Evaluation of surface changes in flat cavities due to ageing by means of phase-angle resolved partial discharge measurement

Abstract

This contribution deals with test probes with flat cavities (height of gap h = 0.5 mm), which arise in reality from delamination processes caused by thermal expansion. These test probes are aged by means of partial discharges (pds). The different changes on the cavity's surface, for example the development of surface conductivity, increased surface roughness or crystal growth, have an obvious impact on the results of the phase-angle resolved pd measurement. This impact is physically substantiated and interpreted, so that it is thus possible to 'look at' the cavity's surface and to assess the damaging relevance of a gap by means of phase-angle resolved pd measurement.

Time behavior of gas pressure and PD activity in insulation cavities under AC voltage

“…However, the difference may also be related to the modification of the PE-cavity interface properties (e.g. conductivity and roughness) induced by the PD [6,15]. Studies on the cavity surface conditions are going on while this paper is written.…”

“…surface chemistry, conductivity and roughness) [6][7][8][9][10][11]. This in turn has an influence on PD activity in terms of PD inception voltage, repetition rate, phase and magnitude distribution, etc.. Consequently, an ageing model would require a description of the gas and cavity surface conditions in order to reproduce as closely as possible the PD pattern at all aging states, thus enabling a prediction of the time needed to produce a sufficiently large degradation of the cavity surface which could promote to electrical treeing.…”

Degradation of solid dielectrics due to internal partial discharge: some thoughts on progress made and where to go now

“…The interaction between PD in a cavity and the surrounding dielectric is complex and many effects have been identified and studied. Part of the complexity stems from the fact that the dielectric is changed (aged) due to the PD activity but at the same time the PD mechanism is affected by the aging dielectric [8,9].…”

“…Temmen [9] recorded the PD phase patterns during the consecutive stages of the PD induced aging process. The changes of the patterns were attributed to changes occurring at a (flat) mica-epoxy resin cavity surface.…”

Estudo dos piezoeletretos na detecção de descargas parciais em transformadores

“…A interação entre a atividade de DP numa cavidade ou vacúolo e a região dielétrica que a cerca é bastante complexa e muitos parâmetros relacionados a isto foram identificados e estudados. Parte da complexidade deriva do fato que o material dielétrico é modificado (envelhece) em virtude da atividade de descarga parcial, ao mesmo tempo em que os mecanismos da descarga parcial mudam com o envelhecimento do material dielétrico (MORSHUIS, 1993(b);TEMMEN, 2000). Porém, quando a cavidade está constantemente submetida a estresse elétrico e a ocorrência de DPs, pode ser estabelecida uma relação entre os mecanismos de descarga tipo avalanche e canal com estágios de envelhecimento do material (MORSHUIS, 1993(MORSHUIS, (a), 1995.…”