ASTM A773/A773M-21

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: A773/A773M − 14 A773/A773M − 21
Standard Test Method for
Direct Current Magnetic Properties of Low Coercivity
Magnetic Materials Using Hysteresigraphs
This standard is issued under the fixed designation A773/A773M; the number immediately following the designation indicates the year
of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.
A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method provides dc hysteresigraph procedures (B-H loop methods) for the determination of basic magnetic properties
of materials in the form of ring, spirally wound toroidal, link, double-lapped Epstein cores, or other standard shapes that may be
cut, stamped, machined, or ground from cast, compacted, sintered, forged, or rolled materials. It includes tests for normal induction
initial and normal magnetization curves and hysteresis loop determination taken under conditions of continuous sweep
magnetization. Rate of sweep may be varied, either manually or automatically at different portions of the curves during
measurement.
1.2 The equipment and procedures described in this test method are most suited for soft and semi-hard materials with intrinsic
coercivity less than about 100 Oersteds [8 kA/M]. Materials with higher intrinsic coercivities should be tested according to Test
Method A977/A977M.
1.3 The values and equations stated in customary (cgs-emu and inch-pound) or SI units are to be regarded separately as standard.
Within this standard, SI units are shown in brackets. The values stated in each system may not be exact equivalents; therefore, each
system shall be used independently of the other. Combining values from the two systems may result in nonconformance with this
standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
A34/A34M Practice for Sampling and Procurement Testing of Magnetic Materials
A340 Terminology of Symbols and Definitions Relating to Magnetic Testing
A341/A341M Test Method for Direct Current Magnetic Properties of Soft Magnetic Materials Using D-C Permeameters and the
Point by Point (Ballistic) Test Methods
This test method is under the jurisdiction of ASTM Committee A06 on Magnetic Properties and is the direct responsibility of Subcommittee A06.01 on Test Methods.
Current edition approved Oct. 1, 2014Feb. 1, 2021. Published October 2014February 2021. Originally approved in 1980. Last previous edition approved in 20092014 as
A773/A773MA773/A773M – 14.–01 (2009). DOI: 10.1520/A0773_A0773M-14.10.1520/A0773_A0773M-21.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
A773/A773M − 21
A343/A343M Test Method for Alternating-Current Magnetic Properties of Materials at Power Frequencies Using Wattmeter-
Ammeter-Voltmeter Method and 25-cm Epstein Test Frame
A596/A596M Test Method for Direct-Current Magnetic Properties of Materials Using the Ballistic Method and Ring Specimens
A977/A977M Test Method for Magnetic Properties of High-Coercivity Permanent Magnet Materials Using Hysteresigraphs
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
2.2 Other:
IEC Publication 60404-4 Ed 2.2 – Part 4: Methods of Measurement of d.c. Magnetic Properties of Magnetically Soft Materials
(2008)
3. Terminology
3.1 Definitions—The terms and symbols used in this test method are defined in Terminology A340.
4. Summary of Test Method
4.1 A specimen is wound with a magnetizing winding (the primary winding) and a search winding (the secondary winding) for
measuring the change in flux. When a magnetizing current, I, is applied to the primary winding, a magnetic field, H, is produced
in the coil. This in turn produces magnetic flux φ in the specimen and the changing flux induces a voltage in the secondary winding
which is integrated with respect to time using a fluxmeter. In specimens with uniform cross-sectional area that do not contain air
gaps, such as rings, all of the magnetizing current is used to magnetize the specimen, and the magnetic field strength, H, is
proportional to I in accordance with the following equation:
H 5 KI (1)
where:
H = magnetic field strength, Oe [A/m];
I = current in the magnetizing winding A; and
K = constant determined by the number of primary turns, the magnetic path length of the specimen and system of units.
4.1.1 The magnetic flux may be determined by integration of the instantaneous electromotive force that is induced in the secondary
winding when the flux is increased or decreased by a varying H. The instantaneous voltage, e, is equal to:
dφ
e 52NK (2)
dt
or
φ5 edt
*
K N
where:
dt = time differential,
N = number of secondary turns,
−8
K = 10 for cgs-emu system, or K = 1 for SI system, and
1 1
e = instantaneous voltage in the secondary winging, V.
