EVS-EN 61788-1:2002

This part of IEC 61788-1 covers a test method for the determination of the d.c. critical current of Cu/Nb-Ti composite superconductors that have a copper/superconductor ratio larger than 1. This method is intended for use with superconductors that have critical currents less than 1 000 A and n-values larger than 12, under standard test conditions and at magnetic fields less than or equal to 0,7 of the upper critical magnetic field. The test specimen is immersed in a liquid helium bath during testing. The Cu/Nb-Ti composite test conductor has a monolithic structure with a round or rectangular cross-sectional area that is less than 2 square milimeters. The specimen geometry used in this test method is an inductively coiled specimen. Deviations from this test method is allowed for routine tests and other specific restrictions are given in this standard.
Cu/Nb-Ti conductors with critical currents above 1 000 A or cross-sectional areas greater than 2 square milimeters could be measured with the present method with an anticipated reduction in precision and a more significant self-field effect (see annex B). Other, more specialized, specimen test geometries may be more appropriate for larger conductor testing which have been omitted from this present standard for simplicity and to retain precision.
The test method given in this standard is expected to apply to other superconducting composite wires after some appropriate modifications.