ASTM A598/A598M-02(2022)
(Test Method)Standard Test Method for Magnetic Properties of Magnetic Amplifier Cores
Standard Test Method for Magnetic Properties of Magnetic Amplifier Cores
SIGNIFICANCE AND USE
5.1 The method of excitation simulates, to a practical degree, the operation of a magnetic core in a self-saturating magnetic amplifier. The properties measured are related to the quality of performance of the cores in magnetic amplifiers and are useful for the specification of materials for such cores.
SCOPE
1.1 This test method covers the determination of the magnetic performance of fully processed cores for magnetic amplifier-type applications.
1.2 Tests may be conducted at excitation frequencies of 60 Hz, 400 Hz, 1600 Hz, or higher frequencies.
1.3 Permissible core sizes for this test method are limited only by the available power supplies and the range and sensitivity of the instrumentation.
1.4 At specified values of full-wave sinusoidal-current excitation, Hmax, this test method provides procedures of determining the corresponding value of maximum induction, Bmax.
1.5 At specified values of half-wave sinusoidal-current excitation, this test method provides procedures for determining the residual induction, Br.
1.6 At increased specified values of half-wave sinusoidal-current excitation, this test method provides procedures for determining the dc reverse biasing magnetic field strength, H1, required to reset the induction in the core material past Br to a value where the total induction change, ΔB1, becomes approximately one third of the induction change, 2 Bp. It also provides procedures for determining the additional dc reset magnetic field strength, ΔH, which, combined with H1, is the value required to reset the induction in the core material past Br to a value where the total induction change, ΔB2, becomes approximately two thirds of the induction change 2 Bp.
1.7 This test method specifies procedures for determining core gain from the corresponding biasing and induction changes, ΔH and ΔB.
1.8 This test method covers test procedures and requirements for evaluation of finished cores which are to be used in magnetic-amplifier-type applications. It is not a test for basic-material magnetic properties.
1.9 This test method shall be used in conjunction with Practice A34/A34M.
1.10 Explanations of symbols and abbreviated definitions appear in the text of this test method. The official symbols and definitions are listed in Terminology A340.
1.11 The values and equations stated in customary (cgs-emu and inch-pound) or SI units are to be regarded separately as standard. Within this test method, 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 test method.
1.12 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.13 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.
General Information
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Standards Content (Sample)
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.
Designation:A598/A598M −02 (Reapproved 2022)
Standard Test Method for
Magnetic Properties of Magnetic Amplifier Cores
This standard is issued under the fixed designationA598/A598M; the number immediately following the designation indicates the year
of original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.
A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 1.9 This test method shall be used in conjunction with
Practice A34/A34M.
1.1 This test method covers the determination of the mag-
netic performance of fully processed cores for magnetic 1.10 Explanations of symbols and abbreviated definitions
appear in the text of this test method.The official symbols and
amplifier-type applications.
definitions are listed in Terminology A340.
1.2 Tests may be conducted at excitation frequencies of
1.11 Thevaluesandequationsstatedincustomary(cgs-emu
60Hz, 400Hz, 1600Hz, or higher frequencies.
and inch-pound) or SI units are to be regarded separately as
1.3 Permissible core sizes for this test method are limited
standard. Within this test method, SI units are shown in
only by the available power supplies and the range and
brackets. The values stated in each system may not be exact
sensitivity of the instrumentation.
equivalents;therefore,eachsystemshallbeusedindependently
1.4 At specified values of full-wave sinusoidal-current
of the other. Combining values from the two systems may
excitation, H , this test method provides procedures of
max result in nonconformance with this test method.
determining the corresponding value of maximum induction,
1.12 This standard does not purport to address all of the
B .
max
safety concerns, if any, associated with its use. It is the
1.5 At specified values of half-wave sinusoidal-current
responsibility of the user of this standard to establish appro-
excitation, this test method provides procedures for determin-
priate safety, health, and environmental practices and deter-
ing the residual induction, B .
mine the applicability of regulatory limitations prior to use.
