as shown in the figure at left. It is an empirical graph showing the strong dependency between the neutral number and the IFT.

Among Megwatt Transformers services, we offer comprehensive tests of transformers. Our analytics lab offers transformer oil testing and among them, we provide DGA, IFT, Acidity and water content.

Contact us for more information.