DocumentCode :
3699406
Title :
Adapting the statistics of soil properties into existing and future lightning protection standards and guides
Author :
William A. Chisholm;Susana de Almeida de Graaff
Author_Institution :
IEEE Power and Energy Society, Transmission and Distribution Committee, Toronto, Canada
fYear :
2015
Firstpage :
7
Lastpage :
20
Abstract :
Risk estimates for lightning faults make use of log-normal distributions for lightning characteristics such as peak current. Simplifications for highly correlated parameters, notably peak current and rate of current rise, justify use of equivalent front time of 2 µs in backflashover calculations for first negative return strokes. The transmission line backflashover rate is also affected by uncorrelated and broad statistical variations in soil resistivity, tower footing impedance Zf and resistance Rf. Statistical properties of Rf from transmission lines in Tennessee USA and Portugal are compared. Modeling of Rf variation using a ten-step distribution from the IEEE Standard 1243 FLASH program is compared with estimates using finer probability step intervals, log-normal and log-logistic models.
Keywords :
"Poles and towers","Lightning","Impedance","Radio frequency","Flashover","Surges","Standards"
Publisher :
ieee
Conference_Titel :
Lightning Protection (XIII SIPDA), 2015 International Symposium on
Type :
conf
DOI :
10.1109/SIPDA.2015.7339338
Filename :
7339338
Link To Document :
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