DEFAULT UK VOTE: UK ABSTAIN NO UK INTEREST COMMENTS TO BEFORE

Transcription

1 PRIVATE CIRCULATION ISE/108_13_0025 For comment/vote - Action Due Date: 2013/09/01 BSI, 389 Chiswick High Road London W4 4AL Tel: +44 (0) Fax: +44 (0) Our Ref: ISE/108 Date: 26 th June 2013 Direct details: Telephone: Fax: peter.slot@bsigroup.com Dear Member ISO NEW WORK ITEM PROPOSAL (NWI) DEFAULT UK VOTE: UK ABSTAIN NO UK INTEREST COMMENTS TO PETER.SLOT@BSIGROUP.COM BEFORE Please find attached the following New Work Item Proposal: IEC : Magnetic materials Part 16: Permanent magnet (magnetically hard) materials Methods of measurement of the magnetic properties by means of a pulse field magnetometer Please consider whether this project should be added to the work programme of the ISO Committee and provide comments on the proposed scope and target date together with relevant details of standards or regulatory matters. If you think the UK should submit a positive or negative vote please give a justification. Please note the following: - if the UK is to vote positively or negatively, then BSI has to answer the questions attached in Annex A and provide justification. - If no comments are received, a default abstention vote will be submitted on behalf of UK with the following justification: - Whilst stakeholders consulted have not indicated a definite market need for this standard in the UK, we have not received any objections to the work proceeding. The UK therefore abstains on this proposal. - if the UK is to vote to participate in the project then BSI has to nominate an expert to the project team. If you want to be nominated please let me know by the date above. When submitting comments please ensure that they are entered into the ISO comments template. If you have any queries on how to use the template then please do not hesitate to contact me. Please notify me if you are aware of any keywords that might assist in classifying or identifying the standard or if the content of this standard: i) has any issues related to 3 rd party IPR, patent or copyright ii) affects other national standard(s) iii) is likely to require additional national guidance or information Yours sincerely Peter Slot Programme Manager Manufacturing and Services -1-

2 Annex A - Ballot responses if the UK does not abstain No. Questions Possible Answers 1 1a. Do you approve, disapprove or abstain on this NWIP? approve * disapprove * abstain Please provide a statement justifying your approval or disapproval vote on the market relevance of this proposal. If no such statement is provided, the vote will not be registered and considered. Justification statements for abstention votes are also encouraged.: * 2 Please also select from one of the following options (note that if no option is selected, the default will be the first option): 3 In case of disapproval, do you believe that further study and consultations are needed first among committee members on this proposal as a preliminary work item before this proposal can be formally accepted? 4 1b. Did you consult with the range of relevant stakeholders identified in the proposal in the development of this voting position and related comments? 5 2. Standard(s), regulation(s), and other relevant documentation existing in our country, with any remarks concerning their application if necessary and consequences for global relevance, as well as copyright information on these documents, are attached: Draft document will be registered as new project in the committee's work programme (stage 20.00) Draft document can be registered as a Working Draft (WD - stage 20.20) Draft document can be registered as a Committee Draft (CD - stage 30.00) Draft document can be registered as a Draft International Standard (DIS - stage 40.00) Yes No Yes No Yes (references provided below) * No 6 3. Do you wish to add any additional comments? Yes * No 7 4. We are committed to participating actively in the development of the project, at least by commenting on working drafts (P-members voting "Disapprove" in Qu. 1a may nevertheless nominate experts): Yes (and we nominate an expert below) * No (*) A Comment is required for this answer value. -2-

