IET Nanodielectrics
Volume 3, Issue 2, June 2020
Volumes & issues:
Volume 3, Issue 2
June 2020
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- Author(s): Joyce Jacob ; P. Preetha ; Sindhu Thiruthi Krishnan
- Source: IET Nanodielectrics, Volume 3, Issue 2, p. 33 –43
- DOI: 10.1049/iet-nde.2019.0038
- Type: Article
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p.
33
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The development of reliable, environmentally safe and economic insulating oil for the transformer is an endless effort of the electrical industry. Recent research is based on natural ester fluid, the green insulating oil which exhibits excellent dielectric performance and environment friendly characteristics. Nanofluids are also emerging as potential replacement for the conventional mineral oil used in transformers. Characterisation of nanoparticle filled mineral oil and natural esters have validated their improved dielectric behaviour in comparison to the unfilled oil. Although the applications are wide, the state of the art technology requires a deeper understanding of the underlying phenomenon. Much work is expected to be done in the application of nanofluids prepared with mineral oil and natural ester, particularly its effect on the cellulose insulation. The study provides an overview of the different materials that have been used as alternatives to the conventional transformer mineral oil, with special emphasis on natural esters and natural ester nanofluids, their advantages and challenges.
Review on natural ester and nanofluids as an environmental friendly alternative to transformer mineral oil
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- Author(s): Baskar Thangabalan ; Ramanujam Sarathi ; Noureddine Harid ; Huw Griffiths
- Source: IET Nanodielectrics, Volume 3, Issue 2, p. 44 –52
- DOI: 10.1049/iet-nde.2019.0041
- Type: Article
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p.
44
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(9)
Silicone rubber is widely used for electrical insulation and may be exposed to a harsh environment. The present study envisaged to improve insulation properties of silicone rubber by adding an optimised quantity of nanofillers. The fundamental space charge and charge trap characteristics were studied by adopting the pulsed electroacoustic analysis technique and through surface potential measurement. The dielectric properties of the materials were analysed through measurement of permittivity and loss factor of the material at different frequencies and temperatures. The influence of gamma irradiation on variations in fundamental properties of the material was characterised. The results of the study indicate that 5 wt.% alumina added nanocomposites had better space charge performance under gamma irradiation compared with virgin silicone rubber.
- Author(s): Romana Zafar and Nandini Gupta
- Source: IET Nanodielectrics, Volume 3, Issue 2, p. 53 –61
- DOI: 10.1049/iet-nde.2019.0037
- Type: Article
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53
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High permittivity materials are currently in use for mitigation of electrical stress in high-voltage apparatus and energy storage systems. In this work, epoxy-based high permittivity nanocomposites with Barium titanate (BaTiO3) nanofillers are considered, for the purpose of stress mitigation. Uniform dispersion of the fillers in the polymer up to 10% by volume is achieved. Apart from the use of as-received fillers, the effect of using surface-functionalised nanoparticles (with 3-glycidoxypropyltrimethoxy-silane) before use is also investigated. The nanocomposite is characterised in terms of its complex permittivity, DC conductivity, short-term AC breakdown strength and space charge accumulation, to gauge its suitability for use in high-voltage insulation. Complex permittivity is measured using broadband dielectric spectroscopy over a broad frequency range of 1 mHz to 1 MHz. DC conductivity is studied from polarisation–depolarisation current measurements. Short-term AC breakdown strength tests are performed at power frequency (50 Hz). Space charge density along the sample thickness is obtained using pulsed electro-acoustic technique. A computational case-study is presented to show the feasibility of using the high permittivity nanocomposite for electric stress control in high-voltage equipment (viz., at mounting flanges of 69 kV bushings).
- Author(s): Allison V. Shaw ; Alun S. Vaughan ; Thomas Andritsch
- Source: IET Nanodielectrics, Volume 3, Issue 2, p. 62 –67
- DOI: 10.1049/iet-nde.2019.0009
- Type: Article
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62
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The dielectric effect, investigated using dielectric spectroscopy and DC dielectric breakdown strength measurements, of introducing xylene into a composite system containing polyethylene, a co-polymer of ethylene and vinyl acetate and an organoclay can be understood in light of X-ray diffraction data. In dielectric spectroscopy, although organoclay alone changes the dielectric response of the polymer blend and xylene has no effect on the unfilled polymer blend, when both xylene and organoclay are present, a synergistic response is revealed at the 1 Vrms amplitude voltage used to acquire the dielectric data. In contrast to this, in DC, dielectric breakdown strength measurements revealed that, under high field conditions, both the xylene and organoclay, independently, caused a decreased breakdown strength. This work was undertaken in order to examine the generality of the possible effects of labile, low molar mass impurities on electrical properties of comparable systems, which may be processed through solvent-based routes.
Analysis of space charge and charge trap characteristics of gamma irradiated silicone rubber nanocomposites
Dielectric characterisation of epoxy nanocomposite with barium titanate fillers
Influence of xylene on the dielectric response of an organoclay-containing nanocomposite
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