ASTM A598/A598M-02(2007)

Standard Test Method for Magnetic Properties of Magnetic Amplifier Cores

SIGNIFICANCE AND USE
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, 400, 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 A 34/A 34.
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 A 340.
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 and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 30-Apr-2007
• ICS: 29.100.10 - Magnetic components
• Technical Committee: A06 - Magnetic Properties
• Drafting Committee: A06.01 - Test Methods

Relations

• Replaces: ASTM A598/A598M-02 - Standard Test Method for Magnetic Properties of Magnetic Amplifier Cores
• Effective Date: 01-May-2007

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:A598/A598M −02(Reapproved 2007)
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
amplifier-type applications.
appear in the text of this test method.The official symbols and
definitions are listed in Terminology A340.
1.2 Tests may be conducted at excitation frequencies of 60,
400, 1600 Hz, or higher frequencies.
1.11 Thevaluesandequationsstatedincustomary(cgs-emu
1.3 Permissible core sizes for this test method are limited
and inch-pound) or SI units are to be regarded separately as
only by the available power supplies and the range and
standard. Within this test method, SI units are shown in
sensitivity of the instrumentation.
brackets. The values stated in each system may not be exact
1.4 At specified values of full-wave sinusoidal-current
equivalents;therefore,eachsystemshallbeusedindependently
excitation, H , this test method provides procedures of
of the other. Combining values from the two systems may
max
determining the corresponding value of maximum induction,
result in nonconformance with this test method.
B .
max
1.12 This standard does not purport to address all of the
1.5 At specified values of half-wave sinusoidal-current
safety concerns, if any, associated with its use. It is the
excitation, this test method provides procedures for determin-
responsibility of the user of this standard to establish appro-
ing the residual induction, B .
r
priate safety and health practices and determine the applica-
1.6 At increased specified values of half-wave sinusoidal- bility of regulatory limitations prior to use.
current excitation, this test method provides procedures for
determining the dc reverse biasing magnetic field strength, H ,
2. Referenced Documents
required to reset the induction in the core material past B to a
r
2.1 ASTM Standards:
valuewherethetotalinductionchange,∆B ,becomesapproxi-
A34/A34MPractice for Sampling and Procurement Testing
matelyonethirdoftheinductionchange,2 B .Italsoprovides
p
of Magnetic Materials
procedures for determining the additional dc reset magnetic
A340Terminology of Symbols and Definitions Relating to
field strength, ∆H , which, combined with H , is the value
Magnetic Testing
required to reset the induction in the core material past B to a
r
A596/A596MTest Method for Direct-Current Magnetic
valuewherethetotalinductionchange,∆B ,becomesapproxi-
mately two thirds of the induction change 2 B . Properties of Materials Using the Ballistic Method and
p
Ring Specimens
1.7 This test method specifies procedures for determining
core gain from the corresponding biasing and induction
3. Terminology
changes, ∆H and ∆B.
3.1 Definitions—Below is a list of symbols and definitions
1.8 This test method covers test procedures and require-
as used in this test method. The official list of symbols and
ments for evaluation of finished cores which are to be used in
definitions may be found in Terminology A340. (See Table 1
magnetic-amplifier-type applications. It is not a test for basic-
material magnetic properties. where indicated).
3.2 Symbols:
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 May 1, 2007. Published January 2008. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1969. Last previous edition approved in 2002 as A598/A598M–02. Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/A0598_A0598M-02R07. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
A598/A598M−02 (2007)
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.
A = cross-sectional area of test specimen core N = test winding primary, ac excitation winding,
2 2
material, cm [m ]. turns.
A = ac ammeter for primary circuit, half-wave, N = test winding primary, dc H biasing winding,
1 2 1
average-responsive, A. turns.
A = dc ammeter for H biasing winding, A. N = test winding primary, dc H biasing winding,
2 1 3 2
A = dc ammeter for H biasing winding, A.
turns.
3 2
A = dc milliammeter for ac voltage calibrator, V. N = test winding secondary, ∆ B pickup winding,
B −B = change in test specimen induction, under half-
turns.
max r
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
NOTE 1—Note that H and B , as used in this test method, are
m
max max
maximum points on the sine-current SCM or corresponding half-wave
flux-current loop Gauss [Tesla] (Note 1).
CMflux-currentloops.Also,thatH andB aremaximumpointsonaCM
B = maximum value of induction in the sine- p p
p
flux-current loop corresponding to the ac half-wave sine current which is
currenthalf-waveCMflux-currentloop,forthe
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.
4.2 Under its provision, a specific predetermined value of
1 2
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
half-wave sinusoidal current of the same magnitude as that
