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 German centenary of the First World War
In the run up to the 2014 centenary of the First World War, the German public was gripped by a heated debate on the origins of the war. This article explores the nature of this controversy and its role in shaping national commemoration of the Great War. It also draws parallels between the commemorations of the fiftieth anniversary of the outbreak of the war in 1964 and those of 2014. Through a comparison of Germany’s national memories of the war with those in Britain and France, the article also reveals how different and sometimes conflicting national interpretations of the history of the First World War have affected centenary commemoration. Memories of the First World War are nation-specific, constructed and developed over time to suit a particular view of a country’s past. Moreover, they can be instrumental in influencing that country’s future development and relations with its neighbours.