Thermal Analysis of the Fuse with Unequal Fuse Links Using Finite Element Method
In this paper a three dimensional thermal model of high breaking capacity fuse with unequal fuse links is proposed for both steady-state or transient conditions. The influence of ambient temperature and electric current on the temperature distribution inside the fuse, has been investigated. A thermal analysis of the unbalanced distribution of the electric current through the fuse elements and their influence on fuse link temperature rise, has been performed. To validate the three dimensional thermal model, some experimental tests have been done. There is a good correlation between experimental and simulation results. Keywords—Electric fuse, fuse links, temperature distribution, thermal analysis.
Experimental investigation on the fusion of thin wire elements exposed in air and silicon oxide granules environments
The use of fusible elements for the protection of the low voltage installations, medium voltage distribution network and a wide variety of other applications against fault currents is mandatory by any regulation. The investigation and analysis of the processes during circuit braking, with the involved arcing phenomena, is required to improve existing knowledge. Furthermore, the reliability and long lasting operation of the fuse elements themselves are very important issues due to their operating characteristics in nominal or excess currents. This work presents measurements of the voltage, current density, magnetic pressure and I2t during the fusion process on thin wire elements exposed in air and silicon oxide granules. The results are analyzed and interpretation of the related phenomena is presented. The results could be found useful in the development of new improved fusion models useful for the development of more advance fuselinks.
Computational Analysis of a Double-Nozzle Crossflow Hydroturbine
The crossflow turbines commonly used in small hydropower systems have a single nozzle. We are unaware of any studies of double-nozzle crossflow turbines which could have twice the power output of the single-nozzle design by doubling the flow through the same runner, with a high maximum efficiency. We present a computational analysis of a double-nozzle crossflow turbine, to determine the turbine efficiency and fundamental flow patterns. This work was based on a single-nozzle crossflow turbine with a maximum efficiency of 88%, one of the highest reported in the open literature through extensive experimental measurements. Previous numerical studies on this turbine have shown that the water flow in the runner was confined to less than half the runner periphery, implying that the other half could be used to double the runner power output by employing a second nozzle. We show that adding a second, identical nozzle without making any other changes to the design achieves a doubling of the power output. The dual-nozzle turbine, therefore, has the same efficiency as the original turbine. We also investigate the use of a slider to control the flow at part-load and show that part-load efficiency of the double-nozzle is very similar to that of the original turbine. This demonstrates the feasibility of using two nozzles for crossflow turbines.