r
1.13 This international standard was developed in accor-
1.6 At increased specified values of half-wave sinusoidal-
dance with internationally recognized principles on standard-
current excitation, this test method provides procedures for
ization established in the Decision on Principles for the
determining the dc reverse biasing magnetic field strength, H ,
Development of International Standards, Guides and Recom-
required to reset the induction in the core material past B to a
r
mendations issued by the World Trade Organization Technical
valuewherethetotalinductionchange,∆B ,becomesapproxi-
Barriers to Trade (TBT) Committee.
matelyonethirdoftheinductionchange,2 B .Italsoprovides
p
procedures for determining the additional dc reset magnetic
2. Referenced Documents
field strength, ∆H, which, combined with H , is the value
2.1 ASTM Standards:
required to reset the induction in the core material past B to a
r
A34/A34MPractice for Sampling and Procurement Testing
valuewherethetotalinductionchange,∆B ,becomesapproxi-
of Magnetic Materials
mately two thirds of the induction change 2 B .
p
A340Terminology of Symbols and Definitions Relating to
1.7 This test method specifies procedures for determining
Magnetic Testing
core gain from the corresponding biasing and induction
A596/A596MTest Method for Direct-Current Magnetic
changes, ∆H and ∆B.
PropertiesofMaterialsUsingthePointbyPoint(Ballistic)
Method and Ring Specimens
1.8 This test method covers test procedures and require-
ments for evaluation of finished cores which are to be used in
3. Terminology
magnetic-amplifier-type applications. It is not a test for basic-
3.1 Definitions—Below is a list of symbols and definitions
material magnetic properties.
as used in this test method. The official list of symbols and
definitions may be found in Terminology A340. (See Table 1
where indicated.)
This test method is under the jurisdiction of ASTM Committee A06 on
MagneticPropertiesandisthedirectresponsibilityofSubcommitteeA06.01onTest
Methods. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Oct. 1, 2022. Published October 2022. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1969. Last previous edition approved in 2015 as A598/A598M–02 Standards volume information, refer to the standard’s Document Summary page on
(2015). DOI: 10.1520/A0598_A0598M-02R22. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
A598/A598M−02 (2022)
TABLE 1 Standard Values of ∆B, ∆B,and ∆B for the Commonly Used Materials
1 2
∆ B (for Test of 10.5) ∆ B (for Test of 10.4) ∆ B or
1 2
A
(∆B −∆B )
Core Material 2 1
kG Tesla kG Tesla kG Tesla
Supermendur 14 1.4 28 2.8 14 1.4
Oriented silicon-iron 10 1.0 20 2.0 10 1.0
50 % nickel-iron:
Oriented 10 1.0 20 2.0 10 1.0
Nonoriented 8 0.8 16 1.6 8 0.8
79 % nickel-iron 5 0.5 10 1.0 5 0.5
Supermalloy 5 0.5 10 1.0 5 0.5
A
Values for other materials may be used by mutual agreement between seller and purchaser.
3.2 Symbols:
∆H = change in dc biasing (reset) magnetic field
strength, Oe [A/m].
A = cross-sectional area of test specimen core
N = test winding primary, ac excitation winding,
2 2 1
material, cm [m ].
turns.
A = ac ammeter for primary circuit, half-wave,
N = test winding primary, dc H biasing winding,
2 1
average-responsive, A.
turns.
A = dc ammeter for H biasing winding, A.
2 1
N = test winding primary, dc H biasing winding,
3 2
A = dc ammeter for H biasing winding, A.
3 2
turns.
A = dc milliammeter for ac voltage calibrator, V.
N = test winding secondary, ∆ B pickup winding,
B −B = change in test specimen induction, under half-
max r
turns.
wave sinusoidal-current excitation specified
SCM = symmetrical cyclic magnetization (see Termi-
for this measurement.
nology A340).
