Materials Literature
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Crosslinked polyethylene (XLPE) insulated cables working in water are known to be easily degraded by forming water trees. This is one of the most serious concerns among users of XLPE cables. The possibility whether measurement of residual charge is usable as a tool to detect water trees in XLPE is discussed. Two types…
The design of XLPE cables, degradation factors to working XLPE cables, and exclusion methods of the degradation factors are reviewed. In addition, the soundness confirmation methods of extra high voltage XLPE cables are reviewed. As degradation factors of XLPE cables, electric stress degradation, partial discharge deg…
In high voltage applications, polymer insulation can be exposed to very high electrical field stress, resulting in long term exposure to corona. The electrical field stress may be much below dielectric breakdown threshold. Eventually the exposure to corona can lead to failure of the high voltage component. Nanometer s…
The authors propose a novel approach based on partial discharge (PD) current pulse waveform analysis (PD-CPWA) in order to assess insulation degradation of solid insulators with different kinds of defects. The CPWA technique focuses on the time transition of individual PD waveform parameters like rise time, fall time…
Gas Insulated transmission Line (GIL) is very well known for its high transmission rating of electrical power and its reliability. The high capacity of the transmission, the thermal, mechanical and the electrical behaviour of the new generation of the directly buried GIL were studied and tested by laying it in the gro…
Abstract New spin-crossover compounds, [Co(phimpy)2](ClO4)2 (1) and [Co(ipimpy)2](ClO4)2 (2) (phimpy = 2,6-bis(N-phenylformimidoyl)pyridine and ipimpy = 2,6-bis(isopropyliminomethyl)pyridine) were prepared, and the crystal structures were determined. The magnetic susceptibility measurements showed gradual transition f…
Design of a tuneable filter-phase shifter is presented. Thin ferroelectric film varactors are used to provide voltage tuneable phase shift in a silicon coplanar waveguide (CPW). Varactors with zero bias capacitance 0.17pF, loss tangent tan/spl delta/-0.04 and 20% tuneability provide continuous voltage tuneable phase s…
The leakage currents of various insulators were monitored together with environmental data at a coastal test site. In addition the daily maximum surface, conductivity was measured. In this paper it is shown how, using multiple regression, the leakage current can be predicted from the measured weather and environmental…
The high voltage transmission network in South Africa contains a relatively high percentage of non-ceramic insulators. Techniques for assessing the condition of these insulators are under investigation. Such techniques include imaging techniques that take either an infra-red image or an ultra-violet image of the insul…
A large-pore iron-substituted aluminophosphate molecular sieve of structure type AlPO 4 -36 was synthesized. Pure and highly crystalline FAPO-36 crystallized hydrothermally from a gel with a molar composition of 0.2:0.9:1:2:50 FeO:Al 2 O 3:P 2 O 5:Pr 3 N:H 2 O at 125°C after 7 days. The effects of the crystallization…
Metal-ferroelectric-insulator-semiconductor (MFIS) capacitors with 390-nm-thick SrBi/sub 2/Ta/sub 2/O/sub 9/ (SBT) ferroelectric film and 8-nm-thick hafnium oxide (HfO/sub 2/) layer on silicon substrate have been fabricated and characterized. It is demonstrated for the first time that the MFIS stack exhibits a large m…
Recombinant collagens are attractive proteins for a number of biomedical applications. To date, significant progress was made in the large-scale production of nonmodified recombinant collagens; however, engineering of novel collagen-like proteins according to customized specifications has not been addressed. Herein we…
Melusin is a muscle specific protein required for heart hypertrophy in response to mechanical overload. Here we describe a protein 63% homologous to melusin, named chp-1, expressed in all tissues tested, including muscles, and highly conserved from invertebrates to human. Both proteins are characterized in their N-ter…
Partial discharge (PD) classification is a powerful way to predict insulation problems of the windings of rotating machinery. While online PD tests have been carried out for over 40 years, effective diagnostic methods are still under development. In this paper, a practical diagnostic method is proposed based on an imp…
[reaction: see text] Reaction of tetraaryl-m-benziporphyrin with pyridine and silver tetrafluoroborate yields 22-pyridiniumyl-m-benziporphyrin as the only substitution product. This compound is further rearranged to a fused m-benziphlorin containing a 4a-azafluorene fragment. A mechanism involving a high-valent silver…
As-synthesized MCM-48 was modified via silylation with Cl−Si(CH 3 ) 3 . The resulting silylated MCM-48 possesses a well-ordered long-range structure, a narrow distribution of nanosized pore diameters, a high mesoporous volume, a large specific surface area, and, most significantly, a hydrophobic surface. A nanocomposi…
Abstract Hyperbranched poly(glycidol) alkali sulfate (SHPG‐M) was prepared based on hyperbranched poly(glycidol). Polyurethane–hyperbranched poly(glycidol) (PU–SHPG‐M) sulfate electrolyte is a kind of single ionic or cationic conducting polymer electrolyte. Such a single ionic polymer electrolyte can obviously reduce…
A large number of distribution transformers, currently utilized in low voltage (LV) power systems are of dry-type design. This includes, the IEEE Class II ventilated dry-type design with 3-phase kVA ratings in the approximate range of 500 kVA - 2.5 MVA and primary voltage ratings ranging from 4.16 kV to 34.5 kV and th…
A new instrument based on acoustic methods has been designed which is offering non-invasive condition assessment of Gas Insulated Substations (GIS) during normal service. The instrument will be able to reveal many of the defects resulting in breakdown of GIS and will in general have a significant cost benefit. Based o…
An analytical technique that can be effectively used for the calculation of the end winding leakage inductance of a turbogenerator has been presented. It is based on a 3-D geometric model of the end winding region in which each coil is modeled as a set of serially connected straight filaments. The calculation of the m…