The RPDIV and the limits of its definition according to IEC 60034-18-41: the effect of voltage conditioning

This paper investigates the behavior of the Repetitive Partial Discharge Inception Voltage (RPDIV), which is defined as the voltage level at which at least one PD occurs in two voltage impulses (or at least five in ten - according to the Standard in use). It has been noted that, increasing by steps the voltage value above the PDIV level, sporadic bursts of PD occur. During the bursts, the conditions for RPDIV are met, but the PD activity is unstable and may well extinguish. Since the definition of RPDIV in the International Standards does not consider PD bursts, the results of RPDIV using different measurement systems might vary depending on how the RPDIV is calculated, affecting the overall comparability of the results. In the test reported here, it came out that conditioning the system above PDIV might be a suitable way to reduce the probability of observing PD bursts. By combining the behavior of PD activity and the impact of conditioning, suggestions to perform more accurate measurements are eventually derived.