A harmonic current generator, comprising: a microcontroller board, an electronic relay, a data collection unit, a panel type computer, a bridge rectifier, a harmonic current withdrawal input, a voltage divider, a buffer and a current shunt, a resistor and a transistor characterized in that - the microcontroller board configured to control the generation of harmonic currents and frequency adaptive operating function, - the electronic relay configured to be controlled and switched over the digital output of the microcontroller, the resistor and the transistor, - the data collection unit to which the voltage divider, the buffer and the current shunt are connected for the measurement of voltage and current harmonics and which is configured to read the current and voltage values and to transfer such values to the panel type computer, - the harmonic current withdrawal input which is configured to permit applying voltage sources with different voltage and frequency value, - a resistive load, - the bridge type rectifier between the harmonic current withdrawal input and the resistive load configured to generate unidirectional currents at resistive load side - the panel type computer which includes software for making, presenting and recording the measurements; the external connections of which are ensured by USB connectors and a LAN connector; which is configured to display the measurement values to the user; and which has push-button for switching on/off operations - the harmonic current generator is frequency adaptive adapted to generate and measure harmonic currents from power supplies in the frequency range of 45 - 65 Hz. a microcontroller board, an electronic relay, a data collection unit, a panel type computer, a bridge rectifier, a harmonic current withdrawal input, a voltage divider, a buffer and a current shunt, a resistor and a transistor characterized in that - the microcontroller board configured to control the generation of harmonic currents and frequency adaptive operating function, - the electronic relay configured to be controlled and switched over the digital output of the microcontroller, the resistor and the transistor, - the data collection unit to which the voltage divider, the buffer and the current shunt are connected for the measurement of voltage and current harmonics and which is configured to read the current and voltage values and to transfer such values to the panel type computer, - the harmonic current withdrawal input which is configured to permit applying voltage sources with different voltage and frequency value, - a resistive load, - the bridge type rectifier between the harmonic current withdrawal input and the resistive load configured to generate unidirectional currents at resistive load side - the panel type computer which includes software for making, presenting and recording the measurements; the external connections of which are ensured by USB connectors and a LAN connector; which is configured to display the measurement values to the user; and which has push-button for switching on/off operations - the harmonic current generator is frequency adaptive adapted to generate and measure harmonic currents from power supplies in the frequency range of 45 - 65 Hz. - the microcontroller board configured to control the generation of harmonic currents and frequency adaptive operating function, - the electronic relay configured to be controlled and switched over the digital output of the microcontroller, the resistor and the transistor, - the data collection unit to which the voltage divider, the buffer and the current shunt are connected for the measurement of voltage and current harmonics and which is configured to read the current and voltage values and to transfer such values to the panel type computer, - the harmonic current withdrawal input which is configured to permit applying voltage sources with different voltage and frequency value, - a resistive load, - the bridge type rectifier between the harmonic current withdrawal input and the resistive load configured to generate unidirectional currents at resistive load side - the panel type computer which includes software for making, presenting and recording the measurements; the external connections of which are ensured by USB connectors and a LAN connector; which is configured to display the measurement values to the user; and which has push-button for switching on/off operations - the harmonic current generator is frequency adaptive adapted to generate and measure harmonic currents from power supplies in the frequency range of 45 - 65 Hz.