ASTM A889 A889M-2014 Standard Test Method for Alternating-Current Magnetic Properties of Materials at Low Magnetic Flux Density Using the Voltmeter-Ammeter-Wattmeter-Varmeter Metho.pdf

1、Designation: A889/A889M 03 (Reapproved 2008)A889/A889M 14Standard Test Method forAlternating-Current Magnetic Properties of Materials at LowMagnetic Flux Density Using the Voltmeter-Ammeter-Wattmeter-Varmeter Method and 25-cm Epstein Frame1This standard is issued under the fixed designation A889/A88

2、9M; the number immediately following the designation indicates the yearof 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 () indicates an editorial change since the last revision or reapprov

3、al.1. Scope1.1 This test method covers tests for the magnetic properties of basic flat-rolled magnetic materials at power frequencies (25to 400 Hz) using a 25-cm Epstein test frame and the 25-cm double-lap-jointed core.1.2 The magnetic properties of materials are determined from measurements on Epst

4、ein core specimens with the core and testcoils treated as though they constituted a series-parallel equivalent circuit (Fig. A1.1) for the fundamental frequency of excitationwhere the apparent parallel inductance, L1, and resistance, R1, are attributable to the test specimen.1.3 This test method is

5、suitable for the determination of core loss, rms volt-amperes, rms exciting current, reactive volt-amperes,and related properties of flat-rolled magnetic materials under ac magnetization.1.4 The frequency range of this test method is normally that of the commercial power frequencies 50 to 60 Hz. It

6、is alsoacceptable for measurements at frequencies from 25 to 400 Hz. This test method is customarily used on nonoriented electricalsteels at inductions up to 10 kG 1.0 T and for grain-oriented electrical steels at inductions up to 15 kG 1.5 T.1.5 For reactive properties, both flux and current wavefo

7、rms introduce limitations. Over its range of useful inductions, thevarmeter is valid for the measurement of reactive volt-amperes (vars) and inductance permeability. For the measurement of theseproperties, it is suggested that test inductions be limited to values sufficiently low that the measured v

8、alues of vars do not differby more than 15 % (Note 1) from those calculated from the measured values of exciting volt-amperes and core loss.NOTE 1This limitation is placed on this test method in consideration of the nonlinear nature of the magnetic circuit, which leads to a differencebetween vars ba

9、sed on fundamental frequency components of voltage and current and current after harmonic rejection and vars computed from rmscurrent, voltage, and watt values when one or more of these quantities are nonsinusoidal.1.6 This test method shall be used in conjunction with Practice A34/A34M.1.7 Explanat

10、ion of terms, symbols, and definitions used may be found in the various sections of this test method. The officiallist of definitions and symbols may be found in Terminology A340.1.8 The values stated in either SI units or inch-pound units and equations stated in customary (cgs-emu and inch-pound) o

11、r SIunits are to be regarded separately as standard. Within this standard, SI units are shown in brackets except for the sectionsconcerning calculations where there are separate sections for the respective unit systems. The values stated in each system maynot be exact equivalents; therefore, each sy

12、stem shall be used independently of the other. Combining values from the two systemsmay result in non-conformance with the standard. Within this standard, SI units are shown in brackets.nonconformance with thisstandard.1.9 This standard does not purport to address all of the safety concerns, if any,

13、 associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to its use.2. Referenced Documents2.1 ASTM Standards:2A34/A34M Practice for Sampling and Procurement Test

14、ing of Magnetic Materials1 This test method is under the jurisdiction of ASTM Committee A06 on Magnetic Properties and is the direct responsibility of Subcommittee A06.01 on Test Methods.Current edition approved May 1, 2008May 1, 2014. Published June 2008May 2014. Originally approved in 1988. Last p

15、revious edition approved in 20032008 asA889/A889M-03. -03 (2008). DOI: 10.1520/A0889_A0889M-03R08.10.1520/A0889_A0889M-14.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. ForAnnual Book ofASTM Standardsvolume information, refer

16、to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all chang

17、es accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. Uni

18、ted States1A340 Terminology of Symbols and Definitions Relating to Magnetic TestingA343/A343M Test Method for Alternating-Current Magnetic Properties of Materials at Power Frequencies Using Wattmeter-Ammeter-Voltmeter Method and 25-cm Epstein Test Frame3. Significance and Use3.1 This test method may

