1、Designation: A 598/A 598M 02Standard Test Method forMagnetic Properties of Magnetic Amplifier Cores1This standard is issued under the fixed designation A 598/A 598M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision, the year of last
2、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. Scope1.1 This test method covers the determination of the mag-netic performance of fully processed cores for magneticamplifier-type
3、 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 full-wave sinuso
4、idal-current ex-citation, Hmax, this test method provides procedures of deter-mining the corresponding value of maximum induction, Bmax.1.5 At specified values of half-wave sinusoidal-current ex-citation, this test method provides procedures for determiningthe residual induction, Br.1.6 At increased
5、 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, DB1, becomes approxi-mately one
6、 third of the induction change, 2 Bp. It also providesprocedures for determining the additional dc reset magneticfield strength, DH, which, combined with H1, is the valuerequired to reset the induction in the core material past Brto avalue where the total induction change, DB2, becomes approxi-matel
7、y two thirds of the induction change 2 Bp.1.7 This test method specifies procedures for determiningcore gain from the corresponding biasing and inductionchanges, DH and DB.1.8 This test method covers test procedures and require-ments for evaluation of finished cores which are to be used inmagnetic-a
8、mplifier-type applications. It is not a test for basic-material magnetic properties.1.9 This test method shall be used in conjunction withPractice A 34/A 34.1.10 Explanations of symbols and abbreviated definitionsappear in the text of this test method. The official symbols anddefinitions are listed
9、in Terminology A 340.1.11 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 u
10、sed 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-pr
11、iate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:A 34/A 34M Practice for Sampling and Procurement Test-ing of Magnetic Materials2A 340 Terminology of Symbols and Definitions Relating toMagnetic Testing2
12、A 596/A 596M Test Method for Direct-Current MagneticProperties of Materials Using the Ballistic Method andRing Specimens23. Terminology3.1 Definitions Below is a list of symbols and definitionsas used in this test method. The official list of symbols anddefinitions may be found in Terminology A 340.
13、 (See Table 1where indicated).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 Oct. 10, 2002. Published November 2002. Originallypublished as A 598 69. Last previous
14、 edition A 598 92 (1997).2Annual Book of ASTM Standards, Vol 03.04.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2 Symbols:A = cross-sectional area of test specimen corematerial, cm2m2.A1= ac ammeter for primary circuit, half-wav
15、e,average-responsive, A.A2= dc ammeter for H1biasing winding, A.A3= dc ammeter for H2biasing winding, A.A4= dc milliammeter for ac voltage calibrator, V.BmaxBr= change in test specimen induction, underhalf-wave sinusoidal-current excitationspecified for this measurement.Bm= maximum induction in a si
16、ne-current SCMac flux-current loop Gauss Tesla (Note 1).Bp= maximum value of induction in the sine-current half-wave CM flux-current loop, forthe reset test Gauss Tesla (Note 1).Br= residual induction in an ac sine-current flux-current loop Gauss Tesla.DB = change in magnetic induction Gauss Tesla(T
17、able 1).DB1= change in induction in the flux-current loopduring H1test Gauss Tesla (Table 1).DB2= change of induction in the flux current loopduring H2test Gauss Tesla (Table 1).CM = cyclic magnetization (see TerminologyA 340).D1and D2= solid state diodes or other rectifiers.D3to D6= silicon diodes.
