Evaluation of electric transport properties of high-temperature superconductor tapes of YBCO

• Grant number: 11/20311-5
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: January 01, 2012
• End date: August 31, 2012
• Field of knowledge: Engineering - Electrical Engineering - Electrical, Magnetic and Electronic Measurements, Instrumentation
• Principal Investigator: Carlos Yujiro Shigue
• Grantee: André Avancini Bernardes
• Host Institution: Escola de Engenharia de Lorena (EEL). Universidade de São Paulo (USP). Lorena , SP, Brazil

Abstract

The commercial superconducting tapes of a second generation (2G), consisting of YBa2Cu3O7-x (YBCO) compound deposited on a substrate of high electrical resistance have been employed in the construction of prototype resistive current limiting devices for use in distribution networks as a part of a research project under development at the School of Engineering of Lorena (USP EEL). As the tapes used in the project are commercial ones, produced by international companies and according to their stage of industrial development, they have diverse architectures and electrical characteristics which may vary from batch to batch and even within the same batch, can occur the variation in electrical resistance as well in the critical current and exponent n of the transition from the superconducting to normal state. Thus, the superconducting tape qualification is a prerequisite for the correct design of superconducting power devices. Due to the morphological complexity and high electrical resistance of 2G YBCO tapes, the transition to the normal state behavior is random, depending on the geometry and the cooling conditions of the sample. The test pulse current of short duration during the transition is one of the techniques used in the evaluation of the transport properties of these tapes. Thus, the analysis of the characteristic curves VI requires the determination of test conditions, such as duration of current pulse, the heat transfer characteristics of phase change of liquid N2 and the architecture of superconducting tape. In this work we propose the study of electrical and thermal behavior of superconducting tapes during the transition from the superconducting to the normal state. The study is based on analysis by finite element method applied to the solution of the equations of thermal balance coupled to the electromagnetic equations. The electrical and superconducting parameters of the model are determined from the experimental results of tests 2G superconducting tapes to be used in the design and construction of fault current limiter.