B = maximum induction in a sine-current SCM ac
m
NOTE 1—Note that H and B , as used in this test method, are
max max
flux-current loop Gauss [Tesla] (Note 1).
maximum points on the sine-current SCM or corresponding half-wave
B = maximum value of induction in the sine-
p CMflux-currentloops.Also,thatH andB aremaximumpointsonaCM
p p
currenthalf-waveCMflux-currentloop,forthe flux-current loop corresponding to the ac half-wave sine current which is
established in the exciting winding, N , and held constant, during the dc
reset test Gauss [Tesla] (Note 1).
current measurements for H , H,or ∆H. These definitions are different
1 2
B = residual induction in an ac sine-current flux-
r
from those used for the same symbols in Terminology A340 for use with
current loop Gauss [Tesla].
dc or sinusoidal-flux ac measurements.
∆B = change in magnetic induction Gauss [Tesla]
(Table 1).
4. Summary of Test Method
∆B = change in induction in the flux-current loop
4.1 Thistestmethodusestheprocedurescommonlyreferred
during H test Gauss [Tesla] (Table 1).
to as the “Constant Current Flux Reset Test Method”
∆B = change of induction in the flux current loop
(C.C.F.R.). For graphic representation of the magnetic ampli-
during H test Gauss [Tesla] (Table 1).
fier core test see Appendix X3.
CM = cyclic magnetization (see Terminology A340).
D and D = solid state diodes or other rectifiers.
1 2
4.2 Under its provision, a specific predetermined value of
D to D = silicon diodes.
3 6
sinusoidal-currentexcitation,H ,(Table2)isestablishedand
max
d = lamination thickness, cm [m].
the corresponding induction change is measured to determine
E = average value of voltage waveform, V.
avg
the value of maximum induction which is then designated
f = frequency of test, Hz.
B .
max
G = core gain ∆ B −B /H,−H ,
2 1 2 1
4.3 The excitation is then changed to a unidirectional
Gauss T
.
F G half-wave sinusoidal current of the same magnitude as that
Oe A/m
used for determining maximum induction. The change in
induction under this excitation then is measured to determine
H = coercive field strength in an SCM flux-current
c
the property designated (B −B ), or the change between the
loop Oe [A/m].
max r
maximum and residual values of induction.
H = maximum magnetic field strength in a sine-
max
current SCM ac flux-current loop, Oe [A/m]
4.4 The ac half-wave sinusoidal-current excitation, as mea-
(Note 1).
sured in the ac exciting winding, is then increased to a new
H = maximum value of the sine-current ac mag-
p
value, designated H (Table 2), which causes the ac induction
p
netic field strength for the CM reset tests, Oe
in the test specimen to rise to a new value which is designated
[A/m] (Note 1).
B . A dc reverse-polarity magnetic field strength is then
p
H = dc biasing (reset) magnetic field strength for
applied.Theopposingdcmagneticfieldstrengthresetstheflux
the H test point, Oe [A/m].
orinductioninthecorematerial,betweeneachhalfcycleofac
H = dc biasing (reset) magnetic field strength for
magnetization, to a value that provides the specified ∆B
the H test point, Oe [A/m].
induction change (Table 1). This dc excitation, designated H ,
A598/A598M−02 (2022)
TABLE 2 Standard Values of Peak Sine Current Magnetic Field Strength to Be Established for Testing the Commonly Used Materials
Half-Wave CM Value of H , (for
p
Full-Wave SCM Value of H , Half-Wave CM Value of H ,
max max
Determining H and H or ∆H
1 2
(for Measurement of B (for Measurement of B −
max max
A
in Testing of 10.4 and 10.5 and
Core Material
in Test of 10.2) B in Test of 10.3)
r
adjustments of 10.1)
Oe A/m Oe A/m Oe A/m
Supermendur 3 240 3 240 6 480
Oriented silicon-iron 3 240 3 240 6 480
50 % nickel-iron 1 80 1 80 2 160
79 % nickel-iron 0.5 40 0.5 40 1 80
Supermalloy 0.25 20 0.25 20 0.5 40
A
Values for other materials may be used by mutual agreement between seller and purchaser.
isthevaluerequiredtoresetpastB toapointthatprovidesthe 4.8 The normal test specimen may have any size or shape.
r
specified change in induction of ∆B which is approximately When used specifically to evaluate materials for core
equal to one third of 2 B . This value of H has some construction, it is limited in size, weight, and method of
p 1
correlation to the coercive field strength, H , of the material. manufacture.
