Значение и использование
Permeameters require the use of yokes to complete the magnetic circuit and are therefore inherently less accurate than ring test methods. Refer to Test Method A596/A596M for further details on ring test methods. However, when testing certain shapes as bars or when magnetic field strength in excess of 200 Oe [15.9 or more kA/m] are required, permeameters are the only practical means of measuring magnetic properties.
This test method is suitable for specification acceptance, service evaluation, research and development and design.
When the test specimen is fabricated from a larger sample and is in the same condition as the larger sample, it may not exhibit magnetic properties representative of the original sample. In such instances the test results, when viewed in context of past performance history, will be useful for judging the suitability of the material for the intended application.
1.1 This test method provides dc permeameter testsfor the basic magnetic properties of materials in the form of bars,rods, wire, or strip specimens which may be cut, machined, orground from cast, compacted, sintered, forged, extruded, rolled, orother fabricated materials. It includes tests for determination ofthe normal induction under symmetrically cyclically magnetized(SCM) conditions and the hysteresis loop (B-H loop) taken underconditions of rapidly changing or steep wavefront reversals of thedirect current magnetic field strength.
1.2 This test method shall be used in conjunctionwith Practice A34/A34M.
1.3 This test method covers a range of magneticfield strength in the specimen from about 0.05 Oe [4 A/m] up toabove 5000 Oe [400 kA/M] through the use of several permeameters.The separate permeameters cover this test region in severaloverlapping ranges.
1.4 Normal induction and hysteresis properties maybe determined over the flux density range from essentially zero tointrinsic saturation for most materials.
1.5 Recommendations of the useful magnetic fieldstrength range for each of the permeameters are shown in Table 1 .Also, see Sections 3 and 4 for general limitations relative to theuse of permeameters.
1.6 The symbols and abbreviated definitions used inthis test method appear with Fig. 1 and in appropriate sections ofthis document. For the official definitions, see Terminology A340. Note that the term flux density used in this document issynonymous with the term magnetic induction.
1.7 WarningMercury has been designatedby EPA and many state agencies as a hazardous material that cancause central nervous system, kidney, and liver damage. Mercury, orits vapor, may be hazardous to health and corrosive to materials.Caution should be taken when handling mercury andmercury-containing products. See the applicable product MaterialSafety Data Sheet (MSDS) for details and EPA’s website(http://www.epa.gov/mercury/faq.htm) for additionalinformation. Users should be aware that selling mercury ormercury-containing products, or both, in your state may beprohibited by state law.
1.8 The values and equations stated in customarycgs-emu and inch-pound or SI units are to be regarded separately asstandard. Within this standard, SI units are shown in bracketsexcept for the sections concerning calculations where there areseparate sections for the respective unit systems. The valuesstated in each system may not be exact equivalents; therefore, eachsystem shall be used independently of the other. Combining valuesfrom the two systems may result in nonconformance with thisstandard.
1.9 This standard does notpurport to address all of the safety concerns, if any, associatedwith its use. It is the responsibility of the user of this standardto establish appropriate safety and health practices and determinethe applicability of regulatory limitations prior touse.
TABLE 1 Permeameters
|Permeameter||UsefulMagnetic Field Strength RangeA||H Measuring|
Super H adapterC
|IEC Type A||0.1/2500||0.008/200||HC,HP||no||yes||IEC 60404-4|
|IEC Type B||0.1/630||0.008/50||RCC||no||no||IEC 60404-4|
AAlthough the permeameters are capable of being used at the lowerend of the measurement range, the measurement accuracy isreduced.
BImagnetizing current; HCfixed H coil; FCflip coil; HPHall probe; RCCRogowski-Chattock coil.
CFahy permeameters require a standard of known magnetic propertiesfor calibration of the H coil.
Note—FIG. 1 Basic Circuit UsingPermeameter
A1Multirange ammeter (maincurrent)
A2Multirange ammeter(hysteresis current)
BFlux density test position for SwitchS3
HMagnetic field strength test positionfor Switch S3
N2Flux sensing (B) coil
N3Magnetic field strengthsensing coil
R1Main current controlrheostat
R2Hysteresis currentcontrol rheostat
S1Reversing switch formagnetizing current
S2Shunting switch forhysteresis current control rheostat