The flux φ can be obtained if ∫edt can be determined. This can be accomplished by several means, as described in ASTM STP
526. (1) The most common method uses an electronic integrator consisting of an operational amplifier with capacitive feedback.
Some fluxmeters employ analog to digital conversion and digital integration techniques. The output voltage of the integrator is
given by:
E 5 edt (3)
*
RC
where:
E = output voltage, V;
R = input resistance of the integrator in the secondary circuit, Ω; and
Available from American National Standards Institute, 25 W. 43rd St., 4th Floor, New York, NY 10036.
The boldface numbers in parentheses refer to a list of references at the end of this standard.
A773/A773M − 21
FIG. 1 Block Diagram of Ring Test Apparatus
C = the feedback capacitance, F.
By combining the two equations:
ERC φNK
φ5 or E 5 (4)
K N RC
The instantaneous value of flux is thus proportional to the integrated voltage which can be recorded in various ways.
4.1.2 Measurement of magnetic field strength and flux by the hysteresigraph method is illustrated in the block diagram of Fig. 1.
The system consists of a magnetizing power source, a magnetizing current controller, an electronic flux integrator, and a data
recorder. As magnetizing current is applied to the primary winding, a voltage proportional to I is produced across the current
measuring resistor which is connected in series with the primary winding. This voltage is proportional to the value of H.
4.1.3 In the testing of soft magnetic materials in the form of wire, bars or rods, or materials which cannot be sufficiently
magnetized in ring form, or which are anisotropic, it is usually necessary to use a permeameter. This is shown in the block diagram
of Fig. 2. When using permeameters, the value of H in the gap is generally not proportional to I that flows through the magnetizing
winding of the yoke. In these cases, the value of H is determined by integration of the electromotive force that is induced in an
H-coil (or Chattock potentiometer) or from the signal developed by a Hall probe which is placed near the specimen. When using
an H-coil, the determination of H is accomplished with an H integrator in exactly the same manner as that used to determine flux
with the B integrator described in 4.1. When using a Hall sensor, the H values are determined from the voltage output which is
linearized to be proportional to H.
5. Significance and Use
5.1 Hysteresigraphs permit more rapid and efficient collection of normal induction and dc hysteresis (B-H loop) data as compared
to the point by point ballistic Test Methods A341/A341M and A596/A596M. The high measurement point density offered by
computer-automated systems is often required for computer aided design of electrical components such as transformers, motors,
and relays.
5.2 Hysteresigraphs are particularly desirable for testing of semihardsemi-hard and hard magnetic materials, where either the
entire second quadrant (demagnetization curve) or entire hysteresis loop is of primary concern. Test Method A977/A977M
describes the special requirements for accurate measurement of hard magnetic (permanent magnet) materials.
5.3 Hysteresigraphs are not recommended for measurement of initial permeability, μ , of materials with high magnetic
i
permeability such as nickel-iron, amorphous, and nanocrystalline materials due to errors associated with integrator drift; in these
cases, Test Method A596/A596M is a more appropriate method.
5.4 Provided the test specimen is representative of the bulk sample or lot, this test method is well suited for design, specification
acceptance, service evaluation, and research and development.
A773/A773M − 21
FIG. 2 Block Diagram of Permeator Test Apparatus
6. Interferences
6.1 Test methods using suitable ring-type specimens are the preferred methods for determining the basic magnetic properties of
a material. When conducting tests on ring specimens, this test method covers a range of magnetic field strengths from about 0.01
Oe [0.8 A/m] up to about 1000 Oe [80 kA/m] or more depending on the specimen dimensions, number of primary turns, available
magnetizing power, and the ability to remove heat generated in the primary winding. However, this test method has several
important requirements. Unless the inside diameter to outside diameter ratio or ring specimens is greater than 0.82, the magnetic
field strength will be excessively nonuniform in the test material and the measured parameters cannot be represented as material
properties. The basic quality of materials having directionally sensitive properties cannot be tested satisfactorily with ring
specimens. With such materials it is necessary to use Epstein specimens cut with their lengths in the direction of specific interest
or to use long link-shaped or spirally wound toroidal core test specimens. The acceptable minimum width of strip used in such
test specimens varies with the material under test. At present, it is recommended that the grain-oriented silicon steels should have
a strip width of at least 3 cm [30 mm]. When ring specimens are large, it is difficult to provide sufficient magnetizing turns or
current-carrying capacity to reach magnetic field strengths above about 1000 Oe [80 kA/m]. In general, magnetic materials tend
to have nonuniform properties throughout the body of the test specimens. For this reason, uniformly distributed test windings and
uniform specimen cross-sectional area are highly desirable to average nonuniform behavior.
