IEC 61788-4:2016

IEC 61788-4 ®
Edition 4.0 2016-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Superconductivity –
Part 4: Residual resistance ratio measurement – Residual resistance ratio of
Nb-Ti and Nb Sn composite superconductors
Supraconductivité –
Partie 4: Mesurage du rapport de résistance résiduelle – Rapport de résistance
résiduelle des composites supraconducteurs de Nb-Ti et de Nb Sn
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IEC 61788-4 ®
Edition 4.0 2016-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Superconductivity –
Part 4: Residual resistance ratio measurement – Residual resistance ratio of

Nb-Ti and Nb Sn composite superconductors

Supraconductivité –
Partie 4: Mesurage du rapport de résistance résiduelle – Rapport de résistance

résiduelle des composites supraconducteurs de Nb-Ti et de Nb Sn
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 17.220.20; 29.050 ISBN 978-2-8322-3129-6

– 2 – IEC 61788-4:2016 © IEC 2016

CONTENTS
FOREWORD . 4

INTRODUCTION . 6

1 Scope . 7

2 Normative references . 7

3 Terms and definitions . 7

4 Principle . 8

5 Apparatus . 8
5.1 Material of measurement mandrel or of measurement base plate . 8
5.2 Diameter of the measurement mandrel and length of the measurement base
plate . 8
5.3 Cryostat for the resistance (R ) measurement . 9
6 Specimen preparation . 9
7 Data acquisition and analysis . 9
7.1 Resistance (R ) at room temperature . 9
*
7.2 Resistance (R or R ) just above the superconducting transition . 9
2 2
7.2.1 Correction of strain effect . 9
7.2.2 Data acquisition of cryogenic resistance . 10
7.2.3 Optional acquisition methods . 12
*
7.3 Correction on measured R of Nb-Ti composite superconductor for bending
strain . 12
7.4 Residual resistance ratio (RRR) . 12
8 Uncertainty and stability of the test method . 12
8.1 Temperature . 12
8.2 Voltage measurement . 12
8.3 Current . 13
8.4 Dimension . 13
9 Test report . 13
9.1 RRR value . 13
9.2 Specimen . 13
9.3 Test conditions . 14
9.3.1 Measurements of R and R . 14
1 2
9.3.2 Measurement of R . 14
9.3.3 Measurement of R . 14
Annex A (informative) Additional information relating to the measurement of RRR . 15
A.1 Recommendation on specimen mounting orientation . 15
A.2 Alternative methods for increasing temperature of specimen above
superconducting transition temperature . 15
*
A.3 Alternative measurement methods of R or R . 15
2 2
A.4 Bending strain dependency of RRR for Nb-Ti composite superconductor . 18
A.5 Procedure of correction of bending strain effect . 21
Annex B (informative) Uncertainty considerations . 23
B.1 Overview. 23
B.2 Definitions. 23
B.3 Consideration of the uncertainty concept . 23

B.4 Uncertainty evaluation example for TC 90 standards . 25

Annex C (informative) Uncertainty evaluation in test method of RRR for Nb-Ti and

Nb Sn composite superconductors . 27
C.1 Evaluation of uncertainty . 27

C.2 Summary of round robin test of RRR of a Nb-Ti composite superconductor . 30

C.3 Reason for large COV value in the intercomparison test on Nb Sn composite
superconductor . 31

Bibliography . 32

Figure 1 – Relationship between temperature and resistance. 8

Figure 2 – Voltage versus temperature curves and definitions of each voltage . 10
Figure A.1 – Definition of voltages . 17
Figure A.2 – Bending strain dependency of RRR value for pure Cu matrix of Nb-Ti
composite superconductors (comparison between measured values and calculated
values) . 19
Figure A.3 – Bending strain dependency of RRR value for round Cu wires . 19
Figure A.4 – Bending strain dependency of normalized RRR value for round Cu wires . 20
Figure A.5 – Bending strain dependency of RRR value for rectangular Cu wires . 20
Figure A.6 – Bending strain dependency of normalized RRR value for rectangular Cu
wires . 21
Figure C.1 – Distribution of observed r of Cu/Nb-Ti composite superconductor . 31
RRR
Table A.1 – Minimum diameter of the measurement mandrel for round wires . 21
Table A.2 – Minimum diameter of the measurement mandrel for rectangular wires. 21
Table B.1 – Output signals from two nominally identical extensometers . 24
Table B.2 – Mean values of two output signals .
...