Under normal conditions, the stable magnetic field generated by the industrial frequency current is relatively small, but under fault conditions, the magnetic field generated by the current is relatively strong, however, the duration is relatively short (about a few milliseconds for the protection of fuses; for the protection of relays, it may be up to 3~5 seconds). The GB/T17626#8 and IEC61000-4-8 standards have been published in order to check the immunity of equipment and systems to magnetic field disturbances when there is an industrial frequency current passing through nearby conductors. Some equipment, such as computer monitors, electronic microscopes and other types of equipment under the action of magnetic fields at work will produce jitter in the electron beam; on the meter and other types of equipment, under the action of magnetic fields at work will produce disorders in the program, the loss of memory data and metering errors; on the internal Hall components and other types of magnetic field-sensitive components of the device, under the action of the magnetic field will be a malfunctioning (inductive proximity switches as an example, may be inaccurate positioning). For devices with Hall elements and other magnetic field-sensitive devices, false operation may occur under the action of magnetic field (inductive proximity switches, for example, may have inaccurate positioning). Therefore, it is of special significance to carry out the immunity test of magnetic field harassment on the above equipment with an industrial frequency magnetic field generator.
The I.F. magnetic field immunity test is designed to evaluate the performance of domestic, commercial and industrial electrical and electronic equipment exposed to I.F. (continuous and at-time) magnetic fields.
Known laboratories capable of conducting IF magnetic field immunity tests include the Environmental Reliability and Electromagnetic Compatibility Test Center, the Aerospace Environmental Reliability Test and Inspection Center, and others.