The Experts below are selected from a list of 12414 Experts worldwide ranked by ideXlab platform
J Ponsllinares - One of the best experts on this subject based on the ideXlab platform.
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reliable detection of induction motor rotor faults under the rotor axial air duct influence
IEEE Transactions on Industry Applications, 2014Co-Authors: Chanseung Yang, Taejune Kang, Doosoo Hyun, Sang Bin Lee, Jose A Antoninodaviu, J PonsllinaresAbstract:Axial cooling air ducts in the rotor of large induction motors are known to produce magnetic asymmetry and can cause steady-state current or vibration spectrum analysis based fault detection techniques to fail. If the number of axial air ducts and that of poles are identical, frequency components that overlap with that of rotor faults can be produced for healthy motors. False positive rotor fault indication due to axial ducts is a common problem in the field that results in unnecessary maintenance cost. However, there is currently no known test method available for distinguishing rotor faults and false indications due to axial ducts other than offline rotor inspection or testing. Considering that there is no magnetic asymmetry under high slip conditions due to limited Flux Penetration into the rotor yoke, the detection of broken bars under the start-up transient is investigated in this paper. A wavelet-based detection method is proposed and verified on custom-built lab motors and 6.6-kV motors misdiagnosed with broken bars via steady-state spectrum analysis. It is shown that the proposed method provides the reliable detection of broken bars under the start-up transient independent of axial duct influence.
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reliable detection of induction motor rotor faults under the rotor axial air duct influence
Energy Conversion Congress and Exposition, 2013Co-Authors: Chanseung Yang, Taejune Kang, Doosoo Hyun, Sang Bin Lee, Jose A Antoninodaviu, J PonsllinaresAbstract:Axial cooling air ducts in the rotor of large induction motors are known to produce magnetic asymmetry, and can cause steady state current or vibration spectrum analysis based fault detection techniques to fail. If the number of axial air ducts and poles are identical, frequency components that overlap with that of rotor faults can be produced for healthy motors. False positive rotor fault indication due to axial ducts is a common problem in the field that results in unnecessary maintenance cost. However, there is currently no known test method available for distinguishing rotor faults and false indications due to axial ducts other than off-line rotor inspection or testing. Considering that there is no magnetic asymmetry under high slip conditions due to limited Flux Penetration into the rotor yoke, detection of broken bars under the startup transient is investigated in this paper. A wavelet-based detection method is proposed and verified on custom-built lab motors and 6.6 kV motors misdiagnosed with broken bars via steady state spectrum analysis. It is shown that the proposed method provides reliable detection of broken bars under the startup transient independent of axial duct influence.
Chanseung Yang - One of the best experts on this subject based on the ideXlab platform.
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reliable detection of induction motor rotor faults under the rotor axial air duct influence
IEEE Transactions on Industry Applications, 2014Co-Authors: Chanseung Yang, Taejune Kang, Doosoo Hyun, Sang Bin Lee, Jose A Antoninodaviu, J PonsllinaresAbstract:Axial cooling air ducts in the rotor of large induction motors are known to produce magnetic asymmetry and can cause steady-state current or vibration spectrum analysis based fault detection techniques to fail. If the number of axial air ducts and that of poles are identical, frequency components that overlap with that of rotor faults can be produced for healthy motors. False positive rotor fault indication due to axial ducts is a common problem in the field that results in unnecessary maintenance cost. However, there is currently no known test method available for distinguishing rotor faults and false indications due to axial ducts other than offline rotor inspection or testing. Considering that there is no magnetic asymmetry under high slip conditions due to limited Flux Penetration into the rotor yoke, the detection of broken bars under the start-up transient is investigated in this paper. A wavelet-based detection method is proposed and verified on custom-built lab motors and 6.6-kV motors misdiagnosed with broken bars via steady-state spectrum analysis. It is shown that the proposed method provides the reliable detection of broken bars under the start-up transient independent of axial duct influence.
