IEC TR 63304-2021 pdf Methods of measurement of the magnetic properties of permanent magnet (magnetically hard) materials in an open magnetic circuit using a superconducting magnet

The magnetic dipole moment of the test specimen is detected by the voltage induced in the M coil due to the movement of the test specimen (see 4.4). The magnetic polarization of the test specimen is calculated from the magnetic dipole moment and the volume of the test specimen (see 7.2). For calibration aspects, see Clause 9. There are two methods different in modes of the movement of the test specimen: a) the SCM-VSM method: the test specimen is vibrated with a small amplitude in the M coil; b) the SCM-Extraction method: the test specimen is extracted through the M coil. NOTE There is another method to determine the magnetic polarization of the test specimen, i.e. the SCM- Magnetometer method. In this method, variation of the magnetic polarization of the stationary test specimen due to variation of the magnetic field strength applied to the stationary test specimen is detected by the voltage induced in the detection coil (J coil) (see Annex A). The measurements are carried out at an ambient temperature of (23 ± 5) °C. For permanent magnet materials which are known to have significant temperature coefficients α(J r ) and α(H cJ ), the temperature of the test specimen should be in a range between 19 °C and 27 °C and controlled within a tolerance of ±1 °C during the measurements in accordance with IEC 60404-5. The temperature of the test specimen should be measured by a non-magnetic temperature sensor. The demagnetization curve measured in an open magnetic circuit is influenced strongly by the self-demagnetizing field in the test specimen which opposes magnetization. In order to determine the intrinsic demagnetization curve of the permanent magnet material, a correction of the influence of the self-demagnetizing field (hereafter demagnetizing field correction) should be applied to the measured demagnetization curve (see Clause 11). Magnetic properties of the permanent magnet material are determined from the corrected demagnetization curve.