Development of a digital acquisition and processing system for partial discharges

A 2-channel data acquisition and processing system (DAPS) for partial discharges (PD) using a fast (20MSa/sec) digitizer (National Instruments 5102) has been developed which can acquire up to 16 million samples per channel (This represents 48 power line cycles (PLCs) at 60Hz), and simultaneously measure the phase '/spl phi/' and 'q' of PDs occurring on a given power line voltage and represent on a 3D plot of n(q,/spl phi/). This system has been tested, using artificially generated PD pulses at constant/variable 'q' and constant/variable '/spl phi/' and experimental data. Good agreement is obtained between the ranges of '/spl phi/' and 'q' in the artificially generated PDs, the raw input data and the resulting n(q,/spl phi/) plots, which is the number of PDs occuring in a given q and /spl phi/ window in a given period. The acquisition and processing programs developed in LabVIEW are optimized to handle 32 million (16 million/channel) samples of data. The resolution of this DAPS system is 50 mV in voltage and 1/spl deg/ in phase, and is limited by the voltage resolution of the digitizer, and the resolution in delay timing of the artificial PD generation system.