1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationSuperconductivityPart 13: AC loss measurements Magnetometer methods for hysteresis loss in superconducting multifilamentary compositesBS EN 61788-13:2012National forewordThis Bri
2、tish Standard is the UK implementation of EN 61788-13:2012. It isidentical to IEC 61788-13:2012. It supersedes BS EN 61788-13:2003 which iswithdrawn.The UK participation in its preparation was entrusted to Technical CommitteeL/-/90, Super Conductivity.A list of organizations represented on this comm
3、ittee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provisions of acontract. Users are responsible for its correct application. The British Standards Institution 2012Published by BSI Standards Limited 2012ISBN 978 0 580 75539 2ICS 17.220; 2
4、9.050Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of the StandardsPolicy and Strategy Committee on 30 November 2012.Amendments issued since publicationAmd. No. Date Text affectedBRITISH STANDARDBS EN 61788-13:
5、2012EUROPEAN STANDARD EN 61788-13 NORME EUROPENNE EUROPISCHE NORM October 2012 CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Management Centre: Avenue Marnix 17, B - 1000 Brussels 2012
6、CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members. Ref. No. EN 61788-13:2012 E ICS 17.220; 29.050 Supersedes EN 61788-13:2003English version Superconductivity - Part 13: AC loss measurements - Magnetometer methods for hysteresis loss in supercon
7、ducting multifilamentary composites (IEC 61788-13:2012) Supraconductivit - Partie 13: Mesure des pertes en courant alternatif - Mthodes de mesure par magntomtre des pertes par hystrsis dans les composites multifilamentaires supraconducteurs (CEI 61788-13:2012) Supraleitfhigkeit - Teil 13: Messung de
8、r Wechselstromverluste - Magnetometerverfahren zur Messung der Hystereseverluste von supraleitenden Multifilament-Verbundleitern (IEC 61788-13:2012) This European Standard was approved by CENELEC on 2012-08-29. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipu
9、late the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CENELEC member. This Europe
10、an Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions. CENELEC memb
11、ers are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Nor
12、way, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. BS EN 61788-13:2012EN 61788-13:2012 - 2 - Foreword The text of document 90/302/FDIS, future edition 2 of IEC 61788-13, prepared by IEC/TC 90 “Superconductivity“ was submitted to the IEC-CEN
13、ELEC parallel vote and approved by CENELEC as EN 61788-13:2012. The following dates are fixed: latest date by which the document has to be implemented at national level by publication of an identical national standard or by endorsement (dop) 2013-05-29 latest date by which the national standards con
14、flicting with the document have to be withdrawn (dow) 2015-08-29 This document supersedes EN 61788-13:2003. EN 61788-13:2012 includes the following significant technical changes with respect to EN 61788-13:2003: - to extend to the measurement of superconductors in general, in various sample sizes an
15、d shapes, and at temperatures other than 4,2 K; - to use the word “uncertainty” for all quantitative (associated with a number) statistical expressions and eliminate the quantitative use of “precision” and “accuracy” in accordance with the decision at the June 2006 IEC/TC 90 meeting in Kyoto. Attent
16、ion is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CENELEC and/or CEN shall not be held responsible for identifying any or all such patent rights. Endorsement notice The text of the International Standard IEC 61788-13:2012 was approved by
17、CENELEC as a European Standard without any modification. BS EN 61788-13:2012- 3 - EN 61788-13:2012 Annex ZA (normative) Normative references to international publications with their corresponding European publications The following documents, in whole or in part, are normatively referenced in this d
18、ocument and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. NOTE When an international publication has been modified by common modifications, indicat
19、ed by (mod), the relevant EN/HD applies. Publication Year Title EN/HD Year IEC 60050 Series International Electrotechnical Vocabulary (IEV) - - IEC 61788-5 - Superconductivity - Part 5: Matrix to superconductor volume ratio measurement - Copper to superconductor volume ratio of Cu/Nb-Ti composite su
