Designation: A 889/A 889M – 03
Standard Test Method for
Alternating-Current Magnetic Properties of Materials at Low
Magnetic Flux Density Using the Voltmeter-Ammeter-
Wattmeter-Varmeter Method and 25-cm Epstein Frame
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This standard is issued under the fixed designation A 889/A 889M; 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
1.1 This test method covers tests for the magnetic properties
of basic flat-rolled magnetic materials at power frequencies (25
to 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 Epstein core specimens with the core
and test coils treated as though they constituted a series-parallel
equivalent circuit (Fig. A1.1) for the fundamental frequency of
excitation where the apparent parallel inductance, L
1
, and
resistance, R
1
, are attributable to the test specimen.
1.3 This test method is suitable for the determination of core
loss, rms volt-amperes, rms exciting current, reactive volt-
amperes, and related properties of flat-rolled magnetic materi-
als 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 is also
acceptable for measurements at frequencies from 25 to 400 Hz.
This test method is customarily used on nonoriented electrical
steels 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 waveforms
introduce limitations. Over its range of useful inductions, the
varmeter is valid for the measurement of reactive volt-amperes
(vars) and inductance permeability. For the measurement of
these properties, it is suggested that test inductions be limited
to values sufficiently low that the measured values of vars do
not differ by more than 15 % (Note 1) from those calculated
from the measured values of exciting volt-amperes and core
loss.
NOTE 1—This limitation is placed on this test method in consideration
of the nonlinear nature of the magnetic circuit, which leads to a difference
between vars based on fundamental frequency components of voltage and
current and current after harmonic rejection and vars computed from rms
current, 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 A 34/A 34M.
1.7 Explanation of terms, symbols, and definitions used may
be found in the various sections of this test method. The official
list of definitions and symbols may be found in Terminology
A 340.
1.8 The values and equations stated in customary (cgs-emu
and inch-pound) or SI units are to be regarded separately as
standard. Within this standard, 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 noncon-
formance with this standard.
1.9 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 appro-
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to its use.
2. Referenced Documents
2.1 ASTM Standards:
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A 34/A 34M Practice for Sampling and Procurement Test-
ing of Magnetic Materials
A 340 Terminology of Symbols and Definitions Relating to
Magnetic Testing
A 343 Test Method for Alternating-Current Magnetic Prop-
erties of Materials at Power Frequencies Using Wattmeter-
Ammeter-Voltmeter Method and 25-cm Epstein Test
Frame
3. Significance and Use
3.1 This test method may be used to determine the specific
core loss, specific reactive power, specific exciting power,
inductance permeability, and impedance permeability of flat-
rolled magnetic materials over a wide range of inductions and
at frequencies up to 400 Hz for symmetrically magnetized test
samples.
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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 Oct. 1, 2003. Published November 2003. Originally
approved in 1988. Last previous edition approved in 1998 as A 889 – 93 (1998).
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
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