1、Designation: A598/A598M 02 (Reapproved 2015)Standard Test Method forMagnetic Properties of Magnetic Amplifier Cores1This standard is issued under the fixed designation A598/A598M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision, the
2、 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. Scope1.1 This test method covers the determination of the mag-netic performance of fully processed cores for magnetica
3、mplifier-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 limitedonly by the available power supplies and the range andsensitivity of the instrumentation.1.4 At specified values of ful
4、l-wave sinusoidal-currentexcitation, Hmax, this test method provides procedures ofdetermining the corresponding value of maximum induction,Bmax.1.5 At specified values of half-wave sinusoidal-currentexcitation, this test method provides procedures for determin-ing the residual induction, Br.1.6 At i
5、ncreased specified values of half-wave sinusoidal-current excitation, this test method provides procedures fordetermining the dc reverse biasing magnetic field strength, H1,required to reset the induction in the core material past Brto avalue where the total induction change, B1, becomes approxi-mat
6、ely one third of the induction change, 2 Bp. It also providesprocedures for determining the additional dc reset magneticfield strength, H, which, combined with H1, is the valuerequired to reset the induction in the core material past Brto avalue where the total induction change, B2, becomes approxi-
7、mately two thirds of the induction change 2 Bp.1.7 This test method specifies procedures for determiningcore gain from the corresponding biasing and inductionchanges, H and B.1.8 This test method covers test procedures and require-ments for evaluation of finished cores which are to be used inmagneti
8、c-amplifier-type applications. It is not a test for basic-material magnetic properties.1.9 This test method shall be used in conjunction withPractice A34/A34M.1.10 Explanations of symbols and abbreviated definitionsappear in the text of this test method. The official symbols anddefinitions are liste
9、d in Terminology A340.1.11 The values and equations stated in customary (cgs-emuand inch-pound) or SI units are to be regarded separately asstandard. Within this test method, SI units are shown inbrackets. The values stated in each system may not be exactequivalents; therefore, each system shall be
10、used independentlyof the other. Combining values from the two systems mayresult in nonconformance with this test method.1.12 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-p
11、riate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2A34/A34M Practice for Sampling and Procurement Testingof Magnetic MaterialsA340 Terminology of Symbols and Definitions Relating toMagnetic TestingA596/
12、A596M Test Method for Direct-Current MagneticProperties of Materials Using the Ballistic Method andRing Specimens3. Terminology3.1 DefinitionsBelow is a list of symbols and definitionsas used in this test method. The official list of symbols anddefinitions may be found in Terminology A340. (See Tabl
13、e 1where indicated).3.2 Symbols:1This test method is under the jurisdiction of ASTM Committee A06 onMagnetic Properties and is the direct responsibility of Subcommittee A06.01 on TestMethods.Current edition approved April 1, 2015. Published April 2015. Originallyapproved in 1969. Last previous editi
14、on approved in 2007 as A598/A598M02(2007). DOI: 10.1520/A0598_A0598M-02R15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe
15、 ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1A = cross-sectional area of test specimen corematerial, cm2m2.A1= ac ammeter for primary circuit, half-wave,average-responsive, A.A2= dc ammeter for H1biasing winding, A.A3
16、= dc ammeter for H2biasing winding, A.A4= dc milliammeter for ac voltage calibrator, V.BmaxBr= change in test specimen induction, under half-wave sinusoidal-current excitation specifiedfor this measurement.Bm= maximum induction in a sine-current SCM acflux-current loop Gauss Tesla (Note 1).Bp= maxim
17、um value of induction in the sine-current half-wave CM flux-current loop, for thereset test Gauss Tesla (Note 1).Br= residual induction in an ac sine-current flux-current loop Gauss Tesla.B = change in magnetic induction Gauss Tesla(Table 1).B1= change in induction in the flux-current loopduring H1t
18、est Gauss Tesla (Table 1).B2= change of induction in the flux current loopduring H2test Gauss Tesla (Table 1).CM = cyclic magnetization (see Terminology A340).D1and D2= solid state diodes or other rectifiers.D3to D6= silicon diodes.d = lamination thickness, cm m.Eavg= average value of voltage wavefo
19、rm, V.f = frequency of test, Hz.G = core gain B2 B1/H2,H1,GaussOeFTA/mG.Hc= coercive field strength in an SCM flux-currentloop Oe A/m.Hmax= maximum magnetic field strength in a sine-current SCM ac flux-current loop, Oe A/m(Note 1).Hp= maximum value of the sine-current ac mag-netic field strength for
20、 the CM reset tests, OeA/m (Note 1).H1= dc biasing (reset) magnetic field strength forthe H1test point, Oe A/m.H2= dc biasing (reset) magnetic field strength forthe H2test point, Oe A/m.H = change in dc biasing (reset) magnetic fieldstrength, Oe A/m.N1= test winding primary, ac excitation winding,tu
21、rns.N2= test winding primary, dc H1biasing winding,turns.N3= test winding primary, dc H2biasing winding,turns.N4= test winding secondary, B pickup winding,turns.SCM = symmetrical cyclic magnetization (see Termi-nology A340).NOTE 1Note that Hmaxand Bmax, as used in this test method, aremaximum points
22、 on the sine-current SCM or corresponding half-waveCM flux-current loops.Also, that Hpand Bpare maximum points on a CMflux-current loop corresponding to the ac half-wave sine current which isestablished in the exciting winding, N1, and held constant, during the dccurrent measurements for H1, H2,orH.
