Andrzej Cichoń

The wavelet analysis the acoustic emission signals generated by multi‐source partial discharges

Within the research work, the results of which are presented in this paper, a comparative analysis of the acoustic emission (AE) signals generated by multi‐source partial discharges (PDs) was carried out. The research investigations were carried out in a model system in which PDs were generated with two spark‐gaps. A spark‐gap in the surface system and a point‐plane spark‐gap were used due to the fact that these are the most commonly occurring PD forms in power transformers. The AE signals were registered with a contact transducer placed on the external part of the tub. The analysis in the time‐frequency domain using a short‐time Fourier transform (STFT) was carried out for the AE signals generated by PDs. The results of the analysis are shown in the form of two‐ and three‐dimensional spectrograms of the power spectral density and three‐dimensional spectrograms of the amplitude spectrum.

Application of Non-destructive Testing for Measurement of Partial Discharges in Oil Insulation Systems

The subject area regards to metrology and measurement methods applied for nondestructive investigation of electrical discharges occurring in oil insulation systems of high-voltage devices. The main aim of performed research studies is a detailed and multivariate analysis of physical phenomena associated with generation of electrical partial discharges (PD), which occur in oil insulation of electrical equipment. An important cognitive component was the verification whether the form of PD has an effect on the energy contribution of the physical phenomena associated with their generation. For investigating the physical processes associated with generation of PD, a system for modelling, the study and analysis of physical phenomena associated with their generation in insulating oil were designed and implemented. In particular, the PD were simulated in three setups: (1) a surface system, (2) needle-needle system in insulating oil and (3) needle-needle system in insulating oil with gas bubbles. In these experimental setups, optical signals (IR, UV and visible), ultra–high frequency electromagnetic and highenergy X-ray radiation, acoustic emission and thermal images were registered. Record‐ ed signals were subjected for multi-variant investigation and analyses in the time and frequency domains. The contribution of particular physical phenomena was determined.

Measurement of the acoustic pressure distribution occurring around an aerial substation adjacent to apartment buildings

The subject matter of the research work presented in this paper refers to the measurements of the values of the acoustic pressure levels (noise) occurring around a main feeding‐point aerial substation adjacent to apartment buildings. The paper presents the values of the noise accompanying the particular power devices, mainly transformers, during their regular operation. The main aim of this research work was the comparison and assessment of the acoustic pressure values measured with the permissible values defined by environmental standards binding in Poland. The research analysis carried out proved that during a long‐term operation of power appliances installed in substations the acoustic pressure level that they emit into the environment is not constant but is subject to changes. Thus the increase of the noise level above the permissible values can be the cause of violation of environmental standards. Due to a significant increase of peoples awareness and readiness to claim their rights, the main conseq...