Search

This paper reported the fabrication and the test results of the high temperature superconducting (HTS) magnet developed for the aluminum billet heater for aluminum extrusion processing. In this magnet, the HTS coils were combined with iron cores, because the required magnetic field in the working region was about 1T. Two HTS coils wound directly on the convex shape iron cores were fabricated. The HTS coils were made by the no-insulation winding of REBCO tape with the YOROI-coil technique. Each of them was separately installed in an individual cryostat. Two HTS coils with iron cores were disposed oppositely to each other and were magnetically connected by a C-shape yoke placed in room temperature. The HTS coil was cooled down to about 15 K by the GM cryocooler in the initial cooling. The magnetic field of 1.06 T at the center of the heating region was stably generated with the rated current of 200 A. It was also demonstrated that the HTS magnet could be charged up to 300 A without quench. According to the observation of the electromagnetic force direction from the outside of the cryostat, it was confirmed the validity of the force balance design of the magnet. [ABSTRACT FROM AUTHOR]

Feasible applications in the industrial regions for the bulk high-temperature superconducting (HTS) magnets have been investigated in two categories of the strong magnetic field generators and the magnetic levitation devices by active and passive field trapping, respectively. When we adopt the system to the active field generators, magnetization procedures are necessary. The authors have studied the field-capturing abilities of the HTS bulk magnets on two ways of the activation procedure and the material designing. In the former, we clarified the magnetic flux behavior that invades into bulk magnets, and that the invading flux motion is affected by the previously existing flux distribution. Therefore, the magnetic flux can be accumulated with successive magnetic fields applications with descending heat generation in order. In the latter, the selective magnetic field invasion was observed between wide- and narrow-growth sector regions. Since the bulk magnets with steep magnetic field distributions deform their own field distribution shape to be uniform by the shielding effect when the ferromagnetic plate was attached on the magnetic pole, we have succeeded in obtaining the uniform magnetic field of several-hundred parts per million in the space between the magnetic poles. [ABSTRACT FROM AUTHOR]

In this work, we exposed a high-temperature superconducting (HTS) tape to a rotating magnetic field, and measured ac losses using a calorimetric method based on the temperature rise caused by the ac loss. To compare the characteristics of the other ac loss conditions, we measured the magnetization losses in the uniform ac magnetic field perpendicular and parallel to the HTS tape face. The losses in the rotating magnetic field are the same as in the perpendicular magnetic field. In addition, we measured the influence of the rotating magnetic field waviness on the ac loss characteristics. [ABSTRACT FROM PUBLISHER]

To optimize pulse field magnetization processes for high-temperature superconducting (HTS) bulk magnets, it is important to control the magnetic field amplitude and the driving temperature. Many publications have reported on the experimental and numerical results of the pulsed-field magnetization method. In the numerical method, the HTS bulk properties are modeled to simplify the calculations, examples being the Bean model and the Kim model, etc. During pulsed-field magnetization the critical current density in the HTS bulk changes dramatically due to the magnetic field and temperature rise induced by the ac losses. For these reasons these properties are key to the analysis of the pulsed-field magnetization process, which is calculated using the measured practical HTS bulk properties, and these results show different temperature rise and trapped magnetic field characteristics. We assumed that HTS bulk has intrinsic deterioration in practice. Therefore, we recalculated using the adjusted parameters, and these analytic results correspond with the experimental results. [ABSTRACT FROM PUBLISHER]

For economic reasons high-temperature superconductor (HTS) machines, such as HTS motors and generators, are designed to use an iron core to reduce the HTS tape length. In these situations, the HTS tapes are positioned in the iron core and transport the ac current within the ac leakage magnetic field. We investigated the influence of the iron core arrangement on ac loss characteristics. We modified the iron core of a transformer by removing a rectangular segment and then positioned an HTS tape in the rectangular recess created. The iron core was affected by the ac magnetic field generated by the ac coil, and the HTS tape transporting the ac current. We placed the HTS tapes in different rectangular positions and varied their shape. In all conditions, the ac transport current losses were greater than losses experienced when the HTS tapes were situated without the iron core, and the ac leakage magnetic fields produce ac magnetization losses. Therefore, how the HTS tape is arranged in the iron core affects the ac loss characteristics and merits further study. [ABSTRACT FROM PUBLISHER]

