20 results on '"Tenbohlen, S."'
Search Results
2. Evolution of bubbles in oil-paper insulation influenced by material quality and ageing.
- Author
-
Koch, M. and Tenbohlen, S.
- Subjects
ELECTRIC insulators & insulation ,ELECTRIC transformers ,HIGH temperatures ,DIELECTRICS ,MICROSTRUCTURE ,CELLULOSE fibers ,VAN der Waals forces - Abstract
This study experimentally investigated and theoretically analysed the evolution of gas bubbles in a wet oil-paper insulation system. Water vapour bubbles significantly decrease the dielectric withstand strength of insulating oil. The influence of moisture content on paper, quality of oil, quality of paper, ageing state and temperature increase on this 'Bubble Effect' was systematically investigated. New thermally upgraded paper combined with new insulation oil shows the best resistibility against bubbling because of its microstructure. Paper ageing increases the bubble inception temperature, whereas oil ageing decreases this parameter. Bubbles appear only for a steep temperature rise of more than 3 K/min; for lower values the moisture diffuses into the oil only. An empirical equation that calculates the inception temperature with respect to paper and oil quality and ageing is derived. The evolution of gaseous bubbles constitutes a risk for transformer operation if a steep temperature gradient occurs, if the moisture in paper is above 2% and if bubbles move into an area with high dielectric stress. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
3. Statistical analysis of the impact of FeO3 and ZnO nanoparticles on the physicochemical and dielectric performance of monoester-based nanofluids.
- Author
-
Jiosseu, Jean Lambert, Jean-Bernard, Asse, Mengata Mengounou, Ghislain, Tchamdjio Nkouetcha, Emeric, and Moukengue Imano, Adolphe
- Subjects
PARTIAL discharges ,STATISTICS ,NANOFLUIDS ,BREAKDOWN voltage ,DIELECTRICS ,CASTOR oil ,GOODNESS-of-fit tests - Abstract
This article deals with a comparative study of the physicochemical and electrical properties of monoesters of castor oil compared with their counterparts based on FeO
3 and Zn O nanoparticles. The results are also compared with those in the literature on triesters, and also with the recommendations of the IEEE C 57.14 standard. The data is analysed statistically using a goodness-of-fit test. The analysis of the viscosity data at 40 °C shows an increase in viscosity. For concentrations of 0.10 wt%, 0.15 wt% and 0.20 wt% these are respectively 5.4%, 9.69%, 12.9% for Fe O3 NFs and 7.6%, 9.91% and 12.7% for Zn O NFs. For the same concentrations, the increase in acid number is respectively 3.2%, 2.9%, 2.5% for FeO3 samples and 3.18%, 2.0%, 1.2% for Zn O samples. For the same concentrations, the fire point shows an increment of 4%, 3% and 2% for Fe O3 samples and a regression of 8.75%, 6.88% and 5.63% for Zn O samples. As for the breakdown voltage, for the same concentrations we observe respectively an increment of 43%, 27%, 34% for the Fe O3 . The results show an improvement on partial discharge inception voltage with FeO3 of 24%, 8.13% and 15.21% respectively for the concentrations 0.10 wt%, 0.15 wt% and 0.20 wt%. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
4. Analiza zmienności w czasie sygnałów generowanych przez wyładowania niezupełne.
- Author
-
KUNICKI, Michał
- Subjects
PARTIAL discharges ,HIGH voltages ,SIGNAL processing ,DIELECTRICS ,INFLUENCE - Abstract
Copyright of Przeglad Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2022
- Full Text
- View/download PDF
5. Influence of additional dielectric coatings on the electrode surfaces on selected parameters of acoustic emission signals in high-voltage gas insulation systems.