23、 These definitions are differentfrom those used for the same symbols in Terminology A340 for use withdc or sinusoidal-flux ac measurements.4. Summary of Test Method4.1 This test method uses the procedures commonly referredto as the “Constant Current Flux Reset Test Method”(C.C.F.R.). For graphic rep
24、resentation of the magnetic ampli-fier core test see Appendix X3.4.2 Under its provision, a specific predetermined value ofsinusoidal-current excitation, Hmax,(Table 2) is established andthe corresponding induction change is measured to determinethe value of maximum induction which is then designate
25、dBmax.4.3 The excitation is then changed to a unidirectionalhalf-wave sinusoidal current of the same magnitude as thatused for determining maximum induction. The change ininduction under this excitation then is measured to determinethe property designated (Bmax Br), or the change between themaximum
26、and residual values of induction.4.4 The ac half-wave sinusoidal-current excitation, as mea-sured in the ac exciting winding, is then increased to a newvalue, designated Hp(Table 2), which causes the ac inductionin the test specimen to rise to a new value which is designatedBp. A dc reverse-polarity
27、 magnetic field strength is thenapplied. The opposing dc magnetic field strength resets the fluxor induction in the core material, between each half cycle of acmagnetization, to a value that provides the specified B1induction change (Table 1). This dc excitation, designated H1,is the value required
28、to reset past Brto a point that provides thespecified change in induction of B1which is approximatelyTABLE 1 Standard Values of B, B1,andB2for the Commonly Used MaterialsCore MaterialA B1(for Test of 10.5) B2(for Test of 10.4) B or(B2 B1)kG Tesla kG Tesla kG TeslaSupermendur 14 1.4 28 2.8 14 1.4Orie
29、nted silicon-iron 10 1.0 20 2.0 10 1.050 % nickel-iron:Oriented 10 1.0 20 2.0 10 1.0Nonoriented 8 0.8 16 1.6 8 0.879 % nickel-iron 5 0.5 10 1.0 5 0.5Supermalloy 5 0.5 10 1.0 5 0.5AValues for other materials may be used by mutual agreement between seller and purchaser.A598/A598M 02 (2015)2equal to on
30、e third of 2 Bp. This value of H1has somecorrelation to the coercive field strength, Hc, of the material.4.5 Holding the same increased value of ac half-wavesinusoidal-current excitation, as described in 4.4, the dcreverse-polarity excitation is increased by the amount H andthe total value of dc rev
31、erse biasing (H1+ H) is designatedH2. It is the value of dc reverse biasing required to reset the fluxbetween ac magnetizing cycles to a value which provides thespecified total change in induction of B2(Table 1) that isapproximately equal to two thirds of 2 Bp.4.6 From the change in dc bias H and th
32、e changes ininduction B corresponding to the change between the H1andH2operating points, the core gain may be determined. It isusually reported as a H value for the core. When required forspecial reasons, it may be reported in terms of core gain, G (see11.5).4.7 It is standard practice to assign val
33、ues to the change ofinduction B1and B2(Table 1). This in turn determines themagnitude of the H1and H2biasing values corresponding tothese changes of induction.4.8 The normal test specimen may have any size or shape.When used specifically to evaluate materials for coreconstruction, it is limited in s
34、ize, weight, and method ofmanufacture.4.9 Heat treatment appropriate to the core material and coreconstruction may be required before test.5. Significance and Use5.1 The method of excitation simulates, to a practicaldegree, the operation of a magnetic core in a self-saturatingmagnetic amplifier. The
35、 properties measured are related to thequality of performance of the cores in magnetic amplifiers andare useful for the specification of materials for such cores.6. Apparatus (see Fig. 1)6.1 Sinusoidal Voltage SupplyThe source of excitationshall be an ac source of sinusoidal voltage which shall have
36、sufficient power to magnetize the largest core to be examinedto the levels of excitation as specified in Table 2. Its harmonicdistortion under load shall be less than 3 %. Its frequencyshould be constant to within 1 % or less. Standard testfrequencies are 60, 400, and 1600 Hz.6.2 Series Impedance, Z
