Applications of an HTS thin film switching element in the inductive current limiter V. Sokolovsky a , V. Meerovich a, * , V. Beilin b , I. Vajda c a Department of Physics, Ben-Gurion University of the Negev, P.O. Box 651, Beer-Sheva 84105, Israel b The Hebrew University of Jerusalem, Jerusalem 91904, Israel c University of Technology and Economics, Budapest H-1111, Hungary Abstract We report the results of the test of a new inductive fault current limiter (FCL), where a secondary coil is fabricated from a superconducting BSCCO wire short-closed by a thin film switching element. This switching element was fab- ricated from an YBCO thin film deposited on a sapphire substrate and covered by Au layer. Under fault conditions the switching element passes into the normal state, whereas the coil remains in the superconducting state in any operation regime. The FCL meets to the basic requirements of power systems: low impedance under a normal regime of the protected circuit; fast increase of its impedance and the current limitation during a fault; quick return to the initial state after a fault ceases. The parameters of a full-scale device are estimated. Ó 2002 Elsevier Science B.V. All rights reserved. Keywords: High-temperature superconductor; Fault current limiter; Power system 1. Introduction Fault current limiters (FCL) can be the primary application of high-temperature superconductors (HTS) in electric power systems. Several high power prototypes of a superconducting FCL have been built and successfully tested showing feasi- bility of various proposed conceptions for appli- cation in power electric systems [1–3]. Presently, the main attention is given to two basic designs: resistive and inductive. The general problem for all theFCLsbasedontheS–Ntransitionistoprovide the quick and homogeneous transition of switch- ing elements into the normal state. The formation of overheating domains in HTS switching ele- ments, especially based on bulk materials, is caused even by small inhomogeneities in the criti- cal current distribution along the superconductor because of the very low propagation velocity of a normal zone (10 2 m/s instead of 10 3 m/s in low- temperature superconducting (LTS) materials) [4]. Design of inductive FCLs employing bulk cylin- ders is usually based on the assumption that the whole of the cylinder undertakes the S–N transi- tion at a fault. In reality, only part of the cylinder possessing a lower critical current passes into the resistive state. The place and length of the quen- ched section cannot be controlled. In early de- signs based on LTS [5], the secondary coil was * Corresponding author. Tel.: +972-86472458; fax: +972- 86472903. E-mail address: victorm@bgumail.bgu.ac.il (V. Meerovich). 0921-4534/02/$ - see front matter Ó 2002 Elsevier Science B.V. All rights reserved. doi:10.1016/S0921-4534(02)02229-3 www.elsevier.com/locate/physc Physica C 386 (2003) 480–484