- Author
-
Dobrzycki, Arkadiusz, Opydo, Władysław, and Zakrzewski, Sebastian
- Subjects
ACOUSTIC emission ,PARTIAL discharge measurement ,SURFACE coatings ,DIELECTRICS ,PARTIAL discharges - Abstract
The paper is devoted to the study of impact of additional dielectric coatings placed on the surface of the electrodes on the operation of a high-voltage insulation system with air as insulating medium. The study mainly focused on measurement of partial discharges (PDs) with the use of acoustic emission method. Tests were conducted in various levels of chamber pressure. Applicable parameters of recorded signals were analyzed with the use of applications developed in the environment of MATLAB software. The results of analyses clearly show that presence of additional coatings has impact on signal parameters and thus indirectly on PDs. The use of coatings reduces the duration of a single pulse (event) and increases its amplitude. Furthermore, the influence of degradation of the coating caused by individual discharges on the values of the analyzed parameters was analyzed. The study has shown, however, that this effect is negligible. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
6. ANALYSIS OF INSULATING PARAMETERS OF OIL TRANSFORMER BY TIME AND FREQUENCY METHODS.
- Author
-
GUTTEN, Miroslav, KUCERA, Matej, BRNCAL, Peter, SEBOK, Milan, and KORENCIAK, Daniel
- Subjects
INSULATING oils ,POWER transformers ,ELECTRIC potential measurement ,DIELECTRICS ,FRENCH fries - Abstract
In the paper is presented experimental analysis and diagnostics of insulating system oil-paper for power transformers. In the first part of the paper is described base theory about measurement and diagnostics insulating part (oil and paper) of transformers. In the other two parts of the paper is presented experimental results of the diagnostic measurement for the transformer 22/0.4 kV at constant temperature. Specifically, in the second part is described measuring time method of insulating diagnostics - return voltage measurement (RVM). This method is used for analysis of condition of paper moisture of high-voltage equipment. In the third part is described measuring method of insulating frequency diagnostics - frequency domain spectroscopy (FDS). This method is used for analysis insulating condition of high-voltage equipment with insulating oil-paper. The both measuring methods are unique in terms of analysis of insulating system of oil power transformers. In comparison with other methods, the RVM and FDS methods it is possible comparison and evaluate the moisture state of the dielectric paper of the power transformer with high reliability and accurate. Their reliability in determining moisture in paper was shown by determining the same result (3.5%) on the same measured transformer. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
7. Influence of Frequency and Distance on Acoustic Emission Velocity Propagating in Various Dielectrics.
- Author
-
Wotzka, Daria
- Subjects
SPEED of sound ,ACOUSTIC emission ,NONLINEAR regression ,LIQUID dielectrics ,DIELECTRICS ,PIEZOELECTRIC transducers - Abstract
The results obtained for the measurements of acoustic emission (AE) signal parameters emitted in three dielectric liquids are presented in this paper. In particular, the velocity of AE wave was calculated based on the time of arrival of the AE signal. A frequency modulated signal was generated by a piezoelectric transducer and measured at various distances by a hydrophone. The changes in velocity values at particular distances and for different frequencies were investigated. The analyses include the determination of the dependency of the velocity values from the distance between the communicating devices. A nonlinear regression model was calculated, and the differences between AE velocities propagating in the considered dielectrics were determined. Similarly, the influence of modulation frequency on the AE velocity was determined using nonlinear regression. Based on the calculation data, it can clearly be stated that the velocity of AE wave depends significantly on the frequency and distance at which it is registered. These two factors may have an important influence on the localization of partial discharges (PD) occurring in these types of dielectric liquids. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
