Transformer diagnostic through combined gas and partial discharge on-line monitoring

Transformer monitoring needs a global approach as diagnostic systems can provide complementary information, working together to reinforce their findings mutually (i.e., in a collaborative way). This paper describes the application of an on-line global monitoring system, comprising PD detector, two-gases DGA and bushing dissipation factor measurement, to an autotransformer affected by abnormal hydrogen levels. The interpretation of the data provided by the monitoring system leads to a univocal way to assess the root cause of this phenomenon, confirming the validity of resorting to global monitoring systems.