The magnetic field distributions of an HTS bulk magnet system were precisely measured between the face-to-face 3.4-T magnetic poles. After the activation by 5-T field cooling magnetization, the magnetic flux density has reached the value of 2.26 T at the center of the 34-mm gap. The sum of the local magnetic fields generated from each magnetic pole coincides with the local field strength in the gap. We estimated the homogeneity of the magnetic flux densities of Bz and By, which were measured at various positions along z and y-axes in the center portion of the 60-mm gap. Since the magnetic flux density becomes smooth with increasing distance, we obtained the smallest distribution range of 123 ppm of Bz = 1.62\ \T at the center of the gap as for Bz. On the other, as for By, the smallest distribution range of 1125 ppm of Bz = 1.20\ \T was obtained at z = 1.7\ \mm distant from the center point. Since there must exist a certain plane which has no vector components along the radius direction at the center of the gap, the closer the z-positions come to the null point, the more homogeneous the field distribution becomes. [ABSTRACT FROM PUBLISHER]

In high temperature superconducting (HTS) AC applications, HTS tapes are assembled into high current capacity conductors. We previously reported our experimental results showing the AC loss reduction in a polygonal arranged single layer YBCO assembled conductor. The AC loss reduction is greatest in round shape arrangements. [ABSTRACT FROM PUBLISHER]

Many papers report the AC transport current loss characteristics in HTS coils, which occur because the HTS tapes in the coil transport a current in a magnetic field generated by the currents in adjacent tapes. We previously reported our experimental results on the loss from HTS tape in an AC and DC mixed electro-magnetic condition which consists of the DC offset transport current, AC transport current and AC magnetic field. Losses were measured in the same segment by the electric and calorimetric methods, and we established the possibility of measuring the loss using the electric method in the AC and DC mixed electro-magnetic condition. [ABSTRACT FROM PUBLISHER]

This paper presents the optimization study of the field winding structure of the 20 MW-class HTS motor for the electric ship propulsion based on the minimization of the flux flow loss. The examples of the optimized shape of the HTS field pole coils obtained by the numerical analysis are presented. By optimizing the cross section of the field pole coil, it is found that the magnetic field perpendicular to the tape surface in the optimized shape coil significantly decreases compared with that in the rectangular shape base coil. As the results of the reduction of the perpendicular magnetic field, it is shown that the flux flow loss remarkably decreases. It is also pointed that the necessary length of the HTS tape for the optimized shape coil increases. [ABSTRACT FROM PUBLISHER]

Demagnetized rare earth magnets (Nd-Fe-B) can be fully magnetized by scanning them in the intense static fields over 3 T of a HTS bulk magnet which was cooled to the temperature range lower than 77K with use of cryo-coolers and activated by the field of 5 T. We precisely examined the magnetic field distributions of magnetized permanent magnets. The magnetic poles were ‘ in the narrow space on the surface of the permanent magnet with varying gap distances between the tracks of the HTS magnetic pole. Steep magnetic transitions between N and S were observed in the magnetic field distribution maps after the HTS magnetic poles were alternatively scanned for several times. The magnetizing method has been proposed for designing novel electromagnetic devices including magnetically excellent rare earth magnets which require intense magnetic fields over 3 T. [ABSTRACT FROM PUBLISHER]

The paper reports on experimental and numerical studies of AC loss in a high temperature superconducting coil wound with a Bi2223/Ag tape. A measurement method of the AC loss in the HTS coil by using a power meter is proposed. The AC loss is measured on the test HTS coil made by stacking pancake coils wound with the Bi2223/Ag tape. The AC loss is also calculated using the numerical method developed in our previous work. The measured AC loss is compared with the calculated one. The agreement of measured and calculated data is reasonable and this shows the validity of the proposed measurement method. [ABSTRACT FROM PUBLISHER]