8. Effect of electrodes material on transient currents in dielectric liquid.
- Author
-
Beldjilali, Abdeslem, Saidi-Amroun, Nadia, Mansour, Mahdi, and Saidi, Mohamed
- Subjects
DIELECTRICS ,ELECTRODES ,NANOPARTICLES ,ELECTRIC conductivity ,OHMIC resistance - Abstract
In this study, results of polarisation and depolarisation currents measured on an insulating liquid are presented. The goal is to contribute to a better understanding of mechanisms occurring at the metal-liquid contact. Electrodes of different metallic nature are associated with the same mineral oil, the metal/liquid/metal structure is submitted to DC voltages and the transient current is recorded with a high sensitive electrometer. The current versus time feature shows that the conduction process is in good compliance with the metal work function rather than with its electric conductivity. The current versus field characteristics indicate a predominance of the ohmic behaviour for the low fields. The space charge limited conduction regime appears as soon as the electrical constraint exceeds ~1 MV/m, which corresponds to 10% of the breakdown voltage. Schottky injection is suspected to occur from the metal into the liquid since the applied fields are uniform and non-extremely intensified. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
9. A Parameterization Approach for the Dielectric Response Model of Oil Paper Insulation Using FDS Measurements.
- Author
-
Yang, Feng, Du, Lin, Yang, Lijun, Wei, Chao, Wang, Youyuan, Ran, Liman, and He, Peng
- Subjects
DIELECTRICS ,HIGH voltages ,ALGORITHMS ,ELECTRIC capacity ,ELECTRIC potential - Abstract
To facilitate better interpretation of dielectric response measurements--thereby directing numerical evidence for condition assessments of oil-paper-insulated equipment in high-voltage alternating current (HVAC) transmission systems--a novel approach is presented to estimate the parameters in the extended Debye model (EDM) using wideband frequency domain spectroscopy (FDS). A syncretic algorithm that integrates a genetic algorithm (GA) and the Levenberg-Marquardt (L-M) algorithm is introduced in the present study to parameterize EDM using the FDS measurements of a real-life 126 kV oil-impregnated paper (OIP) bushing under different controlled temperatures. As for the uncertainty of the EDM structure due to variable branch quantity, Akaike's information criterion (AIC) is employed to determine the model orders. For verification, comparative analysis of FDS reconstruction and results of FDS transformation to polarization--depolarization current (PDC)/return voltage measurement (RVM) are presented. The comparison demonstrates good agreement between the measured and reconstructed spectroscopies of complex capacitance and tan δover the full tested frequency band (10
-4 Hz-10³ Hz) with goodness of fit over 0.99. Deviations between the tested and modelled PDC/RVM from FDS are then discussed. Compared with the previous studies to parameterize the model using time domain dielectric responses, the proposed method solves the problematic matching between EDM and FDS especially in a wide frequency band, and therefore assures a basis for quantitative insulation condition assessment of OIP-insulated apparatus in energy systems. [ABSTRACT FROM AUTHOR]- Published
- 2018
- Full Text
- View/download PDF
10. Assessment of Jatropha Oil as Insulating Fluid for Power Transformers.
- Author
-
Abdelmalik, Abdelghaffar Amoka, Abolaji, Paul Adeoluwa, and Sadiq, Hamzah Abubakar
- Subjects
JATROPHA ,POWER transformers ,VEGETABLE oils ,CELLULOSE ,DIELECTRICS - Abstract
Seed-based oil has been identified as a viable alternative insulating fluid and a number of vegetable oils has been studied for that purpose. Among the seed-based oils studied is Jatropha oil which was reported to have suitable breakdown strength for high voltage application. However, most of the reports did not study the ageing characteristics of the oil and its compatibility with cellulose insulation. In this present study, the properties and ageing behaviour of a freshly prepared Jatropha oil and its compatibility with cellulose insulation paper were evaluated. The oil was purified through modified Dijkstra and Opstal purification method. The thermo-physical and dielectric studies of the oil was performed and thermal ageing of Kraft paper in the prepared ester fluid was performed. Thermally accelerated ageing was performed with an open beaker containing ageing catalysts, thermally upgraded insulation paper, and the fluid at 140°C for 120, 240, 360 and 480 h. Jatropha oil is a high temperature fluid with high specific heat capacity of 2.59 kJ kg
-1 K and low dielectric loss of 0.009. The oil became polymerised with ageing in open cup. This may be due to thermo-oxidative degradation of the oil that progressed with ageing time. This is an indication that the oil is not suitable for use in free breathing power equipment. [ABSTRACT FROM AUTHOR]- Published
- 2018
- Full Text
- View/download PDF
11. Condition assessment of transformer insulation using dielectric frequency response analysis by artificial bee colony algorithm.
