BS EN IEC 61125:2018 describes a test method for evaluating the oxidation stability of insulating liquids in the delivered state under accelerated conditions regardless of whether or not antioxidant additives are present. The duration of the test can be different depending on the insulating liquid type and is defined in the corresponding standards (e.g. in IEC 60296, IEC 61099, IEC 62770). The method can be used for measuring the induction period, the test being continued until the volatile acidity significantly exceeds 0,10 mg KOH/g in the case of mineral oils. This value can be significantly higher in the case of ester liquids.

The insulating liquid sample is maintained at 120 °C in the presence of a solid copper catalyst whilst bubbling air at a constant flow. The degree of oxidation stability is estimated by measurement of volatile acidity, soluble acidity, sludge, dielectric dissipation factor, or from the time to develop a given amount of volatile acidity (induction period with air).


Cross References:
IEC 60422:2013
EN 60422 (IEC 60422:2013) AS
ISO 6344-1
ISO 3104
IEC 62021-3
EN 62021-3
ISO 4793
EN 62021-2
EN 60247
ISO 383
EN ISO 3104
IEC 62021-2
ASTM E287
IEC 60247
EN 62770
IEC 60296
EN 61099
IEC TR 62036
IEC 62770
IEC 60666
IEC 62021-1
EN 60296
IEC 61099
EN 60666
EN 62021-1
IEC 60050-212


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