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reliable detection of induction motor rotor faults under the rotor axial air duct influence
Energy Conversion Congress and Exposition, 2013Co-Authors: Chanseung Yang, Taejune Kang, Doosoo Hyun, Sang Bin Lee, Jose A Antoninodaviu, J PonsllinaresAbstract:Axial cooling air ducts in the rotor of large induction motors are known to produce magnetic asymmetry, and can cause steady state current or vibration spectrum analysis based fault detection techniques to fail. If the number of axial air ducts and poles are identical, frequency components that overlap with that of rotor faults can be produced for healthy motors. False positive rotor fault indication due to axial ducts is a common problem in the field that results in unnecessary maintenance cost. However, there is currently no known test method available for distinguishing rotor faults and false indications due to axial ducts other than off-line rotor inspection or testing. Considering that there is no magnetic asymmetry under high slip conditions due to limited Flux Penetration into the rotor yoke, detection of broken bars under the startup transient is investigated in this paper. A wavelet-based detection method is proposed and verified on custom-built lab motors and 6.6 kV motors misdiagnosed with broken bars via steady state spectrum analysis. It is shown that the proposed method provides reliable detection of broken bars under the startup transient independent of axial duct influence.
T H Johansen - One of the best experts on this subject based on the ideXlab platform.
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Flux Penetration in a superconducting film partially capped with a conducting layer
Physical Review B, 2017Co-Authors: Jeremy Brisbois, V V Moshchalkov, V N Gladilin, J Tempere, J T Devreese, F Colauto, M Motta, T H JohansenAbstract:The influence of a conducting layer on the magnetic Flux Penetration in a superconducting Nb film is studied by magneto-optical imaging. The metallic layer partially covering the superconductor provides an additional velocity-dependent damping mechanism for the Flux motion that helps to protect the superconducting state when thermomagnetic instabilities develop. If the Flux advances with a velocity slower than omega = 2/mu(0)sigma t, where sigma is the cap layer conductivity and t is its thickness, the Flux Penetration remains unaffected, whereas for incoming Flux moving faster than w, the metallic layer becomes an active screening shield. When the metallic layer is replaced by a perfect conductor, it is expected that the Flux braking effect will occur for all Flux velocities. We investigate this effect by studying Nb samples with a thickness step. Some of the observed features, namely the deflection of the Flux trajectories at the border of the thick center, as well as the favored Flux Penetration at the indentation, are reproduced by time-dependent Ginzburg-Landau simulations.
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dendritic Flux instabilities in yb a 2 c u 3 o 7 x films effects of temperature and magnetic field ramp rate
Physical Review B, 2016Co-Authors: E Baruchel, T H Johansen, M Baziljevich, Ya B Shapiro, A Shaulov, Y YeshurunAbstract:Our recent success in triggering dendritic Flux instabilities in $\mathrm{YB}{\mathrm{a}}_{2}\mathrm{C}{\mathrm{u}}_{3}{\mathrm{O}}_{7\ensuremath{-}\ensuremath{\delta}}$ (YBCO) films by applying magnetic fields at ultrahigh rates is followed here by a detailed study of the effect as a function of the field ramp rate, ${\stackrel{\ifmmode \dot{}\else \.{}\fi{}}{B}}_{a}$, and temperature, $T$. We trace the borderline in the ${\stackrel{\ifmmode \dot{}\else \.{}\fi{}}{B}}_{a}\ensuremath{-}T$ plane separating regions of smooth, gradual Flux Penetration and dendritic Flux avalanches. In addition, we describe the changes in the dendritic morphology in the instability region as a result of changes in either ${\stackrel{\ifmmode \dot{}\else \.{}\fi{}}{B}}_{a}$ or $T$. Our experimental results, showing a monotonic increase of the avalanche threshold field ramp rate with temperature, are discussed in the framework of existing theories. On the basis of these theories we also explain the high stability of YBCO to dendritic avalanches as compared to, e.g., $\mathrm{Mg}{\mathrm{B}}_{2}$, identifying the Flux flow resistivity, rather than any of the thermal parameters, as the main parameter governing the film stability.
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local threshold field for dendritic instability in superconductingmgb2films
Physical Review B, 2003Co-Authors: F L Barkov, Eunmi Choi, T H Johansen, D V Shantsev, P E Goa, W N Kang, H J Kim, S I LeeAbstract:Using magneto-optical imaging the phenomenon of dendritic Flux Penetration in superconducting films was studied. Flux dendrites were abruptly formed in a 300-nm-thick film of MeB 2 by applying a perpendicular magnetic field. Detailed measurements of Flux density distributions show that there exists a local threshold field controlling the nucleation and termination of the dendritic growth. At 4 K the local threshold field is close to 12 mT in this sample, where the critical current density is 10 7 A/cm 2 . The dendritic instability in thin films is believed to be of thermomagnetic origin, but the existence of a local threshold field and its small value are features that distinctly contrast with the thermomagnetic instability (Flux jumps) in bulk superconductors.
