The magnetic fields to which equipment is subjected may influence the reliable operation of equipment and systems.
These tests are intended to demonstrate the immunity of equipment when subjected to power frequency magnetic fields related to the specific locations and installation condition of the equipment (e.g. proximity of equipment to the disturbance source). The power frequency magnetic field is generated by power frequency current in conductors or, more seldom, from other devices (e.g. leakage of transformers) in the proximity of equipment.
The EUT is subjected to a continuous magnetic field of 3 A/m or 10 A/m by use of an induction coil of standard dimensions 1m x 1m. The induction coil is then rotated by 90° in order to expose the EUT to the test field with different orientations. Three orthogonal planes are tested. The dwell time at each frequency is not less than the time necessary for the EUT to be exercised, and able to respond.
The preferential range of test levels, respectively for continuous and short duration application of magnetic field, applicable to distribution networks at 50 Hz and 60 Hz, is given below.
The magnetic field strength is expressed in A/m; 1 A/m corresponds to a free space induction of 1.26 µT.
Test Levels for continuous field