3 Proposer GB TC/SC 68 Date of circulation /459/NP NEW WORK ITEM PROPOSAL Date of proposal Secretariat Germany Closing date for voting A proposal for a new work item within the scope of an existing technical committee or subcommittee shall be submitted to the Central Office. The proposal will be distributed to the P-members of the technical committee or subcommittee for voting on the introduction of it into the work programme, and to the O-members for information. The proposer may be a National Committee of the IEC, the secretariat itself, another technical committee or subcommittee, an organization in liaison, the Standardization Management Board or one of the advisory committees, or the General Secretary. Guidelines for proposing and justifying a new work item are given in ISO/IEC Directives, Part 1, Annex C (see extract overleaf). This form is not to be used for amendments or revisions to existing publications. The proposal (to be completed by the proposer) Title of proposal Future IEC : Magnetic materials Part 16: Permanent magnet (magnetically hard) materials Methods of measurement of the magnetic properties by means of a pulse field magnetometer Standard Technical Specification Scope (as defined in ISO/IEC Directives, Part 2, 6.2.1) This standard defines the method of measurement of the magnetic flux density, magnetic polarization and the magnetic field strength and also the determination of the demagnetization curve and recoil line of permanent magnet (magnetically hard) materials using the pulse field magnetometer (PFM) method. Purpose and justification, including the market relevance, whether it is a proposed horizontal standard (Guide 108) 1) and relationship to Safety (Guide 104), EMC (Guide 107), Environmental aspects (Guide 109) and Quality assurance (Guide 102). (attach a separate page as annex, if necessary) Currently, there is no IEC measurement standard for the pulse field magnetometer method. The purpose of the proposed standard is to specify the acceptable practices for characterization of hard magnetic materials utilizing the pulsed field magnetometer method. Pulsed field magnetometry is becoming increasingly common in Europe and especially in Japan and China. The technique offers higher repeatability compared to IEC It has been discussed in IEC technical report TR62331 (2005) and has seen successful validation reported in IEC TC 68 WG2 Round Robin: Comparison of Permanent Magnet Measurements. Report on values measured using methods compliant with IEC part 5 and Pulse Field Magnetometers January 2011 Increasing commercial activity has seen a number of new manufacturers of pulsed field magnetometers enter the market in recent years in response to increased demand from the rare earth, high coercivity hard magnetic material applications. There is an urgent need for an international standard covering the pulsed field magnetometry technique as it gains wider commercial acceptance. Rare earth permanent magnets are important in energy efficient applications and have an increasing role in addressing the causes of global warming. The pulsed field magnetometry technique offers a significant repeatability improvement in hard magnetic material characterisation and has, therefore, an important environmental function. It is necessary for an international standard to be created to address the demands of industry so that the technique can be more readily adopted. Target date for first CD for IS/ TS 2016 Estimated number of meetings 3-4 Frequency of meetings: 1 per year Date and place of first meeting: Sept 2013 Conshohocken, USA Proposed working methods Collaboration tools Relevant documents to be considered IEC , IEC/TR and RRT report Relationship of project to activities of other international bodies Liaison organizations CENELEC (SR/68) Need for coordination within ISO or IEC No Copyright 2013 International Electrotechnical Commission, IEC. All rights reserved. It is permitted to download this electronic file, to make a copy and to print out the content for the sole purpose of preparing National Committee positions. You may not copy or "mirror" the file or printed 1) Other TC/SCs are requested to indicate their interest, if any, in this NP to the TC/SC secretary version of the document, or any part of it, for any other purpose without permission in writing from IEC.

