Lightning trip-out risk evaluation of a 220kV transmission line in Shiyan
The lightning trip-out accidents of Shiyan transmission lines occur frequently. The lightning parameters, lightning faults and geography of 220kV shi-xuan transmission line have been collected. The lightning striking simulation model has been built by using electromagnetic transient calculation software ATP-EMTP and multi-wave impedance model. The lightning withstanding level of tower and the lightning trip-out rate have been calculated. The actual operation of the transmission line has been considered in order to evaluate the risk of lightning trip-out. The results can provide guidance for the lightning protection of transmission linewhich locates in mountains.
Analysis of Lightning Induced Voltages on Multiconductor Distribution Lines
The overhead transmission lines are usually naked in the air, overvoltages induced by lightning can cause frequent outages in power systems. The 110 kV and above overhead lines are mainly damaged by direct lightning, but indirect lightning can cause more interruptions than direct strike because of their more frequent occurrence. The calculation of overvoltages induced by indirect lightning is important in the design and lightning protection of transmission line, it is also the study subject of electromagnetic compatibility. A novel method for calculation of the overvoltages induced by nearby lightning is used in this paper. With the Fast Fourier Transformation(FFT), the spectrum of the transient lightning current is calculated. According the BLT equations, which are used to calculate the load respond of multiconductor transmission lines, the Telegraph equations are solved, and the lightning induced voltages are calculated in frequency domain. Then the transient responds are obtained by inverse FFT. The effect of ground conductivity and the presence of shielding line on the magnitude of the induced voltages are studied. The analysis shows that differential model voltages on vertically-configured lines are more higher then that on horizontally-configured ones. The lower the ground conductivity the better the shielding efficiency of overhead grounding line.
The Invention of the Jewish People
'All modern nation states have a story of their origins, passed down through both official and popular culture, and yet few of these accounts have proved as divisive and influential as the Israeli national myth. The well-known tale of Jewish exile at the hands of the Romans during the first century AD, and the assertion of both cultural and racial continuity through to the Jewish people of the present day, resonates far beyond Israel's borders. Despite its use as a justification for Jewish settlement in Palestine and the project of a Greater Israel, there have been few scholarly investigations into the historical accuracy of the story as a whole. In this bold and ambitious new book, Shlomo Sand shows that the Israeli national myth has its origins in the nineteenth century, rather than in biblical times - when Jewish historians, like scholars in many other cultures, reconstituted an imagined people in order to model a future nation. Sand forensically dissects the official story - and demonstrates the construction of a nationalist myth and the collective mystification that this requires. A bestseller in Israel and France, Shlomo Sand's book has sparked a widespread and lively debate. Should the Jewish people regard themselves as genetically distinct and identifiable across the millennia - or should that doctrine now be left behind and if the myth of the Jewish state is dismantled, could this open a path toward a more inclusive Israeli state, content within its borders?'