ACOUSTIC EMISSION TESTING OF POWER TRANSFORMERS INSULATION

Abstract

Testing results of power transformers insulation for the presence of insulation defects, accompanied by the partial discharges occurrence, by means of the acoustic emission method are presented in this article. In particular, the testing of two power transformers with different lifetime was carried out. One transformer was defect-free and one with a willing insulation defect. Based on the testing results, the features of acoustic emission data for power transformers in the presence of partial discharges are found. High sensitivity of acoustic emission method for acoustic wave registration from partial discharges is shown in the article. A method for filtering of noise hits and extraction of hits from partial discharges is proposed. This method is based on excretion of acoustic emission hits from partial discharges out of total number of hits by means of periodicity of their registration, which is synchronized with power supply frequency on the first step. On the next step based on acoustic emission parameters of hits excretion on the previous step, filtration was carried out. The location of the insulation defect which led to the appearance of partial discharges was determined based on the volume location algorithm, by means of acoustic emission method. The insulation defect was confirmed by verification.