We study the electro-magnetic design of 10 MW-class wind turbine generator with high temperature superconducting field winding by using the FEM analysis. The design examples are presented and the generator characteristics are investigated. The 10 MW-class HTS wind turbine generator is considered to be feasible from the stand point of the electro-magnetic design. In this study, 8-pole and 12-pole generators are investigated. From the results, it is considered that the 8-pole design is preferable compared with the 12-pole design. The analysis also reveals the small synchronous reactance of the HTS wind turbine generator. Therefore, proper protection is necessary for the large short circuit current. [ABSTRACT FROM AUTHOR]

It is considered that particle deposition on the photo mask, such as oil dusts which are generated from mechanical bearings of the spin processors, is one of main causes of the deterioration of pattern preciseness. In our R & D, application of magnetic levitation utilizing bulk HTSs to the spin processors for the photo mask production has been proposed. In this study, we try to develop a new model apparatus demonstrating non-contact spinning clean-up processor in photo mask production system. The levitation and rotation test by using this model apparatus showed that this new model apparatus accomplished the remarkable improvement of the levitation and the rotation ability. This paper describes the levitation and rotation test results of the new model spinner comparing with those obtained in our previous study. [ABSTRACT FROM AUTHOR]

We investigated the validity of AC transport current loss measurement in a high temperature superconducting (HTS) assembled conductor using the four-terminal method. We tested the effect of different arrangements, transport current direction, and transport current distribution in the assembled conductor. Neither the arrangement nor direction of the transport current affects the accuracy of the AC transport current measurement. When transport current distribution in an assembled conductor is unbalanced, it is possible to deduce the loss by the addition of the multiple of the current and voltage from the potential lead loops in each tape. If the transport currents in each HTS tape of the assembled conductor are not uniform and only transport current of the assembled conductor is measured, the AC transport current loss is not estimated exactly. [ABSTRACT FROM AUTHOR]

We study the optimal design of 2- and 4-pole coils wound by YBCO tapes as the case studies of the optimal design of the multiple-coil system based on the AC loss minimization. The winding cross sections of the element coils of the 2- and 4-pole coils were optimized starting from the conventional rectangular cross section to minimize the AC loss. The result shows that the AC loss in the optimized coil is significantly reduced and the critical current of the optimized coil is increased compared with the base coil. According to the results, the validity of our optimal design method is verified to effectively reduce the AC loss in the multi-pole coils wound by the YBCO tapes. Some disadvantageous points of the optimized coil are also discussed. [ABSTRACT FROM AUTHOR]

This paper presents numerical studies on influences of geometrical parameters on AC loss in 2-layer cable conductors assembled by YBCO tapes in polygonal arrangement. By using the numerical model developed in our previous works, the AC loss characteristics of the 2- layer polygonal cable assembled by the YBCO tapes are analyzed with changing the cable geometrical parameters such as the tape width and the tape-to-tape gap. The numerical results show the strong influences of these parameters on the AC loss characteristics. Based on the numerical data, the effects of the decrease in the tape width and the tape-to-tape gap on AC loss reduction were evaluated. The numerical results also give the important information for the design of the multi-layer YBCO cable conductor. [ABSTRACT FROM AUTHOR]

Minimization of circuit patterning on wafers is required for higher integrations of circuit elements in semiconductor devices and, therefore, extremely high preciseness and quality are strictly required for patterning of microstructures on photo masks. Particle deposition on the photo mask, such as oil dusts which are generated from mechanical bearings of the spin processors, is one of main causes of the deterioration of pattern preciseness. In our joint R & D, application of magnetic levitation utilizing HTS bulks to the spin processors for the photo mask production has been proposed. In our previous work, a small size test spinner utilizing the magnetic levitation with the HTS bulks has been developed to investigate its applicability to the spin processors for the photo mask production. In this study, we developed a new test apparatus to investigate the improvement of the levitation and rotation ability. The levitation and rotation test by using this test apparatus showed that the levitation and the rotation ability remarkably improved. This paper describes the design and the fabrication of the test apparatus together with the levitation and rotation test results using the test apparatus. [ABSTRACT FROM AUTHOR]

