Resonant PD signal decoupling circuit for rapidly changing voltages

A method for electrical detection of partial discharges (PDs) when the voltage is rapidly changing has recently been presented. The method is based on moderately sharp frequency filters in the PD decoupler, highresolution digitizers and time-domain stochastic filtering. A limitation with high-resolution digitizers is their lower sample rate. To enable use of faster digitizers with less resolution, the filters in the PD decoupler must be optimized for voltage slew rate and PD magnitude. In this paper, the design of a versatile PD coupler filter is discussed. Although entirely passive, the filter suppression can be made to change two orders of magnitude in half a decade of frequency. Thus, a lowresolution fast digitizer can be employed with which ns variations in the PD duration can be studied. The filter can be optimized by changing a few parameters only. Examples are presented which illustrates the advantages of this modified PD decoupler on actual measured PD