20、perconductors EN 61788-5 - BS EN 61788-13:2012 2 61788-13 IEC:2012 CONTENTS INTRODUCTION . 5 1 Scope . 6 2 Normative references . 6 3 Terms and definitions . 6 4 General specifications 8 4.1 Target uncertainty . 8 4.2 Uncertainty and uniformity of the applied field . 8 4.3 VSM calibration . 8 4.4 Te
21、mperature 9 4.5 Specimen length 9 4.6 Specimen orientation and demagnetization effects 9 4.7 Normalization volume 9 4.8 Mode of field cycling or sweeping 9 5 The VSM method of measurement 10 5.1 General . 10 5.2 VSM measurement principle 10 5.3 VSM specimen preparation 10 5.4 VSM measurement conditi
22、ons and calibration . 12 5.4.1 Field amplitude 12 5.4.2 Direction of applied field 12 5.4.3 Rate of change of the applied field (sweep rate) 12 5.4.4 Waveform of the field change 12 5.4.5 Specimen size and shape correction 12 5.4.6 Allowance for addendum (background subtraction) 13 5.4.7 Data point
23、density 13 6 Test report 13 6.1 General . 13 6.2 Initiation of the test 13 6.3 Technical details . 13 Annex A (informative) The SQUID method of measurement . 15 Annex B (normative) Extension of the standard to the measurement of superconductors in general . 16 Annex C (informative) Uncertainty consi
24、derations 18 Bibliography 23 Figure 1 A typical experimental setup of VSM measurement 11 Figure 2 Three alternative specimen configurations for the VSM measurement 11 Table C.1 Output signals from two nominally identical extensometers 19 Table C.2 Mean values of two output signals . 19 Table C.3 Exp
25、erimental standard deviations of two output signals . 19 Table C.4 Standard uncertainties of two output signals 20 Table C.5 Coefficient of variations of two output signals 20 BS EN 61788-13:201261788-13 IEC:2012 5 INTRODUCTION IEC Technical Committee 90 proposes magnetometer and pickup coil methods
26、 for measuring the AC losses of Cu/Nb-Ti composite superconducting wires in transverse time-varying magnetic fields. These represent initial steps in standardization of methods for measuring the various contributions to AC loss in transverse fields, the most frequently encountered configuration. It
27、was decided to split the initial proposal mentioned above into two documents covering two standard methods. One of them describes the magnetometer method for hysteresis loss and low frequency (or sweep rate) total AC loss measurement in a slowly varying magnetic field, and the other describes the pi
28、ckup coil method for total AC loss measurement in higher frequency (or sweep rate) magnetic fields. The frequency range is 0 Hz 0,06 Hz for the magnetometer method and 0,005 Hz 60 Hz for the pickup-coil method. The overlap between 0,005 Hz and 0,06 Hz is a complementary frequency range for the two m
29、ethods. This standard deals with the magnetometer method. BS EN 61788-13:2012 6 61788-13 IEC:2012 SUPERCONDUCTIVITY Part 13: AC loss measurements Magnetometer methods for hysteresis loss in superconducting multifilamentary composites 1 Scope This part of IEC 61788 describes considerations for the me
30、asurement of hysteretic loss in Cu/Nb-Ti multifilamentary composites using DC- or low-ramp-rate magnetometry. This international standard specifies a method of the measurement of hysteretic loss in multifilamentary Cu/Nb-Ti composite conductors. Measurements are assumed to be on round wires with tem
31、peratures at or near 4,2 K. DC or low-ramp-rate magnetometry will be performed using either a superconducting quantum interference device (SQUID magnetometer, See Annex A.) or a vibrating-sample magnetometer (VSM). In case differences between the calibrated magnetometer results are noted, the VSM re
32、sults, extrapolated to zero ramp rate, will be taken as definitive. Extension to the measurement of superconductors in general is given in Annex B. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its applicati
33、on. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 60050 (all parts), International Electrotechnical Vocabulary (available at 5 Lp. 4.6 Specimen orientation and demagnetization effect
34、s Loss measurements shall be made on strand specimens in a transverse magnetic field. For the fully penetrated fine filaments of a multifilamentary Cu/Nb-Ti strand, demagnetization is negligible. By the same token, it is negligible for round-, flat-, or square-cross-sectioned bundles of such strands
35、. However, for the sake of completeness in reporting the results, the specimen configuration shall be reported. 4.7 Normalization volume It may be desirable to report hysteretic loss in terms of the superconductor volume. To pursue this route, it is necessary to invoke a standard procedure for deter