- Author
-
Bigdeli, Mehdi and Aghajanloo, Jafar
- Subjects
TRANSFORMER insulation ,FREQUENCY response ,BEES algorithm ,DIELECTRICS ,ELECTRIC conductivity ,INSULATING oils - Abstract
Transformers are one of the most important components of the power system. It is important to maintain and assess the condition. Transformer lifetime depends on the life of its insulation and insulation life is also strongly influenced by moisture in the insulation. Due to importance of this issue, in this paper a new method is introduced for determining the moisture content of the transformer insulation system using dielectric response analysis in the frequency domain based on artificial bee colony algorithm. First, the master curve of dielectric response is modeled. Then, using proposed method the master curve and the measured dielectric response curves are compared. By analyzing the results of the comparison, the moisture content of paper insulation, electrical conductivity of the insulating oil and dielectric model dimensions are determined. Finally, the proposed method is applied to several practical samples to demonstrate its capabilities compared with the well-known conventional method. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
12. Author Index 2013.
- Subjects
ELECTRICAL engineering periodicals ,PUBLISHING ,PAGINATION ,PERIODICAL articles ,ABBREVIATIONS ,DIELECTRICS ,SUBJECT headings - Abstract
This index covers all technical items - papers, correspondence, reviews, etc. - that appeared in this periodical during the year, and items from previous years that were commented upon or corrected in this year. Departments and other items may also be covered if they have been judged to have archival value. The Author Index contains the primary entry for each item, listed under the first author's name. The primary entry includes the co-authors' names, the title of the paper or other item, and its location, specified by the publication abbreviation, year, month, and inclusive pagination. The Subject Index contains entries describing the item under all appropriate subject headings, plus the first author's name, the publication abbreviation, month, and year, and inclusive pages. Note that the item title is found only under the primary entry in the Author Index. [ABSTRACT FROM PUBLISHER]
- Published
- 2013
- Full Text
- View/download PDF
13. Influence of thermal ageing on dielectric response of oil-paper insulation.
- Author
-
GIELNIAK, J., GRACZKOWSKI, A., GUBANSKI, S., MORANDA, H., MOŚCICKA-GRZESIAK, H., and WALCZAK, K.
- Subjects
DIELECTRICS ,ELECTRIC insulators & insulation ,AGING ,MOISTURE ,CELLULOSE - Abstract
Results of dielectric response measurements in frequency domain at various temperatures have been presented for oil impregnated paper samples unaged and thermally aged containing various amounts of moisture. The obtained results were used for defining respective master curves and activation energies. Discrepancies of the results for similar samples are also discussed. Finally, statistical spread of the data was presented and the influence of moisture content on the dielectric response of paper samples has been discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2009
14. A Study on the Life Estimation and Cavity Surface Degradation Due to Partial Discharges in Spherical Cavities within Solid Polymeric Dielectrics Using a Simulation Based Approach.
