Please refer to my paper on this topic . IEEE Trans on IAS, 2015, which discusses the various parameters with explanations

Ok Mr Harid

Thank you for your answer

Congratulations Mr Harid, I found large informations in your paper.

It will be better to use it for verify my simulations. I think that I need some informations about your experimental tests (soil permittivity).

Ground connections can be up to 100Ohms in dry areas

Mr Harid , your paper on oil impedance seems to be limited by the impedance of your measurement circuit more than the actual ionization as it is not in a log scale and has very slow rise times. More interesting is not the impedance in kOhm of the shunt path but in the sub Ohm scale that results in detonation of oil into combustible gasses. I have measured about 2W, 20 Ohm, 160nJ per Pd event

Hi Mr Dean Stewart,

The paper of Mr Harid treat the impedance of grounding systems under lightning discharges. An analysis of experimental results on the behaviour under impulse currents of various grounding electrodes is presented.

For more information look at : DOI10.1109/TIA.2015.2442517, IEEE Transactions on Industry Applications

Good Luck,

Omar

EFFET DE L’AJOUT POUZZOLANIQUE SUR LA DURABILITE ET LES PROPRIETES THERMIQUES D’UN MORTIER ARME

Séminaire National sur les Matériaux locaux dans la construction, 26 & 27 Novembre 2012 Université Kasdi Merbah, Ouargla

Mr. Kherif , I understand the paper, but I was merely commenting on the potential measurement errors in the report.  Also the study was very limited to one sample of very low conductivity soil of 6 Ohms with a rise time of about 6us indicating the moisture dielectric of around 1uF of the ground rod and the spectrogram impedance rise at ~ 50kHz indicates a ground rod inductance of 20uH. I am familiar with the Z1,Z2,Z3,Z4 measurements.  I have also measured Z1 for std Impulse tests until arc of 150BIL clean bushings that appeared to pass up to 100kV from observing the waveform but failed at 60~70kV  if you use a LeCroy and measure Z1 drop of more than 10%. Normally the impedance is limited by the oil filled capacitance and the tuning of the  impulse generator to create the standard waveform.  I believe a dry ground rod would lower capacitance more than raising Resistance and a faster rise time would lower the threshold of creepage breakdown.  But ionization time constant may have many variables.

Good luck.

Hi Mr. Kherif and happy new year!

One of the most important parameters that characterizes the impulse behavior of a grounding system is impulse impedance. Impulse impedance is defined as the ratio of the instant value of impulse voltage to the instant value of impulse current and, more particularly, one of the four parameters of impulse impedance (Z1, Z2, Z3, or Z4) can be used for impedance estimation in field experiments.You can see more details and information about such experiments in: V.P. Androvitsaneas et al. "Experimental study on transient impedance of grounding rods encased in ground enhancing compounds", Electric Power Systems Research, vol. 139, pp. 109-115, Oct. 2016, DOI 10.1016/j.epsr.2015.11.032

Mr Stewart, Mr Vasilios

Thank you very much for your help and happy new year

Omar

Dear;

Kindly check:

Article : Experimental study on transient impedance of grounding rods encased in ground enhancing compounds

Regards

Dear;

for more information please check the following documents

"Experimental study on transient impedance of grounding rods encased in ground enhancing compounds",

Regards