The Wavelet Analysis of the Vibroacoustic Signal Measurement in a Transient State Operation of Power Transformer

Abstract

The article presents the results of attempts made to develop a non-invasive diagnostic method of a technical state of a transformer's core based on an analysis of mechanical vibrations registered during the start-up of the transformer analyzed. The paper presents a characteristic of the transformer under study, the measuring systems applied and the method developed for assessing the degree of the core loosening. The original results presented in the paper have been obtained under laboratory conditions during tests conducted on an oil transformer of 200 kVA. The analysis of recorded virboacoustic signals was performed by means of discrete wavelet transform for three di erent operating cases: the transformer with no core defect, the transformer with loose screws of the magnetic circuit of the upper yoke, and the transformer with completely loosen screws of the beam of the upper yoke and the lower core. The signals have been recorded on two perpendicular measuring axes: 0X and 0Y and their measured values were subject to the wavelet analysis.