AC transport current loss in high temperature superconducting (HTS) tapes can be measured without a direct electrical connection by using a pick-up loop method. This method requires a correction factor, which is related to the ratio of the linkage magnetic flux determined by the distribution of the transport current in the HTS tape and pick-up loop. In this study, to determine the accuracy of the AC transport current loss measurement using a pick-up loop method, we measured the critical current and AC transport current loss distribution in the tape axis. We found the pick-up loop voltage of the deteriorated section of the HTS tape to be higher than in the normal section with the same transport current. We concluded that the pick-up loop method accuracy is sufficient to measure the AC transport current loss in HTS tapes. [ABSTRACT FROM AUTHOR]

In this paper, effects of geometrical configuration on AC loss characteristics of cable conductors assembled by multiple YBCO tape in polygonal arrangement were numerically studied. The previously developed numerical model was modified to analyze the AC loss in the HTS tape in the polygonally assembled multi-layer cable. By using the numerical model, the influences of the cable geometrical parameters, especially the effects of the tape width and the tape-to-tape gap, on AC loss properties were evaluated. [ABSTRACT FROM AUTHOR]

Trapped magnetic fields in high temperature superconductor (HTS) bulks are decayed when the bulks are subjected to perturbation of magnetic fields. This phenomenon is inconvenient for the applications of HTS bulks and it is necessary to develop methods to suppress the decay. It was found in a previous study that the decay is caused by temperature rises of the bulks due to AC losses in the bulks. Therefore, it is necessary to develop a method to reduce the AC losses. In this work, a method is proposed to reduce the AC losses by putting HIS shield rings around the bulk and shielding performance of the rings were investigated. The experimental result shows that the shielding rings can drastically suppress the decay, even if the bulk is used in the same cooling condition and the effectiveness of the method was demonstrated. [ABSTRACT FROM AUTHOR]

Influence of copper layer and mechanical stress on AC losses in copper stabilized YBCO coated conductor (CC) was investigated. The uni-axial tensile stress was applied to the sample CC in liquid nitrogen at atmospheric pressure, and the AC losses (transport, magnetization and total AC losses) were measured by an electric method. Influence of the copper layer was investigated by investigating frequency dependence of the AC losses. The experimental results show that there are some influences of the copper layer. However, the influence of the copper layer is not significant from the stand point of practical applications. As to the stress dependences, experimental results show that, when stress dependences of the transport current and magnetization losses are expressed by properly normalized values using stress dependent critical currents, the loss curves fall close to unified curves, respectively and that the stress dependence of the AC losses can be estimated by knowing stress dependent critical current and AC losses in CCs without stresses. [ABSTRACT FROM AUTHOR]

We suggested a pick-up loop method for measuring AC transport current loss in high temperature superconducting (HTS) tapes, which avoids a direct electrical connection with the HTS tape. This method requires a correction factor, which is related to the ratio of the linkage magnetic flux determined by the distribution of the transport current in the HTS tape and pick-up loop. We reported previously that the correction factor for an HTS tape obtained experimentally corresponded with the numerical analysis result. In this study, we numerically analyzed the correction factor for rectangular and spiral pick-up loops. The correction factor for an ideal pick-up loop does not depend on the amplitude of the transport current and is not affected by the position of the HTS tape, even if slightly altered. Our numerical analysis suggests the ideal shape for a pick-up loop to measure AC transport current loss without an electrical connection. [ABSTRACT FROM AUTHOR]

