BS EN 61788-8-2010 Superconductivity AC loss measurements Total AC loss measurement of round superconducting wires exposed to a transverse alternating magnetic field at liquid heli.pdf

1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationSuperconductivityPart 8: AC loss measurements Total AC loss measurement of round superconducting wires exposed to a transverse alternating magnetic field at liquid helium tempera

2、ture by a pickup coil methodBS EN 61788-8:2010National forewordThis British Standard is the UK implementation of EN 61788-8:2010. It isidentical to IEC 61788-8:2010. It supersedes BS EN 61788-8:2003 which iswithdrawn.The UK participation in its preparation was entrusted to Technical CommitteeL/-/90,

3、 L/-/90 Super Conductivity.A list of organizations represented on this committee 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. BSI 2010ISBN 978 0 580 64251 7ICS 17.

4、220.20; 29.050Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of the StandardsPolicy and Strategy Committee on 31 December 2010.Amendments issued since publicationAmd. No. Date Text affectedBRITISH STANDARDBS EN

5、61788-8:2010EUROPEAN STANDARD EN 61788-8 NORME EUROPENNE EUROPISCHE NORM November 2010 CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Management Centre: Avenue Marnix 17, B - 1000 Brusse

6、ls 2010 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members. Ref. No. EN 61788-8:2010 E ICS 17.220 Supersedes EN 61788-8:2003English version Superconductivity - Part 8: AC loss measurements - Total AC loss measurement of round superconducting wire

7、s exposed to a transverse alternating magnetic field at liquid helium temperature by a pickup coil method (IEC 61788-8:2010) Supraconductivit - Partie 8: Mesure des pertes en courant alternatif - Mesure de la perte totale en courant alternatif des fils supraconducteurs ronds exposs un champ magntiqu

8、e alternatif transverse par une mthode par bobines de dtection (CEI 61788-8:2010) Supraleitfhigkeit - Teil 8: Messung der Wechselstromverluste - Messung der Gesamtwechselstromverluste von runden Supraleiterdrhten in transversalen magnetischen Wechselfeldern mit Hilfe eines Pickupspulenverfahrens bei

9、 der Temperatur von flssigem Helium (IEC 61788-8:2010) This European Standard was approved by CENELEC on 2010-10-01. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard withou

10、t any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CENELEC member. This European Standard exists in three official versions (English, French, German). A version in any other language

11、 made by translation under the responsibility of a CENELEC member into its own language and notified to the Central Secretariat has the same status as the official versions. CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republi

12、c, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. BS EN 61788-8:2010EN 61788-8:2010 - 2 - Foreword T

13、he text of document 90/243/FDIS, future edition 2 of IEC 61788-8, prepared by IEC TC 90, Superconductivity, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as EN 61788-8 on 2010-10-01. This European Standard supersedes EN 61788-8:2003. The main changes with respect to the

14、previous edition are listed below: extending the applications of the pickup coil method to the a.c. loss measurements in metallic and oxide superconducting wires with a round cross section at liquid helium temperature; u1 in accordance with the decision at the June 2006 IEC/TC90 meeting in Kyoto. At

15、tention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and CENELEC shall not be held responsible for identifying any or all such patent rights. The following dates were fixed: latest date by which the EN has to be implemented at nation

16、al level by publication of an identical national standard or by endorsement (dop) 2011-07-01 latest date by which the national standards conflicting with the EN have to be withdrawn (dow) 2013-10-01 Annex ZA has been added by CENELEC. _ Endorsement notice The text of the International Standard IEC 6

17、1788-8:2010 was approved by CENELEC as a European Standard without any modification. In the official version, for Bibliography, the following notes have to be added for the standards indicated: 2 IEC 61788-13:2003 NOTE Harmonized as EN 61788-13:2003 (not modified). 3 IEC 61788-1:2006 NOTE Harmonized

18、 as EN 61788-1:2007 (not modified). 9 IEC 61788-2 NOTE Harmonized as EN 61788-2. _ BS EN 61788-8:2010- 3 - EN 61788-8:2010 Annex ZA (normative) Normative references to international publications with their corresponding European publications The following referenced documents are indispensable for t

19、he application of this document. 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, indicated by (mod), the r

