Acoustic Emission Partial Discharge Detection Technique Applied to Fault Diagnosis: Case Studies of Generator Transformers

Abstract

In power transformers, locating the partial discharge (PD) source is as important as identifying it. Acoustic Emission (AE) sensing offers a good solution for both PD detection and PD source location identification. In this paper the principle of the AE technique, along with in-situ findings of the online acoustic emission signals captured from partial discharges on a number of Generator Transformers (GT), is discussed. Of the two cases discussed, the first deals with Acoustic Emission Partial Discharge (AEPD) tests on two identical transformers, and the second deals with the AEPD measurement of a transformer carried out on different occasions (years). These transformers are from a hydropower station and a thermal power station in India. Tests conducted in identical transformers give the provision for comparing AE signal amplitudes from the two transformers. These case studies also help in comprehending the efficacy of integrating Dissolved Gas is (DGA) data with AEPD test results in detecting and locating the PD source.