Self-controlled pre-breakdown discharges in planar symmetry

Altafim, Ruy Alberto Corrêa; Ferreira, G.F. Leal; Giacometti, J.A.

doi:10.1109/94.660774

Cited by 5 publications

(9 citation statements)

References 5 publications

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“…As shown in Ref. [9], the charging voltage v DC is equal to 2v min in this case, as also illustrated in Fig. 3.…”

Section: Cmentioning

confidence: 83%

“…[9], was developed for impulse voltages and planar metal electrodes with an insulating barrier in between, its use to explain the charging process of air channels in dielectrics under high DC voltages can be justified as follows: The initial behavior at the beginning of the voltage impulses is similar to the onset of a high DC voltage from zero to any value. Furthermore, the channels can be approximated by the same geometry as the gaps in the model system as illustrated in Fig.…”

Section: Amentioning

confidence: 99%

“…However, when an insulating barrier is placed between the two electrodes, the charges trapped on the barrier could work as a control element, keeping the electric field inside the air gap practically constant and thus not allowing the transition into the breakdown regime. Such a dielectric-barrier-discharge (DBD) mechanism was observed during the charging of electrets with impulse voltages [11]. In these experiments, impulse voltages with peak values between V b and 2V b were applied to Teflon-FEP films and produced very uniformly charged samples whose charge levels depended linearly on the respective peak voltage, indicating that no breakdown occurred.…”

Section: Introductionmentioning

confidence: 98%

“…In 1998, Altafim et al [9] proposed a mechanism for the electrical pre-discharge across an air gap with insulating barriers between two electrodes. Their model was based on Townsend's gas-discharge mechanism with avalanche processes [10].…”

Section: Introductionmentioning

confidence: 99%

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Dielectric barrier discharges in multi-layer polymer ferroelectrets

Altafim

Basso

Qiu

et al. 2009

2009 IEEE Conference on Electrical Insulation and Dielectric Phenomena

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Cellular polymer foams with bipolar internal space charge are known as ferro-and piezoelectrets. Light emission from the internal voids of such polymer foams during electrical charging was already reported a few years ago and allows the investigation of the underlying dielectric barrier discharges. More recently, polymeric layer structures with well-defined voids were presented as an alternative to polymer-foam ferroelectrets. The simpler and more uniform voids in layered ferroelectrets are more suitable as model systems for dielectric barrier discharges across a single gap between two polymer layers and two external electrodes. In this contribution, we report and discuss first results from electrical and optical experiments and propose a theoretical explanation for the internal charging process (including eventual back discharges) in simple multi-layer ferroelectrets.

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“…As shown in Ref. [9], the charging voltage v DC is equal to 2v min in this case, as also illustrated in Fig. 3.…”

Section: Cmentioning

confidence: 83%

Section: Amentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Dielectric barrier discharges in multi-layer polymer ferroelectrets

Altafim

Basso

Qiu

et al. 2009

2009 IEEE Conference on Electrical Insulation and Dielectric Phenomena

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“…Contudo, devido ao elevado tempo de exposição e custos envolvidos no processo, Altafim et al (1992Altafim et al ( , 1998 …”