4 /Ed1/NP IEC 2 68/459/NP Preparatory work Ensure that all copyright issues are identified. Check one of the two following boxes A draft is attached for comment* An outline is attached * Recipients of this document are invited to submit, with their comments, notification of any relevant patent rights of which they are aware and to provide supporting documentation. We nominate a project leader as follows in accordance with ISO/IEC Directives, Part 1, (name, address, fax and e- mail): Mr J Dudding, Hirst Magnetic Instruments Ltd, Tesla House, Tregonigge, Falmouth, Cornwall, TR11 4SN john.dudding@hirst-magnetics.com Concerns known patented items (see ISO/IEC Directives, Part 2) Name and/or signature of the proposer Yes. If yes, provide full information as an annex no J Dudding Comments and recommendations from the TC/SC officers 1) Work allocation Project team New working group Existing working group no: WG 2 2) Draft suitable for direct submission as CD CDV/ DTS 3) General quality of the draft (conformity to ISO/IEC Directives, Part 2) Little redrafting needed Substantial redrafting needed no draft (outline only) 4) Relationship with other activities In IEC In other organizations 5) Proposed horizontal standard 1) Remarks from the TC/SC officers The proposed measurement method would extend the existing IEC standard methods to the combination "open circuit" and "fast measurement". This opens new categories of error sources represented through the parameters sample shape and size, electrical conductivity, magnetic viscosity of the sample material and the speed and mode of excitation. The impact of these parameters on the measurement result are not sufficiently known for an independent measurement standard which is to deliver correct results with dispersions within reasonable limits. This holds at least for the quantity which mostly is used to justify the method, the coercivity related to the polarization, H cj. Whilst this cognition is prevalent among the most of respective experts, it is generally acknowledged that the PFM is an excellent in-house standard, i.e. method for quality control of production under the conditions of constant shape, volume and physical properties of samples. Therefore it seems to be appropriate to aim at a Technical Specification (see Directives 1, section 3) instead of a standard. This might open later the way to a standard soundly based on the needed metrological experience. The market situation seems not really clear because the IEC TR 62331, the review of methods of pulse field magnetometry published in 2005, attracted only little interest (6 copies sold in 8years). Thus, National Committees are requested to define their economic interest in such a Standard or Technical Specification and to communicate the comments of their experts. 1) Other TC/SCs are requested to indicate their interest, if any, in this NP to the TC/SC secretary. Approval criteria: Approval of the work item by a simple majority of the P-members voting; At least 4 P-members in the case of a committee with 16 or fewer P-members, or at least 5 P-members in the case of committees with more than 17 P-members, have nominated or confirmed the name of an expert and approved the new work item proposal. Elements to be clarified when proposing a new work item Title Indicate the subject matter of the proposed new standard or technical specification. Indicate whether it is intended to prepare a standardor a technical specification. Scope Give a clear indication of the coverage of the proposed new work item and, if necessary for clarity, exclusions. Indicate whether the subject proposed relates to one or more of the fields of safety, EMC, the environment or quality assurance. Purpose and justification Give details based on a critical study of the following elements wherever practicable.

5 /Ed1/NP IEC 3 68/459/NP a) The specific aims and reason for the standardization activity, with particular emphasis on the aspects of standardization to be covered, the problems it is expected to solve or the difficulties it is intended to overcome. b) The main interests that might benefit from or be affected by the activity, such as industry, consumers, trade, governments, distributors. c) Feasibility of the activity: Are there factors that could hinder the successful establishment or general application of the standard? d) Timeliness of the standard to be produced: Is the technology reasonably stabilized? If not, how much time is likely to be available before advances in technology may render the proposed standard outdated? Is the proposed standard required as a basis for the future development of the technology in question? e) Urgency of the activity, considering the needs of the market (industry, consumers, trade, governments etc.) as well as other fields or organizations. Indicate target date and, when a series of standards is proposed, suggest priorities. f) The benefits to be gained by the implementation of the proposed standard; alternatively, the loss or disadvantage(s) if no standard is established within a reasonable time. Data such as product volume of value of trade should be included and quantified. g) If the standardization activity is, or is likely to be, the subject of regulations or to require the harmonization of existing regulations, this should be indicated. If a series of new work items is proposed, the purpose and justification of which is common, a common proposal may be drafted including all elements to be clarified and enumerating the titles and scopes of each individual item. Relevant documents List any known relevant documents (such as standards and regulations), regardless of their source. When the proposer considers that an existing well-established document may be acceptable as a standard (with or without amendments), indicate this with appropriate justification and attach a copy to the proposal. Cooperation and liaison List relevant organizations or bodies with which cooperation and liaison should exist. Preparatory work Indicate the name of the project leader nominated by the proposer.

6 /Ed1/NP IEC 4 68/459/NP Magnetic materials Part 16: Permanent magnet (magnetically hard) materials Method of measurement of the magnetic properties by means of a pulse field magnetometer 1 Scope This Part of this International Standard defines a method of measurement of the magnetic flux density, magnetic polarization, magnetic field strength xxxx the properties of which are assumed to be homogeneous throughout their volume. The methods described in this standard refer to the measurement of the magnetic properties in an open magnetic circuit utilising the pulsed field magnetometry technique (PFM) This standard primarily considers measurements in a uniform field along a single axis and is not directly concerned with characterisation of materials in radial, or other orientations. The methods of measurement of the magnetic properties of magnetically hard materials are specified in IEC [1] for closed magnetic circuits and in IEC [2] for open magnetic circuits. The measurement result of the magnetic properties of magnetically hard materials at elevated temperatures is given in IEC [3]. 2 Normative references The following referenced documents are indispensable for the 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. IEC , International Electrotechnical Vocabulary Part 121: Electromagnetism IEC , International Electrotechnical Vocabulary Chapter 221: Magnetic materials and components 3 Terms and definitions For the purposes of this standard, the terms and definitions given in IEC and IEC apply. 4 Pulsed field magnetometer (PFM) 4.1 General Pulsed field magnetometer measurements are carried out in an open magnetic circuit and are primarily intended as a method for the measurement for permanent magnet (magnetically hard) materials. A pulsed field magnetometer consists of the following parts: a) Test specimen to be measured; b) Magnetic field strength generator consisting of: Capacitive discharge system power supply; Magnetizing solenoid, primarily consisting of non magnetic material; Polarisation sensor pick-up coil. (J coil); Magnetic field strength sensor pick-up coil. (H coil);

