Nowadays the advancement of technology and equipment to monitor the operating performance of power transformer has achieved a high level. So, the monitoring system enables the continued investigation of the operational work of power transformer parameters as well as the prevention of failures and enhance reliability. However, the monitoring of power transformers is of unquestionable value for the electrical power systems and consumers to have more reliability in supplying. Therefore, given that monitoring involves a considerable number of parameters and elements of transformers, in the present case the overview of the monitoring of some of the most important parameters has been taken into account. Thus, the paper includes the monitoring parameters such as; partial discharges, oil and winding temperatures, bushing currents, tap changer, moisture and dissolved gas analysis. Also, in the paper are presented data for the operation of these parameters in different periods as well as with different loading regimes. The reports of events that correspond to the operational performance of the transformer, which are a good cause for diagnosis and preliminary actions in transformers, are also presented.
Diagnosis, Electrical power system, Online monitoring, Sensors, Transformer monitoring