The aim of the research was to take the discovery of a new low-cost superconducting material - Magnesium Diboride (MgB2) – to the reality of a simple working prototype wire-wound fault current limiter and demonstrate that it could operate successfully and reliably.
The research challenges were how to take simple laboratory wire samples to full-scale coil structures that could withstand kV and kA in a cryogenic environment. The research demonstrated that these basic engineering ideas could be ‘scaled-up’ to the required distribution voltage and current levels.
The superconducting properties of MgB2 were only first discovered in 2001. The research team at Manchester quickly recognised the potential of this wire-form superconducting material.
Working with Rolls Royce, following the official opening of their University Technology Centre (UTC) at Manchester in 2004, the research was focussed on developing the first commercial superconducting fault current limiter using MgB2 to operate on the UK national grid. The commercial significance of the research into MgB2 SFCLs at Manchester was quickly recognised by Rolls-Royce who have filed six patents to date.
Superconducting fault current limiters (SFCLs) are situated at strategic points in an electrical network. Under normal operation, they remain in the superconducting state and are virtually ‘invisible’ to the network. If a fault occurs and the current rises beyond the material critical current, the superconductor transitions to a normal conductor and introduces a resistance into the fault path, limiting the fault current.
Research on wire-form MgB2 is now pushing into other strands of research that continues to develop the impact of this work. Recent work on AC superconducting coil designs using a modified form of the superconducting wire has produced further developments and patents in the area of AC Superconducting electrical machines. Significant interest is also being shown into superconducting DC electrical systems in aerospace.
- Smith A.C., Oliver A., Pei X., Husband M. and Rindfleisch, M.:’ Experimental testing and modelling of a resistive type superconducting fault current limiter using MgB2 wire’, Supercond. Sci. Technol. Vol 25, No. 12 (2012) 125018. doi: 10.1088/0953-2048/25/12/125018
- Pei, X., Smith, A.C., Zeng, X., Husband, M., Rindfleisch,M.: ‘Design, build and test of a superconducting machine AC stator coil using MgB2 wire’, IEEE Transactions on Applied Superconductivity, 2013, DOI:10.1109/TASC.2013.2245715