In high temperature superconducting (HTS) AC applications, HTS tapes are assembled into a conductor with a high current capacity and transport AC current in an AC magnetic field generated by currents in neighboring tapes. It is important to clarify the AC loss characteristics of each HTS tape in the assembled conductor. In this work, we compared measured and numerical analysis of AC transport current loss characteristics in three HTS tapes with edge-to-edge or face-to-face configuration and parallel or anti-parallel transport currents. Losses were measured by the calorimetric method, which gives actual losses regardless of the electro-magnetic environment around the sampled tape. The numerical analysis is based on the relationship between the current distribution and the inductive voltage. Our results show that the AC transport current loss in HTS tapes in an assembled conductor depends on the tape arrangement and the direction of the transport current. [ABSTRACT FROM AUTHOR]

This paper presents an optimal design method of winding cross section of high temperature superconducting coils wound by Bi2223/Ag tape based on AC loss minimization. We try to optimize the winding cross section starting from the conventional HTS coil with the rectangular cross section to minimize the AC loss. An example of the optimal cross section coil is presented. The result shows that the AC loss in the optimized coil is significantly reduced and the critical current of the optimized coil is increased compared with the rectangle cross section coil. It is verified that our optimal design method is effective to reduce the AC loss in the HTS coil. The disadvantageous points of the optimized coil are also discussed. [ABSTRACT FROM AUTHOR]

Numerical simulation results for characteristics of separating multiple kinds of magnetic particles with different magnetic susceptibility by magnetic chromatography using high temperature superconducting bulk magnet are presented in this paper. The transient particle transport process of two kinds of particles with different magnetic, susceptibility are numerically simulated. The calculated time evolutions of the particle concentration in the narrow channel of the spiral arrangement placed in the magnetic field produced by the highly magnetized high temperature superconducting bulk magnet show the flow velocity difference of the particle transport corresponding to the difference of the magnetic susceptibility. The numerical results also show that the separation of paramagnetic particles of 20 nm diameter is possible. [ABSTRACT FROM AUTHOR]

The trapped magnetic field in an HTS bulk is decayed and even erased by the application of an AC magnetic field whose amplitude is much smaller than the maximum trapped magnetic field. In previous experiments, the decay of the trapped magnetic field was shown to be due to the temperature rise of the bulk caused by the AC losses. Especially, in a high frequency magnetic field, AC losses are larger and the decay of the trapped magnetic field is accelerated by this AC loss increase. We investigated the time relationships of the AC loss of the HTS bulk in a high frequency magnetic field using the thermal equilibrium equation. [ABSTRACT FROM AUTHOR]

In designing an HTS coil, it is necessary to secure the large magnetic field and/or the stored energy with shorter tape length. From this point of view, the transport current performance of the HTS coil needs to be improved. The critical current and n value depends on the magnitude and direction of the traversing magnetic field against the Bi-2223/Ag tapes. The critical current and n value of the tape was measured with various magnitude and direction of the traversing magnetic field. From this, the fitting equations of the critical current and n value for any magnitude and direction of the traversing magnetic field were obtained. Considering this anisotropic property of the tape, we considered the analytical model to obtain the coil critical current. As an initial coil shape, the minimum volume coil derived from the Fabry Factor constant curve is taken, which is often employed in low temperature superconducting coils. The electric field distribution within the coil cross-section was calculated to examine its effect on a current carrying capability. It was clear that high electric field portions appear at the coil edges due to the inclined magnetic flux against the tapes. In this study, the external corner portions of the coil are displaced under the condition that the total coil volume is kept constant. As a result of this, the coil critical current increased and the stored energy was improved by 20%. [ABSTRACT FROM AUTHOR]

Dispersed generators are being introduced to power systems to secure the electric power supply. However, a short-circuit capacity of the power system increases with the introduction of dispersed generators. As a result, there is concern that a fault current will increase further, and instantaneous voltage sag might be caused. It is proposed to apply a superconducting fault current limiter in the distribution system with dispersed generators to solve these issues. In this paper, the effect of superconducting fault current limiter in this power system is studied by the analysis with EMTP and the confirmation test is conducted with a simulator. [ABSTRACT FROM AUTHOR]

