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Two AC 5 kArms-50kVrms hybrid superconducting leads have been built and tested. These developments are now possible due to the progress of the MCP Bi-2212 superconducting material from Hoechst. Siemens has developed a top loading current lead pair suitable for the transformer applications and Alcatel Alsthom followed the horizontal and coaxial lead design suitable for current limiters a design which comes close to the requirements for feed through for power links. These designs are both using very short lead superconducting Bi-2212 parts. Both designs have turned out to be a good compromise between AC losses, heat conduction, cryogenics, vacuum and high voltage requirements. High voltage and high current tests have been carried out successfully at the target values. The 4K heat load value can be reduced by a factor 7 and the global refrigeration load (room temperature power consumption) was reduced by a factor of 3 compared to a classical all metal AC lead.
The objective of the proposed project is to develop demonstration examples of low loss current leads for application at technical frequencies (50 Hz) and high current levels. In the majority of power devices and magnet systems applying metallic superconductors at about 4K, current leads are key components dominating dominating the overall energy balance. The proposed research will focus on the development of high Tc superconducting materials (HTSC) in bulk form and on novel design concepts for AC leads incorporating such parts. Loss reduction to about 1/3 of conventional solutions is aimed at.

The major project tasks are defined as:

1) adaptation of effective numerical tools and development of novel design concepts,
2) development of reliable HTSC bulk material and electrical contacts, both for low losses at high AC currents,
3) realisation and testing of models and demonstration leads designed for two practical power application cases in the 5 kA range for AC and transient loads.

The successful outcome of the proposed R&D work will yield one of the first practical HTSC AC applications, will demonstrate the benefits of HTSC due to saving energy and will, in the same way, strongly support the development and acceptance of low Tc superconducting power devices with their great potential of saving weight, volume, losses and costs on a large scale in the power engineering industry.

Funding Scheme

CSC - Cost-sharing contracts


Siemens AG
Hammerbacher Straße 12-14
91058 Erlangen

Participants (2)


91460 Marcoussis

5030 Köln