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In the framework of the project where space in a cryostat is strictly limited, the high temperature superconductor (HTS) segments of the current leads have to be placed horizontally and in a scattered magnetic field. We developed the current leads optimization model for such conditions. In this paper, we present the results of optimization for 2000AHTS current leads, comprised of 2G HTS tapes and able to work in the magnetic field up to 2 T. The optimal parameters of the current leads segments have been determined using a numerical simulation. In order to approach the maximum efficiency, it is necessary to have a very good heat exchange between the current leads and evaporating helium gas. The impact of the external magnetic field on the heat leak from current leads into liquid helium is studied. [ABSTRACT FROM AUTHOR]

Triaxial HTS power cables are the optimal solution for low and medium voltages. This design permits to save expensive HTS conductor and to increase the power density transmitted. They could be used at medium voltages ∼10–20 kV for distribution grids. At relatively low voltages (<1–10 kV), triaxial cables could be used for ship propulsion systems or in electrical aircraft, where higher voltages are prohibited due to operational conditions. Prototypes of HTS “triaxial” cables made of both Bi-2223 and ReBaCuO HTS wires have been developed and tested in the Russian Scientific R&D Cable Institute. The calculations to optimize the cables with three superconducting layers and outer copper shield have been performed. The optimal parameters have been determined. The Bi-based 10-m cable has been inserted in a full-size flexible cryostat with current leads developed and has been tested at dc and ac conditions. The 4-m ReBaCuO cable has been tested in a laboratory cryostat and tested at dc and ac conditions also. AC tests of both cables were performed at different frequencies from ∼37 to ∼400 Hz. The cables designs, test results, and their analysis are presented. [ABSTRACT FROM PUBLISHER]

The test facility developed in Russian Scientific R&D Cable Institute permits to perform extensive tests of heavily instrumented HTS cable models with length up to 5 m. Several HTS cables with different design have been developed and tested at this facility. The test programs included, besides usual critical current measurements, current distribution measurements among layers, joint resistance test, etc. The facility's equipment permits digital measurements of voltage and current with high accuracy and, therefore, digital ac loss analysis in model cables. In this paper we present the details of the test facility and results of tests and ac loss measurements in few 5 m model cables. ac losses in model cables made of 1 G and 2 G wires and other cable parameters are discussed and compared. [ABSTRACT FROM AUTHOR]

In the framework of the Russian R&D Program for superconducting power devices, the 30 m HIS power cable has been developed made of 1 G Bi-2223 tapes. Before the full length cable production, as the first prototype the short 5 m cable model was produced and tested. After 30 m cable production the 5 m witness sample has been cut from the long piece and tested as well. To verify the calculations and designing principles both S m cables were heavily instrumented by potential taps and sensors to measure current distribution among layers, voltage-current characteristics and other parameters. AC losses in these short cable pieces have been analyzed by use of digital measurements of current and voltages along the cable. The witness sample has been provided by thermocouples to evaluate AC losses by calorimetric method. The details of AC losses measurements are discussed. Their analysis and comparison with calculations by standard theoretical models are presented. [ABSTRACT FROM AUTHOR]

In the framework of the Russian R&D Program for superconducting power devices, an experimental 30 m HTS power cable has been developed. Three 30 rn phases with nominal current of ∼2 kA and 20 kV operating voltage were delivered as the result of the project. Variations were used in basic HTS materials, cryostats and current leads for the cable design in this research project. All phases were made of 1G HTS Bi-based tape. The details of the design of the cable are discussed. Before the full length cable test a 5 m witness sample has been cut, heavily instrumented and tested. Results of the witness sample tests and analysis of fault current behavior of the cable are presented. [ABSTRACT FROM AUTHOR]

2G HTS wires produced with the MOD/RABiTS process with NiW substrates have weak magnetism and therefore extra losses in a substrate. The goal of this paper is to find out the model that could describe losses just in a substrate only. Two and three dimensional numerical electromagnetic field analysis has been developed for two-layer cables made of 2G HTS conductors with magnetic substrates. Two arrangements were used for the 2G conductors between the inner and outer layers: tape-on-tape and tape-on-gap. Comparisons of calculations with measured ac loss are presented. [ABSTRACT FROM AUTHOR]