Problems and limitations of using DAQ systems based on PC plug-in boards for measurement of distorted waveforms in power networks

Active compensating devices based on power electronics have been developed and used to suppress distortion of the waveform in a power network, to improve the power factor and to minimize line losses. It is necessary to test their efficiency for different conditions and for their other qualities in the course of this development DAQ systems based on PC plug-in boards are often used in this case, but a number of limitations and imperfections have to be corrected or taken into account when realising of the virtual instrument in order to reach credible results. A detailed analysis of these influences is published in this paper, together with an example of a virtual instrument which was designed and realised for this purpose. It shows the precision of results and the time of data processing that can be achieved