Lightning Attachment on Overhead Telephone Line:Experience from Tanzania Telephone Network
Telephone line provides a vital link and gateway for various services to the telephone subscribers. These subscriber interfaced equipments comprise of electronic devices or microprocessor controls that operate at low voltages, which can be super ceded by even distant lightning strike. Induced overvoltages on a telephone line due to lightning strike have been identified as one of the causes of transient and electromagnetic interference on the telephone line. Direct and indirect strikes on an overhead telephone line were modeled in this paper. Induced overvoltages on a conductor of 7m above ground, where ground serves as a return conductor are calculated as a function of distance from the strike point using Finite Difference Time Domain (FDTD) method, as it could be a necessary data for deciding the possible future protection scheme. It has been observed from the induced overvoltages simulated results that direct strike is more severe compared to indirect strike. The effect of the finitely conducting ground using a time domain expression for the transient ground impedance were considered in the analysis of induced overvoltages of the telephone line. The analysis presented here is based on the transmission line solutions both under lossless (without ground return) and lossy (with ground return) conditions. It has been shown that the effects of ground conductivity in the lossy case for induced overvoltages calculations on the telephone line are predominant as compared to lossless case and therefore can not be neglected.
Jacqueline Damas Nerey H. Mvungi Mighanda J. Manyahi
Faculty of electrical and Computer Systems Engineering,University of Dar es Salaam, P. O. Box 35131, Dar es Salaam, Tanzania
国际会议
第13届国际大气电学会议(The 13th International Conference on Atmospheric Electricity)
北京
英文
2007-08-13（万方平台首次上网日期，不代表论文的发表时间）