A method and an arrangement for limiting the interference to a common electric power network, generated by a power electronics device, e.g. a frequency converter, which power electronics device comprises of at least one switch type component being able to change the output voltage value at a predefined permissible switching frequency range. The method comprises scanning through the permissible switching frequency range, recording measured common mode current values as a function of the switching frequency, and setting the final switching frequency of the switch type component out of a value where a local maximum value of the common mode current has been recorded.