ASTM A598-92(1997)

Standard Test Method for Magnetic Properties Of Magnetic Amplifier 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 magnetizing force, H1 , required to reset the induction in the core material past Br to a value where the total induction change, [delta] B1 , becomes approximately one third of the induction change, 2 Bp . It also provides procedures for determining the additional dc reset magnetizing force, [delta] , 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, [delta] B2 , 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, [delta] and [delta] .  
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.  
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. This standard does not purport to address all of the safety problems, 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.  
1.11 The preferred units and corresponding values appearing in this standard are customary (cgs-emu) units. SI units are indicated in parentheses. When necessary, separate equations, conversion factors, and inclusions for SI values are given in the text or tables.

General Information

• Status: Historical
• Publication Date: 09-Oct-1997
• ICS: 29.100.10 - Magnetic components
• Technical Committee: A06 - Magnetic Properties
• Drafting Committee: A06.01 - Test Methods

Relations

• Replaced By: ASTM A598/A598M-02 - Standard Test Method for Magnetic Properties of Magnetic Amplifier Cores
• Effective Date: 10-Oct-2002

Standards Content (Sample)

Designation: A 598 – 92 (Reapproved 1997) An American National Standard
AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Test Method for
Magnetic Properties Of Magnetic Amplifier Cores
This standard is issued under the fixed designation A 598; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope This standard does not purport to address all of the safety
concerns, if any, associated with its use. It is the responsibility
1.1 This test method covers the determination of the mag-
of the user of this standard to establish appropriate safety and
netic performance of fully processed cores for magnetic
health practices and determine the applicability of regulatory
amplifier-type applications.
limitations prior to use.
1.2 Tests may be conducted at excitation frequencies of 60,
1.11 The preferred units and corresponding values appear-
400, 1600 Hz, or higher frequencies.
ing in this standard are customary (cgs-emu) units. SI units are
1.3 Permissible core sizes for this test method are limited
indicated in parentheses. When necessary, separate equations,
only by the available power supplies and the range and
conversion factors, and inclusions for SI values are given in the
sensitivity of the instrumentation.
text or tables.
1.4 At specified values of full-wave sinusoidal-current ex-
citation, H , this test method provides procedures of deter-
max
2. Referenced Documents
mining the corresponding value of maximum induction, B .
max
2.1 ASTM Standards:
1.5 At specified values of half-wave sinusoidal-current ex-
A 34 Practice for Sampling and Procurement Testing of
citation, this test method provides procedures for determining
Magnetic Materials
the residual induction, B .
r
A 340 Terminology of Symbols and Definitions Relating to
1.6 At increased specified values of half-wave sinusoidal-
Magnetic Testing
current excitation, this test method provides procedures for
A 596 Test Method for Direct-Current Magnetic Properties
determining the dc reverse biasing magnetizing force, H ,
of Materials Using the Ballistic Method and Ring Speci-
required to reset the induction in the core material past B to a
r
mens
value where the total induction change, DB , becomes approxi-
mately one third of the induction change, 2 B . It also provides
p
3. Terminology
procedures for determining the additional dc reset magnetizing
3.1 Definitions— Below is a list of symbols and definitions
force, DH, which, combined with H , is the value required to
as used in this test method. The official list of symbols and
reset the induction in the core material past B to a value where
r
definitions may be found in Terminology A 340. (See Table 1
the total induction change, DB , becomes approximately two
where indicated).
thirds of the induction change 2 B .
p
3.2 Symbols:
1.7 This test method specifies procedures for determining
core gain from the corresponding biasing and induction
changes, DH and DB.
A 5 cross-sectional area of test specimen core
2 2
1.8 This test method covers test procedures and require-
material, cm (m ).
ments for evaluation of finished cores which are to be used in
A 5 ac ammeter for primary circuit, half-wave,
magnetic-amplifier-type applications. It is not a test for basic-
average-responsive, A.
material magnetic properties.
A 5 dc ammeter for H biasing winding, A.
2 1
1.9 This test method shall be used in conjunction with
A 5 dc ammeter for H biasing winding, A.
3 2
Practice A 34.
A 5 dc milliammeter for ac voltage calibrator, V.
B −B 5 change in test specimen induction, under
1.10 Explanations of symbols and abbreviated definitions
max r
appear in the text of this test method. The official symbols and half-wave sinusoidal-current excitation
