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The testing of the fabricated superconducting traction transformer for Shinkansen rolling stock is discussed. Results suggest that the superconducting traction transformer cleared the vibration test in accordance with JIS, E4031.

A 1T cryocooler-cooled oxide superconducting pulsed coil, which is a 16 layer solenoidal coil wound with an interlayer-transposed 4-strand parallel conductor composed of Bi2223 multifilamentary flat wires is fabricated. The thermal properties of the cryocooler-cooled oxide superinducting pulsed coil is described, taking into account the heat generation of ac loss and flux-flow loss and the cooling capacity of a cryocooler Ac loss and the cooling capacity of the cryocooler have been studied.

Two high-temperature superconducting (HTS) coils are fabricated that simulate the windings of a HTS traction transformer for railroad rolling stock.

Development and testing of a cryocooler-cooled superconducting pulse coil is described and discussed.

Superconductors were studied under fast current change to determine quench development and ultimate normal zone propagation velocity.

The magnetic phase diagram was constructed in small-volume high temperature superconductors using an open-flat coil magnetometer.

The applicability of high-Tc superconducting parallel conductors to pancake coils was investigated and small test coils were would with NbTi 3-strand parallel conductors to verify the theoretical result.

A study of the possible solutions to the problem of 'single strand stability' in multistrand superconducting cables is presented. A proposed change in the design of the cable, aimed at improving its stability in relation to the quench of a single strand, is evaluated. This is accomplished by testing a number of multistrand superconducting cables manufactured from insulated superconducting strands that utilizes varying cabling techniques.

The design and fabrication of a 1T cryocooler-cooled pulse coil operating at 40 K are described. To realize a uniform current distribution and to lessen the alternating current loss density down to the level of a single strand, a 4-strand interlayer-transposed parallel conductor composed of Bi2223 rectangular cross-sectional multifilamentary wires was adopted. Results indicate that the highest temperature of the coil was 40.5 K and the difference in temperature inside the winding was about 2 K.

Research was conducted to evaluate a high temperature superconducting (HTS) cooling model coil for superconducting magnet energy storage. The objective was to make a HTS coil that is cooled to 40 K by a single-stage cryocooler and continuously operated at 1 Hz with a field amplitude of 1 T. The cooling model coil system was made to examine the effective arrangement of the heat drains. Results indicate that the HTS coil temperature is 43 K level when the alternating current losses are about 7 W and the temperature difference between HTS conductor and AIN plate is estimated to be 0.2 K.

A 1kWh/1MW module-type semiconducting magnet energy storage (SMES) called Experimental SMES of Kyushu Electric Power Company Inc has been developed. The main points of its design are the converter-coil module system, modified-D shaped coil with mechanical support, newly developed high temperature superconducting current leads, total system operation and liquid helium-vessel type cooling. Results of preliminary test indicate the expected control function of the SMES system in the extent of its capacity.

A design study for the fabrication of a module-type Superconducting Magnetic Energy Storage system with a 1 kWh maximum stored energy and 1 MW maximum power capability was conducted. Design considerations include module-type coils consisting of three coils and a converter, low loss stranded cables, modified D shape coils and high temperature superconducting current leads. The system is scheduled for installation in a power system after completion in 1997 and 1998.

A 500 kVa-class oxide superconducting transformer for subcooled nitrogen operations was designed, constructed and tested. Three- and six-strand parallel conductors of Bi-2223 silver-sheathed multifilamentary tapes acted as the primary and secondary windings, respectively. The transformer was then installed in a continuous flow subcooled nitrogen system. It was operated up to critical current levels of 66 K without quenching.

A theoretical study was conducted on the alternating current losses in superconducting parallel conductors consisting of Bi2223 multifilamentary wires for power transformer windings. An analytical expression was developed for the additional coupling loss. The current distribution in solenoidal coil strands of the parallel conductor was also calculated experimentally and the influence of transposition on current distribution was examined.

The ac losses induced by periodic longitudinal fields in superconducting wires were studied. Specifically, ac loss measurements of short samples of multifilamentary niobium titanium wires subjected to an oblique external field were carried out at one hertz and 60 Hz. The measurements were repeated on triple-twisted superconducting cables. Both experiments demonstrated that ac losses at 60 Hz are equivalent to the sum of hysteresis loss and coupling-current losses due to the transverse component and longitudinal component of the external fields, respectively.

Changes in the flux pinning force and other superconducting features of NbTi superconductors due to ribbon-shaped artificial pins were examined. Experimental analysis involved the utilization of superconductivity and magnetization measurements. Results of the experiment were subjected to theoretical verification. It was found that artificial pins significantly enhance the critical current density of the NbTi superconductors.

Atheoretical study of additional ac losses in the armature winding of a superconducting generator is presented. The analysis, which concerns multiply-layered cables composed of multifilamentary superconductors, was conducted under conditions of an applied ac transport current and ac transverse magnetic field. To lower the total ac loss, issues related to the optimization of the winding's cable structures are also presented.

In order to investigate the cause of quenching at the joint between a multifilamentary superconducting cable and a normal conducting cable, the 3-D current distribution is analyzed. It is found that the cause of quenching is the extreme concentration of current in the joint due to the pronounced skin effect at liquid helium temperature. The mechanism of the concentration of current which is affected by the twist pitch and skin depth is also clarified quantitatively by numerical analysis.