Sub station earthing
Sub station earthing
(OP)
I am interested in Knowing sub station earthing with specific reference to step potential and touch potential and how to calculate it.This I would like to know with respect to IEC.
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RE: Sub station earthing
RE: Sub station earthing
As far as free online information is concerned, there is a limited description in: www.tradeport.on.ca/old_site/ApplicationNotes/aemc.pdf
RE: Sub station earthing
http://www.netaworld.org/files/ItemFileA173.pdf
Old telegraph engineers used to say earth conductivity (near zero resistance) was because the earth acted as an infinite number of parallel resistors. The the use of concentric shells or hemispheres to explain low resistivity is a "new" twist on that theory. Atmospheric physicists present a different theory, but I don't see any "earth conductivity measurement" articles using their approach.
RE: Sub station earthing
RE: Sub station earthing
http://www.tscm.com/MIL-HDBK-419A.PDF
The conductive quality of the ground in Australia must be quite good in that they run a 12.7 KV 50 HZ power transmission line with just a single-wire earth return (SWER).
http://tdworld.com/ar/power_one_wire_enough/
I found the next article interesting in that the design criteria used for a SWER system assumes a 0.05 ohm/km for the earth return resistance, page 16.
http://www.stonepower.se/Images/SWER.pdf
If the earth resistance is only 0.05 ohm/km, there must be something wrong with the "fall of potential" ground tests that struggle to get a 5 ohm resistance with less than a 100 foot spread between the ground rod and the sensors.