specified for this measurement.
definitions are listed in Terminology A 340.
B 5 maximum induction in a sine-current SCM
m
ac flux-current loop Gauss (Tesla) (Note 1).
This test method is under the jurisdiction of ASTM Committee A-6 on
Magnetic Properties and is the direct responsibility of Subcommittee A06.01 on Test
Methods.
Current edition approved Sept. 15, 1992. Published November 1992. Originally
published as A 598 – 69. Last previous edition A 598 – 69 (1986). Annual Book of ASTM Standards, Vol 03.04.
A 598
CM flux-current loops. Also, that H and B are maximum points on a CM
p p
B 5 maximum value of induction in the sine-
p
flux-current loop corresponding to the ac half-wave sine current which is
current half-wave CM flux-current loop, for
established in the exciting winding, N , and held constant, during the dc
the reset test Gauss (Tesla) (Note 1).
current measurements for H , H ,or DH. These definitions are different
1 2
B 5 residual induction in an ac sine-current flux-
r
from those used for the same symbols in Terminology A 340 for use with
current loop Gauss (Tesla).
dc or sinusoidal-flux ac measurements.
DB 5 change in magnetic induction Gauss (Tesla)
(Table 1).
TABLE 1 Standard Values of DB, DB , and DB for the
1 2
DB 5 change in induction in the flux-current loop
Commonly Used Materials
during H test Gauss (Tesla) (Table 1).
DB 5 change of induction in the flux current loop
DB (for Test of DB (for Test of DB or
1 2
during H test Gauss (Tesla) (Table 1). A
10.5) 10.4) (DB − DB )
2 2 1
Core Material
CM 5 cyclic magnetization (see Terminology
kG Tesla kG Tesla kG Tesla
A 340).
Supermendur 14 1.4 28 2.8 14 1.4
D and D 5 solid state diodes or other rectifiers.
1 2 Oriented silicon-iron 10 1.0 20 2.0 10 1.0
50 % nickel-iron:
D to D 5 silicon diodes.
3 6
Oriented 10 1.0 20 2.0 10 1.0
d 5 lamination thickness, cm (m).
Nonoriented 8 0.8 16 1.6 8 0.8
E 5 average value of voltage waveform, V.
avg
79 % nickel-iron 5 0.5 10 1.0 5 0.5
f 5 frequency of test, Hz.
Supermalloy 5 0.5 10 1.0 5 0.5
G 5 core gain DB − B /H ,−H ,
A
2 1 2 1
Values for other materials may be used by mutual agreement between seller
Gauss T
and purchaser.
.
S D
Oe A/m
H 5 coercive force in an SCM flux-current loop
c
4. Summary of Test Method
Oe (A/m).
4.1 This test method uses the procedures commonly referred
H 5 maximum magnetizing force in a sine-
max
to as the “Constant Current Flux Reset Test Method”
current SCM ac flux-current loop, Oe (A/m)
(C.C.F.R.). For graphic representation of the magnetic ampli-
(Note 1).
fier core test see Appendix X3.
H 5 maximum value of the sine-current ac mag-
p
4.2 Under its provision, a specific predetermined value of
netizing force for the CM reset tests, Oe
sinusoidal-current excitation, H , (Table 2) is established and
(A/m) (Note 1). max
the corresponding induction change is measured to determine
H 5 dc biasing (reset) magnetizing force for the
the value of maximum induction which is then designated
H test point, Oe (A/m).
B .
H 5 dc biasing (reset) magnetizing force for the
2 max
4.3 The excitation is then changed to a unidirectional
H test point, Oe (A/m).
DH 5 change in dc biasing (reset) magnetizing half-wave sinusoidal current of the same magnitude as that
force, Oe (A/m). used for determining maximum induction. The change in
N 5 test winding primary, ac excitation winding, induction under this excitation then is measured to determine
turns.
the property designated (B − B ), or the change between the
max r
N 5 test winding primary, dc H biasing winding,
maximum and residual values of induction.
2 1
turns.
4.4 The ac half-wave sinusoidal-current excitation, as mea-
N 5 test winding primary, dc H biasing winding,
3 2 sured in the ac exciting winding, is then increased to a new
turns.
value, designated H (Table 2), which causes the ac induction
p
N 5 test winding secondary, DB pickup winding,
in the test specimen to rise to a new value which is designated
turns.
B . A dc reverse-polarity magnetizing force is then applied.
p
SCM 5 symmetrical cyclic magnetization (see Ter-
The opposing dc magnetizing force resets the flux or induction
minology A 340).
in the core material, between each half cycle of ac magnetiza-
tion, to a value that provides the specified DB induction
NOTE 1—Note that H and B , as used in this test method, are 1
max max
maximum points on the sine-current SCM or corresponding half-wave change (Table 1). This dc excitation, designated H ,isthe
TABLE 2 Standard Values of Peak Sine Current Magnetizing Forces 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 DH
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.
A 598
value required to reset past B to a point that provides the to the levels of excitation as specified in Table 2. Its harmonic
r
specified change in induction of DB which is approximately distortion under load shall be less than 3 %. Its frequency
equal to one third of 2 B . This value of H has some should be constant to within 1 % or less. Standard test
p 1
correlation to the coercive force, H , of the material. frequencies are 60, 400, and 1600 Hz.
