GB/T 17626.10 is the Chinese national standard for the damped oscillatory magnetic field immunity test and is an identical adoption of IEC 61000-4-10, so the field waveform, the coil arrangements and the severity levels follow the international document exactly. It is the text cited by Chinese product standards and by the certification schemes that equipment must satisfy for the domestic market, and Chinese laboratories are accredited against it. The test reproduces the transient magnetic fields produced in high-voltage substations during switching and fault clearing, at 1 MHz, and the comparable phenomena on medium-voltage installations and near thyristor-driven industrial loads, at 100 kHz. The standard defines the generation and the shape of the field, the Helmholtz and induction coils that produce a uniform field over the equipment, the field strengths used as severity classes, the orientation of the equipment in the field and the method of measuring the field strength, with performance judged against functional criteria.