IEC 61125 Insulating Fluids - Test Methods for Oxidation Stability - Test Method for Evaluating the Oxidation Stability of Insulating Fluids at Delivery

The IEC 61125 standard, developed by the International Electrotechnical Commission (IEC), defines a test method for evaluating the oxidation stability of insulating fluids in the delivered condition under accelerated conditions, regardless of the presence of antioxidant additives. The duration of the test is different depending on the insulating fluid type. These times are specified in the relevant standards, such as IEC 60296, IEC 61099 or IEC 62770.

A number of technical changes have been made in the last update of this standard. For example,

• The cap has been modified to contain different insulating fluids from mineral insulating oils.
• The method is applicable to insulating liquids in the delivered condition.
• The old method C is now the main normative method.
• The precision data of the main normative method have been updated with respect to the dispersion factor.
• The old method A has been deleted.

The standard appendix describes a test method for evaluating the oxidation stability of inhibited mineral insulation oils in the delivery state by measuring the induction period with oxygen. This method is intended solely for quality control purposes. The results do not necessarily provide information about performance in use. The degree of oxidation stability is estimated by the time it takes for the oil to develop a certain amount of volatile acidity . Additional criteria such as soluble and volatile acids, sludge, and dielectric dissipation factor are also determined after a certain period.

The standard appendix also describes a test method aimed at simulating the thermo-oxidative behavior of ester insulating fluids. Where necessary, additional test methods based on differential scanning calorimetry, such as those described in the IEC 62036 standard, can be used as screening tests, but are beyond the scope of this standard.

Oxidation stability is one of the most important properties of fatty acid alkyl esters (biodiesel fuel) and affects the stability of biodiesel during long-term storage. Oxidation stability refers to the tendency of fuels to react with oxygen at certain temperatures and describes the fuel's susceptibility to degradation by oxidation. These reactions are much slower than those that occur at higher temperatures.

Among the numerous test, measurement, analysis and evaluation studies it provides for businesses in various sectors, our organization also provides testing services to evaluate the oxidation stability of insulating liquids in the delivery state, within the scope of the IEC 61125 standard, with its trained and expert staff and advanced technological equipment.