IEC 61000-4-7: General Guide on Harmonics and Interharmonics Measurements and Instrumentation
IEC 61000-4-7 is applicable to instrumentation intended for measuring spectral components in the frequency range up to 9 kHz which are superimposed on the fundamental of the power supply systems at 50 Hz and 60 Hz. For practical considerations, IEC 61000-4-7 distinguishes between harmonics, interharmonics and other components above the harmonic frequency range, up to 9 kHz.
IEC 61000-4-7 defines the measurement instrumentation intended for testing individual items of equipment in accordance with emission limits given in certain standards (for example, harmonic current limits as given in IEC 61000-3-2) as well as for the measurement of harmonic currents and voltages in actual supply systems. Instrumentation for measurements above the harmonic frequency range, up to 9 kHz is tentatively defined.