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HVDC technology is increasingly adopted for long distance transmission of bulk power at reduced cost in comparison with HVAC systems. Epoxy is a popular material for insulators/spacers used in sealed space such as in GIS or wall bushings with selected fillers, providing excellent electrical insulation and mechanical support. Practical operation and previous research [1-5] has however suggested that...
Heat shrinkable tubes were investigated as HV insulation for complex conductor configuration in terms of applicability and thermo-electrical performance. Overall, the tests show the high potential of heat shrinkable systems for such application. However, for producing insulated conductors from the pre-manufactured tubes, further improvements of the electrical configuration of the full insulation system...
Chemometrics is the science of applying multivariate mathematical and statistical analysis methods to the extraction of maximum information from complex data sets and the determination of inter-relationships between variables controlling outcomes and properties.
It is almost always the case that multiple partial discharge (PD) sources are active in high-voltage equipment as a result of insulation defects or ageing. Therefore, over the years, different clustering techniques have been tested and used, so that each individual PD source can be separated and subsequently recognized, e.g. by means of the phase resolved PD patterns (PRPD)[1].
Recent advances in low voltage motor designs and their control by power electronics, as well as rapid expansion of the electric motor technology into passenger vehicle e-mobility, have driven innovation efforts at the level of electrical insulation components by many suppliers.
High voltage bushings play a critical role in the operation of the transformer and when the bushing fails the results can be catastrophic causing considerably collateral damage and posing a risk to safety of personnel. A time-based-maintenance scheme based on manufacturer's manual has already been proved to be not sufficient to recognize rapid degradation of insulation in the high voltage bushing...
Medium frequency (MF) transformers are key components of power electronic topologies of modern energy supply systems. The insulation of MF transformers is exposed to the low frequency AC or DC grid voltage and at the same time to rectangular medium frequency converter switches featuring high amplitude and steepness. The high harmonic content of such voltage can cause increased dielectric losses in...
Partial discharge (PD) analysis is an important technique for diagnosis and online monitoring of transformer insulation systems. PD within transformer windings may be due to several causes such as manufacturing defects, degradation of the primary insulation or contamination of the oil. The degradation processes occurring in dielectric insulation components can lead to development of different types...
Ageing assessment of transformer paper insulation is commonly conducted through measurement of different chemical indicators in oil such as carbon oxide gases and furanic compounds [1]. Apart from these conventional paper ageing indicators, recent research success has shown that methanol and ethanol in transformers can also be used to indicate the degradation of transformer paper insulation [2].
Voltage source, pulse width modulated (PWM) drive system finds many industrial applications such as pumps, fans, compressors and other equipment, with the benefit of both productivity improvement and greater energy efficiency. However, medium and high voltage PWM motors suffer from premature insulation ageing. Several types of ageing processes in medium and high-voltage stator windings has been identified...
The transients generated by drives based on pulse width modulation (PWM) have adverse effects on the insulation system of rotating machines, especially the stress grading (SG) system used in the endturn region. The surface corona inception voltage on SG system under repetitive impulse, 1kHz sinusoidal, and 1kHz square voltages was measured using a photomultiplier connected to optical fiber bundle,...
Gas Insulated Substation (GIS) under High Voltage Direct Current (HVDC) are becoming widely investigated with the development of DC networks. Under DC voltage, mechanism of charge accumulation on the insulation surface is of major importance since it may distort the electric field distribution. The latter directly depends on material's conduction and so, on its volume and surface conductivities. Previous...
Safe operation of electrical power network relies on healthy electrical insulation of all of its components. In general, the condition of insulation is unknown and appropriate periodic electrical testing is required to detect potential deterioration and avoid catastrophic failure of the given system.
The decentralized generation of electrical power continues to rise which means that also the transport of electrical power over larger distances is gaining more and more importance. High voltage direct current (HVDC) transmission provides an efficient means to transmit large amounts of electrical power over long distances.
The present paper reports on the analysis of space charge evolution in alumina-filled epoxy resin for high voltage applications and especially HVDC equipment using the thermal step method.
Self-healing materials (SHMs) are those which, when damaged, are capable of responding to restore their pre-damage state. As such, they are of particular interest for deployment within high-value assets which cannot be readily accessed or maintained, including underground and offshore cables. Although SHMs confer a number of benefits upon the host asset, it is necessary to consider a range of factors...
In order to ensure the energetic transition, the electrical network is changing to connect renewable energy production sites and countries together. HVDC systems used in the last decades allow to interconnect countries and connect high power production sites sometimes far from shore. The constant growth of high voltage direct current networks brings about improvements in several fields. With a view...
The National Grid is planning for the new 400 kV overhead line with T-pylon towers where diamondlike insulation structures comprising of silicone rubber insulators according to Figure 1 will be used. In order to verify the dielectric (lightning and switching overvoltages) and ice performance of these structures, specially designed tests were performed at STRI. However, another issue for the environment...
The continuing growth of energy from renewable resources demands for structural changes of energy transmission systems. These changes are on the one hand related to the increasing decentralized power generation and on the other to different power flow scenarios due to fluctuation in power generation. For example, offshore wind parks require a high transmission capacity over long distances. In order...
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