The Experts below are selected from a list of 5547 Experts worldwide ranked by ideXlab platform
J J Erbrink - One of the best experts on this subject based on the ideXlab platform.
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Diagnosis of degradation effects of On-Load Tap Changer in power transformers
2014 ICHVE International Conference on High Voltage Engineering and Application, 2014Co-Authors: Rogier Jongen, Jarosław Parciak, Krzysztof Siodła, Edward Gulski, J J ErbrinkAbstract:By performing diagnostics on On-Load Tap Changers by means of dynamic resistance measurements a condition diagnosis of high-speed resistor-type Tap Changers can result in pre-failure detection of contact degradation. It provides the measurement parameters that are most suitable for detecting these defects, such as the presence of a contact film, contact wear and pitting. The resistance curves of OLTCs are interpreted, to determine the occurring degradation mechanisms, which can be used to support strategic decisions about the maintenance or overhaul of the Tap Changer.
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on load Tap Changer diagnosis on high voltage power transformers using dynamic resistance measurements
2011Co-Authors: J J ErbrinkAbstract:High-voltage transformers have Tap Changers to regulate the voltage in the high-voltage network when the load changes. Those Tap Changers are subject to different degradation mechanisms and need regular maintenance. Various defects, like contact degradation, often remain undetected and the probability of maintenance errors cannot be neglected. Preventive diagnosis of dynamic resistance can be used to determine the contact condition and to check the basic function of the Tap Changer. This can guarantee that the high-voltage transformer can be put back into operation safely after maintenance. In addition, the information obtained can be used for condition-based maintenance. The research of Jur Erbrink elaborates on the condition assessment of Tap Changers using dynamic resistance measurements. He describes in his thesis the different ways in which the measurements can be performed and how this influences the measurement results. In particular it was emphasized that the dynamic resistance measurements at a lower the test current are more sensitive for long term aging effects. It is also investigated which defects can be detected and how the results can be interpreted.
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on load Tap Changer diagnosis interpretation of dynamic resistance deviations
IEEE International Symposium on Electrical Insulation, 2010Co-Authors: J J Erbrink, P P Seitz, R Leich, Edward Gulski, J.j. Smit, Ben QuakAbstract:This paper discusses the recently developed analysis method for service aged power transformers equipped with an OLTC: dynamic resistance measurements (DRM). Because the On-Load Tap Changer contributes to many power transformer failures the emphasis is on OLTC diagnosis. Off-line diagnosis of On-Load Tap Changers during regular maintenance can detect maintenance errors and assess the condition of OLTC parts not accessible for inspection. DRM can be valuable to On-Load Tap Changer (OLTC) condition assessment because of the large variety of defects and OLTC degradation mechanisms that can be found. This paper deals with the results that can be measured with DRM. Besides undisturbed DRM-data, most common deviations originating from degraded and defect Tap Changers will be discussed. It is explained how these different types of defects appear in the DRM results. The location and shape of the deviation can be used to find the cause and importance of the defect. A subdivision is made between OLTC's in good condition, OLTC's with increased contact resistance, OLTC's with open contacts and OLTC's with deviating switch times. By doing so, an overview of possible DRM results is gained. The seriousness of the defects is also discussed in this paper. Differences between the DRM results of different types of OLTC's will be discussed by showing results of DRM tests. Most graphs presented in this paper are recorded on service-aged OLTC's in the Dutch utility grid. Some measurement results are performed during experiments in a high voltage laboratory.
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experimental model for diagnosing on load Tap Changer contact aging with dynamic resistance measurements
Electricity Distribution - Part 2 2009. CIRED 2009. The 20th International Conference and Exhibition on, 2009Co-Authors: J J Erbrink, Edward Gulski, J.j. Smit, R LeichAbstract:It is known that many failures of power transformers are related to aging effects of the On-Load Tap Changer. Especially the OLTC contacts are prone to several aging mechanisms. To understand the aging mechanisms and to develop knowledge rules to interpret different failure mechanisms a test model has been developed. The effect of the several aging stages of Tap Changer change-over selector contacts on dynamic resistance measurements (DRM) has been considered, by several experiments with aged Tap Changer contacts. These aging phases include clean contacts, contacts with an oil film layer and contacts with coking. Based on these experiments it is shown that the DRM method is very sensitive to aged change-over selector contacts of an On-Load Tap Changer. In addition to laboratory experiments, the same measurements are performed on naturally aged changeover selector contacts at a Dutch utility. This change-over selector was accessible so the physical status of the Tap Changer contacts can be compared with the measurement results.
