Application of the joint electro-acoustic method for partial discharge investigations within a power transformer

Analysis results of partial discharges (PD) measurements within a power transformer situated in a testing station, carried out by the so-called joint electro-acoustic method, is presented in the paper. Basing on measurements resultant from the electric method apparent charge values at different test voltage levels have been determined. Such charges are introduced by PD sources within one of three phases of high-voltage winding whereas two remaining phases are shorted and grounded. An analysis of acoustic emission (AE) measurement results allows us: to identify the main band of other acoustic phenomena (Barkhausen's acoustic effect, magnetostrictive phenomena, noises connected with circulation of the oil and other noises), to show the local character of PD measurements coming from AE method, to identify AE signals characterized by maximum value of ADC descriptor, to locate measuring points on the tank for mentioned signals. The correlation between apparent charge values in particular phases and ADC descriptor values (as maximum ones in AE signal sets, recorded at different measuring points for respective phases) is managed to settle.