20、elevant EN/HD applies. Publication Year Title EN/HD Year IEC 60050-815 2000 International Electrotechnical Vocabulary (IEV) - Part 815: Superconductivity - - BS EN 61788-8:2010 2 61788-8 IEC:2010(E) CONTENTS INTRODUCTION.6 1 Scope.7 2 Normative references .7 3 Terms and definitions .7 4 Principle .9

21、 5 Apparatus.10 5.1 Testing apparatus .10 5.2 Pickup coils.10 5.3 Compensation circuit.10 6 Specimen preparation.11 6.1 Coiled specimen11 6.1.1 Winding of specimen .11 6.1.2 Configuration of coiled specimen .11 6.1.3 Maximum bending strain11 6.1.4 Treatment of terminal cross section of specimen .11

22、6.2 Specimen coil form11 7 Testing conditions 11 7.1 External applied magnetic field11 7.1.1 Amplitude of applied field 11 7.1.2 Direction of applied field 11 7.1.3 Waveform of applied field 12 7.1.4 Frequency of applied field .12 7.1.5 Uniformity of applied field 12 7.2 Setting of the specimen.12 7

23、.3 Measurement temperature.12 7.4 Test procedure 12 7.4.1 Compensation .12 7.4.2 Measurement of background loss 12 7.4.3 Loss measurement 13 7.4.4 Calibration.13 8 Calculation of results13 8.1 Amplitude of applied magnetic field .13 8.2 Magnetization13 8.3 Magnetization curve 14 8.4 AC loss .14 8.5

24、Hysteresis loss14 8.6 Coupling loss and coupling time constant 5,6 14 9 Uncertainty.14 9.1 General .14 9.2 Uncertainty of measurement apparatus .15 9.3 Uncertainty of applied field 15 9.4 Uncertainty of measurement temperature 15 10 Test report15 10.1 Identification of specimen15 BS EN 61788-8:20106

25、1788-8 IEC:2010(E) 3 10.2 Configuration of coiled specimen.15 10.3 Testing conditions .16 10.4 Results16 10.5 Measurement apparatus16 10.5.1 Pickup coils .16 10.5.2 Measurement system.17 Annex A (informative) Additional information relating to Clauses 1 to 1019 Annex B (informative) Explanation of A

26、C loss measurement with Poyntings vector 10 21 Annex C (informative) Estimation of geometrical error in the pickup coil method 22 Annex D (informative) Recommended method for calibration of magnetization and AC loss.23 Annex E (informative) Coupling loss for various types of applied magnetic field25

27、 Annex F (informative) Uncertainty considerations 26 Annex G (informative) Evaluation of uncertainty in AC loss measurement by pickup coil method 13 31 Bibliography34 Figure 1 Standard arrangement of the specimen and pickup coils 17 Figure 2 A typical electrical circuit for AC loss measurement by pi

28、ckup coils18 Figure C.1 Examples of calculated contour line map of the coefficient G22 Figure D.1 Evaluation of critical field from magnetization curves 24 Figure E.1 Waveforms of applied magnetic field with a period T = 1/f.25 Table F.1 Output signals from two nominally identical extensometers 27 T

29、able F.2 Mean values of two output signals27 Table F.3 Experimental standard deviations of two output signals27 Table F.4 Standard uncertainties of two output signals 28 Table F.5 Coefficient of variations of two output signals.28 Table G.1 Propagation of relative uncertainty in the pickup coil meth

30、od ( = 0,5).33 BS EN 61788-8:2010 6 61788-8 IEC:2010(E) INTRODUCTION Magnetometer and pickup coil methods are proposed for measuring the AC losses of composite superconducting wires in transverse time-varying magnetic fields. These represent initial steps in standardization of methods for measuring

31、the various contributions to AC loss in transverse fields, the most frequently encountered configuration. It 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

32、 (or sweep rate) total AC loss measurement, and the other describes the pickup coil method for total AC loss measurement in higher frequency (or sweep rate) magnetic fields. The frequency range is 0 Hz to 0,06 Hz for the magnetometer method and 0,005 Hz to 60 Hz for the pickup coil method. The overl

33、ap between 0,005 Hz and 0,06 Hz is a complementary frequency range for the two methods. This standard covers the pickup coil method. The test method for standardization of AC loss covered in this standard is partly based on the Versailles Project on Advanced Materials and Standards (VAMAS) pre-stand

