The author presents a bibliography and survey of the literature concerned with theory and measurement of the stochastic behavior of pulsating partial-discharge (PD) phenomena that can occur when insulation is subjected to electrical stress. The types of PD phenomena considered include AC and DC generated electron avalanches, pulsating positive and negative corona in gases, and PD that occur in liquid media and in the presence of solid dielectric surfaces. The basic physical mechanisms of discharge initiation, growth, and memory propagation that determine the probability distributions for pulse occurrence times and pulse amplitudes are discussed. Consideration is also given to special problems associated with the measurement and interpretation of data on the various statistical properties of PD phenomena. >

Stochastic properties of partial-discharge phenomena

Stochastic Properties of Partial Discharge Phenomena

An overview of automated recognition of partial discharges (PD) is given. The selection of PD patterns, extraction of relevant information for PD recognition and the structure of a data base for PD recognition are discussed. Mathematical methods useful for the design of the data base are examined. Classification methods are interpreted from a geometrical point of view. Some problems encountered in the automation of PD recognition are addressed. >

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Automated recognition of partial discharges

The effects of long exposure of epoxy resin surfaces to partial discharges under AC field stress were examined. The use of electrical pulse measuring techniques in conjunction with light emission measurements using a photomultiplier tube, which allowed simultaneous detection of both spark and glow discharges, permitted the establishment of a definite transition from spark to glow discharges. Spark discharges were found to be responsible for the initial surface modification leading to increased surface conductivity, which favored the transition to a pulseless glow type discharge within the cavity. The latter form of discharge was found to prevail over the major portion of the remainder of the exposure period. >

Spark-to-glow discharge transition due to increased surface conductivity on epoxy resin specimens

Long-time accelerated aging tests in a laboratory environment have been conducted on generator stator insulation to identify meaningful diagnostic measures for the assessment of degradation and identification of aging mechanisms. A plurality of techniques are investigated and diagnostic parameter, the dynamic stagnation voltage, which appears to be correlated with delimination in the epoxy-mica structure, is proposed. The results provide a basis for an online interpretation method for insulation condition. >

Assessment of deterioration in epoxy/mica machine insulation

The methods of analysing the various individual partial discharge patterns using discriminating pulse amplitude techniques, in particular a multi-channel analyser (MCA) with several hundred pre-selected amplitude gates/channels, is in many instances a powerful method for assessing the relative quality of electrical insulating materials and systems to discharge attack.

http://ieeexplore.ieee.org/iel7/7464418/7464419/07464439.pdf

W.K. Hogg

Papers

The relationship of partial discharge amplitude distributions with dielectric damage at different levels of voltage and frequency