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  • Author: Andrzej Cichoń x
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Sebastian Borucki, Tomasz Boczar and Andrzej Cichoń

Abstract

The subject presented in this paper refers to measurements and assessment of the corrected sound pressure level values (noise) occurring around a medium-power transformer. The paper presents the values of noise accompanying the operation of the power object before and after its modernization, which consisted in repeated core pressing and replacement of the cooling system. The main aim of the research work was the assessment of the influence of the repair work on the noise level emitted into the environment.

Open access

Daria Wotzka, Andrzej Cichoń and Tomasz Boczar

Abstract

A verification study of ultrasound transmission numerical simulation results with experiment results is presented in this paper. The work considers a model of a transformer tank which is filled with electro insulating oil. In the experiment, performed under laboratory conditions, an ultrasound wave is generated by a piezoelectric transducer that is fixed in the centre of the tank and measured by another transducer mounted inside the tank at three distances: 10, 20 and 30 cm from the sound source. The transducer is able to measure and generate acoustic waves in the ultrasound frequency band up to 1 MHz. The simulation considers numerical calculation of acoustic pressure distribution inside the tank in which acoustic source emits waves with frequency equal to 100 kHz. Verification analysis has confirmed consistency of the numerically calculated values with the measurement results.

Open access

Andrzej Cichoń, Sebastian Borucki and Tomasz Boczar

Abstract

On-load tap changers (OLTC) are some of the main transformer elements that make voltage adjustment in a power network possible. Their failures often cause shutdowns of distribution transformers. The paper presents research work aimed at the assessment of the technical condition of OLTCs by the acoustic emission method (EA). This method makes the OLTC diagnosis possible without the need of disconnecting the transformer from the system. The measurements were taken in laboratory conditions. The influence on the operation non-concurrence of the power tap changer contacts on the AE registered signals has been investigated. The signals registered were subjected to analyses in the time and time-frequency domains. The result analysis in the time domain was carried out using the Hilbert transform and calculating characteristic times for the particular runs. A short-time Fourier transform was used for the assessment of results in the time-frequency domain.

Open access

Henryk Majchrzak, Andrzej Cichoń and Sebastian Borucki

Abstract

This paper provides an example of the application of the acoustic emission (AE) method for the diagnosis of technical conditions of a three-phase on-load tap-changer (OLTC) GIII type. The measurements were performed for an amount of 10 items of OLTCs, installed in power transformers with a capacity of 250 MVA. The study was conducted in two different OLTC operating conditions during the tapping process: under load and free running conditions. The analysis of the measurement results was made in both time domain and time-frequency domain. The description of the AE signals generated by the OLTC in the time domain was performed using the analysis of waveforms and determined characteristic times. Within the time-frequency domain the measured signals were described by short-time Fourier transform spectrograms.

Open access

Michał Kunicki, Andrzej Cichoń and Sebastian Borucki

Abstract

An acoustic emission method (AE) is widespread and often applied for partial discharge (PD) diagnostics, mainly due to its ease of application as well as noninvasiveness and relatively high sensitivity. This paper presents comparative analysis of AE signals measurement results archived under laboratory conditions as well as on-site actual AE signals generated by inside PDs in electrical power transformer during its normal service. Three different PD model sources are applied for laboratory research: point to point, multipoint to plate and surface type. A typical measuring set up commonly used for on-site transformer PD diagnostics is provided for the laboratory tasks: piezoelectric joint transducer, preamplifier, amplifier and measuring PC interface. During the on-site research there are three measuring tracks applied simultaneously. Time domain, time-frequency domain and statistical tools are used for registered AE signals analysis. A number of descriptors are proposed as a result of the analysis. In the paper, at- tempt of AE signals descriptors, archived under laboratory condition application possibilities for on-site PD diagnostics of power transformers during normal service is made.

Open access

Sebastian Borucki, Andrzej Cichoń, Henryk Majchrzak and Dariusz Zmarzły

Abstract

This article presents the results of research connected with the development and industrial use of vibroacoustic methods for the evaluation of the technical condition of the active part of transformers. The article presents the results of the analysis of vibrations generated by the high power transformer in which a defect was found on the basis of tests of oil carried out using the chromatography tests. In order to confirm the damage of the active part of this transformer, vibroacoustic measurements were performed in three states of its operation. The measurement using the classical vibroacoustic method included the registration of vibrations at the idle speed and during the load operation of the transformer. The original diagnostic method, so-called the modified vibroacoustic method, was also used during the measurement. The analysis of signals recorded using the classical vibroacoustic method was carried out in the frequency domain by indicating the amplitude of even harmonic vibrations. However, the analysis of signals measured during the commissioning of the transformer was conducted in the time-frequency domain using the short-time Fourier transform (STFT), continuous wavelet transform (CWT), and discrete wavelet transform (DWT). On the basis of the analysis of the results obtained it was stated that the increased level of vibrations of this transformer is a consequence of the loss of rigidity of the mechanical structure of its core.

Open access

Sebastian Borucki, Jacek Łuczak, Dariusz Zmarzły, Andrzej Cichoń, Jerzy Filipiak, Tadeusz Gudra, Dariusz Banasiak, Krzysztof Herman, Krzysztof Opieliński, Tomasz Hejczyk, Krzysztof Jasek, Mateusz Pasternak, Michał Grabka, Witold Kardyś, Andrzej Milewski, Adam Kawalec, Michał Kunicki, Marta Okoń-Fąfara, Bartłomiej Fąfara, Aneta Olszewska, Piotr Pruchnicki, Marcin Wrzosek, Józef Nicpoń, Przemysław Podgórski, Tadeusz Pustelny, Tomasz Rogala, Piotr Serafin, Marta Okon-Fafara, Marcin Szugajew, Czeslaw Lesnik, Adam Kawalec, Olga Stec, Tomasz Rogala, Adam Kawalec, Grzegorz Szerszeń, Franciszek Witos, Daria Wotzka, Agnieszka Boruń, Adam Bald, Marzena Dzida, Sylwia Jężak, Monika Geppert-Rybczyńska, Katarzyna Kaczmarek, Tomasz Hornowski, Arkadiusz Józefczak, Arkadiusz Józefczak, Tomasz Hornowski, M. Kubovčíková, A. Skumiel, Z. Rozynek, M. Timko, Krzysztof Klimaszewski, Peter Kopcansky, Bogumił Linde, Milan Timko, Vyacheslav N. Verveyko, Marina V. Verveyko, Darya V. Verveyko, Andrey Yu. Verisokin, Nikita S. Chebrov, Witold Mikulski, Dariusz Pleban, Danuta Augustyńska and Bożena Smagowska