Intelligenz von Hochspannungs-Leistungsschaltern — Mode oder Erfordernis?

It is discussed to what extent tools, provided by modern information technology, reasonably improve the performance of high voltage circuit breakers in transmission systems of electric power. Controlled switching, properly applied, has a high potential to increase life expectancy of the breaker itself and of the adjacent equipment. Power quality can also be improved. The technical advantage of controlled switching is beyond doubt, although the economic benefits are not easily quantified. In terms of breaker intelligence, another very important aspect is condition diagnosis. In particular a model based diagnosis seems to point to the future. Condition diagnosis giving maintainance requirements and pre-warning of impending failures should facilitate the tasks of the operating personnel. As a conclusion it can be stated that more intelligence of circuit breakers would be useful.     

Influence of Solution Composition on the Formation of Crystalline Scales

Scale formation is a difficulty encountered with water containing ions of sparingly soluble salts that can readily precipitate on heat transfer surfaces in evaporative concentration operations. Scale formation, hindering the heat transfer process, increases specific energy consumption and operating costs and causes frequent shut down of the evaporator for cleaning. The effects of changes in composition of the solution due to evaporation and CO₂ release on the formation of crystalline scales in seawater evaporators are studied. A model that predicts the CO₂ release is presented. The carbonate system in the salt solution on its whole flow path through the evaporator and the scaling (crystallization) tendency are described. Simulation results for different process configurations are shown and the differences are discussed, particularly with regard to the incrustation tendency.     

Formation of droplets on Si surfaces bombarded by In from a capillary type liquid metal ion source

Droplet formation on Si surfaces bombarded by 10 keV beams from a liquid metal indium ion source has been observed. It has been verified that excess indium is transported in the ion beam, probably in the form of charged droplets. SIMS, SEM and RBS techniques have been used to study the distribution of droplets at the surface. At the specified ion source operating conditions, equilibrium droplet coverage is of the order of 25%. Individual droplets have an average diameter of 0.35 ωm and an average height of 2.2 nm. At a bombardment current density of 0.1 mA cm^?2, equilibrium coverage is reached in about 1 s.     

Formation of pearlitic banded structures in ferritic-pearlitic steels

The conditions for ferrite and pearlite banding in strip and plate made of structural steels were investigated. Factors found to influence the formation of banded structures were the cooling rate during the γ/α-transformation, the former austenite grain size, and the work-hardened condition of the former austenite. Analyses with the aid of an electron beam microprobe made it possible to demonstrate that the carbon-rich bands correspond locally with banded manganese enrichments, yet that they do not form before the course of the γ/α-transformation as a result of secondary segregation. It was possible to explain the mechanism of action of the influencing factors on the basis of this model.     

Windenergieausbau als Teil der Ökostromentwicklung

The new law for the support of electricity produced by renewable sources in Austria (Ökostromgesetz) which came into force with the beginning of 2003, shows its impacts already after the first months. Investments into wind power have increased considerably. These will be accompanied by activities for electricity production by biomass and biogas. The 4%-target quota will probably be reached earlier than the 2008 target period of the law.     

Schätzung der modalen Parameter unter Berücksichtigung systematischer Fehler der Frequenzgänge

Zusammenfassung Aufgrund von Eingangs- und Ausgangsst?rungen des Me?systems sowie einer endlichen Frequenzaufl?sung treten stets systematische (Bias-) und zuf?llige Fehler bei gemessenen Frequenzg?ngen und deren Varianzen auf. Auf solchen Frequenzg?ngen und Varianzen beruhende Sch?tzungen der modalen Parameter sind damit ebenfalls systematisch verzerrt. Um die Genauigkeit und Sicherheit der modalen Parameter zu erh?hen, wird ein Sch?tzverfahren vorgestellt, in dem der Einflu? der Biasfehler auf die Sch?tzung n?herungsweise in einer diagonalen Wichtungsmatrix berücksichtigt wird. Es wird gezeigt, da? die systematischen Fehler Einflu? auf die Absch?tzung der statistischen Sicherheit der modalen Parameter haben. Anhand zweier Beispiele wird die Wirksamkeit des Sch?tzverfahrens demonstriert. Prof. Dr.-Ing. Dr.-Ing. E.h.H.K. T?nshoff: Dipl.-Ing.Z. Liu, Institut für Fertigungstechnik und Spanende Werkzeugmaschinen (IFW), Universit?t Hannover.