7 /Ed1/NP IEC 5 68/459/NP c) Test specimen temperature measurement; d) Instrumentation for transient signal processing and digitizing hardware; e) Integration; f) Digitization; g) Data processing facilities to enable the processing of: Zero signal; J(H) loop positioning; Self-demagnetization factor conversion; Low band pass filtering; Pulsed field magnetometer calibration; Eddy current correction (if used). 4.2 Test specimen Positioning The test specimen will be held in the polarisation sensor pick-up coil during the measurement process Test specimen geometry The test specimen may be of any geometry for which a self demagnetisation factor is known, or can be determined Test specimen maximum volume The test specimen maximum volume shall only be limited by the size of the pulsed field magnetometer s measurement volume and dynamic characteristics (see 4.4.3) Test specimen minimum volume The test specimen minimum volume shall only be limited by the pulsed field magnetometer s sensitivity and noise performance. NOTE When small volume test specimens are measured, the surface area can be large compared to the overall volume of the test specimen. In these circumstances, surface effects may have a significant effect on the measured properties. 4.3 Magnetic field strength generator System The magnetic field generator shall consist of a system that enables the magnetic field to be applied to the test specimen. The magnetic field generator shall consist of a capacitive discharge power supply and a magnetizing solenoid. The power supply shall provide the magnetizing current to the magnetizing solenoid in order to generate the applied magnetic field. NOTE Direct mains supply type pulsed field magnetometers are not considered directly in this standard.

8 /Ed1/NP IEC 6 68/459/NP Power supply General The power supply shall be a capacitive discharge arrangement and shall supply current to the magnetizing solenoid in both positive and negative polarities The repeatability of the applied voltage The repeatability of the voltage applied to the capacitor of the capacitor discharge system, shall be better than ± 0,1 % of the pulsed field magnetometer maximum operating voltage. 4.4 Magnetizing solenoid Design The design of the solenoid shall take into account the factors specified in to Peak magnetic field strength The peak value of magnetic field strength produced by the magnetizing solenoid, when powered by the capacitive discharge power supply shall be a minimum of 110 % of the magnetic field strength required to saturate the test specimen in both positive and negative polarities. NOTE The required magnetic field strength required to saturate the test specimen will be a function of the test specimen material characteristics, the test specimen orientation and the demagnetization factor of the test specimen geometry Volume of the magnetizing solenoid The volume of the magnetizing solenoid shall be such as to apply to the test specimen and the pick-up coil system, the required magnetic field strength homogeneity Magnetic field strength homogeneity The homogeneity of the magnetic field throughout the volume of the test specimen and the magnetic field strength pick-up coil (H coil), shall be better than ± 1 % Field frequency The rate of change of the applied magnetic field strength with time, (dh/dt,) shall be kept as low as necessary to either avoid inducing significant eddy currents in conductive specimens, (EC 0) (see and Table 1) or to be suitable for the eddy current correction process employed (EC 1). The applied magnetic field strength frequency, or frequencies, employed should not vary appreciably from measurement to measurement. 4.5 Polarization sensor pick-up coil (J coil) The polarization sensor pick-up coil, or coils, shall be coupled to the polarisation of the test specimen, but not significantly coupled to the magnetic field strength in the region of the test specimen. NOTE The polarization sensor pick-up coil is usually referred to as the J coil, although it is truly a dj/dt coil. The polarization pick-up coil response will be uniform over its maximum test volume, that is, for a homogeneous test specimen material, the coil response shall be strictly proportional to the volume of the test specimen. The polarization pick-up coil response will have a homogeneity of better than ± 1 % over the volume of the test specimen.