36、mining the matrix (Cu)/superconductor volume ratio (see IEC 61788-5). For the purposes of this standard, these steps are eliminated, and AC loss is to be reported in terms of total composite volume. Volume should be measured with a relative combined standard uncertainty not to exceed 0,5 %. 4.8 Mode
37、 of field cycling or sweeping The applied field may be changed point-by-point over the field cycle starting and ending at Hmax.SQUID magnetometry is restricted to this mode of field change, and it is optional for the VSM to be operated in point-by-point mode. The VSM may also be operated semicontinu
38、ously, the M-H loop being constructed from 200 or so (M,H) data-pairs. BS EN 61788-13:2012 10 61788-13 IEC:2012 5 The VSM method of measurement 5.1 General For a full description of the application of VSM technique, the paper by Collings et al. 11) is recommended. 5.2 VSM measurement principle The b
39、asic principle of the Foner 2 VSM is as follows. The specimen to be measured is located in a uniform magnetic field, which causes it to become magnetized. The specimen is mechanically oscillated near a set of pickup coils. The oscillating magnetic moment causes an oscillation in the magnetic field l
40、inking the pickup coils, thereby inducing an AC voltage which is then detected and converted into a magnetic moment value by electronic circuitry. The magnetometer is a “substitution“ rather than “absolute“ device and its output signal requires calibration against a reference. Custom-made (hand-made
41、) VSMs do exist, but increasingly, commercial versions of this machine are used. In general, they share the following characteristics. The specimen to be measured is typically mounted on a vertical rod which vibrates longitudinally (vertically) with a position amplitude of about 1 mm and at a suitab
42、ly low frequency. The magnetic field may be supplied by either a horizontally mounted iron-core electromagnet (EM) or a vertically mounted superconducting solenoid (SCS) the conventional attitudes in each case causing the vibration direction of the sample to be perpendicular or parallel, respectivel
43、y, to the field direction. The pickup coils are appropriately located and connected in pairs such that any external field oscillations (magnetic noise) are cancelled and only the specimen-generated field oscillations are detected. A typical experimental setup of VSM measurement is given in Figure 1.
44、 The loss is determined from the numerically integrated area of the full M-H loop. The specimen is positioned at the “sweet spot“, a small region of the pickup coil space within which the detected signal changes only slightly with variation of vertical or horizontal positioning of the specimen. Usin
45、g a small calibrating specimen of, for example Ni, the specimen space is to be explored and the sweet spot determined as the volume within which the response does not change more than 2 %. Suppose Z to be the vertical direction, Y the direction along the magnet-pole axis, and X the direction normal
46、to the magnet-pole axis, then the center of the sweet spot is located by a procedure known as “saddling“, viz seeking the maximum signal along Z combined with the maximum along X and the minimum along Y. 5.3 VSM specimen preparation The size of the sweet spot in the typical VSM restricts specimen vo
47、lume to less than about 30 mm3. For the VSM measurement of Cu/Nb-Ti multifilamentary composite wires, it is permissible to use one of three alternative specimen configurations as shown in Figure 2. a) Short straight specimen: This consists of one or more straight pieces of strand (the size of the bu
48、ndle depending on the signal strength required) up to about 1 cm in length. The ends of the strand pieces are to be finely ground flat (see for example 1). b) Multiturn coil: If long lengths of fine wire are to be measured, they may be wound for measurement into a multiturn coil (see for example 3).
49、 For EM-VSM measurement, the coil may be oval in shape and mounted with its long axis vertically (parallel to the vibration axis). The plane of the coil will be normal to the field direction. For SCS-VSM measurement, the multiturn coil should be round and mounted with its plane perpendicular to the vibration axis. _ 1)Numbers in square brackets refer to the Bibliography. BS EN 61788-13:201261788-13 IEC:2012 11 To minimize the possibility of interstrand coupling, the strands of the
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