Materials Literature
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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…
The application of power semiconductors at cryogenic temperatures has recently gained significance in protection elements of SMES (superconducting magnetic energy storage) operating at LHT (liquid helium temperature). The evolution of HT (high temperature)-superconductors, however, is still proceeding and will provide…
Abstract A detailed analysis of isotropic and anisotropic Raman spectra of carbonyl stretching vibrations of ethylene carbonate in different systems was conducted. The variation of Fermi resonance perturbed spectral profiles was used to investigate changes in local molecular surroundings in polymer gel–electrolyte sys…
This paper presents the computer simulation of the transient space-charge distribution in degassed and non-degassed cross-linked polyethylene (XLPE) which was measured by a pulsed electroacoustic method by Li and Takada (1991). The simulation was made on the transport of both bulk-excited and electrode-injected carrie…
This paper presents the design and application of permanent magnets in hysteresis motors with a view to improve the overall performances of such motors. The novel rotor consists of 36% cobalt steel alloys with neodymium boron iron permanent magnets. This hybrid design combines advantageous performance features of both…
The variations of crystal structure, magnetization, and conductivity resulting from the chemical pressure effects of substituting Sr 2+ by the smaller Ca 2+ in the double-perovskite (Sr 2 - x Ca x )FeMoO 6 have been investigated. An increase in the Ca content leads to an increase in the Fe/Mo ordering in the materials…
We are able to analyse the SF/sub 6/ decomposition directly during a discharge by means of a FT-IR (Fourier transform infrared) spectrometer and a 2.51 stainless steel discharge cell with infrared windows and a path length of 0.175 m. With this cell we investigated the influence of water vapour and oxygen on the produ…
The presence of metal particles within gas insulated switchgear (GIS) might initiate a sparkover and lead to fatal failure of electric power transmission system. In order to investigate the behavior of a particle in GIS, model electrodes and a measuring system were constructed. The motion of a particle was investigate…