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Liquid dielectric

About: Liquid dielectric is a research topic. Over the lifetime, 3702 publications have been published within this topic receiving 45150 citations.


Papers
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Journal ArticleDOI
E.O. Forster1
TL;DR: In this paper, a survey of the special instruments used in these studies is presented, and the advantages and disadvantages of the various measuring techniques are discussed, as well as the information obtained with the latest ultra-high-speed electrooptical equipment.
Abstract: It is noted that the past three decades have seen significant changes in the types of materials used for electrical insulation. These changes were brought about by the realization that some of the previously used materials were detrimental to the environment and to the people who came in contact with them. The use of polychlorinated biphenyls was prohibited, and replacement materials had to be developed. Paper was replaced to a large extent by polymer film, and paraffinic oils were finally used as replacement for oils derived from naphthene. At the same time progress was made in the understanding of the nature of electrical charges and how they move through dielectric fluids under the influence of externally applied electrical fields. The impact of these developments on the field of liquid insulating materials is discussed. Attention is also given to the information obtained with the latest ultra-high-speed electrooptical equipment. The generation and propagation of charge carriers are examined in detail, and their relation to electrical breakdown is analyzed. A brief survey of the special instruments used in these studies is presented, and the advantages and disadvantages of the various measuring techniques are discussed. >

45 citations

Patent
18 Aug 1977
TL;DR: In this article, the phase coils of an armature winding are arrayed in outwardly spiralling paths about the rotor, and smooth and continuous interphase spaces are formed between the coils for containment of interphase insulating layers.
Abstract: A rotating electrical machine having a winding configuration and insulating system permitting very high voltage operation. The phase coils of the armature winding are arrayed in outwardly spiralling paths about the rotor. Smooth and continuous interphase spaces are formed between the coils for containment of interphase insulating layers. Each interphase layer comprises laminated sheets of permeable material impregnated with a dielectric liquid. The phase coils are formed into inner and outer layers with each coil layer subdivided into a plurality of sections having series connected turns. Spaces between or within the layers contain dielectric liquid which is circulated for cooling the winding. Intracoil insulation between the coil layers is comprised of laminated sheets of permeable material impregnated with a dielectric liquid. The coil sections are coupled in series in a manner to minimize the maximum voltage differentials between the conductors and adjacent coil sections. In another embodiment the turns of each coil are arranged in adjacent layers separated by intracoil insulation material. The adjacent layers are further subdivided into pairs of sublayers formed of parallel conductors separated by a cooling duct through which a dielectric liquid circulates.

45 citations

Proceedings ArticleDOI
26 Nov 2012
TL;DR: In this article, the dielectric and thermal properties of Zirconia and Titania nano particles were measured for different concentrations of nanofillers and specific resistivity and dissipation factor were carried out with reference to IS 6103:1971 and IS 6262:1971 respectively.
Abstract: Liquid dielectrics play a major role in the insulation system used in high voltage equipments. The most commonly used liquid dielectric is transformer oil which serves the dual purpose as insulation and a coolant. It also acts as insulation between the conductingparts and as an arc quenching medium. Moreover the breakdown strength of the paper and the pressboard insulation depends on the properties of the oil in which it is impregnated. Therefore investigations have been attracted towards the development of nano fluids with better thermal and dielectric properties. In this work, ceramic nano particles are chosen because of their electrical insulating property. Because of higher relative permittivity Zirconia(ZrO2) and Titania(TiO2) nano particles are used here. The dielectric and thermal properties are measured for different concentrations of nanofillers. AC and Impulse breakdown voltage measurements were performed as per IS 6792:1972 and IS 11697:1986 respectively. The specific resistivity and the dielectric dissipation factor measurement were carried with reference to IS 6103:1971 and IS 6262:1971. The kinematic viscosity and flash point are measured as per IS 1448 Part-25:1970 and IS 1448 Part-21:1970 respectively.

45 citations

Proceedings ArticleDOI
08 Jul 1991
TL;DR: In this paper, the internal and external interfaces for composite HV insulation systems are defined for fiber glass-reinforced polymeric materials, both under dry conditions and in the presence of water.
Abstract: HV insulation systems are often composed of different insulating materials. In the contact areas between these materials (interfaces) interfacing polarization may occur, resulting in an increase of both permittivity and loss tangent and, consequently, of dielectric losses. By the interaction of humidity such interfacial phenomena may be enhanced. Other important characteristics of insulating systems such as the treeing strength and the breakdown strength are also lowered by interfaces, especially when humidity has been adsorbed. Microscopic and macroscopic, internal and external interfaces are defined for composite insulation systems. Interfacial phenomena in such systems, for instance made out of fiber glass-reinforced polymeric materials, are described both under dry conditions and in the presence of water. It is demonstrated that the hydrophobic properties of materials improve the dielectric characteristics; this is true for bulk and surface properties. >

44 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202328
202267
202191
2020122
2019142
2018120