Methodology for the detection of partial discharges in power transformers using the acoustic method

The occurrence of partial discharges (PDs) in power transformers is a phenomenon inherent to their operation and one of the factors that can cause failure of these devices, leading to major disruptions and high financial losses, and compromising the image of the electric energy provider. Dissolved gas analysis (DGA) is a widely accepted predictive technique, but its sensitivity is low when used for the detection of partial discharges, and it does not identify the location of incipient faults in power transformers. On the other hand, the detection of partial discharges by the acoustic emission (AE) method allows the levels of partial discharges inside transformers to be monitored and their location to be pinpointed. However, to increase the quality of the analyses of results, it is important to observe some requirements and to carry out several procedures that contribute to a more effective diagnosis. This paper describes a methodology that increases the analyst´s efficacy in evaluating the results of acoustic detection tests of power transformers in operation.