9 /Ed1/NP IEC 7 68/459/NP 4.6 The magnetic field strength pick-up coil (H coil) The magnetic field strength sensor pick-up coil, (H coil) or coils, shall be coupled to the magnetic field strength in the region of the test specimen, but not significantly coupled to the test specimen. NOTE The magnetic field strength coil is usually referred to as the H coil, although it is truly a dh/dt coil. The magnetic field pick-up coil will have coupling to the applied magnetic field strength generator so that the coil output will be linear to the dh/dt of the applied magnetic field strength within 0,1 %. 4.7 Test specimen temperature measurement General Test specimen temperatures shall be recorded at the time of measurement. The temperature of the specimen immediately before a measurement magnetic field strength is applied shall be considered as the measurement temperature at which the measurement has taken place. The pulsed field magnetometer measurement will be performed after temperature stabilization. That is, the measured temperature is known to be the uniform temperature throughout the test specimen Temperature compensation Measurements which are taken at temperatures other than the exact target temperature, but within +/- 5 C of the target temperature, shall be permitted. These measurement values shall, however, be compensated by means of the use of appropriate temperature coefficients. Measurement records shall state the actual temperature at which the measurement was taken and shall be stated in the measurement report Temperature measurement sensors The temperature of the test specimen shall be determined by a suitable temperature sensor which shall be in direct thermal contact with the test specimen at the time of measurement. Temperature measurements shall be resolved within ± 0,1 C Test sample measurement at temperatures elevated and reduced, compared to room temperature Test specimens shall be heated, or cooled by processes that will not introduce erroneous signals to the pulsed field magnetometer by way of eddy currents, electrical interference, magnetic fields (through the introduction of magnetic material of electrical current etc.) or other deleterious phenomena. Test specimens shall be held at the specific temperature required for the measurement for a period of not less than 150 % of the period which has been determined experimentally to give good temperature homogeneity throughout the test specimen volume. Temperature homogeneity shall be better than +/- 1 % of the temperature difference between the nominal sample temperature and ambient temperature throughout the sample volume. (i.e. +/- 1 % of (T actual T ambient)) 4.8 Transient instrumentation and digitizing hardware Integration The signals from the polarisation sensor pick-up coil (J coil) and magnetic field strength pickup coils (H coil) shall be integrated with an electronic, analogue integrator. NOTE Digitization and numerical integration will not be permitted, due to the reduced dynamic input range of the analogue to digital converter, compared to that of the electronic analogue integrator.

10 /Ed1/NP IEC 8 68/459/NP Digitzation The analogue outputs of the analogue integrators shall be digitized in an analogue to digital converter (ADC). The ADC will provide a minimum of 12 bits of converted data and a minimum rate of minimum sample rate of 2 x 10 5 samples/s. The digitization process shall occur at a rate that is high enough to obtain sufficient points over the minimum data density region of the test specimen response. In the region of the coercivity, within the limits of +/1?5% of remanence, the measured results will include not less than yyyy/t measurement points. 4.9 Data processing General The data processing of the signals digitised shall provide a measured characteristic (see clause 6). The H coil output is proportional to dh/dt. In order to process this data to obtain valid H data (applied magnetic field strength), it is necessary to integrate the signal and apply an H channel calibration factor. The H channel calibration factor is specific to the H coil and H channel integrator arrangement of the individual PFM system. The J channel signal processing involves more steps: The J pick-up coil output is proportional to dφ/dt plus the derivative of the zero signal (where Φ is the flux produced by the magnetisation of the test specimen.) This signal is first integrated and the zero signal (see 4.9.2) removed to obtain an M signal, that is, a signal proportional to Φ. The M signal is then multiplied by the J channel calibration factor and divided by the test specimen volume consideration, in order to obtain M*, that is, the intrinsic open magnetic circuit polarization of the test specimen material. By applying a self-demagnetization factor to the M* signal the intrinsic J signal can be obtained (see 4.9.4). The J calibration factor is specific to the J coil and J channel integrator arrangement of the individual PFM system (see 4.9.4). As the initial magnetization of the test specimen is unknown, it may be necessary to position the M* signal in the M* domain (see ). The synchronized J and H signals can now be combined to obtain a J(H) hysteresis loop. It is not uncommon to carry out many or all of the J channel processing steps in the J(H) domain (i.e. the M (H), M*(H) or J(H) domains). The B(H) loop can be obtained by the usual conversion. In the event that eddy currents have been induced in the test specimen during the measurement process, an eddy current correction may need to be considered (see 4.9.6). Data processing elements The following shall be taken into consideration when carrying out data processing: zero signal; loop positioning; self-demagnetization;