6.2 When conducting permeameter tests on bars, rods, and other appropriate specimens, this test method covers a range of
magnetic field strengths from about 0.05 Oe [4 A/m] up to about 20 000 Oe [1600 kA/m] or more, depending on the specimen
geometry and the particular permeameter (measuring fixture) that is used. In general, the lower limit of magnetic field strength is
determined by the area-turns of the H coil -coil (or the sensitivity of the Hall probe if it is used), the sensitivity of the integrator,
and the sensitivities of the measuring and recording components. The upper limit in magnetic field strength is determined by the
type of permeameter appropriate for the specimen, the power supply, and the heat generated in the yoke windings.
Recommendations of the useful range of magnetic field strength for the various permeameters are shown in Table 1.
6.2.1 In general, permeameters do not produce a uniform magnetic field in either the axial or radial directions around the test
specimen. The field gradients in both of these directions will differ in the various permeameters. Also, the H-coils and B-coils of
the different permeameters are not identical in area, in turns, or in length or identically located. Although test specimens are
prepared to have uniform physical cross section, they may still have undetected nonuniform magnetic properties radially or axially
along the specimen length adjacent to the H or B coils. Some permeameters may also introduce clamping stresses into the test
specimen. For these reasons test results obtained on a test specimen with one type of permeameter may not compare closely with
those obtained on the same specimen from another permeameter type.
Link-shaped specimens are defined in Practice A34/A34M.
A773/A773M − 21
TABLE 1 Permeameters Recommended for Use Withwith
Hysteresigraphs
NOTE 1—Other permeameters may be suitable for use with dc hyster-
esigraphs where appropriate modifications are made. Refer to Test Method
A341/A341M for other permeameters.
Permeameter Magnetic Field Strength Range H Measurement
Device
Oe kA/m
Babbit (2, 3) 40/100 3.2/8 current, H coil
Fahy Simplex (4-6) 0.1/300 0.008/24 H coil
Fahy Simplex Super 100/2500 8/200 H coil
H Adapter (6)
IEC Type A 12/2500 1/200 H coil, Hall probe
IEC Type B 12/620 1/50 H coil
Isthmus (6, 7) 100/20 000 + 8/1600 + H coil, Hall probe
6.2.2 The limitation in the B measurement by this test method is determined by the number of secondary (B) turns on the specimen,
the specimen cross-sectional area, the permeability, and the gain and drift of the fluxmeter and data recording device. In general,
−5
normal induction and hysteresis data may be determined from a flux linkage corresponding to 1000 Maxwell turns [10 Weber
turns] to an upper magnetic flux density that corresponds to the intrinsic saturation.saturation magnetization.
6.2.3 Some permeameters use compensation coils and require continual adjustment of the current flowing through these coils. This
may not be compatible with hysteresigraphs.
6.2.4 The magnetic test results, particularly for high permeability alloys such as nickel-iron alloys, may not exactly agree with test
results obtained by the ballistic methods, Test Methods A341/A341M and A596/A596M. For ring specimens, this is due to the
influence of eddy currents, the different nature of the magnetizing waveform between hysteresigraph and ballistic testing, and
possible disaccomodation.disaccommodation. For testing using permeameters, residual magnetism of the yoke can be a significant
source of error when measuring high permeability materials, especially when testing at low applied magnetic fields.field strengths.
