The device calculates 150 harmonic waveforms (10 kHz cut-off frequencies of anti-aliasing filters in input channels) and measures the following three-phase signal parameters: RMS values of currents and voltages, harmonic distortion factors such as THD (Total Harmonic Distortion), TIHD (Total Interharmonic Distortion), TWD (Total Waveform Distortion), active power, reactive power, apparent power, power factor and powers of fundamental components and selected harmonics, respectively.