Materials Literature
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In this work, a neural network algorithm using the standardization method was developed to discriminate phase-shifted partial discharge (PD) patterns. Previous efforts to recognize PD patterns have been performed by applying the neural network to the /spl phi/-q-n pattern, which is composed of phase angle /spl phi/, d…
This paper describes monitoring of SOF/sub 2/ and SO/sub 2/F/sub 2/ in SF/sub 6/ insulated switchgear as indicators of the need to perform maintenance. The paper describes the results of routine monitoring for these byproducts in 131 sections of bus and 25 breakers over a period of three years. It describes an inciden…
The ferroelectric imprint is measured on thin-film PLZT capacitors with lanthanum strontium cobalt oxide top and bottom electrodes. The data show a significant amount of imprint with a combined elevated temperature and alternating (unipolar) voltage stress. No imprint was observed on samples that were temperature stre…
The leakage resistance of transmission line insulators suspended along the coast decreases with the accumulation of sea-salt blown from the sea, particularly when the relative humidity is high and the shed surface is slightly wet with rain or wet snow. In order to measure, automatically, by a leakage resistance data a…
Presents a study of the effects of coating thickness, various coating substrates and adding extra silicone fluid in RTV liquid on the electrical performance of RTV coatings. The leakage current and time to failure were monitored as a function of time of exposure to combined electrical stress and salt-fog in order to d…
In 1921 Joseph Valasek recognized for the first time ferroelectric properties in a crystal, namely in Rochelle salt. In this lecture we review the story of this discovery, of Valasek's origin and career.
The effects of acetophenone (AP) and cumylalcohol (CA) on the tan/spl delta/ of low density polyethylene (LDPE) were investigated in detail taking the temperature range of 25 to 100/spl deg/C and electrical stress range of 5 to 40 kV/mm. The tan/spl delta/ of LDPEs to which AP and CA (reagent special grade) and these…
In HVDC application, the interdisc winding insulation of a converter transformer is subjected to superimposed AC and DC voltages. Therefore, a knowledge of the behaviour of such an insulation system subjected to AC, DC and superimposed AC and DC voltages is essential. In order to simulate similar conditions in the int…
A new actuator for a robotic hand, composed of two NiTi shape memory alloy (SMA) springs, is studied. First, the properties of NiTi SMA springs, including load-displacement dependences at various temperatures, resistance-temperature dependence, and recovery-temperature dependence are tested and analyzed. It is found t…
Abstract Optical absorption and fluorescence emission spectra of 1,5‐diaminoanthraquinone (1,5‐DAAQ) in different solvents and the surface‐enhanced Raman scattering (SERS) spectrum of 1,5‐DAAQ in silver sol were investigated. Optical absorption and fluorescence emission studies revealed that the internal and external…
This paper describes the principle of the pulsed electroacoustic method (PEA) for space charge profile measurement in lossy and/or dispersive media. The method comprises the following aspects: analyze the principle of the PEA method in lossy and/or dispersive media; estimate the attenuation and dispersion factors in l…
In this paper the relation between successive partial discharges in insulating materials at DC voltage is discussed. Based on a few assumptions a DC voltage model, based on an RC-circuit, is presented and experimentally verified. Measurements of partial discharges have been made on samples containing air filled voids.…
The theoretical analysis of carrier scattering mechanisms in electronic lead chalcogenide crystals was carried out. The calculation of carrier mobility in wide temperature (4.2300 ) and concentration (10 16 10 20 m 3 ) ranges is carried out from the viewpoint of interaction of conductivity electrons with deformation p…
High permeability magnetic films used for shielding or absorption of electromagnetic interference (EMI) are commonly built in a multilayer stack to maximize the permeability by eliminating or reducing the number of domain walls. The choice of spacer material is driven by the fact that electrically insulating spacer ma…
The existing techniques for the detection and location of incipient faults (e.g. electrical trees) in extruded shielded power cables are reviewed. Only the techniques developed for field applications are included. The advantages and disadvantages of each technique are evaluated from the point of view of a power engine…
XLPE insulation used in high-voltage cables is not only subjected to electrical stress but also to mechanical strains, either from internal residual strains created during manufacturing or externally applied when the cable is bent sharply. Due to thermally activated viscoelastic motion in the polymeric material, the o…
For many years the IEC 270 partial discharge (PD) measurement technique has been the international standard. To improve the ratio of PD signal to thermal amplifier noise and to reduce sensitivity to external noise, "ultra"-wideband techniques have been proposed as an alternative to IEC 270. This paper will show that i…
The loss of hydrophobicity of room temperature vulcanizing (RTV) silicone rubber coating on insulators, due to dry band arcing in the presence of contamination and moisture, causes a deleterious effect in the electrical performance of the coating. For example the growth of the leakage current is accelerated resulting…
This paper is an extension of the gyrator-capacitor more model introduced by D.C. Hamill (1994). This core model is simple, efficient and handles both linear and nonlinear cores. The only item lacking is an efficient core loss element for determining circuit Q and efficiency. The gyrator re-cap core model contains a c…
Plane-parallel electrodes coated with epoxy resin have been used to investigate partial discharge (PD)-induced degradation of the insulating material. The mean amplitude of pulse-type discharges has been measured as a function of PD exposure duration, while light emission from the discharge space was simultaneously mo…