6.3 The standard Epstein frame as defined in A343/A343M has an assumed magnetic path length of 94 cm [0.94 m]. This may
or may not be correct when conducting dc magnetic tests; however, the user of this test method should use this value for
consistency of results.
7. Apparatus
7.1 The apparatus shall consist of as many of the components described in 7.2 – 7.8 as required to perform the tests.
7.1.1 All apparatus used in this test method shall be calibrated against known standards to ensure the accuracy limits given below.
7.2 Balance or Scales:
7.2.1 The balance or scales used to weigh the test specimen shall be capable of weighing to an accuracy of 60.2 % of the
measured value.
7.2.2 The micrometer or calipers, or both, used to determine specimen dimensions for calculation of cross-sectional area shall be
capable of measuring to an accuracy of at least 60.1 % of the measured value.
7.3 Magnetizing Power Source—The power source may range from batteries to regulated, low-ripple, protected, programmable
power supplies. It shall have sufficient capacity to produce the maximum currents required for magnetization of the specimen under
test.
7.4 Magnetizing Current Controller—Instantaneous value of magnetizing current, and its rate of change, may be controlled
entirely manually by means of rheostats, potentiometers, shunts, reversing switches, and so forth; semiautomatically by means of
variable-speed motors or sweep generators, and so forth; or entirely automatically by means of rate sensors, and so forth. In all
cases, components shall be capable of carrying the required currents without overheating, and controls shall be of such design that
the magnetizing current may be increased or decreased in a uniform manner.
A773/A773M − 21
7.5 B Integrator—The B integrator shall be an electronic integrator with a full-scale accuracy of 60.5 % or better. The integrator
shall have a calibration traceable to a national standards laboratory and should preferably have a calibration self-check capability.
7.6 H Integrator (Optional)—The H integrator shall be an electronic integrator with a full-scale accuracy of 60.5 % or better. The
integrator shall have a calibration traceable to a national standards laboratory and should preferably have a calibration self-check
capability. This integrator is only required when testing using a permeameter and an inductive H sensor.
7.7 Current Measuring Resistor—When the magnetic field strength is to be determined from the magnetizing current, a
non-inductive resistor with a low temperature coefficient of resistance shall be used. The resistor shall have a power rating capable
of handling the largest currents capable of being produced by the power supply. Ideally, the resistor should be rated for two or more
times the expected maximum power dissipation. The rated accuracy of the resistor shall be 60.5 % or better.
7.8 Data Recorder—The B and H values can be recorded and displayed by either analog or digital X-Y chart recorders, dataloggers,
or computers. The recording device shall be capable of resolving B or H values of 61 % of the full-scale value. For analog to
digital converters, twelve-bit resolution or higher is desirable.
8. Test Specimens for Ring and Epstein Strip Measurements
8.1 The information in 8.2 – 8.9 covers the general case for specimens in which magnetic field strength is proportional to the
magnetizing current, that is, H = kI.
8.2 When the test specimen represents a test lot of material, sampling shall conform to the requirements of Practice A34/A34M,
unless superseded by a specification.
8.3 To qualify as a test specimen suitable for evaluation of material properties, the effective ratio of mean diameter to radial width
shall be not less than 10 to 1 (or an inside diameter to outside diameter ratio not less than 0.82). When the test specimen has a
smaller ratio than the above requirement, the test data shall not be represented as material properties but shall be called core
properties because of nonuniform flux and field distribution.
8.4 When link, oval-shaped, or rectangular test specimen forms are used, the requirements of 8.3 apply to the end or corner
sections where flux crowding may occur. When straight-sided test specimens are very long relative to the length of the corner or
end sections, they are suitable for basic material properties evaluation with relatively unoriented materials, provided the uncertainty
in determination of true (effective) magnetic path length is less than 61 % of the total magnetic path length. When this uncertainty
in magnetic path length (shortest or longest relative to the mean magnetic-path length) exceeds 61 %, the test values shall be
reported as core properties and not basic material properties.
8.5 Test specimen cores made from strip may be laminated, machined, spirally wound, or Epstein specimens. The method of
selection for Epstein specimens is described in Annex A3 of Test Method A343/A343M. When the material is to be tested half
transverse and half longitudinal, the material shall be cut into Epstein strips or square laminations of appropriate dimensional ratio.
