IEC 61788-24:2018 describes a test method for determining the retained critical current after double bending at room temperature of short and straight Ag- and\/or Ag alloy-sheathed Bi-2223 superconducting wires that have the shape of a flat or square tape containing mono- or multicores of oxides. The wires can be laminated with copper alloy, stainless steel or Ni alloy tapes. The test method is intended for use with superconductors that have a critical current less than 300 A and an n-value larger than 5.<\/p>\n
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| 2<\/td>\n | undefined <\/td>\n<\/tr>\n | ||||||
| 5<\/td>\n | Annex ZA(normative)Normative references to international publicationswith their corresponding European publications <\/td>\n<\/tr>\n | ||||||
| 7<\/td>\n | English CONTENTS <\/td>\n<\/tr>\n | ||||||
| 9<\/td>\n | FOREWORD <\/td>\n<\/tr>\n | ||||||
| 11<\/td>\n | INTRODUCTION <\/td>\n<\/tr>\n | ||||||
| 12<\/td>\n | 1 Scope 2 Normative references 3 Terms and definitions <\/td>\n<\/tr>\n | ||||||
| 13<\/td>\n | 4 Principle 5 Apparatus 5.1 General 5.2 Bending mandrel 5.3 Critical current measurement holder <\/td>\n<\/tr>\n | ||||||
| 14<\/td>\n | 5.4 Critical current measuring system 6 Specimen preparation and set up 6.1 Length of specimen Figures Figure 1 \u2013 Sample holder <\/td>\n<\/tr>\n | ||||||
| 15<\/td>\n | 6.2 Mounting of the specimen 7 Measurement procedures 7.1 Critical current measurement 7.2 Double bending <\/td>\n<\/tr>\n | ||||||
| 16<\/td>\n | 7.3 Retained critical current after bending 8 Calculation of results 8.1 Critical current criteria 8.2 n-value (optional) 9 Test report 9.1 Identification of test specimen <\/td>\n<\/tr>\n | ||||||
| 17<\/td>\n | 9.2 Report of Ic values and\/or retained Ic ratio 9.3 Report of Ic test conditions Figure 2 \u2013 Intrinsic U-I characteristic Figure 3 \u2013 U-I characteristic with a current transfer component <\/td>\n<\/tr>\n | ||||||
| 18<\/td>\n | Annex A (informative)Additional information relating to Clauses 1 to 9 A.1 General A.2 Measurement condition A.3 Apparatus measurement holder material <\/td>\n<\/tr>\n | ||||||
| 19<\/td>\n | Tables Table A.1 \u2013 Thermal expansion data of Bi-2223 superconductors and selected materials <\/td>\n<\/tr>\n | ||||||
| 20<\/td>\n | Figure A.1 \u2013 Measurement configuration for a few hundred ampere class conductor Figure A.2 \u2013 Clips <\/td>\n<\/tr>\n | ||||||
| 21<\/td>\n | A.4 Specimen preparation A.5 Measurement procedures A.5.1 Critical current measurement Figure A.3 \u2013 Additional strain caused by voltage tap wires and solders <\/td>\n<\/tr>\n | ||||||
| 22<\/td>\n | Figure A.4 \u2013 Boiling temperature of liquid nitrogen versus atmospheric pressure <\/td>\n<\/tr>\n | ||||||
| 23<\/td>\n | A.5.2 Bending Figure A.5 \u2013 Critical current versus temperature for a typical Bi-2223 wire <\/td>\n<\/tr>\n | ||||||
| 24<\/td>\n | A.6 Calculation of results A.6.1 Critical current criteria A.6.2 n-value Figure A.6 \u2013 Bending process <\/td>\n<\/tr>\n | ||||||
| 25<\/td>\n | A.7 Relative standard uncertainty <\/td>\n<\/tr>\n | ||||||
| 26<\/td>\n | Table A.2 \u2013 Average of the degree of retained critical current (Ic\/Ic0),their relative standard uncertainty and coefficient of variance <\/td>\n<\/tr>\n | ||||||
| 27<\/td>\n | Annex B (informative)Evaluation of combined standard uncertainty for the retained Ic after double bending B.1 Practice of critical current measurement B.2 Model equation Figure B.1 \u2013 U-I diagram Table B.1 \u2013 Precondition for evaluating standard uncertainty <\/td>\n<\/tr>\n | ||||||
| 28<\/td>\n | B.3 Operation for the retained Ic measurement B.4 Combined standard uncertainty <\/td>\n<\/tr>\n | ||||||
| 29<\/td>\n | B.5 Evaluation of standard uncertainty (SU) for each measurand B.5.1 Voltage tap length (L) B.5.2 Voltage (U) <\/td>\n<\/tr>\n | ||||||
| 30<\/td>\n | B.5.3 Current (I) <\/td>\n<\/tr>\n | ||||||
| 31<\/td>\n | B.6 Evaluation of combined standard uncertainty Table B.2 \u2013 Partial sum (Equation (B.17) of standard uncertainty as related to the current measurement) <\/td>\n<\/tr>\n | ||||||
| 32<\/td>\n | Table B.3 \u2013 Budget table of standard uncertainty for each component Table B.4 \u2013 Combined standard uncertainty <\/td>\n<\/tr>\n | ||||||
| 33<\/td>\n | Figure B.2 \u2013 Bending diameter dependence of the retained Ic and , where the calculated curve of Ic\/Ic0 gives Equation (B.24) <\/td>\n<\/tr>\n | ||||||
| 34<\/td>\n | Bibliography <\/td>\n<\/tr>\n<\/table>\n","protected":false},"excerpt":{"rendered":" Superconductivity – Critical current measurement. Retained critical current after double bending at room temperature of Ag-sheathed Bi-2223 superconducting wires<\/b><\/p>\n |