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advanced on site diagnosis of transformer on load Tap Changer
IEEE International Symposium on Electrical Insulation, 2008Co-Authors: J J Erbrink, P P Seitz, Edward Gulski, R LeichAbstract:It is known that many failures of power transformers are related to aging effects of the On-Load Tap Changer contacts. This paper discusses the recently developed analysis method for service aged power transformers. In particular, the effect of several aging stages of the Tap Changer change-over selector contacts on dynamic resistance have been considered. As a result, to assess on-site the condition of a power transformer, the following approaches are combined: - The dynamic resistance measurement, to detect deviant contact resistances inside an On-Load Tap Changer; - The velocity measurement to the driving axis of the Tap Changer drive mechanism and the motor power measurement on the drive motor of the Tap Changer, to detect mechanical wear or damage inside the drive mechanism; - Transformer turns ratio measurement and DC winding resistance measurement, to diagnose the transformer windings. This paper also presents decision support rules for dynamic resistance measurements to make an unambiguous decision about the status of the Tap Changer contacts.
Fenghua Wang - One of the best experts on this subject based on the ideXlab platform.
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fault diagnosis of on load Tap Changer in converter transformer based on time frequency vibration analysis
IEEE Transactions on Industrial Electronics, 2016Co-Authors: Ruochen Duan, Fenghua WangAbstract:The suitable condition of an On-Load Tap-Changer (OLTC) is essential for the operation of converter transformer due to its frequent switch for the voltage regulation of power system. This paper describes a methodology to obtain the OLTC vibration characteristics in time–frequency domain. Considering the possible aliasing effect in vibration signal processing, an improved empirical mode decomposition (EMD) is proposed with masking signals of multiple frequencies added, which has obvious superiority in aliasing reduction compared with conventional methods. Then, an effective fault-diagnosis strategy based on energy distributions variations of OLTC vibration signals according to Lorentz information measure is brought up. The calculated results under normal and typical fault conditions of model and real OLTC have shown that the energy spectrums of different conditions vary significantly so that the similarity index can measure the difference degree of energy distribution. Meanwhile, the index of contact looseness is higher than the insulated panel looseness which indicates that the contact looseness fault has greater influence on switch-over process of OLTC.
Ronghao Zheng - One of the best experts on this subject based on the ideXlab platform.
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a fault diagnosis method for on load Tap Changer of aerospace power grid based on the current detection
IEEE Access, 2018Co-Authors: Zhenhua Li, Qiuhui Li, Zhengtian Wu, Jie Yu, Ronghao ZhengAbstract:As one of the key components of aerospace power grid, the performance of on load Tap Changer (OLTC) of power transformer is very important. So it is necessary to realize real-time monitoring of its status. At present, there is no feasible monitoring scheme to carry out on-line monitoring and fault diagnosis for detecting faults of OLTC. The current waveform of the switching process will be abnormal due to the contact fault, the transition resistance fault, and most of the mechanical faults. This paper presents a fault diagnosis method for OLTC based on the current detection in the process of switching. Through on-line acquisition of current waveform in the switching process, empirical mode decomposition and Hilbert–Huang transform is used to calculate normalized time-frequency spectrum, and extract fault characteristic quantity, which can realize the comprehensive diagnosis of the running state of the equipment, and identify the early fault characteristics, and promote the process of the OLTC’s maintenance, from regular test to condition based maintenance. Experiment results prove that the designed fault diagnosis instrument can effectively monitor the working condition of OLTC during the switching process and make effective fault diagnosis.
Daniel Martin - One of the best experts on this subject based on the ideXlab platform.
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Transformer Over Passivation to Prevent On-Load Tap Changer Silver Sulphide Corrosion
2019 IEEE Innovative Smart Grid Technologies - Asia (ISGT Asia), 2019Co-Authors: Sameera Samarasinghe, Daniel MartinAbstract:On-Load Tap Changer (OLTC) is designed to change transformer turn ratio while transformer is under load. According to many surveys, majority of transformer failures were occurred due to OLTC failures. An understanding of OLTC failure mechanisms can help to ensure OLTC reliability and develop appropriate failure mitigation techniques. The formation of a thick layer of silver sulphide on the contacts is one such failure mode. It is caused by the corrosive Sulphur compounds in transformer insulating oil. Silver sulphide is a semi-conductive particle. Therefore, it can enhance the Tap selector contact resistivity. Also, dielectric properties of insulating oil reduces when it mixes with oil. Although transformer oil passivation has been used to mitigate copper sulphide corrosion in transformer windings, it has not been effective for silver sulphide. In this paper, the results of a laboratory-based experiment on passivator effectiveness for silver sulphide is presented.
R Leich - One of the best experts on this subject based on the ideXlab platform.