- Author
-
Rodríguez-Serna, Johnatan M., Albarracín-Sánchez, Ricardo, and Bayraktar, Emin
- Subjects
PARTIAL discharges ,DIELECTRICS ,CHARGE carriers ,DIELECTRIC measurements ,SOLIDS ,DETERIORATION of materials - Abstract
Partial Discharges (PD) in cavities are responsible for the greatest ageing rate in polymeric solid dielectrics due to chemical and physical deterioration mechanisms activated by the charge carriers, Ultra Violet (UV) radiation and local temperature rising during PDs activity. From the above, it is necessary to develop prognosis tools based on PDs measurements as diagnostic quantities in order to infer the time-to-breakdown, life, of solid dielectrics for improving the reliability of electrical assets, especially in current applications where they are subject to great electrical stresses in voltage frequency and magnitude. In this paper, the degradation in polymeric materials induced by PDs in cavities is briefly discussed from a phenomenological point of view, and then it is quantitatively evaluated using a simulation-based approach and a new proposed damage function. The time-to-breakdown calculated from simulations exhibits good agreement when compared with experimental measurements. Additionally, an analysis on the effect of the magnitude and frequency of the applied voltage on the degradation rate is also presented and the effectiveness of a degradation indicator, proposed by other authors, is evaluated under different stress conditions. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
15. Towards Modeling Partial Discharge Phenomena and Propagation in Power Networks Using the Transmission-Line Matrix Method.
- Author
-
Ragusa, Antonella, Sasse, Hugh, Duffy, Alistair, and Xu, Zheng
- Subjects
PARTIAL discharges ,ELECTRIC lines ,ATMOSPHERICS ,ELECTROMAGNETIC interference ,DIELECTRICS - Abstract
Partial discharge (PD), where high field strengths on power cables cause charge build up and discharge within a dielectric at sites of imperfections or inhomogeneities, can lead to noise issues and potential failure of the dielectric. This paper presents the first stage of a research activity that aims to develop a transmission-line matrix (TLM)-based simulation "workbench" useful to investigate PD events in a transmission line. The proposed approach allows the predicting of the electromagnetic disturbances generated by the PD event, and the analysis of external field coupling, such as from intentional electromagnetic interference or lightning, which can add to the field stresses. The paper is focused on defining the right modeling method to simulate PD phenomena in a transmission line context. The best approach to integrate the PD model with the model of the transmission line, useful to describe the propagation of the conducted and radiated emissions produced by PD, is analyzed. A first workbench is proposed, and the first simulation results are described. The paper concludes with the topics of further research. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
16. Condition Assessment of HV Bushings with Solid Insulation based on the SVM and the FDS Methods †.
- Author
-
Subocz, Jan, Mrozik, Andrzej, Bohatyrewicz, Patryk, and Zenker, Marek
- Subjects
ELECTRIC potential measurement ,BUSHINGS ,POWER transformers ,DIELECTRICS ,HIGH temperatures - Abstract
This paper presents the dielectric response of the insulation of bushings as an effect of the simulated long-term aging process. The experiment was conducted under a condition of a high temperature difference between the current circuit and the cover. The dielectric response was measured with the FDS (Frequency Dielectric Spectroscopy) and the SVM (Step Voltage Measurement) methods. The research has shown the correlation between the aging time and some parameters obtained with the FDS and SVM analysis. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
17. Design and Application of a Metamaterial Superstrate on a Bio-Inspired Antenna for Partial Discharge Detection through Dielectric Windows.
- Author
-
Xavier, George Victor Rocha, Serres, Alexandre Jean René, da Costa, Edson Guedes, de Oliveira, Adriano Costa, Nobrega, Luiz Augusto Medeiros Martins, and de Souza, Vladimir Cesarino
- Subjects
METAMATERIAL antennas ,PARTIAL discharges ,DIELECTRICS ,MONOPOLE antennas ,BEAM steering ,ANTENNAS (Electronics) ,ANECHOIC chambers - Abstract
The adaptation of dielectric windows as metamaterial superstrate over a bio-inspired Printed Monopole Antenna (PMA) was evaluated in order to improve the detection sensitivity of Ultra High Frequency (UHF) sensors designed for Partial Discharge (PD) measurement. For this purpose, rectangular and circular Split Ring Resonators (SRR) structures were designed and evaluated aiming to achieve a metamaterial superstrate that improves the characteristics of the bio-inspired PMA as the gain, bandwidth, and radiation pattern. Measurements of the PMA with metamaterial superstrate were carried out in an anechoic chamber and compared to the simulations performed. The results show that the metamaterial superstrate insertion did not impact the original operating bandwidth, covering most of the characteristic frequency range of PD activity. Moreover, this insertion resulted in a mean gain enhancement of 0.7 dBi regarding the reference PMA, resulting in an antenna with better sensitivity for PD detection (mean gain of 3.61 dBi). The PMA-metamaterial set PD detection sensitivity was evaluated through laboratory tests with a point-to-plane PD generator setup and in field with measurements from a 230 kV current transformer. The developed PMA-metamaterial set was able to detect, successfully, the activity of PD for both tests, being classified as an optimized sensor for PD detection through dielectric windows. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
