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EARTH MAT DESIGN CALCULATION
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(REF - IEEE STD-80, 2000)
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PROJECT:
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SUBSTATION
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LOA NO:
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CLIENT:
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DOC. NO.:
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CONSIDERATIONS FOR E-MAT DESIGN FOR MANTHALI S/STN.
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1.
Average Resistivity was measured ( during summer season ) is about ohm-m.
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However for severe most condition we have considered maximum resistivity i.e.
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ohm-m for design calculation.
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2.
Consider KA fault level as per specification.
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3.
Duration of fault level is 1sec.as per technical specification.
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We have not considered Current Diversion and multiple path. So corrosion factor is also
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not considered for conductor sizing. Sq mm is sufficient to withstand
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specified fault level.
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4.
Conductor Details.
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Main Earth Mat Conductor is 100 Sq mm Copper Rod
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Risers are of 100Sq mm Copper Rod
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Functional earthing i.e. MOM Box, Cable Trench Rack etc are of - 50 Sq mm copper Rod
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5.
For Main Earth mat design a site surfacing of 100mm thick Crushed rock surface layer
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has been considered. Step & Touch potential cannot be restricted within safe limit
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without such surface layer.
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6.
We have considered:
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a. Riser to main Equipment & Bus support structure : 50 Sqmm Copper rod
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b. Riser to HT Panel : 50Sq. mm Copper Rod
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c. Riser to C R Panel : 50Sq. mm Copper
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d. Riser to JBs & Marshaling Box :25 Sq.mm Copper rod
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e. Fencing Earthing : 25 Sqmm Copper rod
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f. Transformer Neutral Earthing : 2 Nos 100 Sq. mm copper Rod
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