c
4.5 Holding the same increased value of ac half-wave 6.2 Series Impedance, Z , or Resistor, R —This impedance
1 1
sinusoidal-current excitation, as described in 4.4, the dc should provide a voltage drop much larger than the voltage
reverse-polarity excitation is increased by the amount DH and appearing across the excitation winding. Then, the distortion of
the total value of dc reverse biasing (H + DH) is designated current waveform as a result of the nonlinear impedance of the
H . It is the value of dc reverse biasing required to reset the flux core will be minimized. It may be a power resistor for small
between ac magnetizing cycles to a value which provides the size cores. For larger cores, a series resonant circuit may be
specified total change in induction of DB (Table 1) that is used, which reduces the voltage requirements of the power
approximately equal to two thirds of 2 B . source. The voltage across this impedance or a reactive element
p
4.6 From the change in dc bias DH and the changes in in Z must be greater than 25 times the average voltage induced
induction DB corresponding to the change between the H and in the excitation turns, N .
1 1
H operating points, the core gain may be determined. It is 6.3 Diodes (Note 2), D and D may be fast solid state
2 1 1
usually reported as a DH value for the core. When required for devices (Note 3), high-vacuum rectifiers, or Schottky rectifiers.
special reasons, it may be reported in terms of core gain, G (see
NOTE 2—During the interval between half-wave pulses, when the
11.5).
excitation should be nominally zero, the average leakage current shall be
4.7 It is standard practice to assign values to the change of
less than 0.1 % of the peak value of excitation current during a pulse.
induction DB and DB (Table 1). This in turn determines the
NOTE 3—In the case of solid-state devices, a capacitative charging
1 2
pulse of reverse current is sometimes observed, particularly at the higher
magnitude of the H and H biasing values corresponding to
1 2
frequencies. Its integrated value, in ampere-seconds, at any test frequency
these changes of induction.
shall be limited to 1.0 % of the ampere-seconds of the exciting half-wave.
4.8 The normal test specimen may have any size or shape.
6.4 The test fixture shall be composed of four sets of
When used specifically to evaluate materials for core construc-
windings enclosing the core and a means of compensating for
tion, it is limited in size, weight, and method of manufacture.
air-flux effect in induced voltage in N .
4.9 Heat treatment appropriate to the core material and core
6.4.1 The exciting winding N shall contain as small a
construction may be required before test.
number of turns as practical to limit the exciting-current
5. Significance and Use
waveform distortion (see 6.1).
6.4.2 The B-coil, pickup winding, N , may contain any
5.1 The method of excitation simulates, to a practical
degree, the operation of a magnetic core in a self-saturating convenient number of turns. This winding shall be maintained
in a fixed position in relation to the excitation windings to
magnetic amplifier. The properties measured are related to the
quality of performance of the cores in magnetic amplifiers and eliminate variations in the air-cored inductive or capacitive
coupling between them. Compensation for such coupling may
are useful for the specification of materials for such cores.
be accomplished with the air-cored bucking transformer, T .
6. Apparatus (see Fig. 1)
NOTE 4—The coils of the test fixture, including the air-cored bucking
6.1 Sinusoidal Voltage Supply—The source of excitation
transformer, T , if used, shall be initially adjusted such that the voltage
shall be an ac source of sinusoidal voltage which shall have
coupling between the exciting and pickup windings will be minimized
sufficient power to magnetize the largest core to be examined when no specimen is in place, and maximum full-wave exciting current
FIG. 1 Basic Diagram for Magnetic Amplifier Core Test
A 598
for a given-size core is applied. The cancellation will be considered
ammeters or dc digital voltmeters reading voltages across
adequate when the flux voltmeter indicates the equivalent of 15 G (0.0015
precision resistors and must have a full-scale accuracy of at
T) or less for that size core. The pickup circuit should be shielded from
least 60.5 %. For measurement of properties of very-high-gain
stray fields, when this cannot be accomplished an adjustable coil may be
cores, these ammeters must have an accuracy of at least
used to buck out voltages picked up from external fields (see 10.1).
60.25 % of full scale.
6.4.3 The dc reset windings shall use a small number of
6.11 Resistor, R —This resistor compensates for the amme-
turns to help minimize the ac transformer loading of the test
ter’s impedance and nonequality of the two diodes. It is
core. The impedances, Z and Z , described in 6.9 and 11.5 also
2 3 adjusted to provide equal values of crest current, in the two half
help to limit this loading effect to acceptable values.
waves, when full-wave excitation is being used.
6.5 Fl
...