Simon Bending - One of the best experts on this subject based on the ideXlab platform.
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Mapping the Flux Penetration profile in a 2G-HTS tape at the microscopic scale: deviations from a classical critical state model
Superconductor Science and Technology, 2019Co-Authors: Estefani Marchiori, Simon BendingAbstract:Datasets underpinning the 6 Figures for "Mapping the Flux Penetration profile in a 2G-HTS tape at the microscopic scale: deviations from a classical critical state model" in Superconductor Science and Technology. The data files consist of .txt files for each figure organised in individual folders and presented in labelled columns (tab delimited). The data was acquired by scanning Hall microscopy (SHM) in two operation modes: the 'local' magnetometry mode where ‘local’ magnetic induction is measured, and the rapid 'flying' mode that makes a rapid 2D scan of the maximum field of view. The data files consist of individual graph curves and SHM images. A critical state model was used to fit the experimental data and estimate the superconducting critical temperature at different temperatures.
Fedor Gomory - One of the best experts on this subject based on the ideXlab platform.
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numerical simulation of magnetic Flux Penetration and ac loss in htsc coated conductor tapes
Journal of Superconductivity and Novel Magnetism, 2011Co-Authors: Mykola Solovyov, Fedor GomoryAbstract:The critical state model developed nearly 50 years ago by Bean (Phys. Rev. Lett. 8:250, 1962) allows finding analytical solutions for the magnetization of a superconducting slab in a parallel field and for a thin strip in perpendicular field, as well as the transport of AC current by a tape with elliptic or strip-like cross-section. Direct application of these models to the currently available HTSC coated conductor tapes is problematic because of several factors: Dependence of critical current on the magnitude of magnetic field and its orientation Non-uniformity of superconductor properties across the tape width or thickness Magnetism of the substrate
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magnetic Flux Penetration and ac loss in a composite superconducting wire with ferromagnetic parts
Superconductor Science and Technology, 2009Co-Authors: Fedor Gomory, Enric Pardo, Michal Vojenciak, Jan SoucAbstract:The current distribution and the AC loss in a composite superconducting tape containing a layer of magnetic material is calculated and compared with experiments, showing a very good agreement. The situations of an alternating uniform applied field or a transport current are studied. The newly developed numerical model is an approximation to the critical state model, adapted for applicability to commercial finite element codes that solve the vector potential. A substantial feature of this procedure is that it can be carried out in the case when the critical current density in the superconductor depends on the magnetic field and the magnetic layer material is nonlinear. Additionally, the hysteresis loss in the magnetic material is estimated, based on its measured magnetization loops. Measurements on Bi-2223 multifilamentary tapes covered on edges by nickel confirmed our predictions, showing a substantial ac loss reduction in both the investigated regimes.
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Magnetic Flux Penetration and Transport AC Loss in Superconductor Coated Conductor on Ferromagnetic Substrate
IEEE Transactions on Applied Superconductivity, 2009Co-Authors: Fedor Gomory, Enric Pardo, Michal Vojenciak, Jan SoucAbstract:A numerical investigation was carried out to assess the influence of ferromagnetic substrate on the transport losses in YBCO coated conductor. We used an improved version of the method that was proposed recently by A. Campbell to simulate the evolution of current and field distributions in wire from hard superconductor carrying ac. It was found that this technique is able to cope with field dependent critical current density in superconductor in the presence of ferromagnetic material with non-linear properties. Our results indicate that the magnetic substrate is a significant factor in the loss behavior.
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reduction of ac transport and magnetization loss of a high tc superconducting tape by placing soft ferromagnetic materials at the edges
Applied Physics Letters, 2007Co-Authors: Fedor Gomory, Michal Vojenciak, Jan Souc, A K M Alamgir, Ch GuAbstract:Reduction of dissipation at the transport of alternating current as well as when exposed to a time varying magnetic field has been observed in the tape from high-temperature superconductor Bi2Sr2Ca2Cu3O10 covered by a Ni sheath at the edges. The improvement of critical current can explain this achievement only in part. Analysis of experimental data shows that also a more favorable pattern of the magnetic Flux Penetration should take place.