Electrical aging and life models: the role of space charge

Abstract

This paper has the aim of providing a view of a lively debated topic which has broad impact on the design of electrical apparatus and new insulating materials, that is, the interaction between space charge and aging processes of polymeric insulation. Aging models developed in recent decades that consider explicitly or implicitly the contribution of space charge to insulation degradation, under both dc and ac voltage, are dealt with, with the intention to point out their range of validity. Some conventional phenomenological models that have been used for much more than two decades without referring to space charges can be exploited to account for electrical field and activation energy modification due to space charge. These, together with models conceived considering space charges as the driving force for aging, are especially examined. In addition, recent models that disregard the action of space charge as an ageing factor, but consider space charge as the consequence of degradation processes are also discussed.

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“…Also, it is noticed that increasing TiO 2 nanoparticles from 5%wt up to 10%wt decreasing charge density in the nanocomposite molecules at electrodes. On the other wise, Figure's (8,9) show the effect of raising concentration of Al 2 O 3 nanofillers in polyvinyl chloride increases its dielectric constant as shown in table I, the charging density at the cathode is more than charging density at the anode with increasing Al 2 O 3 nanoparticles percentage and impulse applied voltages; especially through 1%wt specimens and there is no heterocharge accumulated between electrodes through 5%wt and 10%wt of aluminum oxide. Also, it is noticed that there is no increasing in charge density at both electrodes with remaining impulse voltages at cathode and there is no hetero-charge accumulated between anode and cathode.…”

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“…charge density vs. distance) and their evolution as a function of the electric field, quantities were extracted from space charge profiles detected by PEA, such as threshold for space charge accumulation. This is a fundamental parameter for the characterization of insulating material for DC applications, because, as mentioned above, the presence of space charge in the insulation can modify substantially the electric field distribution and, hence, the insulation life [10]- [12]. The space charge measurements were performed on thermally pre-treated specimens (72 hours at 60° C in vacuum).…”

The chemical analysis and replication of polydimethylsiloxane by-products located within electrical trees

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