On assessing the quality of the voltage in three-phase systems

Difference between real phase voltages and ideal ones given quantitative information about the quality of the voltages. Difference values δ are time functions, the behaviour of which depends on the nature of processes causing the voltage distortion. For assessing an auxiliary function is introduced called in all the modes 'modulus of an indicating voltage vector' (IVV). If the IVV in a three phase system is equal to the nominal value of the amplitudes of phase voltages, then this is a sign of the ideal quality of the voltage. The considered behaviour in variation of the modulus of a IVV shows that this artificially obtained indicator is highly informative.