As part of the "Ampacity" project, the Karlsruhe Institute of Technology will alaso analyse suitable superconducting and insulating materials. Recently its new superconductor current limiter technology has been exported for use in South Africa.



The three-phase, concentric 10 kV cable produced by Nexans is designed for a transmission capacity of 40MW. This installation will be the first to combine a superconducting cable with a resistive superconducting fault current limiter for overload protection.

The limiter is to be manufactured in Hürth, Germany by a Nexans unit specialising in superconductors.

 Following successful completion of a 2-year field test, it should be possible to install 10kV superconducting links in large sections of the backbone of the Essen distribution network as part of efforts to reduce high-voltage installations. 

This would lead to greater efficiency as well as lower operating and maintenance costs simultaneously reducing land use. The dismantling of numerous 110/10kV transformer stations would help to free up valuable space in inner-city areas. The AmpaCity, the project is being supported by the energy research department of the Federal Ministry of Economics and Technology (BMWi).



The project was preceeded by a detailed study in which a number of research institutes, under the leadership of the Karlsruhe Institute of Technology, worked alongside with the project partners Nexans and RWE to analyse the technical feasibility and economic efficiency of a superconductor solution at medium-voltage level.

That study revealed superconducting cables are the only reasonable alternative to high-voltage cables in city networks and that their use would mean that resource-and land-intensive transformer stations could be demolished.

Although copper medium-voltage cables could also be used in inner-city areas to transmit high power, the cost efficiency of this solution would be cancelled out by the much higher ohmic drop.

Further, conventional medium-voltage cables for the Essen project are also out of the question, requiring much more routing space: instead of a single 10kV superconductor cable, five copper cables would need to be laid in parallel – a largely impossible task given limited space under the city streets.



State-of-the-art high-temperature superconductors (cooled with liquid nitrogen) such as those used in AmpaCity have been ready for deployment in energy-related applications for some years now, although they have yet to be used on a large scale. Thanks to improved production processes, superconducting wires are only now available in sufficient lengths and quantities.

Superconductivity is an efficiency technology because it helps to protect material and energy resources. Experts anticipate that these innovative cables will soon be able to compete with copper solutions in energy-intensive applications. The BMWi sees superconducting equipment as an important component in future energy supply concepts.



The technical predominance of superconducting cables can be attributed to the material properties of the conductor. At temperatures of around -200°C, the material transforms into an almost perfect electrical conductor being able to transport at least 100 times more electricity than copper.  Despite the cooling jacket, the compact design of the superconductor means it can transport five times the electricity as a similarly sized copper cable – and with much fewer electrical losses. 

UK works on Prague superconductor magnetic field coils
UK fusion research company Tokamak Solutions working with partners at Oxford Instruments, the Czech Technical University and Institute of Plasma Physics, Prague to use high temperature superconducting magnets on a tokamak for the first time.

High temperature superconductors have remarkable properties: they conduct electricity with zero resistance, even with simple cooling by liquid nitrogen; they can withstand high magnetic fields and huge current densities – and they continue to be superconducting throughout the plasma pulse in a tokamak.

High temperature superconductors could have an important role to play in the future of tokamak fusion research, but this is the first time they have actually been used for magnetic field coils on a tokamak.

In the experiment, two of the copper magnetic field coils on the Golem tokamak in Prague (below) were replaced by high temperature superconductor in a simple cooling system known as a cryostat. Plasma pulses were then created in the normal way and the tokamak operated exactly as expected. A whole series of further experiments is now planned.