IEC 61000-4-10 defines the immunity test in which a damped oscillatory magnetic field is applied to equipment. Two frequencies are used: the 1 MHz component, which is associated with the transient magnetic fields produced in high-voltage substations during switching operations and fault clearing, and the 100 kHz component, which represents similar phenomena on medium-voltage installations and in industrial plants containing large thyristor-driven loads. The standard specifies the generation and the waveform of the field, the coil arrangements by which a uniform field over the equipment under test is obtained, and the field strength levels from which the applicable severity is chosen. It explains how the coil is positioned relative to the equipment, how the test is performed for the different orientation of the field with respect to the three axes of the enclosure, and how the field strength is measured and verified. Equipment performance is assessed against functional criteria, and the test is applied in combination with the power frequency and impulse magnetic field tests of the same series to cover the full range of magnetic disturbances encountered in service.