System for measuring conditional amplitude, phase, or time distributions of pulsating phenomena

Abstract

A detailed description is given of an electronic stochastic analyzer for use with direct “real-time” measurements of the conditional distributions needed for a complete stochastic characterization of pulsating phenomena that can be represented as random point processes. The measurement system described here is designed to reveal and quantify effects of pulse-to-pulse or phase-to-phase memory propagation. The unraveling of memory effects is required so that the physical basis for observed statistical properties of pulsating phenomena can be understood. The individual unique circuit components that comprise the system and the combinations of these components for various measurements, are thoroughly documented. The system has been applied to the measurement of pulsating partial discharges generated by applying alternating or constant voltage to a discharge gap. Examples are shown of data obtained for conditional and unconditional amplitude, time interval, and phase-of-occurrence distributions of partial-discharge pulses. The results unequivocally show the existence of significant memory effects as indicated, for example, by the observations that the most probable amplitudes and phases-of-occurrence of discharge pulses depend on the amplitudes and/or phases of the preceding pulses. Sources of error and fundamental limitations of the present measurement approach are analyzed. Possible extensions of the method are also discussed.

Research for electric energy systems - an annual report

“…It was determined that the bimodal structure in po(Q +) is due primarily to the difference in total charge on the positive half-cycle resulting from one and two discharge events. This characteristic has also been seen in experimental results [71]. Because the distribution functions shown in Figures 11-13 are not independent when memory is important, the bimodal structure originating in po(Q +) can also be reflected in the other unconditional distributions such as P0(¢i-).…”

Importance of unraveling memory propagation effects in interpreting data on partial discharge statistics

“…The existence and relative significance of memory effects can be established by determining various conditional pulse-amplitude and phase-of-occurrence distributions. Detailed definitions and discussions of the various properties of conditional distributions are given elsewhere [13][14][15][16] and will not be repeated here. The purpose of this discussion is to consider some specific examples that are easily interpreted and unequivocally indicate the existence of memory effects for ac-generated PD.…”

“…The~t control logic circuit is similar to that previously described [14]. Details of this measurement system are given elsewhere [16]. Table 1.…”

“…Before one can assess the reliability of signatures based on pulse phase or amplitude distributions, it is essential to understand more about the basic mechanisms that determine the stochastic behavior of PD phenomena under different conditions. It has been shown [13][14][15][16][17][18][19] that pulsating PD is in general a complex stochastic process characterized by significant effects of memory propagation. From measurement of conditional phase-of-occurrence and pulse amplitude distributions it can be shown that the amplitude and phase-of-occurrence of any discharge event depends on the amplitudes and phases-of-occurrence of previous events.…”

A brief history of gaseous dielectrics research at NIST

“…In response to' this need, NIST developed an electronic system for measuring conditional amplitude, phase, and time probability distributions of pulsating phenomena [13].…”