8.6 Test specimens used for basic material evaluation shall be cut, machined, ground, slit, or otherwise formed to have a cross
section that remains sufficiently uniform that its nonuniformity will not materially affect the accuracy of establishing and measuring
magnetic flux density, B, or magnetic field strength, H, in the test specimen. It is recommended that the cross-sectional not vary
by more than 61 % anywhere in the magnetic path. The possible effects of mechanical preparation on the magnetic properties must
be considered prior to testing.
8.7 Laminated ring specimens or specimens of strain sensitive materials shall be enclosed by a nonmagnetic, nonconductive core
box prior to applying the primary and secondary windings unless it has been established by prior testing that the test results are
not materially affected. Air flux correction will typically be required when core boxes are used if testing is to be done at high
magnetic field strengths.
A773/A773M − 21
TABLE 2 Number of Test Strip
Nominal Thickness Electrical Sheet Number of
Gage Number Strips
in. mm
0.0100 to 0.0250 0.254 to 0.635 32 to 24 12
0.0280 to 0.0435 0.711 to 1.105 23 to 19 8
0.0500 and over 1.270 and over 18 and thicker 4
8.8 For laminated ring and spirally wound cores, the specimen cross-sectional area shall be computed from the mass, magnetic
path length, and density. For Epstein specimens, the specimen cross-sectional area shall be computed from the mass, physical
length, and density.
8.9 When required for material properties development, the test specimen shall have received a stress relief or other heat treatment
after specimen preparation. This heat treatment is subject to agreement between the producer and the user.
9. Test Specimens for Permeameter Measurements
9.1 The information in 9.2 – 9.9 covers the general case for specimens that must be tested using a permeameter, and where the
magnetic field strength is not proportional to the magnetizing current.
9.2 When the test specimen represents a test lot of material, sampling shall conform to the requirements of Practice A34/A34M,
unless superseded by a specification.
9.3 Test specimens in bar form may be of round, square, or rectangular cross-section. In some permeameters, the bar specimen
may be a half round or any shape having a uniform cross-sectional area. Permeameters must have a good magnetic joint between
the ends of the test specimen and the permeameter yoke or pole faces. Generally, to achieve a good magnetic joint, the test
specimen must be of square or rectangular cross section and must be machined or ground to have straight and parallel surfaces.
For permeameters using specimens butted to the pole tips, the specimen ends must be smooth and parallel.
9.4 Where possible, test specimen cross-sectional area shall be directly measured using calipers or micrometers. If not possible
because of cross-sectional shape or surface roughness, then the cross-sectional area shall be determined from the mass, length, and
density of the test specimen. For testing Epstein specimens in permeameters, the cross-sectional area shall be determined from the
mass, length, and density.
9.5 When the material is in flat-rolled form and is to be evaluated as half transverse-half longitudinal, the test sample shall be
sheared to have strip specimens in accordance with Table 2 except that multiples of four are not required. When flat-rolled material
is to be evaluated in only one direction, the test specimen shall conform to Table 2 or to the requirements for best test quality for
the particular permeameter being used. For flat-rolled materials of thickness 0.0100 in. [0.254 mm] or thinner, the test specimen
2 2 2 2
cross-sectional area shall be not less than 0.310 in. [200 mm ] and not more than 0.620 in. [400 mm ].
9.6 When the test specimen for strip materials is to be half transverse and half longitudinal, the preferred method is to test the
transverse strips as one specimen and the longitudinal strips as another specimen. Mixing the specimens when significant
anisotropy is present could result in unrealistic test results.
9.7 For best testing accuracy, the length and size of the test specimen must meet the requirements of the permeameter being used.
Generally, for most permeameters, a test specimen length of 10 in. [254 mm] or more is required. Shorter specimens with some
permeameters require the use of pole-piece extensions and may cause a reduction in testing accuracy. Other permeameters are
designed for short specimens without loss of testing accuracy.
