-Deregulation and an increasing competition in electricity markets urge energy suppliers to optimize the utilization of their equipment, focusing on technical and cost-effective aspects.As a respond to these requirements utilities introduce methods formerly used by investment managers or insurance companies. The article describes the usage of these methods, particularly with regard to asset management and risk management within electrical grids. The essential information needed to set up an appropriate asset management system and differences between asset management systems in transmission and distribution systems are discussed.The bulk of costs in electrical grids can be found in costs for maintenance and capital depreciation. A comprehensive approach for an asset management in transmission systems thus focuses on the "life-cycle costs" of the individual equipment. The objective of the life management process is the optimal utilisation of the remaining life time regarding a given reliability of service and a constant distribution of costs for reinvestment and maintenance ensuring a suitable return.In distribution systems the high number of components would require an enormous effort for the consideration of single individuals. Therefore statistical approaches have been used successfully in practical applications. Newest insights gained by a German research project on asset management systems in distribution grids give an outlook to future developments.
A switching arc in a model circuit breaker is studied by means of CFD simulations and optical emission spectroscopy. The arc is initiated between tungsten–copper electrodes in a carbon dioxide atmosphere and is led through PTFE (polytetrafluorethylene) nozzles. Radiation emitted by the arc plasma is absorbed by the surface of the nozzles leading to ablation of the wall material. The CFD simulations are based on a model of the arcing zone including a consistent treatment of the radiation transport and wall ablation. Carbon ion line radiation is analysed in the experiment using an optical path in the heating channel between the nozzles. Temperature profiles obtained from spectroscopy and simulations are compared. The pressure value in the arc is estimated based on the line width-intensity dependence. The obtained values correspond to the measured pressure outside the arc. Coincidence in temperature for the peak current and discrepancy on the falling edge are found and discussed.
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