Recent developments on the interpretation of dissolved gas analysis in transformers.

Dissolved gas analysis (DGA) is widely used for monitoring faults in insulating fluid-filled HV equipment in service. New DGA laboratory extraction techniques have been introduced into revised IEC Publication 60567 and interpretation of DGA results have been deeply revised in 1999 in IEC Publication 60599. Following questions about the typical gas concentration and rates of increases observed in service, raised by IEC TC14 (transformers), a joint TF started in 2001 to clarify the isssue and examine other aspects of DGA interpretation which needed clarifications or improvements.