Ms. Rohitha Dhara Profile

Rohitha Dhara

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Publications (7)

SPIE Journal Paper | 30 November 2015

Effect of variation in main field and nanoparticle content on the partial discharge characteristics of polypropylene nanocomposites

Md Afzalur Rab, Rohitha Dhara, Prathap Basappa, Anil Poda

JNP, Vol. 9, Issue 01, 093588, (November 2015) https://doi.org/10.1117/12.10.1117/1.JNP.9.093588

KEYWORDS: Nanoparticles, Electrodes, Polymers, Dielectrics, Nanocomposites, Particles, Shape analysis, Polymer thin films, Palladium, Statistical analysis

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SPIE Journal Paper | 24 November 2015

Role of type and content of nanoparticles on certain dielectric characteristics of polypropylene nanocomposites

Md Rab, Rohitha Dhara, Prathap Basappa

JNP, Vol. 9, Issue 01, 093589, (November 2015) https://doi.org/10.1117/12.10.1117/1.JNP.9.093589

KEYWORDS: Polymers, Nanoparticles, Dielectrics, Resistance, Statistical analysis, Nanocomposites, Electrodes, Interfaces, Shape analysis, Mica

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In practical power apparatus, the insulation under high electrical stress is exposed to recurrent partial discharge pulses, and the utility of the insulation is largely determined by its resistance to aging by partial discharges. The occurrence of partial discharges is largely governed by a combination of the applied field and the space charges that are generated due to these discharges. Since the space charge profile generated by a time-varying voltage and, thus, the resultant field would be much different from that of a constant ac voltage, this work investigates how the partial discharge characteristics, the resulting erosion, and remnant breakdown strength change when samples are aged with a step voltage profile. Since incorporation of nanofillers in controlled quantities is known to alter the space charge formation and transportation, this work also focuses on understanding the effect of incorporation of different quantities of natural (cloisite 20 A° natural montmorillonite clay) and synthetic (tetrasilisic fluro mica) nanofillers into a pure polypropylene matrix on its partial discharge characteristics and the resulting effect when aged under the application of step voltages. Isotactic polypropylene films with different filler concentrations of natural and synthetic nanofillers were aged. The cumulative effect of the partial discharge behavior was investigated through analysis of the erosion depth produced by these pulses on sample surface and remnant breakdown strengths of aged samples. Results indicate that maximum partial discharge magnitudes become prominently lower in nanofilled samples as compared to that of base polypropylene only when the applied voltage is beyond a certain level. Up to that voltage, the average discharge magnitude is significantly lower in samples whose filler content is below a percolation threshold, but above that voltage, the average magnitude depends on the aspect ratio of the nanofillers. Partial discharge resistance and characteristic breakdown strength increases with increase in filler content in both types of nanofilled samples, but excessive filler content is not effective in enhancing these parameters.

Proceedings Article | 31 August 2015 Paper

Statistical analysis of partial discharges evolved during aging of synthetic nanofilled polypropylene

Prathap Basappa, Charles Taylor, Antwarn Watson, Rohitha Dhara

Proceedings Volume 9558, 955817 (2015) https://doi.org/10.1117/12.2195949

KEYWORDS: Autoregressive models, Stochastic processes, Statistical analysis, Polymers, Nanocomposites, Resistance, Data modeling, Time series analysis, Analytical research, Shape analysis

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Proceedings Article | 31 August 2015 Paper

Effect of type of aging voltage on the residual breakdown strength of polypropylene films with natural and synthetic nanofillers

Charles Taylor, Antwarn Watson, Rohitha Dhara, Prathap Basappa

Proceedings Volume 9558, 955819 (2015) https://doi.org/10.1117/12.2196407

KEYWORDS: Electrodes, Nanocomposites, Polymers, Statistical analysis, Nanoparticles, Transformers, Dielectrics, Failure analysis, Resistance, Capacitors

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Proceedings Article | 27 August 2014 Paper

Study of partial discharge characteristics of nano filled polypropylene films according to the variation in electric field distribution on the sample

Md. Rab, Rohitha Dhara, Prathap Basappa, Anil Poda

Proceedings Volume 9172, 91720K (2014) https://doi.org/10.1117/12.2062149

KEYWORDS: Electrodes, Polymers, Nanoparticles, Transformers, Statistical analysis, Dielectrics, Software development, Magnetism, Capacitors, Calibration

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Proceedings Article | 27 August 2014 Paper

Effect of aging with partial discharges on the remnant breakdown strength of polypropylene films with natural and synthetic nanofillers

Md. Rab, Rohitha Dhara, Prathap Basappa, Anil Poda

Proceedings Volume 9172, 917214 (2014) https://doi.org/10.1117/12.2062095

KEYWORDS: Polymers, Electrodes, Statistical analysis, Nanoparticles, Dielectrics, Resistance, Surface finishing, Transformers, Interfaces, Capacitors

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Proceedings Article | 27 August 2014 Paper

Investigation into the effect of space charges on the surface erosion of synthetic and natural organoclay nanofilled PP films

Rohitha Dhara, Md. Rab, Prathap Basappa

Proceedings Volume 9172, 91720O (2014) https://doi.org/10.1117/12.2062043

KEYWORDS: Resistance, Polymers, Electrodes, Natural surfaces, Palladium, Transformers, Statistical analysis, Nanoparticles, Particles, Polymer thin films

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Showing 5 of 7 publications

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