9.8 All test specimen forms shall be cut, machined, or ground to have a uniform cross-sectional area along the active length of
the test specimen. The cross-sectional area shall be sufficiently uniform so that its nonuniformity does not materially affect the
Densities of magnetic materials can be found in Practice A34/A34M.
A773/A773M − 21
accuracy of establishing and measuring flux density in the test specimen. It is recommended that the cross-sectional area not vary
by more than 61 % anywhere in the magnetic path. The possible effects of mechanical preparation on the magnetic properties must
be considered prior to testing.
9.9 When required for development of material properties, the test specimen shall receive a stress relief or other heat treatment
after preparation. This anneal is subject to agreement between the producer and the user.
10. Calibration of Integrator(s)
10.1 The integrator(s) shall be calibrated either by a national standards laboratory or using secondary standards traceable to a
national standards laboratory to ensure an integration accuracy of at least 60.5 %. Calibration may be accomplished by means of
a certified Maxwell-turns generator, or volt-seconds generator, or mutual inductor. The integrators may have built-in volt-second
sources that require periodic return to the equipment manufacturer for calibration.
11. Calibration of Current Measuring Resistor
11.1 In cases in which the magnetic field strength is proportional to the magnetizing current, such as in ring and Epstein
specimens, the resistance of the current measuring resistor(s) shall be verified to be accurate to within 60.5 % of the stated value
when measured at the maximum current at which the resistor will be used when making tests.
12. Calibration of H-Coils and Hall Probes
12.1 The area-turns of H-coils shall be calibrated either by a national standards laboratory or using secondary standards traceable
to a national standards laboratory.
12.2 Hall Probes shall be calibrated using standards traceable to a national standards laboratory.
13. Calibration of Data Recorder
13.1 The various scales of the data recorder shall be calibrated by means of a verified voltage source to at least the quoted accuracy
of the recorder in use. The data recorder shall be calibrated using standards traceable to a national standards laboratory.
14. System Calibration Checks
14.1 Due to the nature of measurement systems, it is not always possible to check the calibration of the individual components.
In some instances, attempts to do so may void the equipment manufacturer’s warranty. Accordingly, it is strongly recommended
that users of these measurement systems create or obtain a set of master specimens representative of the magnetic materials
routinely tested by them. These specimens should be periodically tested to verify the overall functioning of the measurement
system. The use of control charting techniques is recommended. It is recommended but not required that these mastersmaster
specimens be tested periodically by a national standards laboratory or by using equipment whose calibration is traceable to a
national standards laboratory.
15. Procedure
15.1 The following test procedure is representative of most analog and digital hysteresigraphs. The details of some operating steps
may vary with the particular make and model of hysteresigraph. However, the general test procedures are similar in all units. The
following procedure covers manual current sweeping, automatic current sweeping, and automatic current sweeping with
symmetrical tracing.
15.2 Setup—The procedures of 15.2.1 – 15.2.6 should be observed for all methods of current sweep.
15.2.1 Before beginning a test, allow a minimum warm-up period for all apparatus and instrumentation as recommended by the
equipment manufacturer.
15.2.2 Connect the specimen, observing polarity so that the first quadrant of the hysteresis loop is being measured on initial
application of the magnetizing current. (It is imperative that proper polarity be established before demagnetization of the test
specimen.) Some computer controlled computer-controlled equipment automatically corrects the polarity if it is reversed.
A773/A773M − 21
15.2.3 Before testing, demagnetize the specimen by establishing a magnetic field strength sufficiently large to reach a point well
above the knee of the magnetization curve. Then, while continuously cycling the magnetization between + and - polarity, slowly
reduce the magnetizing current to zero. (In the demagnetization process, down-switching of voltage taps to reduce current may
result in current surges. It is advisable to select voltage sources and controls that have the ability to reduce current to a low value
without switching taps, preferably to a current level that does not exceed a value of 0.1 times the coercivity of the material.)
15.2.4 For the B measurement, set the B integrator range and scaling circuitry or software so that B is displayed or recorded, or
both, directly.
15.2.5 For the H measurement, select the appropriate current measuring resistor (current range) and set the scaling circuitry or
software so that H is displayed or recorded, or both, directly.
15.2.6 Before
...