19、 be used to determine the specific core loss, specific reactive power, specific exciting power, inductancepermeability, and impedance permeability of flat-rolled magnetic materials over a wide range of inductions and at frequencies upto 400 Hz for symmetrically magnetized test samples.3.2 These meas

20、urements are used by the producer and user of the flat-rolled material for quality control purposes. Thefundamental assumption inherent in these measurements is that they can be correlated with the electromagnetic characteristics ofa core fabricated from the flat-rolled material.4. Test Specimen4.1

21、Select and prepare the specimens for this test in accordance with Practice A34/A34M.5. Basic Circuit5.1 Fig. 1 shows the essential apparatus and basic circuit connections for this test. Terminals 1 and 2 are connected to a sourceof adjustable ac voltage of sinusoidal waveform of sufficient power rat

22、ing to energize the primary circuit without appreciablevoltage drop in the source impedance. All primary circuit switches and all primary wiring should be capable of carrying muchhigher currents than are normally encountered to limit primary circuit resistance to values that will not cause appreciab

23、le distortionof the flux waveform in the specimen when relatively nonsinusoidal currents are drawn. The ac source may be an electronicamplifier which has a sine-wave oscillator connected to its input and may include the necessary circuitry to maintain a sinusoidalflux waveform by using negative feed

24、back of the induced secondary voltage. In this case, higher primary resistance can be toleratedsince this system will maintain sinusoidal flux at much higher primary resistance. Although the current drain in the secondary isquite small, especially when using modern high-input impedance instrumentati

25、on, the switches and wiring should be selected tominimize the lead resistance so that the voltage available at the terminals of the instruments is imperceptibly lower than the voltageat the secondary terminals of the Epstein test frame.6. Apparatus6.1 The apparatus shall consist of as many of the fo

26、llowing component parts as are required to perform the desired measurementfunctions:6.2 Epstein Test Frame used for this test shall be in conformity with Annex A1.1 of Test Method A343/A343M.6.3 Voltage and Current Signal Scaling AmplifiersThese amplifiers are used to amplify or attenuate the voltag

27、e induced in thesecondary winding of the test frame and the voltage appearing across the potential terminals of the current shunt, RS, to ranges thatare suitable for electronic circuitry. The input circuitry of the voltage scaling amplifier must have an input impedance sufficientlyhigh that the conn

28、ection of the circuitry to the secondary winding of the test fixture does not change the terminal voltage of thesecondary by more than 0.05 %. The input circuitry of the current scaling amplifier must have an input impedance sufficiently highthat the connection of the circuitry to the potential term

29、inals of the current shunt does not change the terminal voltage by morethan 0.05 %. These amplifiers should have a linear frequency response up to about 20 times the test frequency and a gain accuracyof 0.1 % or better since all instrumentation may be, and preferably will be, connected to the output

30、 of these amplifiers. Care shouldbe exercised in the design of the amplifiers so that no phase shift is introduced into either the current or the voltage signal.6.4 Flux VoltmeterThe flux voltmeter for this test shall be a true average-responsive voltmeter calibrated to read average voltsFIG. 1 Basi

31、c Circuit for Wattmeter-Varmeter MethodA889/A889M 142times =2 pi/4, so that its indications will be identical with those of a true rms voltmeter on a pure sinusoidal voltage. Ahigh-input-resistance, multirange electronic meter with a full-scale accuracy rating of 0.25 % or better is the preferred in

32、strument.6.5 RMS VoltmeterAtrue rms-indicating voltmeter is needed if measurements of exciting current are to be made by measuringthe voltage drop across the potential terminals of the current shunt. A high-input-resistance, multirange electronic instrument witha full-scale accuracy of 0.25 % or bet

33、ter is required for this instrument. This voltmeter may also be used to measure the true rmsvoltage on the secondary of the Epstein test frame.6.6 Wattmeter and VarmeterA wattmeter is required for the measurement of core loss, and a varmeter is needed for themeasurement of reactive power. Since both

