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Three-dimensional (3-D) hexahedral finite element method (FEM) was used for examining the current distribution and AC loss in each shield layer of the co-axial multi-layered High Temperature Superconducting (HTS) power cable. Findings revealed that the current distribution in the shield layers can be controlled by adjusting the pitches of shield layers.

An experiment is conducted for analysing the current distribution in high T(sub c) superconducting (HTS) power cable based on E-J power law. The results show that the AC losses in shield layer with intervals are increased when the interval between wires becomes large.

A method for analyzing the current distribution in high-To superconducting (HTS) power cable is examined by the aid of the novel use of anisotropic conductivity and three-dimensional finite element method in consideration of the E-J power law characteristic. The detailed current distribution in the cable is illustrated and the shielding effect of HTS shield is also examined. Index Terms--E-J power law characteristics, HTS power cable, HTS shield, three-dimensional finite element analysis.

AC loss characteristics in HTS tape in AC magnetic field carrying AC transport current are investigated and reported.

The development of a device comprising YBCO thin films and normal conducting films, aimed at the practical use of a superconducting fault current limiter, is described.

Research describing the stability criteria of YBCO high temperature superconducting tape is presented. In particular the transport current characteristics for a range of currents above the critical current are investigated.

Research is presented on how stable superconducting rotor windings are in static conditions, and how the stability of the windings in rotating conditions can be estimated from the results of the static test. Design methods for the quench current of high current density rotor windings, based on the static test findings, are also investigated.

A study conducted on hot spot temperature and stability of magnets is presented. Minimum quench energies, Stekly's stability factors and minimum propagating zones were derived using the superconducting magnet data base compiled from 1988 to 1998 by the Institute of Electrical Engineers of Japan. The dependence of the stability parameters on the scale of the magnet is analyzed and the resulting trends in magnet design are also discussed.

The [Nb.sub.3]Sn superconductor possesses a higher critical temperature than the NbTi strand. Therefore, it is now possible to make highly stable superconducting strands. We examined the manufacturing process of AC [Nb.sub.3]Sn strands. The internal Sn diffusion process showed a higher critical current density than the conventional process. [Nb.sub.3]Sn strands for AC use have a high Jc with low temperature reaction heat treatment, because they have fine filaments to decrease AC loss. We made a 400kVA class superconducting coil using the developed [Nb.sub.3]Sn cable with the React & Wind method. The loss density of this coil was 25.7MW/[m.sup.3] at the point just before the quench. In this case, the temperature of the cable increases about 3.39K. This means that the coil using [Nb.sub.3]Sn cables has a very high stability in AC use.

For implementation of AC superconducting equipment, it is imperative to develop low loss cables having highly stable characteristics. Here, newly developed NbTi superconducting cables using a CuSi alloy matrix are of low loss and are very promising as cables for practical application. However, since the CuSi alloy is a new material as a matrix for NbTi superconducting cables, many unknown factors as regards to optimum conditions for the manufacture of long cables, as well as superconducting characteristics are involved. For this new superconducting cable, a long strand (km class) was manufactured as a step for practical application, and a primary twisted cable was fabricated. Using this cable, a coil of the 100kVA class was fabricated for trial, and its performance characteristic with transport current was evaluated. This coil had no training phenomenon and had a high stabilities. Furthermore, it permitted full AC current transmission of up to DCIc. Upon analysis of the coil loss, the hysteresis loss was smaller than coupling loss, and there was little increase of loss due to the current flow to the coil. Consequently, by using CuSi alloy matrix superconducting cables, it was possible to provide an AC coil of low loss and high stability, and the present cable was found to be promising as a new AC superconducting cable in the future.

Critical currents of [Nb.sub.3]Sn cabled superconductors were measured under cyclic mechanical compressive force of 30 MPa up to 10,000 times. The conductors were developed for a superconducting generator under the Super-GM project. The conductors were designed to apply the field winding of the 70 MW-class superconducting generator. The 10,000 repetitions of force application simulate 30 years of centrifugal and electromagnetic force produced by the daily start-and-stop (DSS) operation of the superconducting generator. In the test facility constructed at the Akagi Testing Center of the Central Research Institute of Electric Power Industry (CRIEPI), mechanical compressive force is generated by the cyclic fatigue test machine, which can generate 100 kN of force and is located on top of a cryostat at room temperature. Measured critical currents of two types of [Nb.sub.3]Sn conductor did not change throughout the test.

3-D finite element analysis of current distribution taking account of the nonlinear E - J characteristic is carried out. In order to study the ac loss of multi-layered HTS power cable, the analysis region is considerably reduced by modeling spirally wound superconducting tapes as conductors having an anisotropic conductivity and using the periodic boundary condition. By using this model, the effect of the twist pitch on the current distribution of multi-layered HTS power cable with a shield layer is illustrated and the structure with low ac loss is discussed. [ABSTRACT FROM AUTHOR]

Part II. Investigates the stability and hot-spot temperature of superconducting magnets at the Institute of Electrical Engineers of Japan. Calculation of minimum quench energies, propagating zones and Stekly's stability factors using a data base on superconducting magnets; Dependence of stability parameters on the magnet scale.

Examines the manufacturing process of an alternating current strands using the React and Wind method. Background information on conductors and coil; Coil performance and loss analysis; Thermal analysis at quenching; Conclusions.