c
4.5 Holding the same increased value of ac half-wave 4.9 Heat treatment appropriate to the core material and core
sinusoidal-current excitation, as described in 4.4, the dc construction may be required before test.
reverse-polarity excitation is increased by the amount ∆H and
the total value of dc reverse biasing (H +∆H) is designated 5. Significance and Use
H .Itisthevalueofdcreversebiasingrequiredtoresettheflux
5.1 The method of excitation simulates, to a practical
between ac magnetizing cycles to a value which provides the
degree, the operation of a magnetic core in a self-saturating
specified total change in induction of ∆B (Table 1) that is
magnetic amplifier. The properties measured are related to the
approximately equal to two thirds of 2 B .
p
quality of performance of the cores in magnetic amplifiers and
are useful for the specification of materials for such cores.
4.6 From the change in dc bias ∆H and the changes in
induction∆B corresponding to the change between the H and
H operating points, the core gain may be determined. It is 6. Apparatus (see Fig. 1)
usually reported as a∆H value for the core.When required for
6.1 Sinusoidal Voltage Supply—The source of excitation
specialreasons,itmaybereportedintermsofcoregain,G(see
shall be an ac source of sinusoidal voltage which shall have
11.5).
sufficient power to magnetize the largest core to be examined
4.7 It is standard practice to assign values to the change of to the levels of excitation as specified in Table 2. Its harmonic
induction ∆B and ∆B (Table 1). This in turn determines the distortion under load shall be less than 3%. Its frequency
1 2
magnitude of the H and H biasing values corresponding to should be constant to within 1% or less. Standard test
1 2
these changes of induction. frequencies are 60Hz, 400Hz, and 1600Hz.
FIG. 1 Basic Diagram for Magnetic Amplifier Core Test
A598/A598M−02 (2022)
6.2 Series Impedance, Z , or Resistor, R —This impedance 6.6 Calibration Source—An adequate means shall be pro-
1 1
should provide a voltage drop much larger than the voltage vided to calibrate the flux voltmeter. A source of accurately
appearingacrosstheexcitationwinding.Then,thedistortionof known ac voltage, or the output of a core whose saturation has
current waveform as a result of the nonlinear impedance of the been carefully measured by dc ballistic methods may be used.
core will be minimized. It may be a power resistor for small The reference voltage calibrator shown in Appendix X2
size cores. For larger cores, a series resonant circuit may be providesasuitablevoltagesourcehavingawaveformapproxi-
used, which reduces the voltage requirements of the power mating that of cores tested by this test method, with a test
source.Thevoltageacrossthisimpedanceorareactiveelement method for determining the average voltage (see 9.2).
inZ mustbegreaterthan25timestheaveragevoltageinduced
6.7 DC Power Supply for H —This power supply shall
in the excitation turns, N .
provide sufficient voltage to overcome the voltage drop across
6.3 Diodes (Note 2), D and D may be fast solid state impedance, Z , and sufficient current capacity to saturate any
1 1 2
devices(Note3),high-vacuumrectifiers,orSchottkyrectifiers. core to be tested. The rms value of the ac ripple of the dc
power-supply voltage shall not exceed 0.25% of the test
NOTE 2—During the interval between half-wave pulses, when the
voltage required under the conditions of maximum or mini-
excitation should be nominally zero, the average leakage current shall be
less than 0.1% of the peak value of excitation current during a pulse. mum dc load currents.
NOTE3—Inthecaseofsolid-statedevices,acapacitativechargingpulse
6.8 DC Power Supply for ∆H—This power supply shall
of reverse current is sometimes observed, particularly at the higher
provide sufficient voltage to overcome the voltage drop of
frequencies. Its integrated value, in ampere-seconds, at any test frequency
shallbelimitedto1.0%oftheampere-secondsoftheexcitinghalf-wave. impedance, Z , and sufficient current capacity to provide ∆H
foranycoretobetested.Itsrmsripplevoltageshallnotexceed
6.4 The test fixture shall be composed of four sets of
0.25% of the
...
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