Plant ground testing frequency
Plant ground testing frequency
(OP)
Is there any code/recommendations for testing frequency of ground grids.
I'm not talking 50Hz vs 60Hz. I'm looking for a schedule frequency 6 months vs annually vs 5 years, etc.
I'm not talking 50Hz vs 60Hz. I'm looking for a schedule frequency 6 months vs annually vs 5 years, etc.
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RE: Plant ground testing frequency
Sorry, couldn't resist.
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Plant ground testing frequency
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This is normally the space where people post something insightful.
RE: Plant ground testing frequency
RE: Plant ground testing frequency
Some parts of the world don't use or much care about NFPA standards because we aren't governed by them. Can you quantify 'should never exceed three years' with any data to support the choice of three instead of (say) one year or five years?
For example, doing a proper test on the fully welded copper earth grid at our power plant would require a full station outage because of the amount of noise in the ground which consistently foils any attempt at measuring earth grid resistance into the bulk of earth. The earth grid is also heavily tied to two major transmission substations which makes things even harder to test. Three yearly testing simply isn't going to happen. We just about manage to maintain visual inspection of the thousands of above ground connections to the structural steel at five yearly intervals. We prove earth connections from the switchgear and other major electrical plant to the earth grid much more frequently, at roughly two year intervals.
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Sometimes I only open my mouth to swap feet...
RE: Plant ground testing frequency
I think that you should always perform a fall of potential test on a new installation, and then retest if you suspect there may be a problem due to water table changes, people getting shocked off equipment, failure of a GF relay, etc. But that is just my 2 cents.