34、ardization work on the AC loss of Nb-Ti composite superconductors 11). _ 1)Numbers in square brackets refer to the bibliography. BS EN 61788-8:201061788-8 IEC:2010(E) 7 SUPERCONDUCTIVITY Part 8: AC loss measurements Total AC loss measurement of round superconducting wires exposed to a transverse alt

35、ernating magnetic field at liquid helium temperature by a pickup coil method 1 Scope This part of IEC 61788 specifies the measurement method of total AC losses by the pickup coil method in composite superconducting wires exposed to a transverse alternating magnetic field. The losses may contain hyst

36、eresis, coupling and eddy current losses. The standard method to measure only the hysteresis loss in DC or low-sweep-rate magnetic field is specified in IEC 61788-13 2. In metallic and oxide round superconducting wires expected to be mainly used for pulsed coil and AC coil applications, AC loss is g

37、enerated by the application of time-varying magnetic field and/or current. The contribution of the magnetic field to the AC loss is predominant in usual electromagnetic configurations of the coil applications. For the superconducting wires exposed to a transverse alternating magnetic field, the pres

38、ent method can be generally used in measurements of the total AC loss in a wide range of frequency up to the commercial level, 50/60 Hz, at liquid helium temperature. For the superconducting wires with fine filaments, the AC loss measured with the present method can be divided into the hysteresis lo

39、ss in the individual filaments, the coupling loss among the filaments and the eddy current loss in the normal conducting parts. In cases where the wires do not have a thick outer normal conducting sheath, the main components are the hysteresis loss and the coupling loss by estimating the former part

40、 as an extrapolated level of the AC loss per cycle to zero frequency in the region of lower frequency, where the coupling loss per cycle is proportional to the frequency. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated refer

41、ences, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 60050-815:2000, International Electrotechnical Vocabulary (IEV) Part 815: Superconductivity 3 Terms and definitions For the purposes of this document,

42、the following terms and definitions, as well as those of IEC 60050-815, apply. 3.1 AC loss P power dissipated in a composite superconductor due to application of time-varying magnetic field or electric current IEC 60050-815:2000, 815-04-54 BS EN 61788-8:2010 8 61788-8 IEC:2010(E) 3.2 hysteresis loss

43、 Phloss of the type whose value per cycle is independent of frequency arising in a superconductor under a varying magnetic field NOTE This loss is caused by the irreversible magnetic properties of the superconducting material due to pinning of flux lines. IEC 60050-815:2000, 815-04-55 3.3 eddy curre

44、nt loss Peloss arising in the normal conducting matrix of a composite superconductor or the structural material when exposed to a varying magnetic field, either from an applied field or from a self-field IEC 60050-815:2000, 815-04-56, modified 3.4 (filament) coupling (current) loss Pcloss arising in

45、 multi-filamentary superconducting wires with a normal matrix due to coupling current IEC 60050-815:2000, 815-04-59 3.5 (filament)coupling time constant characteristic time constant of coupling current directed perpendicularly to filaments within a strand for low frequencies IEC 60050-815:2000, 815-

46、04-60 3.6 shielding current current induced by an external magnetic field applied to a superconductor and which includes coupling current and eddy current after a field change in composite superconductors 3.7 critical (magnetic) field strength Hcmagnetic field strength corresponding to the supercond

47、ucting condensation energy at zero magnetic field strength IEC 60050-815:2000, 815-01-21 3.8 magnetization (of a superconductor) magnetic moment divided by the volume of the superconductor NOTE The macroscopic magnetic moment is also equal to the product of the shielding current and the area of the

48、closed path in a composite superconductor together with the magnetic moment of any penetrated trapped flux. BS EN 61788-8:201061788-8 IEC:2010(E) 9 3.9 magnetization method for AC loss method to determine the AC loss of materials from the area of the loop of the magnetization curve NOTE When pickup

49、coils are used to measure the change in flux, which is then integrated to get the magnetization of stationary coiled specimens, the method is called the pickup coil method. IEC 60050-815:2000, 815-08-15, modified 3.10 pickup coil method method to determine the AC loss of materials by evaluating electromagnetic power flow into the materials by pickup coils NOTE The pickup coil arrangement consists essentially of a pri