EN 61788-1:2007

FOREWORD
INTRODUCTION
1 Scope
2 Normative references
3 Terms and definitions
4 Principle
5 Requirements
6 Apparatus
   6.1 Measurement mandrel material
   6.2 Mandrel construction
7 Specimen preparation
   7.1 Specimen bonding
   7.2 Specimen mounting
8 Measurement procedure
9 Uncertainty of the test method
   9.1 Critical current
   9.2 Temperature
   9.3 Magnetic field
   9.4 Specimen and mandrel support structure
   9.5 Specimen protection
10 Calculation of results
   10.1 Critical current criteria
   10.2 n-value (optional calculation, refer to A.7.2)
11 Test report
   11.1 Identification of test specimen
   11.2 Report of I[c] values
   11.3 Report of test conditions
Annex A (informative) Additional information relating to
        the standard
Annex B (informative) Self-field effect
Annex C (normative) Test method for Cu/Cu-Ni/Nb-Ti
        composite superconductors
Annex D (informative) Guidance for estimating winding
        tensile force
Annex ZA (normative) Normative references to international
         publications with their corresponding European
         publications
Bibliography

This part of IEC 61788 covers a test method for the determination of the d.c. critical current of either Cu/Nb-Ti composite superconductors that have a copper/superconductor ratio larger than 1 or Cu/Cu-Ni/Nb-Ti wires that have a copper/superconductor ratio larger than 0,9 and a copper alloy (Cu-Ni)/superconductor ratio larger than 0,2, where the diameter of Nb-Ti superconducting filaments is larger than 1 micrometre. The changes for the Cu/Cu-Ni/Nb-Ti are described in Annex C. The Cu-Ni uses all of the main part of the standard with the exceptions listed in Annex C that replace (and in some cases are counter to) some of the steps inthe main text. 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 at a known temperature during testing. The test conductor has a monolithic structure with a round or rectangular cross-sectional area that is less than 2 mm2. The specimen geometry used in this test method is an inductively coiled specimen. Deviations from this test method that are allowed for routine tests and other specific restrictions are given in this standard. Test conductors with critical currents above 1 000 A or cross-sectional areas greater than 2 mm2 could be measured with the present method with an anticipated increase in uncertainty 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 a lower uncertainty. The test method given in this standard is expected to apply to other superconducting composite wires after some appropriate modifications.