18. Variability of the UHF Signals Generated by Partial Discharges in Mineral Oil.
- Author
-
Kunicki, Michal
- Subjects
UHF detectors ,MINERAL oils ,PARTIAL discharges ,POLYTEF ,ELECTRIC potential - Abstract
The paper presents the results of the analysis on the variability of the ultra-high frequency (UHF) signals generated by partial discharges (PD) under the long-term AC voltage. Surface PD (SD) are generated by model PD source (PDS) immersed in brand new mineral oil. Three scenarios are compared and investigated, where different solid dielectrics are applied: pressboard paper (PBP), polytetrafluoroethylene (PTFE) and glass-ceramic (GLS). The PDS is powered continuously by the AC voltage with its relative level of 1.3 of the inception voltage (U
i ) within 168 h. UHF signals generated by the continuously occurred SD within 168 h are registered. Various indicators describing the variability of the UHF signals emitted by SD are assigned and analyzed in order to discover if there are any relevant trends presented. Furthermore, some long-term characteristics of the UHF signals emitted by the applied PDS are also announced. As a result, some relevant trends are discovered and related to the properties of the applied dielectric materials, thus the variability of the UHF signals emitted by SD is confirmed. The highest variability of the UHF signals is associated with PBP and the first 48 h after PD inception. Moreover achieved results may be potentially applied for modeling of the PD variability in time, which may be useful for works that concern the development of the UHF method. [ABSTRACT FROM AUTHOR]- Published
- 2019
- Full Text
- View/download PDF
19. Ageing Study of Palm Oil and Coconut Oil in the Presence of Insulation Paper for Transformers Application.
- Author
-
Mohamad, Nur Aqilah, Azis, Norhafiz, Jasni, Jasronita, Ab Kadir, Mohd Zainal Abidin, Yunus, Robiah, and Yaakub, Zaini
- Subjects
PALM oil ,COCONUT oil ,DIELECTRICS ,PERMITTIVITY ,CARBON - Abstract
This paper presents a sealed ageing study of palm oil (PO) and coconut oil (CO) in the presence of insulation paper. The type of PO under study is refined, bleached, and deodorized palm oil (RBDPO) olein. Three different variations of RBDPO and one sample of CO are aged at temperatures of 90 °C, 110 °C, and 130 °C. The properties of RBDPO and CO as well as paper under ageing are then analysed through dielectric and physicochemical measurements. It is found that the effect of ageing is not significant on the alternating current (AC) breakdown voltages and relative permittivities of RBDPO and CO. There is a slight increment trend of the resistivity for CO, while for all of the RBDPO, the resistivity slightly decreases as the ageing progresses. Only CO shows an apparent reduction of the dielectric dissipation factor. Throughout the ageing time, the acidities of all of the RBDPO and CO remain at low level, while the moisture in oils decreases. The tensile index (TI) of the papers for all of the RBDPO and CO retain more than 50% of the TI. A significant increment of the paper ageing rates of all of the RBDPO and CO is observed at an ageing temperature of 130 °C. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
20. Partial discharge localisation in transformers using UHF technique: non-iterative method
- Author
-
Antony, Deepthi, Mishra, Prashwar, Todi, Akshat, John, Nikhil Abhishek, and Patankar, Ananya M.
- Published
- 2021
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.