As for the stored energy density, the solenoid coil has the larger value. On the other hand, the toroidal field coil has the least leakage flux. The primary concern of HTS SMES coil is the reduction of the cost, while securing superconducting coil performance. For this purpose, the required HTS tape length needs to be as short as possible. The critical current and n values of HTS tapes depends on the magnetic fields as well as its field angle to the tapes. Therefore, the performance of magnets wound with HTS tapes needs to be analyzed based on above factors. The current-voltage characteristics of the HTS coil were analyzed by means of fitting equations of the critical current and n value obtained from the measured values of the Bi2223/Ag tape. The stored energy of four kinds of coil arrangement was analyzed, thereby pursuing the shortest length of HTS tapes. The toroidal coil requires 58 % longer HTS tapes than the solenoidal coil to store the energy of 100 kJ, but 0.01 T leakage field region at the mid-plane is about a half of the solenoid coil. [ABSTRACT FROM AUTHOR]

Numerical studies on a AC transport loss measurement method for assembled conductors of multiple HTS tapes in multi-layer polygonal arrangement by using a spiral pick-up loop without electrical contacts are presented in this paper. The previously developed numerical model to analyze the electro-magnetic field distribution and the AC loss in the HTS tape in the polygonally assembled conductor was modified. The AC loss measurement using the spiral pick-up loop for single and multi layered polygonal conductors assembled by this HTS tapes was numerically simulated. The detection properties of the AC transport loss by the spiral pick-up loop were evaluated and the validity of this measurement method was verified. [ABSTRACT FROM AUTHOR]

This paper presents numerical studies on structures to minimize AC losses in high temperature superconducting tri-axial multi-layer three-phase cable conductors. The simulations were performed for tri-axial cables of 2-layer/phase configuration under 3-phase AC operation. From the numerical results, the relation between the AC loss and the layer-to-layer current sharing showed that the AC loss can be minimized by adjusting the layer-to-layer current sharing. The reason was clarified from the numerical data of the current density profiles across the superconducting layers. Based on the numerical analysis, the twist pitch formulation for the AC loss minimization was obtained. [ABSTRACT FROM AUTHOR]

In this work we present numerical analysis results of the magnetization loss in a perpendicular AC magnetic field. The numerical analysis is based on the relation of the linkage magnetic flux to current distribution, and takes into account the Jc - B characteristic, and n value-B characteristic. We discuss the relation between the magnetization losses with striated superconducting tape and the semicylindrical intrinsic critical current density distribution across the width of the superconducting tape. The result shows that the magnetization loss of monocore superconducting tape in a low magnetic field is affected by the intrinsic semicylindrical critical current density distribution. With a striated structure, the influence of the intrinsic critical current density distribution is reduced. [ABSTRACT FROM AUTHOR]

We experimentally and numerically investigated the characteristics of the AC losses in Bi2223/Ag sheathed tape by the phase difference between the transport current and external magnetic field perpendicular and parallel to the tape face. The characteristics can be explained by the time evolution of the current density distributions of the cross section of superconducting tape. [ABSTRACT FROM AUTHOR]

This paper presents numerical simulation results for characteristics of separating multiple kinds of magnetic particles with different magnetic susceptibility by magnetic chromatography using quadrupole magnetic field. The dependencies of separation of two kinds of particles with different magnetic susceptibility on the system parameters are evaluated by the model to analyze the transient particle transport process developed in our previous study. The calculated time evolutions of the particle concentration in the narrow cylindrical channel placed in the quadrupole magnetic field show the flow velocity difference of the particle transport corresponding to the difference of the magnetic susceptibility. The numerical results also show that the separation of paramagnetic particles of 50nm is possible. [ABSTRACT FROM AUTHOR]

Numerical studies on AC loss characteristic of a assembled conductors of multiple HTS tapes with high aspect ratio simulating YBCO tape in polygonal arrangement were presented in this paper. We developed a numerical model to analyze the AC loss in the HTS tape in the polygonally assembled conductor based on our previously developed model. The relations between the geometrical configuration and the AC loss properties of the conductor were made clear by the numerical simulation. The numerical results give the important information for the design of the cable conductor assembled by the HTS tapes with high aspect ratio such as YBCO tapes. [ABSTRACT FROM AUTHOR]

