Dissolved gas analysis of overheating fault in bio-degradable transformer oil

This paper presents results of experiments performed on laboratory to simulate overheating fault on bio-degradable transformer insulation oil. Dissolved hydrocarbon gas products generated by such a fault in three oil conditions (normal, dried and wet) and with and without presence of pressboard are analyzed. For comparison, the tests are also performed on conventional mineral. Results obtained indicate that existing DGA technique which were developed for monitoring overheating faults in mineral oil need to be modified when used for insulation assessment of bio-degradable oil.