The current-voltage characteristics and the magnetic field dependence of the critical current of a range of mono-core BSCCO 2223 tapes are presented, illustrating the complementary use of transport and magnetization experiments in determining and analysing the current-limiting dissipation processes in these HTS conductors. Below a magnetic cross-over field H * the samples resemble a Josephson-linked current network, with the dominant dissipation at the weakest grain boundaries. In this regime, increasing field leads to a gradual fragmentation of the network. The network homogeneity and connectivity can be inferred from screening current length-scale measurements and comparison of transport and magnetization measurements. Above the cross-over field H * , flux motion within the surviving strongly linked backbone dominates the dissipation. The details of the dependences of the critical current and flux creep rate on magnetic field can be used to examine the intragranular pinning potential in the tapes. We show that, despite the wide range of transport critical-current values of the samples examined, the intragranular pinning proves to be remarkably sample independent. We conclude that while J c at low fields may be increased by improved processing that yields better intergrain connectivity, the high-field J c can be enhanced only by strengthening the pinning within the BSCCO 2223 crystallites themselves.

The design principles and performance characteristics of a prototype high-temperature superconductor saturable magnetic core-type fault current limiter are described. These are based on a distribution network service provider feasibility specification that included the footprint and regulatory requirements for limiting fault currents. Time-domain simulations using PSCAD/EMTDC are given to illustrate specific applications and the transient behavior of the different distribution system configurations are investigated. Disciplines Physical Sciences and Mathematics Publication DetailsThis article was originally published as: Abbott, SB, Robinson, DA, Perera, S, et al, Abstract-The design principles and performance characteristics of a prototype high-temperature superconductor saturable magnetic core-type fault current limiter are described. These are based on a distribution network service provider feasibility specification that included the footprint and regulatory requirements for limiting fault currents. Time-domain simulations using PSCAD/EMTDC are given to illustrate specific applications and the transient behavior of the different distribution system configurations are investigated.

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Ag-sheathed Bi-2223 multifilamentary tapes were prepared with a hot-pressing technique to study its effect on grain connectivity. The critical current density after hot-pressing was significantly enhanced with the maximum increase reached more than double that before. Hot pressing raised the from to for 81-filament tape. However, the critical current density in an applied magnetic field was not improved by hot-pressing. The in a magnetic field of 1 T decreased from 33% of for the original tape to 21% of for the hot-pressed tapes before and after hot pressing. The fraction of strong links was improved from 64% to 73% for the 81-filament tape as a result of hot pressing. Microstructural analysis showed that hot pressing chiefly improved grain connectivity, increased core density, recovered microcracks and reduced secondary phase impurities.