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Electrical Aspects
Published in Frank R. Spellman, The Science of Wind Power, 2022
Two fundamental but distinctly different properties of insulation materials (e.g., rubber, glass, asbestos, and plastics) are insulation resistance and dielectric strength. Insulation resistance is the resistance to current leakage through and over the surface of insulation materials.Dielectric strength is the ability of the insulator to withstand potential differences and is usually expressed in terms of the voltage at which the insulation fails because of the electrostatic stress.
From Insulating to Conducting Polyimides
Published in Andreea Irina Barzic, Neha Kanwar Rawat, A. K. Haghi, Imidic Polymers and Green Polymer Chemistry, 2021
Göknur Dönmez, Ayça Ergün, Merve Okutan, Hüseyin Deligöz
Dielectric strength is the specialty of an insulating material that allows it to resist a given electric field magnitude without a failure/defect. In general, it is expressed in terms of the minimum electric field magnitude (i.e., potential difference per unit thickness) that will reason the dielectrics to failure or breakdown under given circumstances, for example, the shape of the electrodes, the method of applying temperature and voltage, and many other parameters affect the breakdown behavior of the material under electrical voltage. The electric strength of most materials reduces with temperature and hence, it is usual to carry out the relevant tests at elevated temperatures. The loss tangent (tanδ) varies, sometimes significantly, with frequency and temperature. tanδ generally increases with temperature as well as the dielectric permittivity, especially when moisture is present. In short, high temperature is often liable to a considerable increase in dielectric losses.57
Overview of Ceramic Interconnect Technolgy
Published in Fred D. Barlow, Aicha Elshabini, Ceramic Interconnect Technology Handbook, 2018
Aicha Elshabini, Gangqiang Wang, Dan Amey
The dielectric strength of ceramics in V/mm (or voltage per unit length in general) varies considerably as a function of temperature, frequency, and the material’s physical properties (such as density, porosity, purity, and physical dimensions of the ceramic sample). A sharp decline of the dielectric strength of ceramics is experienced upon an increase of frequency and/or temperature. Adequate dielectric strength is needed to withstand an applied voltage without breakdown. Dielectric strength of ≥ 15 KV/mm has been observed for most ceramics (26–24 for Al2O3, 9.5 for BeO, and 10–14 for AlN).
Natural fibre filament for Fused Deposition Modelling (FDM): a review
Published in International Journal of Sustainable Engineering, 2021
H. J. Aida, R. Nadlene, M.T. Mastura, L. Yusriah, D. Sivakumar, R. A. Ilyas
Produce composites by combining polymer and natural fibre as filler, can produce the insulator materials, such as wire and cable wrapper. In Narayan Nayak (Narayan Nayak, Dr. Reddappa H. N, Ganesh R Kalagi, & Vijendra Bhat, 2017) paper has extract about electrical properties of natural fibre reinforced polymer. Dielectric strength is one of the important parameter in electrical which measure the withstand of voltage without breakdown. Along with the mechanical, physical and thermal properties, electrical properties also play an important role in producing composites. Mechanical is about the durability in term of tensile, bending, fatigue, and impact. Physical are about the durability of composites in moisture, flow, and density, while thermal properties are about how high the composite can withstand in certain temperature without degrade. In this paper also stated that 1.8–2.6 is the constant for dielectric constant that non-polar polymer lies and might be greater than that one for another polymer. Lesser the value of dielectric constant, the more efficient it might be (Narayan Nayak et al. 2017). But due to some of disadvantages of natural fibre especially the hydrophilic properties, it might increase the value of dielectric and lower the efficiency itself. In way to prevent this issue, the chemical treatment is done towards the natural fibre as to decrease the moisture absorption. By doing the alkaline treatment, not just can increase the efficiency in electrical insulator properties, but also in term of mechanical and physical properties (Narayan Nayak et al. 2017).
Strategies for ultrahigh outputs generation in triboelectric energy harvesting technologies: from fundamentals to devices
Published in Science and Technology of Advanced Materials, 2019
Very high electric potentials in the range of several hundred to several thousand voltages were commonly generated between the two separated materials with the opposite triboelectric charges. Wang et al. reported that a high voltage of 1.5 × 105 V would be induced with a charge density of 300 μC/m2 [46]. When the dielectric was stressed by such high voltage (that is, high electric field), the air and the dielectric can begin to break down, becoming partially conductive. Table 1 shows the dielectric constants and dielectric strengths of various materials at room temperature [61–63]. The dielectric strength is the maximum electric field that can exist in a dielectric without electric breakdown. The electric fields are in the range of several tens of 106 V/cm, not significantly dependent on the dielectric constant. Thus, the breakdown mechanism may limit the maximum retainable charge density which can be generated in TENGs.
Experimental correlation between varying cassava cortex and dielectric properties in epoxy/cassava cortex dielectric particulates composites
Published in Particulate Science and Technology, 2018
A. D. Omah, B. A. Okorie, E. C. Omah, I. C. Ezema, V. S. Aigbodion, U. U. Orji
The test was carried out at 1 MHz frequency and at room temperature and pressure. The test was conducted in accordance with ASTM D149–09 (2013). The cylindrical sample of 25 mm diameter (see Figure 2a) was placed in a dielectric testing machine, and an impulse voltage was gradually applied to the sample from the control desk until the specimen fails at a given voltage. The failure was characterized by a loud sound. The value at which the material failed was recorded and the dielectric strength was calculated by dividing the breakdown voltage by the thickness of the specimen. The breakdown voltage of all the specimens were recorded via the same procedure and their corresponding dielectric strength was calculated. Five tests were run for each sample and the average was taken.