Pulsed Magnetic Field

The pulsed magnetic field tests are intended to demonstrate the immunity of equipment to this kind of disturbances related to the specific location and installation condition of the equipment (e.g. proximity of equipment to the disturbance source). The magnetic field strength ranges from a few hundreds A/m up to the order of 1 kA/m in the proximity of earth conductors, intended for protection from lightning and metal structures involved in the conduction of such transient currents. Lower field strength values are representative of environments for equipment and systems installed inside buildings.

Pulse magnetic fields are generated by lightning strokes on buildings and other metal structures including aerial masts (GSM), earth conductors and earth networks and by initial faults transients in low-voltage, medium-voltage and high-voltage electrical systems. In high-voltage sub-stations, a pulse magnetic field may also be generated by the switching of high-voltage busbars and lines by circuit breakers.

The test is mainly applicable to electronic equipment to be installed in electrical plants as well as in telecontrol centres. It is not relevant for distribution network equipment. Equipment shall not become dangerous or unsafe as a result of the application of the tests.

When performing the tests it is required that the EUT and possible auxiliary equipment are exercising all normal modes of operation. The test results may be classified on the basis of the operating conditions and functional specifications of the EUT, according to the following performance criteria:

• (A) Normal performance within the specification limits;
• (B) Temporary degradation or loss of function or performance which is self-recoverable;
• (C) Temporary degradation or loss of function or performance which requires operator intervention or system reset;
• (D) Temporary degradation or loss of function or performance which is not recoverable, due to damage of equipment (components) or software, or loss of data.