Bernd Sailer

Progress in the preparation of technical HTS-tapes of type Bi-2223/Ag-alloy of industrial lengths

We report about the improvements on overall critical current density j/sub e/, long-length processing, mechanical properties, and insulation. These topics are discussed for Bi-2223/Ag-alloy tapes for typical DC-applications, for AC-applications which require twisted filaments to achieve low-loss properties and for current-lead-applications (EAS is producing Bi-2223/AgMgAu-HTS-tapes for the CERN-LHC-Project). The state-of-the art production of Bi-2223/Ag-alloy tapes at EAS allows for overall current densities of >100 A/mm/sup 2/. There is progress out of the development line to a value of more than 120 A/mm/sup 2/, which will be transferred to the production line in the near future. Regarding AC-tapes with twisted filaments, it is possible to prepare tapes without a reduction in overall current density if the preparation parameters are kept within a well defined window. Both types of tapes are available in piece-lengths of up to 1500 m. The requirements on the piece-lengths of Bi-2223/AgMgAu-HTS-tapes for current leads are less stringent. This type of tape is available in piece-lengths up to 300 m with overall current densities up to 90 A/mm/sup 2/.

Bi-2223 tapes - specific performance for different applications

In the past (Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ Ag/Ag-alloy-sheathed High-Temperature Superconductor (HTS) tapes (Bi-2223 tapes) have been proven being suitable for building quite different system components for a variety of applications. Nevertheless it revealed that applications like Power Transmission Lines, Transformers, Motors/ Generators, SMES, very high field magnets and MRI put very special requirements on the tapes which differ from application to application. The most important point is that the tapes will provide cost-efficient performance for the special application. This means that its not sufficient to analyze the price in

Slimformer—Self-Limiting Transformer Pre-Prototype and Pilot Plant Design, Construction, and Tests

/kAm, but additionally its necessary to consider e.g., AC-losses, geometry, mechanical strength and insulation properties and how they contribute to cost. We discuss a subset of the different requirements from the view of a tape supplier. We depict the current status of the tape production unit lengths >1000 m, overall current densities /spl ges/100 A/mm/sup 2/, steep E-I-characteristics n-value /spl ges/30 at standard conditions and even at low temperatures and/or high magnetic fields), low AC-losses combined with remarkable critical currents of 50 A/mm/sup 2/, reliable properties of mechanics and insulation.

High temperature superconductor current lead for connecting a superconducting load system to a current feed point

The current limiting or self-limiting transformer, (CLT) is a multifunctional device, which combines the functions of a power transformer with the functions of a current limiter. The investigated SLIMFormer consists of a room temperature primary winding and a secondary high temperature superconductor (HTS) winding (BSCCO 2223) divided into two parts located on different limbs and up to 4 HTS ring (BSCCO 2212). The primary winding is connected to the electrical network, the secondary winding is intended to supply an HTS cable. As a result the SLIMFormer is an inductive terminal between the room temperature network and a projected HTS cable. For investigation of the SLIMFormer a 100 kVA rating experimental device (pilot plant) was designed, built and tested. The design and optimization aspects as well as the construction of the pilot plant will be presented. The present work is based on the previous 20 kVA SLIMFormer pre-prototype device which was tested at Lab of DEPE BME. The SLIMFormer was investigated experimentally for both sudden short circuit and steady-state (transformer) operational modes. The activation currents were determined for both operational modes with the rated secondary winding turn ratio. SLIMFormer work is being performed as part of an EC funded project, project name: acronym SLIMFormer.