The advent of low loss alternating current superconducting wires opens the way to a whole new current limiting technique : that of extremely fast transition from a superconducting state to a resistive state when the fault current exceeds the conductor's critical current.The 25 kV single phase prototype is constituted of a Nb Ti superconducting coil without iron core and very low inductance, lodged inside a conventional cryostat with liquid helium ; each terminal of the coil is linked to a current lead and to a voltage bushing.The results obtained in power tests with voltage up to 16 kV and short circuit current up to 15 kA are given. The fault current, limited to 350 A in a few microseconds, confirms the feasibility of this type of current limiting device.

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The delamination process of thin films on rigid substrates is investigated. Such systems are typically subject to high residual compression and modest adhesion causing them to buckling driven blisters. In certain cases buckles with the shape of telephone cords are observed. A finite element model for quasi-static delamination growth is developed. Applying a Reissner-Mindlin shell kinematic for the film allows C 0 − continuous shape functions. The traction vector at the film-substrate interface is obtained from the derivative of a cohesive free energy. Incorporation of loading and unloading conditions is considered for the irreversible process. The equilibrium state is computed iteratively in dependence of the compressive residual stresses. The computed telephone cord delaminations are stable asymmetric configurations whereas the symmetric configurations are unstable.

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