Ground ring purpose

[Sahib]

Ground resistance has very little if anything to do a good LPS. A 10 foot section of 750 MCM exhibits roughly 3K ohms of impedance at lightning frequencies. Does not make one bit of difference if the earth electrode is 1 or 100 ohms if it is in series with 3K ohms. Either way you still have 3K ohms.

It depends on the grounding model you adopt. A grounding model with purely DC resistance is applicable in cases where the longest length of the grounding system conductor is less than 10% of the lightning penetration depth.

As for a sub-station even though they are designed to obtain 10-Ohms, anything 200 ohms or less is more than adequate to operate the switch gear. However that has nothing to do with life safety as not even a 1 Ohm ground would save your life, it would only make you vaporize faster.

Operating the switchgear to cut off the supply during a ground fault in a substation is one thing. Obtaning lower GPR (ground potential rise), lower touch and step potentials due to lower grid ground resistance is another. Which you prefer, one or both?

 

[ActionDave]

Operating the switchgear to cut off the supply during a ground fault in a substation is one thing. Obtaning lower GPR (ground potential rise), lower touch and step potentials due to lower grid ground resistance is another. Which you prefer, one or both?

You really don't get it do you?

 

[Sahib]

You really don't get it do you?

What is it, man?

 

[ActionDave]

What is it, man?

I'm not even half as smart, or at least half as educated as you are so so I am not going to debate.
The whole issue of grounding, earth, and safety is either something you just like to pick at with others on this forum or something you have made your mind up about and don't care to learn about from others on this forum.

 

[Sahib]

ActionDave:
Thanks for your remarks.
Surely I learn from others in the forum, provided I am able to verify it from other reliable sources outside the forum. In the given case the concepts under section grounding resistance given in chapter 11 'substation grounding'of the book Electric power substation Engineering in http://www.crcpress.com/product/isbn/9781439856383 do not agree with those of other forum members like you.