34、 are needed to make all measurements, the preferred instrumentation is onehigh-accuracy watt converter and a 90 phase-shift circuit to be used with the watt converter to measure the reactive power byshifting the phase of the secondary voltage.Alternatively, a wattmeter and a varmeter may be used as

35、required to make the desiredmeasurements. The rated accuracy of the wattmeter at the test frequency and unity power factor should be less than 0.25 % of fullscale. The power factor encountered by the wattmeter during a core loss test on a specimen is always less than unity and, atinductions well abo

36、ve the knee of the magnetization curve, approaches zero. The wattmeter must maintain adequate accuracy (1 %of reading) even at the most severe (lowest) power factor which will be presented to it. The accuracy requirements for the varmeterare the same as for the wattmeter.6.6.1 Watt Converter and Pha

37、se ShifterAn electronic watt converter that has two high impedance inputs and an output thatis proportional to the product of the signals that are applied to these inputs is the preferred instrument for the measurement of bothpower and reactive power. Such devices will probably require the use of sc

38、aling amplifiers for the voltage and current signals. Thisdevice, which is used for the measurement of power, is also used for the measurement of reactive power by shifting the phase ofthe voltage signal by 90.This can be done since the secondary voltage is essentially a pure sinusoid at low-to-mode

39、rate inductions,especially if negative feedback of the secondary voltage is used in the test power supply circuitry. The phase shifter that is usedfor this purpose should be a modern operational amplifier device which will accurately shift the phase of the input signal by exactly90 (tolerance of 0.1

40、) without affecting the amplitude of the signal.6.6.2 WattmeterAn electronic wattmeter with appropriate voltage and current ratings is the preferred instrument if the separatescaling amplifiers and phase-shift circuits are not used. The voltage input circuitry of the electronic digital wattmeter mus

41、t havean input impedance sufficiently high that the connection of the circuitry to the secondary winding of the test fixture does not changethe terminal voltage of the secondary by more than 0.05 %. The voltage circuit must also be capable of accepting the maximumpeak voltage which is induced in the

42、 secondary winding during testing. The current input circuitry of the electronic digitalwattmeter must have an input impedance of no more than 1 , and preferably no more than 0.1 . The current input circuitry mustalso be capable of handling the maximum rms current and the maximum peak current drawn

43、by the primary winding of the testfixture when core loss tests are being performed.6.6.3 VarmeterAn electronic instrument with appropriate voltage and current ratings is the preferred instrument if the separatescaling amplifiers and phase-shift circuits are not used. The accuracy and impedance chara

44、cteristics for the varmeter should be thesame as for the wattmeter described in 6.6.2.6.7 Current ShuntThis should be a noninductive resistor with an accuracy rating of 0.1 % or better. This resistor must becapable of handling the full exciting current of the test winding at the maximum test inducti

45、on without destructive heating or morethan specified loss of accuracy as a result of self heating. To avoid intolerable levels of distortion, the value of the resistor shouldbe reasonably low. However, a large value of resistance is desirable to maximize the signal and reduce the effects of noise. F

46、ixedresistors of 100, 10, and 1 are useful values. The selection of shunt should be guided primarily by the primary current and shouldbe the lowest value which retains an adequate signal-to-noise ratio.6.8 Power SupplyA source of sinusoidal test power of low-internal impedance and excellent voltage

47、and frequency stabilityis required for this test.Voltage stability within 0.1 % and frequency accuracy within 0.1 % should be maintained. Electronic powersources using negative feedback from the secondary winding of the test fixture to reduce flux waveform distortion have been foundto perform quite

48、satisfactorily in this test method.7. Procedure7.1 The first steps of procedure for this test method concern the preparations for testing Epstein specimens which are the samefor this method as given in 6.1, 6.2, and 6.3 of Test Method A343/A343M.7.2 DemagnetizationConnect the required apparatus as i

49、n Fig. 1 with the air-flux compensator in the test frame and Terminals1 and 2 connected to a suitable power source. With Switch S1 closed in the position to short RS, increase the voltage supplied tothe test frame from zero to a value in which the flux-voltmeter indicates an induction above the knee of the magnetization curve(where the exciting current increases sharply for a small increase in induction). At this point, decrease the voltage slowly andprogressively during an elapsed time of 5 to 10 s so that the induction will be reduced smoothly to a point bel