IEC 60599-2015 pdf free download.Mineral oil-filled electrical equipment in service – Guidance on the interpretation of dissolved and free gases analysis. Low-energy faults, such as partial discharges of the cold plasma type (corona discharges). favour the scission of the weakest C-H bonds (338 kJ/mol) through ionization reactions and the accumulation of hydrogen as the main recombination gas. More and more energy and/or higher temperatures are needed for the scission of the C-C bonds and their recombination into gases with a C-C single bond (607 kJ/mol), CC double bond (720 kJ/mol) or CC triple bond (960 kJ/mol). following processes bearing some similarities with those observed in the petroleum oil-cracking industry. Ethylene is thus favoured over ethane and methane above temperatures of approximately 500 ‘C (although still present in lower quantities below). Acetylene requires temperatures of at least 800 ‘C to 1 200 ‘C, and a rapid quenching to lower temperatures, in order to accumulate as a stable recombination product. Acetylene is thus formed in significant quantities mainly in arcs, where the conductive ionized channel is at several thousands of degrees Celsius. and the interface with the surrounding liquid oil necessarily below 400 ‘C (above which oil vaporizes completely), with a layer of oil vapour/decomposition gases in between. Acetylene may still be formed at lower temperatures (
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