AC loss characteristics of high temperature superconducting coils wound by Bi2223/Ag tape with various cross sections are numerically investigated. The numerical results show that the smaller coil aspect ratio, the smaller AC losses in the HTS coil. It was considered from the numerical results that the coil aspect ratio giving the minimum coil volume is the better shape judging from the many aspects such as the required length of tape, the stored energy, the central magnetic field and the critical current together with the AC loss. It was also shown by the numerical study that the optimal coil design giving the reduced AC loss can be done by employing the stepped cross section coil and the turn number graded coil. [ABSTRACT FROM AUTHOR]

This paper presented numerical studies on layer-to-layer current distributions and AC losses in triaxial multi-layer three-phase cable conductors. The simulations were performed for triaxial cables of 2-layer/phase configurations with several combinations of twist pitch to investigate the influence of the cable twist configuration on the layer-to-layer current distribution and the AC loss under 3-phase AC operation. From the numerical results, it was shown that the twist pitch combinations for uniform layer-to-layer current distributions could be found. The numerical results also showed, however, that the AC loss can not be reduced by equalizing the layer-to-layer current distribution. The reason is clarified from the numerical data of the current density profiles across the superconducting layers. For the cable design, it is necessary to select proper twist configuration considering not only the equalization of current distribution but also the minimization of AC loss. [ABSTRACT FROM AUTHOR]

A method is proposed to reduce AC magnetization losses in YBCO tape-shaped coated conductors subject to external AC magnetic fields. To reduce the magnetization losses, it is well known that the YBCO film should be subdivided into multiple filaments. In this multifilamentary conductor, the electromagnetic coupling between the filaments should be suppressed to reduce the AC losses by twisting the conductor somehow. The proposed method is that a YBCO layer on a substrate of a coated conductor is subdivided into multiple filaments by slanted striations and that a quasi-twisted assembled conductor is composed by soldering a pair of those striated tapes. The effect of the twisting is obtained by this composition without twisting the conductor itself. A numerical simulation showed that magnetization losses in a quasi-twisted conductor were greatly reduced at a sacrifice of a slight increase of the transport current losses. [ABSTRACT FROM AUTHOR]

Fault current limiting and interrupting performances of three types of fault current limiting interrupter (FCLI) are compared; a DC reactor type, a DC S/N transition type and a DC hybrid type, which are made of the Bi-2223 tape and bulk. The DC hybrid type FCLI can limit a fault current by means of the inductance of HTS coil and the normal resistance of high temperature super- conducting bulk (HTSB). In the case of an accident, the normal transition of the bulk can be accelerated by the magnetic field of the HTS coil. In this paper, performances of the DC hybrid type three-phase FCLI are compared analytically with the DC reactor type and the DC S/N transition type. Features derived from the combination of a reactor coil and an S/N transition element for the DC hybrid type are discussed and as an example it is applied to 6.6 kV-2000 A power distribution system. [ABSTRACT FROM AUTHOR]

This paper reports an analytical study on AC loss characteristics of a high temperature superconducting coil wound with a Bi2223/Ag tape. The electromagnetic AC loss in the high temperature superconducting coil made by stacking pancake coils wound with the Bi2223/Ag tape was numerically calculated by using the measured DC data of the HTS tape. The calculated AC loss was compared with measured AC losses in Bi2223 HTS coils obtained in a previous study. It had been found that the measured AC losses in the coils contained large mechanical loss. For the comparison of the measured and calculated losses, the mechanical loss was subtracted from the measured total loss data to estimate the electromagnetic loss. The calculated AC losses were compared with the measured electromagnetic losses in the coils, producing rather good agreement. A possible way to reduce the AC loss in the HTS coil was also presented and discussed. [ABSTRACT FROM AUTHOR]