The magnetic fields to which equipment is subjected may influence the reliable operation of equipment and systems.

This magnetic field test is intended to demonstrate the immunity of equipment when subjected to impulse magnetic fields related to specific location and installation condition of the equipment (e.g. proximity of equipment to the disturbance source).

Pulse magnetic fields are generated by lightning strikes to buildings and other metal structures including aerial masts, earth conductors and earth networks and by initial fault transients in High Voltage sub stations. In High Voltage sub stations a pulse magnetic field may also be generated by the switching of High Voltage bus bars and lines by circuit breakers.

The test is mainly applicable to electronic equipment to be installed in electrical plants as well as in telecontrol centers. It is not relevant for distribution network equipment.