11 /Ed1/NP IEC 9 68/459/NP filtering; calibration factors / scaling; eddy currents. In order to convert the raw data ( J and H ) from the measurement, into a J(H) and/or B(H) data set it is necessary to process the data with respect to the following elements: Zero signal When a measurement is made on a PFM system, without a test specimen, a polarisation signal is normally observed. This signal shall be known as the zero signal. The zero signal shall be less than 5 % of the overall polarisation signal as measured with the test specimen, when compared after integration. The repeatability of the zero signal shall be better than +/-1 % J(H) loop positioning General The pulsed field magnetometry technique normally requires the integration of signals obtained from a test specimen during a dynamic measurement process. At the start of a measurement the state of polarisation of the test specimen is often unknown. In order to obtain meaningful measurement results the resulting data shall need to be centred Polarisation centring In the case of conventional magnetic materials with symmetric characteristics, and where the material has been saturated in both positive and negative directions of the applied magnetic field strengths, then the midpoint between the remanence values can be considered to occur at J = Magnetic field strength centring In the case of conventional magnetic materials with symmetric characteristics, and where the material has been saturated in both positive and negative applied magnetic field strengths, then the midpoint between the coercivity values can be considered to occur at H = Self-demagnetization The pulsed field magnetometer measurement is an open magnetic circuit. A selfdemagnetising factor (sdf) correction shall be applied to open circuit measurements to obtain the intrinsic magnetic characteristics of the test specimen. The measurement records and report shall state the self demagnetisation factor(s) employed in the conversion in the recorded measurement. NOTE As this standard is concerned with pulsed field magnetometry and not with the more general matter of selfdemagnetization factors for open magnetic circuit measurements, a detailed discussion is not considered here. It is, however, appropriate to point out that tables of correction values for simple geometries such as cylinders are available (ref [Chen]) while more recent work offers self-demagnetization factors for any complexity of a threedimensional shape that is an extrusion of a two-dimensional shape (refs. [xx] to [xx] Filtering Signal filtering shall be permitted to reduce measurement noise, particularly for small test specimens. The filtering that is permitted shall not introduce phase shift nor use a cut-off frequency which could introduce distortion. This filtering may be implemented electronically or numerically (software).

12 /Ed1/NP IEC 10 68/459/NP Eddy currents Eddy current classification When an electrically conductive material, such as some permanent magnet materials, is subjected to a time varying magnetic field, such as in the case of a pulsed magnetic field, it will experience eddy currents. These eddy currents will, in turn, produce magnetic fields. These eddy current originated magnetic fields distort the measurement in a pulsed field magnetometer. For a given conductive test specimen and magnetic field strengths of a given transient magnetic field profile and magnitude, the resultant eddy currents will increase with increasing frequency of the applied magnetic field strength. The following situations may be considered: Table 1 Classification of the influences of eddy currents EC 0 EC 1 EC 2 EC 3 Eddy currents are small and their resultant magnetic field is not significant compared to the magnetization of the specimen under measurement. Eddy currents are large enough to create a resultant magnetic field that is significant compared to the polarization of the specimen under measurement. The eddy currents are not large enough to distort the distribution of magnetic field strength within the body of the test specimen under measurement to a degree that will significantly affect the magnetization of the test specimen. Eddy currents are large enough to create resultant magnetic fields that are significant compared to the polarization of the specimen under measurement. The eddy currents are also large enough to significantly distort the distribution of magnetic field strength within the body of the test specimen under measurement but not large enough to stop field penetration completely. Eddy currents are large enough to create resultant magnetic fields that are significant compared to the polarization of the specimen under measurement. The eddy currents are also large enough to significantly distort the distribution of magnetic field strength within the body of the test specimen and large enough to stop field penetration completely in some parts of the body of the specimen under measurement Eddy current scope The scope of this standard with respect to eddy currents is limited to eddy currents falling within the classifications EC 0 and EC 1. (reference??) In situations where measurements are carried out under EC 0 conditions, eddy current correction shall not be required. In situations where measurements are carried out under EC 1 conditions, eddy current correction shall be employed (see clause 6, 6.3, and 8). 5 Pulsed field magnetometer calibration The pulsed field magnetometer shall be indirectly calibrated through the use of a calibrated reference specimen with known intrinsic characteristics that are traceable to national standards. These indirect calibrations provide discrete calibration points and care should be taken when making measurements at other points. When bound by calibration points, then interpolation can be used and an allowance will need to be made for interpolation errors that result. If used outside of the bound of values provided by the discrete calibration points, then extrapolation will be required and must be performed with an understanding that large errors could result.

