The IEC 61000-4-9 ( Impulse magnetic Field Immunity Test) is an EMC standard by the International Electrotechnical Commission specifies the immunity requirements, test procedures, and range of recommended test levels for equipment subjected to impulse magnetic disturbances mainly encountered in industrial installations, power plants, railway installations, and medium voltage and high voltage sub-stations.

These impulse fields are undesirable and are mainly caused by:

• Industrial installations and power plants;
• Medium voltage and high voltage substations.

Under IEC 61000-4-9 the EUT is subjected to an array of magnetic fields. These may influence the reliable operation of equipment and systems. The following are some of the IEC standard test procedures to demonstrate the immunity of equipment when subjected to impulse magnetic fields: 

• Immersion method – In this method, the magnetic field is applied by placing EUT in the center of an induction coil.
• Proximity method – In this method, the magnetic field is applied to the EUT, where a small induction coil is moved along the side of the EUT to detect particularly sensitive areas.

For accurate and reliable test results, the standard has specified test procedures for verification of the laboratory reference conditions. IEC 61000-4-9 test results are classified in terms of the loss of function and/or degradation of performance of the EUT. The EUT is made to run on full load or normal conditions to get the realistic immunity test results. 

Click here to view the IEC 61000-4-9 Testing labs.