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外文翻译冲压模具.doc

发布:2016-12-01约1.85万字共9页下载文档
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AN IMPROVED INSULARION SYSTEM FOR THE NEWEST GENERATION OF STATOR WINDINGS OF ROTATING MACHINES Summary: In recent years there has been a distinct trend to utilize machines with indirectly cooled stator windings also for the higher ratings, up to about 300 MVA with air cooling and about 450 MVA with hydrogen cooling. This imposed new demands on the well-known dielectric requirements, as this is a key item when laying out the machine. This report describes the modified structure of an improved synthetic resin insulation Matador-Plus. The most significant change was the introduction of powdered metaloxyde to the insulation structure used hitherto, which it enable the thermals conductivity to be doubled. The resulting characteristically changes are described relative to both short and long term behaviors of the insulation system. Based on the improved insulating qualities it was possible to reoptimize machine designs, which is fundamentally demonstrated. Key words: Turbo-generator, stator winding, insulation system, indirect conductor cooling, thermal conductivity. 1:Introduction Over the last decades the development of turbo-generators with indirect conductor cooling in the stator winding has led to ever increasing ratings. Today, machines are being built with this technology for ratings which ,just a few years ago, were only possible with direct water or hydrogen cooling of the stator winding conductors. Air—cooled machines with ratings of up to 130 MVA were already in service by 1970.With the development of gas turbines with larger unit ratings there is a trend today for air-cooled turbo-generators with ratings of 300 MVA. Hydrogen cooling in turbo generators permitted much higher unit ratings. By the of the 50’s, machines with indirect conductor cooling had been realized up to 250 MVA and today the limit is above 350 MVA. Compared with direct conductor cooling used on larger generators , indirect cooling of the stator ending has the advantages that, bar production
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