CEI EN 62021-3 PDF

This part of IEC 62021 describes two procedures for the determination of the acidity of unused and used electrical non-mineral insulating oils. Method A is potentiometric titration and Method B is colourimetric titration.

NOTE 1 In unused and used non-mineral insulating oils, the constituents that may be considered to have acidic characteristics include organic acids, phenolic compounds, some oxidation products, resins, organometallic salts and additives.

The method may be used to indicate relative changes that occur in non-mineral insulating oil during use under oxidizing conditions regardless of the colour or other properties of the resulting non-mineral oil.

The acidity can be used in the quality control of unused non-mineral insulating oil.

As a variety of oxidation products present in used non-mineral insulating oil contribute to acidity and these products vary widely in their corrosion properties, the test cannot be used to predict corrosiveness of non-mineral insulating oil under service conditions.

NOTE 2 The acidity results obtained by potentiometric test method may or may not be numerically the same as those obtained by colourimetric methods, but they are generally of the same magnitude.