Transition of a superconductor from its super conducting to its dissipative state appears as a very neat solution to avoid high Fault Current values in High Voltage (HV) networks. During normal operation Fault Current Limiter (FCL) losses are very low. On the other hand any excessive current increase induces electrical field inside the superconductor equilibrating network voltage and then limits maximum value of the current. Circuit opening is then made greatly easier using classical circuit breaker. Fault time could be less than a wave of 50 (or 60) Hz, e.g. 20 (or 16.6) ms. Such a device permits size reduction of conventional equipments for power distribution such as switch-gears, cables, transformers and especially increases reliability of power distribution by allowing interconnection between networks without increasing fault strength Reproducibility of 1 kV/ m for a current limitation of few hundred Amperes in small YBCO bars has been recently shown.
We propose an innovative way using ReBaCuO (RE = Y, Nd) single domains for current limitation. We want to improve and use large single crystals (available up to 7 cm in Europe up to now) and also long textured bars prepared by top seeding or Bridgman growth. The material will be cut, shaped and assembled in order to build and test three phase high voltage 17 MVA prototypes. Aims of the project are: Material improvement in such a way that the size of the super conducting circuit will be minimised after assembly of the different elements each producing 1 kV. Cost of super conducting materials and of the whole assembly would then be small. Industrialisation in Europe of a technology to grow crystals. Simulation of HVSFCLs and its interaction with its networks. Places of FCL will be studied and determined, like bus bar coupling, equipment reinforcement, networks interconnection.
fabrication of two three phase 25 kV /400 A HVSFCLs: one resistive and one inductive having a resistive secondary winding short-circuited by the superconductor. Installation in a power network of one or both of these HVSFCLs. Full size behaviour of FCL and network will be then studied. BE97-4829
Funding SchemeCSC - Cost-sharing contracts