This paper presents methodology of defining the sources of interferences on the basis of measuring the quality of electrical energy and monitoring the selected parameters of voltage and current waveforms. The presented methodology was based on the example of industrial power network that supplied the new electroprecipitator cooperating with sulphuric acid recovery installation. After a few weeks of proper operation, the Ż electroprecipitator started to report frequent alarms that hindered its effective use. The measurements aimed at specifying the effect of the quality of electrical energy and disturbances occurring in the network on the alarms generated by the electroprecipitator automatic control system. The example shows that as a result of use sophisticated measuring equipment and the analysis of preliminary (short-term) measurements and long-term measurements with the appropriate setting of recording events, it is possible to confirm or reject the hypothesis about the negative effect of low quality energy on the electroprecipitator operation.