Section: Eletretosunclassified

Estudo dos piezoeletretos na detecção de descargas parciais em transformadores

Gutnik¹

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DedicatóriaA meus pais, Jorge e Vera. AgradecimentosPrimeiramente a Deus, pela misericórdia e graça que me alcançou e alcança a todo o que nele crê.Aos meus pais e a minha irmã, por estarem sempre comigo em qualquer situação.Aos grandes amigos, que não desistiram de serem meus grandes amigos.Ao professor Ruy Alberto Corrêa Altafim, pelo incentivo na realização deste projeto; ao professor Ruy Alberto Pisani Altafim pelo apoio. À professora Cacilda de Jesus Ribeiro, por conceder os sensores padrão na medição das descargas parciais.Ao professor Paulo Roberto Veronese, pela ajuda no desenvolvimento dos circuitos eletrônicos. Ao professor Marcelo Basílio Joaquim, pela ajuda no processamento de todas as medidas.À FAPESP, pela concessão da bolsa de mestrado e o auxílio de reserva técnica. À companhia ELEKTRO e a ANEEL, pelo financiamento do projeto.Por fim, a todos que contribuíram direta e indiretamente para a realização deste trabalho. A detecção de descargas parciais em transformadores consiste em importante metodologia de manutenção preventiva e preditiva. Neste contexto, a proposta desta pesquisa com o uso de sensores acústicos de piezoeletreto apresenta-se como um tema original e altamente relevante no desenvolvimento da tecnologia brasileira. A multidisciplinaridade do tema exigiu a realização de uma extensa pesquisa bibliográfica envolvendo os temas descargas parciais, métodos de detecção das descargas, piezeletricidade, eletretos, piezoeletretos, técnicas de manufatura do piezoeletreto proposto para a detecção de descargas e ferramentas de processamento de sinais, sendo a principal a deconvolução homomórfica. O Trabalho evoluiu para a elaboração de um primeiro protótipo laboratorial, constituído basicamente de um sensor piezoeletreto e um circuito amplificador, ambos abrigados em um invólucro metálico para assegurar uma blindagem eletromagnética. Os primeiros ensaios, em face da característica "sui generis" do protótipo, apontaram para a necessidade de novos circuitos e aprimoramento das metodologias desses ensaios laboratoriais, as quais também fazem parte do escopo deste trabalho. O desenvolvimento de um sistema de alta tensão autônomo, eletromagneticamente blindado e gerador de descargas elétricas impulsivas é um exemplo dos circuitos mencionados. A nova metodologia de testes buscou apresentar a evolução do comportamento acústico de uma descarga em diferentes ambientes, isto é, desde sinais sem ecos até sinais carregados com ecos e distorcidos pelo meio. Finalizando o trabalho, outra contribuição importante foi a decisão de analisar os sinais acústicos das descargas parciais pela deconvolução homomórfica, que mostrou ser essencial na remoção de ecos e na reconstrução do sinal acústico original. EpígrafePalavras Chave: Descargas parciais. Detecção acústica de descargas parciais. Partial discharges acoustic detection is a very important preventive and predictive maintenance tool for transformers. In this research, a new acoustic piezoelectric sensor, based in Brazilian technology, was presented. However, be...

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Electrode poling of cellular polypropylene films with short high-voltage pulses

Gerhard

Wegener

Wirges

et al.

Annual Report Conference on Electrical Insulation and Dielectric Phenomena

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Recently, piezoelectric cellular polypropylene (PP) was proposed as a new tjpe of quasi-ferroelectric. The observed hysteresis of the charge density as a function of the electric field could be explained as fielddependent charging inside the gasfiled voids. Interestingly enough, the measurable poling behavior of the macroscopic "dipoles" formed by charges that are trapped at the internal void surfaces is phenomenologically completely identical to the cooperative poling behavior of microscopic molecular dipoles in ferroelectric polymers. Therefore, it can be assumed that charge separation (or charge redistribution) and subsequent trapping in cellular PP is arather fast "switching" process.In order to examine the poling dynamics, we developed an experimental setup for pulsed poling. High-voltage pulses with a duration of 45 ps were applied in direct contact to two-side metallized cellular PP films. The pulsed poling yields piezoelectricity in the cellular PP. We study and discuss the dependence of the resulting piezoelectricity on the poling field. We also characterize the charge separation during application of higher electric poling fields of up to -10 kV in direct contact to the two-side metallized films for longer times.

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Self-controlled pre-breakdown discharges in planar symmetry

Cited by 5 publications

References 5 publications

Dielectric barrier discharges in multi-layer polymer ferroelectrets

Dielectric barrier discharges in multi-layer polymer ferroelectrets

Estudo dos piezoeletretos na detecção de descargas parciais em transformadores

Electrode poling of cellular polypropylene films with short high-voltage pulses

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