Provides guidance on the instrumentation intended for measuring voltage or current components with frequencies in the range of d.c. to 2500 Hz which are superimposed on the voltage or current at the power supply frequency. The Standard also provides guidance on measurement instrumentation intended for testing individual items of equipment in accordance with emission limits given in Standards as well as for the measurement of harmonic voltages and currents in actual supply systems. Frequency domain and time domain instrumentation are both considered in this Standard. This Standard is technically equivalent to and has been reproduced from IEC 61000-4-7:1991.