It was found in some research that the frequency dependence of soil parameters is accountable for affecting the grounding potential rise of electrodes. For this purpose, many models have been developed to describe this assignment are ; Scott’s model and there of Smith and Longmire, Messier, Visacro and Portela, Portela, and finally Visacro and Alipio, which were more particularly proposed for the representation of the soil electrical parameters.
The double exponential expression is adopted to simulate this current. It happens to be very simple to treat the pulse amplitude, rise time and pulse duration.
What is the expression of the lightning frequency for the double exponential waveform (in time domain)? and how to calculate its approximate value for the grounding systems analysis?
Hi Omar,
I think you will have a spectrum of frequencies - just that the magnitude at high frequencies will rapidly become negligible.
If you define a suitable double-exponential signal and do an FFT, you should immediately get to see what I mean ! You should then be able to choose the prominent frequencies and use them for your analysis.
The same can be done through analytical expressions of the Fourier Transform as well.
-Sanjay
dear kherif
hope fully this is one of ours research result
I have worked on this a few years ago. As you can see on page 43 of the following publication, for the 8/20us waveform the FFT show a frequency component around 10-20kHz.
https://www.researchgate.net/publication/281202416_Comparative_Study_of_Metal_Oxide_Varistors_MOVs_for_Failure_Mode_Identification
Thesis Comparative Study of Metal Oxide Varistors (MOVs) for Failur...
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