37、1, or Resistor, R1This impedanceshould provide a voltage drop much larger than the voltageappearing across the excitation winding. Then, the distortion ofcurrent waveform as a result of the nonlinear impedance of thecore will be minimized. It may be a power resistor for smallsize cores. For larger c
38、ores, a series resonant circuit may beused, which reduces the voltage requirements of the powerTABLE 2 Standard Values of Peak Sine Current Magnetic Field Strength to Be Established for Testing the Commonly Used MaterialsCore MaterialAFull-Wave SCM Value of Hmax,(for Measurement of Bmaxin Test of 10
39、.2)Half-Wave CM Value of Hmax,(for Measurement of BmaxBrin Test of 10.3)Half-Wave CM Value of Hp, (forDetermining H1and H2or Hin Testing of 10.4 and 10.5 andadjustments of 10.1)Oe A/m Oe A/m Oe A/mSupermendur 3 240 3 240 6 480Oriented silicon-iron 3 240 3 240 6 48050 % nickel-iron 1 80 1 80 2 16079
40、% nickel-iron 0.5 40 0.5 40 1 80Supermalloy 0.25 20 0.25 20 0.5 40AValues for other materials may be used by mutual agreement between seller and purchaser.FIG. 1 Basic Diagram for Magnetic Amplifier Core TestA598/A598M 02 (2015)3source.The voltage across this impedance or a reactive elementin Z1must
41、 be greater than 25 times the average voltage inducedin the excitation turns, N1.6.3 Diodes (Note 2), D1and D1may be fast solid statedevices (Note 3), high-vacuum rectifiers, or Schottky rectifiers.NOTE 2During the interval between half-wave pulses, when theexcitation should be nominally zero, the a
42、verage leakage current shall beless than 0.1 % of the peak value of excitation current during a pulse.NOTE 3In the case of solid-state devices, a capacitative charging pulseof reverse current is sometimes observed, particularly at the higherfrequencies. Its integrated value, in ampere-seconds, at an
43、y test frequencyshall be limited to 1.0 % of the ampere-seconds of the exciting half-wave.6.4 The test fixture shall be composed of four sets ofwindings enclosing the core and a means of compensating forair-flux effect in induced voltage in N4.6.4.1 The exciting winding N1shall contain as small anum
44、ber of turns as practical to limit the exciting-currentwaveform distortion (see 6.1).6.4.2 The B-coil, pickup winding, N4, may contain anyconvenient number of turns. This winding shall be maintainedin a fixed position in relation to the excitation windings toeliminate variations in the air-cored ind
45、uctive or capacitivecoupling between them. Compensation for such coupling maybe accomplished with the air-cored bucking transformer, T1.NOTE 4The coils of the test fixture, including the air-cored buckingtransformer, T1, if used, shall be initially adjusted such that the voltagecoupling between the
46、exciting and pickup windings will be minimizedwhen no specimen is in place, and maximum full-wave exciting currentfor a given-size core is applied. The cancellation will be consideredadequate when the flux voltmeter indicates the equivalent of 15 G 0.0015T or less for that size core. The pickup circ
47、uit should be shielded fromstray fields, when this cannot be accomplished an adjustable coil may beused to buck out voltages picked up from external fields (see 10.1).6.4.3 The dc reset windings shall use a small number ofturns to help minimize the ac transformer loading of the testcore. The impedan
48、ces, Z2and Z3, described in 6.9 and 11.5 alsohelp to limit this loading effect to acceptable values.6.5 Flux Voltmeter:6.5.1 The flux voltmeter must respond to the true averagevalue of the pickup-winding voltage. The average value of thevoltage waveform is directly proportional to the total change o
49、fmagnetic flux in the core. The flux-voltmeter accuracy shall be1 % or better.NOTE 5For medium- or small-size cores, the ordinary rectifier acvoltmeters are not sensitive enough to accurately measure Bmax Br, andconventional average-responsive vacuum-tube voltmeters are subject toexcessive errors as a result of the extremely peaked nature of the voltagewaveform and to the high ratio of peak to average values. Therefore,special instruments must be used. Some typical schemes appear inAppendix X1.6.5.2 The