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on load Tap Changer diagnosis interpretation of dynamic resistance deviations
IEEE International Symposium on Electrical Insulation, 2010Co-Authors: J J Erbrink, P P Seitz, R Leich, Edward Gulski, J.j. Smit, Ben QuakAbstract:This paper discusses the recently developed analysis method for service aged power transformers equipped with an OLTC: dynamic resistance measurements (DRM). Because the On-Load Tap Changer contributes to many power transformer failures the emphasis is on OLTC diagnosis. Off-line diagnosis of On-Load Tap Changers during regular maintenance can detect maintenance errors and assess the condition of OLTC parts not accessible for inspection. DRM can be valuable to On-Load Tap Changer (OLTC) condition assessment because of the large variety of defects and OLTC degradation mechanisms that can be found. This paper deals with the results that can be measured with DRM. Besides undisturbed DRM-data, most common deviations originating from degraded and defect Tap Changers will be discussed. It is explained how these different types of defects appear in the DRM results. The location and shape of the deviation can be used to find the cause and importance of the defect. A subdivision is made between OLTC's in good condition, OLTC's with increased contact resistance, OLTC's with open contacts and OLTC's with deviating switch times. By doing so, an overview of possible DRM results is gained. The seriousness of the defects is also discussed in this paper. Differences between the DRM results of different types of OLTC's will be discussed by showing results of DRM tests. Most graphs presented in this paper are recorded on service-aged OLTC's in the Dutch utility grid. Some measurement results are performed during experiments in a high voltage laboratory.
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experimental model for diagnosing on load Tap Changer contact aging with dynamic resistance measurements
Electricity Distribution - Part 2 2009. CIRED 2009. The 20th International Conference and Exhibition on, 2009Co-Authors: J J Erbrink, Edward Gulski, J.j. Smit, R LeichAbstract:It is known that many failures of power transformers are related to aging effects of the On-Load Tap Changer. Especially the OLTC contacts are prone to several aging mechanisms. To understand the aging mechanisms and to develop knowledge rules to interpret different failure mechanisms a test model has been developed. The effect of the several aging stages of Tap Changer change-over selector contacts on dynamic resistance measurements (DRM) has been considered, by several experiments with aged Tap Changer contacts. These aging phases include clean contacts, contacts with an oil film layer and contacts with coking. Based on these experiments it is shown that the DRM method is very sensitive to aged change-over selector contacts of an On-Load Tap Changer. In addition to laboratory experiments, the same measurements are performed on naturally aged changeover selector contacts at a Dutch utility. This change-over selector was accessible so the physical status of the Tap Changer contacts can be compared with the measurement results.
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advanced on site diagnosis of transformer on load Tap Changer
IEEE International Symposium on Electrical Insulation, 2008Co-Authors: J J Erbrink, P P Seitz, Edward Gulski, R LeichAbstract:It is known that many failures of power transformers are related to aging effects of the On-Load Tap Changer contacts. This paper discusses the recently developed analysis method for service aged power transformers. In particular, the effect of several aging stages of the Tap Changer change-over selector contacts on dynamic resistance have been considered. As a result, to assess on-site the condition of a power transformer, the following approaches are combined: - The dynamic resistance measurement, to detect deviant contact resistances inside an On-Load Tap Changer; - The velocity measurement to the driving axis of the Tap Changer drive mechanism and the motor power measurement on the drive motor of the Tap Changer, to detect mechanical wear or damage inside the drive mechanism; - Transformer turns ratio measurement and DC winding resistance measurement, to diagnose the transformer windings. This paper also presents decision support rules for dynamic resistance measurements to make an unambiguous decision about the status of the Tap Changer contacts.
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experimental model of aging mechanisms of on load Tap Changer contacts
International Conference on Condition Monitoring and Diagnosis, 2008Co-Authors: J J Erbrink, P P Seitz, Edward Gulski, J.j. Smit, R LeichAbstract:It is known that most failure of power transformers are related to aging effects of the On-Load Tap Changer contacts. To understand the aging mechanisms and to develop knowledge rules to interpret different failure mechanisms a test model has been developed. In particular, the effect of the several aging stages of Tap Changer change-over selector contacts on dynamic resistance measurements (DRM) has been considered, by several measurements with aged Tap Changer contacts. These aging phases include clean contacts, contacts with an oil film layer, contacts with coking and contacts with pitting. Based on these experiments it is shown that the DRM method is very sensitive to aged change-over selector contacts of an On-Load Tap Changer. In addition to laboratory experiments, the same measurements are performed on naturally aged change-over selector contacts at a Dutch utility.
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Advanced on-site diagnosis of power transformers
2008 International Conference on Condition Monitoring and Diagnosis, 2008Co-Authors: P P Seitz, J J Erbrink, Edward Gulski, Ben Quak, R LeichAbstract:This paper discusses the recently developed analysis method for service aged power transformers. This is a complete approach to assess the condition of a power transformer, both the On-Load Tap Changer as well as the transformer windings. This paper also presents several case studies of Tap Changer defects that are discovered with the dynamic resistance measurement function.