.
F G
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
max r
loop Oe [A/m].
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 ,
∆H = change in dc biasing (reset) magnetic field
isthevaluerequiredtoresetpastB toapointthatprovidesthe
r
strength, Oe [A/m].
specified change in induction of ∆B which is approximately
A598/A598M−02 (2007)
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.
equal to one third of 2 B . This value of H has some 4.9 Heat treatment appropriate to the core material and core
p 1
correlation to the coercive field strength, H , of the material. construction may be required before test.
c
4.5 Holding the same increased value of ac half-wave
5. Significance and Use
sinusoidal-current excitation, as described in 4.4, the dc
5.1 The method of excitation simulates, to a practical
reverse-polarity excitation is increased by the amount ∆H and
degree, the operation of a magnetic core in a self-saturating
the total value of dc reverse biasing (H +∆H) is designated
magnetic amplifier. The properties measured are related to the
H .Itisthevalueofdcreversebiasingrequiredtoresettheflux
quality of performance of the cores in magnetic amplifiers and
between ac magnetizing cycles to a value which provides the
are useful for the specification of materials for such cores.
specified total change in induction of ∆B (Table 1) that is
approximately equal to two thirds of 2 B .
p
6. Apparatus (see Fig. 1)
4.6 From the change in dc bias ∆H and the changes in
6.1 Sinusoidal Voltage Supply—The source of excitation
induction∆BcorrespondingtothechangebetweentheH and
shall be an ac source of sinusoidal voltage which shall have
H operating points, the core gain may be determined. It is
sufficient power to magnetize the largest core to be examined
usually reported as a∆H value for the core.When required for
to the levels of excitation as specified in Table 2. Its harmonic
specialreasons,itmaybereportedintermsofcoregain,G(see
distortion under load shall be less than 3%. Its frequency
11.5).
should be constant to within 1% or less. Standard test
4.7 It is standard practice to assign values to the change of frequencies are 60, 400, and 1600 Hz.
induction ∆B and ∆B (Table 1). This in turn determines the
1 2
6.2 Series Impedance, Z , or Resistor, R —This impedance
1 1
magnitude of the H and H biasing values corresponding to
1 2
should provide a voltage drop much larger than the voltage
these changes of induction.
appearingacrosstheexcitationwinding.Then,thedistortionof
4.8 The normal test specimen may have any size or shape. current waveform as a result of the nonlinear impedance of the
When used specifically to evaluate materials for core core will be minimized. It may be a power resistor for small
construction, it is limited in size, weight, and method of size cores. For larger cores, a series resonant circuit may be
manufacture. used, which reduces the voltage requirements of the power
FIG. 1 Basic Diagram for Magnetic Amplifier Core Test
A598/A598M−02 (2007)
source.Thevoltageacrossthisimpedanceorareactiveelement mating that of cores tested by this test method, with a test
inZ mustbegreaterthan25timestheaveragevoltageinduced method for determining the average voltage (see 9.2).
in the excitation turns, N .
6.7 DC Power Supply for H —This power supply shall
6.3 Diodes (Note 2), D and D may be fast solid state provide sufficient voltage to overcome the voltage drop across
1 1
devices(Note3),high-vacuumrectifiers,orSchottkyrectifiers. impedance, Z , and sufficient current capacity to saturate any
core to be tested. The rms value of the ac ripple of the dc
NOTE 2—During the interval between half-wave pulses, when the
power-supply voltage shall not exceed 0.25% of the test
excitation should be nominally zero, the average leakage current shall be
voltage required under the conditions of maximum or mini-
less than 0.1% of the peak value of excitation current during a pulse.
NOTE3—Inthecaseofsolid-statedevices,acapacitativechargingpulse
mum dc load currents.
of reverse current is sometimes observed, particularly at the higher
6.8 DC Power Supply for ∆H—This power supply shall
frequencies. Its integrated value, in ampere-seconds, at any test frequency
provide sufficient voltage to overcome the voltage drop of
shall be limited to 1.0% of the ampere-seconds of the exciting half-wave.
impedance, Z , and sufficient current capacity to provide ∆H
6.4 The test fixture shall be composed of four sets of
foranycoretobetested.Itsrmsripplevoltageshallnotexceed
windings enclosing the core and a means of compensating for
0.25% of the test voltage required under the conditions of
air-flux effect in induced voltage in N .
maximum or minimum dc load currents.
6.4.1 The exciting winding N shall contain as small a
6.9 AC Blocking Impedances, Z and Z —These imped-
number of turns as practical to limit the exciting-current
2 3
waveform distortion (see 6.1). ances are dc current-passing elements that reduce the ac
loading effects of the H and ∆H windings and their dc power
6.4.2 The B-coil, pickup winding, N , may contain any
4 1
convenient number of turns. This winding shall be maintained supplies to acceptable limits. Minimum values for impedances
Z or Z may be calculated from the equation of 11.6.
in a fixed position in relation to the excitation windings to
2 3
eliminate variations in the air-cored inductive or capacitive
6.10 Amm
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