AS/NZS 61000.4.8:2012 PDF – Electromagnetic compatibility (EMC) Part 4.8: Testing and measurement techniques—Power frequency magnetic field immunity test

AS/NZS 61000.4.8:2012 PDF – Electromagnetic compatibility (EMC) Part 4.8: Testing and measurement techniques—Power frequency magnetic field immunity test
6.3 Inductive coil
6.3.1 Field distribution
For the two 1 turn standard coils 1 m × 1 m and 1 m × 2,6 m, the field distribution is known and shown in Annex B. Therefore, no field verification or field calibration is necessary, the current measurement as shown in Figure 4 is sufficient. Other coils such as multi-turn coils may be used in order to have a lower testing current, or for EUT not fitting into the two standard coils, inductive coils of different dimensions may be used. For these cases, the field distribution (maximum variation of ±3 dB) shall be verified.
6.3.2 Characteristics of the inductive standard coils 1 m × 1 m and 1 m × 2,6 m
The inductance for the 1 turn standard 1 m × 1 m coil is approximately 2,5 μH, for the 1 m × 2,6 m standard coil approximately 6 μH. The inductive coil shall be made of copper, aluminium or any conductive non-magnetic material, of such cross-section and mechanical arrangement as to facilitate its stable positioning during the tests. For continuous tests up to 1 00 A/m the cross section of aluminium should be 1 ,5 cm 2 and for short time test up to 1 000 A/m the cross section should be 4 cm 2 . The tolerance of the standard coils is ±1 cm, measured between the centre lines (centre of the cross section). The characteristics of inductive coils with respect to the magnetic field distribution are given in Annex B.
6.3.3 Characteristics of the inductive coils for table top and floor standing equipment
The list below gives the testing requirements for table top and floor standing equipment. a) Inductive coil for table-top equipment The inductive coil of standard dimensions for testing small equipment (e.g. computer monitors, watt-hour meters, transmitters for process control, etc.) has a square form with 1 m side. The test volume of the standard square coil is 0,6 m × 0,6 m × 0,5 m (height). Any other coils can be used to obtain a field homogeneity better than 3 dB. For example, a double coil of standard size (Helmholtz coil) could be used in order to obtain a field homogeneity better than 3 dB or for testing larger EUTs. The double coil (Helmholtz coil) shall be comprised of two or more series of turns, properly spaced (see Figure 7, Figure B.4, Figure B.5). The test volume of a double standard size coil, 0,8 m spaced, for a 3 dB homogeneity is 0,6 m × 0,6 m × 1 m (height). For example, the Helmholtz coils, for a 0,2 dB inhomogeneity, have dimensions and separation distances as given in Figure 7. No GRP is permitted as part of the coil nor on the insulating table below the EUT (see Figure 3).

Download