progress in power engineering is a continuous increase of so called non-linear loads in amount and power. Such loads in electrical networks result in high harmonics production of voltage which causes a number of negative effects in electrical network equipment functioning. The valve inverter and regulating devices are the most widely used among nonlinear loads. These devices operate at 380/220 V. This work is aimed at analyzing high harmonics currents consumed by modern widely used non-linear electrical devices (TVs, computers, washing machines etc.). It is also analyzed the operation mode of the induction motor which is also equipped with ACS 550 frequency converter. If a larger number of such devices is used it is necessary to minimize up to standard values high harmonics current and voltage in 380/220 V networks.