Chemical degradation of oil

IEC 60296:2012, Fluids for electrotechnical applications – Unused mineral insulating oils for transformers and switchgear IEC 60422:2013, Mineral insulating oils in electrical equipment – Supervision and maintenance guidance IEC 60944:1988, Guide for the maintenance of silicone transformer liquids IEC 60666:2010, Detection and determination of specified additives in mineral insulating oils IEC 61203:1992, Synthetic organic esters for electrical purposes – GuideRead more

Properties and deterioration/degradation of oilFrom Chap. 4 of IEC 60422 Ed.4-2013 The reliable performance of mineral insulating oil in an insulation system depends upon certain basic oil characteristics that can affect the overall performance of the electrical equipment. In order to accomplish its multiple roles of dielectric, coolant and arc-quencher, the oil needs to possess certain properties, in particular: high dielectricRead more

Useful elements to define the scenario and priorities– type, size, and total mass of electrical equipment; – installation of electrical equipment; – financial value of the electrical equipment and cost of decontamination/disposal; – type and amount of insulating liquid; – concentration of PCBs in electrical equipment; – state of degradation and effects on the functionality of the electric equipment; –Read more

Degradation (of performance) (from IEC Electropedia)an undesired departure in the operational performance of any device, equipment or system from its intended performance Note – The term “degradation” can apply to temporary or permanent failure. IEV ref. 161-01-19  [source]Mineral insulating oil, natural esters, synthetic organic esterMineral insulating oil insulating liquid derived from petroleum crudes Note – Petroleum crude is a complex mixtureRead more

For diagnosis of the "Chemical degradation of oil" criticality, Sea Marconi uses its own diagnostic metrics, namely: visual signs on the transformer (and those from any internal inspection) are interpreted;  through analysis of oil the symptoms are identified, i.e. the symptomatic indicators (aspect, colour, TAN, dielectric dissipation factor, particulate matter) and their characteristic values. The limits given in IEC 60422Read more

Signs (visual inspection) Oil affected by "chemical degradation of oil" appears dark in color and sometimes with a pungent odour.The appearance may show signs of sediment or particulate matter. In the case of internal inspection of the transformer, there are deposits of sludge at the bottom of the transformer casing, on insulating papers and in oil circulation ducts used forRead more

Oil sampling must be carried out by qualified professionals according to procedures Laboratory analyses must be carried out using methods set by reference standards, as guaranteed by accredited laboratories The countermeasures to the "Chemical degradation of oil" criticality, in this case oil changes and depolarisation of the transformer must be carried out using technologies that are safe and fit toRead more

The "Chemical degradation of oil" criticality is caused mainly by the mechanisms of normal ageing and thermal stress of oil, and secondly by problems of cross-contamination and the use of improper practices in the handling of insulating liquids and the transformer. The aforementioned improper practices have an impact on the life cycle of the electrical equipment with insulating fluids: CausesRead more

It is recommended that strategic information be updated through a "dynamic inventory" of oils and transformers, indicating the values of symptomatic markers. It is recommended that maintenance practices be changed: buying new mineral oils compliant with IEC 60296, or natural ester oils compliant with IEC 62770, or synthetic ester oils compliant with IEC 61099 or silicone oils compliant with IECRead more

Symptoms (analysis) The specific symptom of the "chemical degradation of oil" criticality is related to the presence of the following diagnostic indicators with typical values that do not conform with those recommended by IEC 60422: Water in oil (IEC 60814) Appearance (ISO 2049) Colour (ISO 2049) Total acidity – TAN (IEC 62021-1 or IEC 62021-2) Dielectric dissipation factor (IEC 60247)Read more