18、d = lamination thickness, cm m.Eavg= average value of voltage waveform, V.f = frequency of test, Hz.G = core gain DB2 B1/H2,H1,GaussOeFTA/mG.Hc= coercive field strength in an SCM flux-current loop Oe A/m.Hmax= maximum magnetic field strength in a sine-current SCM ac flux-current loop, Oe A/m(Note 1)
19、.Hp= maximum value of the sine-current ac mag-netic field strength for 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.DH = change in dc biasing (reset) magnetic f
20、ieldstrength, Oe A/m.N1= test winding primary, ac excitation winding,turns.N2= test winding primary, dc H1biasing winding,turns.N3= test winding primary, dc H2biasing winding,turns.N4= test winding secondary, DB pickup winding,turns.SCM = symmetrical cyclic magnetization (see Ter-minology A 340).NOT
21、E 1Note that Hmaxand Bmax, as used in this test method, aremaximum points 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
22、, N1, and held constant, during the dccurrent measurements for H1, H2,orDH. These definitions are differentfrom those used for the same symbols in Terminology A 340 for use withdc or sinusoidal-flux ac measurements.4. Summary of Test Method4.1 This test method uses the procedures commonly referredto
23、 as the “Constant Current Flux Reset Test Method”(C.C.F.R.). For graphic representation 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 i
24、s measured to determinethe value of maximum induction which is then designatedBmax.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
25、determinethe property designated (Bmax Br), or the change between themaximum 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
26、 specimen to rise to a new value which is designatedBp. A dc reverse-polarity 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 DB1induct
27、ion change (Table 1). This dc excitation, designated H1,is the value required to reset past Brto a point that provides theTABLE 1 Standard Values of DB, DB1, and DB2for the Commonly Used MaterialsCore MaterialADB1(for Test of 10.5) DB2(for Test of 10.4) DB or(DB2 DB1)kG Tesla kG Tesla kG TeslaSuperm
28、endur 14 1.4 28 2.8 14 1.4Oriented 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.A
29、598/A 598M 022specified change in induction of DB1which is approximatelyequal to one 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 dcre
30、verse-polarity excitation is increased by the amount DH andthe total value of dc reverse biasing (H1+ DH) 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 DB2(Table 1) th
31、at isapproximately equal to two thirds of 2 Bp.4.6 From the change in dc bias DH and the changes ininduction DB corresponding to the change between the H1andH2operating points, the core gain may be determined. It isusually reported as a DH value for the core. When required forspecial reasons, it may
32、 be reported in terms of core gain, G (see11.5).4.7 It is standard practice to assign values to the change ofinduction DB1and DB2(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
33、shape.When used specifically to evaluate materials for core construc-tion, it is limited in size, weight, and method of manufacture.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
34、 practicaldegree, the operation of a magnetic core in a self-saturatingmagnetic amplifier. The 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 Volt
35、age SupplyThe source of excitationshall be an ac source of sinusoidal voltage which shall havesufficient 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
36、 within 1 % or less. Standard testfrequencies are 60, 400, and 1600 Hz.6.2 Series Impedance, Z1, 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 impeda
37、nce of thecore will be minimized. It may be a power resistor for smallsize cores. For larger cores, a series resonant circuit may beused, which reduces the voltage requirements of the powersource. The voltage across this impedance or a reactive elementin Z1must be greater than 25 times the average v
38、oltage inducedin the excitation turns, N1.TABLE 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 10.2)Half-Wave CM Value of Hmax,(for Measurement of Bma
39、xBrin Test of 10.3)Half-Wave CM Value of Hp, (forDetermining H1and H2or DHin 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 % nickel-iron 0.5 40 0.5 40 1 80Supermalloy 0.25 20
40、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 TestA 598/A 598M 0236.3 Diodes (Note 2), D1and D1may be fast solid statedevices (Note 3), high-vacuum rectifiers, or Schottky rectifiers.NOTE 2Durin
41、g the interval between half-wave pulses, when theexcitation should be nominally zero, the average 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 chargingpulse of reverse current is sometimes obse
42、rved, particularly at the higherfrequencies. Its integrated value, in ampere-seconds, at any 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-fl
43、ux effect in induced voltage in N4.6.4.1 The exciting winding N1shall contain as small anumber 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
44、position in relation to the excitation windings toeliminate variations in the air-cored inductive 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 buckingtrans
45、former, T1, if used, shall be initially adjusted such that the voltagecoupling between the 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 vol
46、tmeter indicates the equivalent of 15 G 0.0015T or less for that size core. The pickup circuit 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 sm
47、all number ofturns to help minimize the ac transformer loading of the testcore. The impedances, 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 volta
48、ge. The average value of thevoltage waveform is directly proportional to the total change ofmagnetic 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,
49、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 input impedance of the flux voltmeter as con-nected to the pickup winding of the core shall exceed the valueof Z for any coil load as specified in 11.6.6.6 Calibration SourceAn adequate means shall be pro-vided to calibrate the flux voltmeter