13 /Ed1/NP IEC 11 68/459/NP (This sample may be one of the calibrated reference samples used in 6.1) The calibrated reference specimen shall be used for the calibration of both magnetic polarisation and magnetic field strength. The temperature at which the pulsed field magnetometer is calibrated shall be determined in accordance with 4.7. The calibrated reference specimen shall be of one of the following standard forms: a) Cylinder 10 mm diameter, 10 mm length (nominal); b) Cylinder 10 mm diameter, 7 mm length (nominal); c) Cube 7 mm x 7 mm x 7 mm (nominal). d) Other geometries and sizes of calibrated reference specimen may be used as appropriate when the standard forms in (a-c) are considered to be limited through volume and in agreement with a national metrology institute. NOTE Magnetic viscosity effects exist within almost all magnet materials. The calibration process described above will circumvent any significant effects for normal commercial magnet materials as the calibration process and measurement processes will be carried out with effectively the same frequency of applied magnetic field strength. 6 Determination of the pulsed field magnetometer s performance 6.1 General Pulsed field magnetometer designers and builders shall be permitted to implement hardware design and data processing as they wish. The performance specification of the system shall be stated in the pulsed field magnetometer performance report. The performance specification will be determined by the normal practices of metrology and shall also include the additional requirements. 6.2 Multiple calibrated reference specimens Please note, this clause is a suggestion and may be greatly modified after further consideration and discussion with others in the field. The calibrated pulsed field magnetometer shall be required to measure a number of additional calibrated reference specimens. These samples will be of the same geometry and dimensions material type as the calibrated reference specimen. i) A calibrated reference specimen with a high coercivity; (values) ii) iii) iv) A calibrated reference specimen with a low coercivity; (values) A calibrated reference specimen with a high remanence; (values) A calibrated reference specimen with a low remanence. (values) The comparison between reference and measured values will be included in the pulsed field specification. 6.3 Eddy currents performance testing Please note, this clause is a suggestion and may be greatly modified after further consideration and discussion with others in the field.

14 /Ed1/NP IEC 12 68/459/NP Where eddy current correction is used, the method shall be explained and the performance reported. The calibrated reference specimen in 6.2 i) to 6.2 iv) above shall be measured, including a copper disk of the same diameter, or cross section, as the sample and a thickness that is 2 % of the sample axial length. The calibrated reference specimen and disk shall be in contact and placed axially in line. This arrangement shall be measured in the normal procedure for the pulsed field magnetometer. The resulting measurements shall be compared to the measured results in 6.2 and shall be recorded in the pulsed field magnetometer performance report (see clause 8). 7 The measurement report In addition to the intrinsic measured values, etc. the measurement report generated for each measurement shall also state: i) the self-demagnetization factor (sdf) used in converting the open magnetic circuit measurement to the closed magnetic circuit equivalent; ii) the temperature for which the measurements are made; iii) where the measurement carried out is at a temperature which was not that of (ii) above, and a temperature compensation technique has been employed, a indication that the measurement values have been temperature compensated shall be given and the actual measurement temperature stated along with the temperature coefficients used. 8 The pulsed field magnetometer performance report The pulsed field magnetometer performance report shall include the performance specification determined under 6.1 and 6.3.

15 /Ed1/NP IEC 13 68/459/NP Bibliography [1] IEC , Magnetic materials Part 5: Permanent magnet (magnetically hard) materials Methods of measurement of magnetic properties [2] IEC , Magnetic materials Part 7: Method of measurement of the coercivity of magnetic materials in an open magnetic circuit [3] IEC 61807, Magnetic properties of magnetically hard materials at elevated temperatures Methods of measurement [4] IEC/TR 62331, Pulsed field magnetometry [5] Round robin Test report, Internal IEC WG2 document N200