Materials Literature
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A digital integrated system is developed to record partial discharge (PD) pulses and to recognize their patterns by waveforms. Special considerations on the experiment circuit are given to electromagnetic shielding, system bandwidth and pattern variety. Both typical laboratory models and simulation models of stator wi…
Time-lag of void discharges was measured in order to establish the physical model for the formation of partial discharge pattern under AC voltages. The measurement with step voltages, using CIGRE Method II electrode system, showed that the statistical distribution of the discharge time-lag depends on the applied volta…
The partial discharge (PD) measurement is a very well known possibility to assess the quality of an insulation system. The aim of the PD-diagnostic is the detection of destruction of electrical insulation as a result of electrical stress especially of PD during operation. Therefore many methods of PD-measurement techn…
The extensive advent of optical communication networks requires new generations of large integrated optical switch matrices able to route information and data streams. We report a novel low cost bistable coupled-waveguide switch based on voltage controlled reorientation of a surface stabilised ferroelectric liquid cry…
Partial discharge detection using optical technique is studied with a view toward its application to explosion-proof motors and power transformers. For this purpose, an optical partial discharge measurement system has been established and some fundamental investigations such as attenuation of light intensity in differ…
Silicone rubber is a new insulating material for HV outdoor insulators. In order to know the long term of its performance we investigated the aging of the material under a natural tropical environment. This paper reports the investigation results on surface degradation of silicone rubber with different filler content…
In this paper a novel high voltage (HV) system for testing five specimens in parallel under different combinations of voltage and temperature is presented. When partial discharges (PD) are present, the system allows under a computer supervision the cyclic acquisition of PD signals coming out from each specimen by mean…
Considering various contaminated environments in the field, research on the hydrophobicity transfer properties of different pollutants is necessary for the proper selection and maintenance of polymeric insulators. In the paper, hydrophobicity of SR polluted by several kinds of pollutants such as kieselguhr, kaolin, To…
Vibro-acoustic diagnostic of on-load tap changers (OLTC) offer numerous advantages: applicable online, sensitive to mechanical as well as electrical malfunctions, retrofitable to old equipment, simple and low-cost. Over the last few years, Hydro-Quebec has spent considerable efforts in the development of a reliable ac…
To investigate the reliability of the insulation of equipment having vacuum incorporated as an insulation medium, a study was carried out to clarify breakdown probability distributions in the vacuum gap. Experiments were carried out to investigate the effects of test methods, electrode area, and electrode materials on…
Polycrystalline cerium hydroxysulfate powders have been prepared by soft solution processing using various basic solvents. The crystals prepared have varying morphologies, spherical and flaky, depending on the solvent used. The crystals obtained from distilled water–pyridine and aqueous ammonia solvent mixtures are sp…
Polyconjugated regular bithiophene-alt-thiophene-S,S-dioxide copolymers were produced by anodic coupling of variously 3,4-ethylenedioxy-substituted 2,5-bis(2-thienyl)thiophene-S,S-dioxide. The polymers were characterized by cyclic voltammetry, FTIR reflection-absorption and UV-vis spectroscopy, MALDI-TOF mass spectros…
This paper presents the variation of breakdown voltages experimentally obtained under high frequency high voltage stress on different insulating materials viz., PTFE, polypropylene and paper. An experimental facility using a vacuum tube oscillator circuit has been developed for the generation of high frequency high vo…
The aim of this work is to propose a new approach for the iron losses prediction, in soft magnetic materials with any voltage supply, starting from the knowledge of the iron losses with sinusoidal supply. The model is based on the separation of the loss contributions due to hysteresis, eddy currents and excess losses…
A new approach for experimental determination of stray capacitances in high frequency transformers is proposed in this paper. This approach identifies the stray capacitances of a two winding transformer by conducting open and short circuit tests on both windings within the range of normal operation frequencies and fit…
We have conducted detailed comparisons of the predictions of self-consistent mean-field (SCMF) theory with results of Monte Carlo simulations for bulk lamellar structures of symmetric diblock copolymers A−B in concentrated solutions. Large differences are found among the values of the Flory−Huggins parameter extracted…
This paper provides the failure analysis of three phase, dry type, silicone resin vacuum pressure encapsulated, 750/1000 kVA, AA/FA, 34.5 kV-480 Y/277 V, delta-wye, power transformer. Transient overvoltage switching surge propagation through the transformer winding and protection margin is discussed. An arbitrary sens…
After the local breakdown of the metallized film, the self-healing of the capacitor is influenced by several factors, including the capacitance of metallized capacitor, pressure, as well as the applied voltage. In this paper, they are investigated fundamentally in reference to their influence towards the insulation re…
A modified cable pulsed electro-acoustic (PEA) system using the plate outer electrode, which enables the technique to be applied to different cable sizes, is introduced to measure space charge distribution in extruded polymeric power cables. Some preliminary measurement results from cable samples are presented.
The complex [[Cu3(HpztBu)4(mu-pztBu)2(mu-F)2(mu 3-F)]2]F2 (HpztBu = 3[5]-tert-butylpyrazole) has a cyclic, C2v-symmetric hexacopper core. The two non-coordinated F- anions are encapsulated within cavities formed by three HpztBu ligands.