NATIONAL ALUMINIUM COMPANY LIMITED - Rites

1. Earthing ring mains at WT substation and all the electrical rooms/premises
2. Equipment earthing
3. Transformer neutral earthing prov providing dedicated pits
Bidder shall include complete earthing material including earthing strips, earth electrodes
other accessories for treated earth pits, etc. and carry out earthing ring mains, earth pits,
interconnections, equipment earthing, all assoc associated iated civil works, etc at all the ubstations.
All the connections of earthing ring mains with available underground earthing grid of
respective substation/premise shall be under scope of the Bidder.
Separate dedicated treated earth pits shall be provid provided ed for transformer neutrals. Two nos.
such earth pits shall be provided for each of the transformers. The treated earth pits shall be
consisting of 3 mtr 65 NB GI pipes, funnels, clamps, 3 mtr long 40 mm MS rod electrodes, MS
cover with lifting lugs, assoc associated civil works, etc.
All the equipment located in the WT premises / sub sub-premises e.g. 33 KV switchboard, LT PCCs,
busducts, transformer bodies, charger panels, DCDBs, LDBs, SLDBs, receptacles, control panels,
MCCs, etc shall be connected by the Bidder with earthing ring mains at least two different
points.
Electronic earthing shall be considerd for PLC, etc
Bidder shall also consider earthing of following equipment to be installed by the bidder.
• 33kV kV WT switchboard at WT substation in switchgear cum MCC room
• WT distribution transformers (2 nos.) – Neutral as well as body earthing
• 415 WT SYSTEM PCC at WT SYSTEM substation in switchgear cum MCC room
• Control panel for power distribution equipment at existing WT control room
• LT busducts (2 sets)
• Charger panels, DCDB, etc at WT substation in switchgear cum MCC room
Bidder shall consider earthing ring mains at each electrical premise and connect the electrical
equipment with the rings. The earthing rring
ing mains shall be connected with underground
earthing mats (consisting of 2x40MM dia to be installed by the bidder. . For transformer neutral
earthing, bidder shall consider dedicated plate earthing.
Bidder shall include complete earthing material includin including g earth electrodes, risers, GI earthing
strips, other accessories, etc. and carry out main earth grid mat, earthing ring mains, earth
pits, risers, interconnections, equipment earthing, all associated civil works, etc within battery
limit of the package. All ll the interconnections with other earthing systems of the plant and
with existing systems shall be under scope of the Bidder.
The Bidder shall obtain the actual soil resistivity of the plant area by carrying out soil resistivity
tests and design the earthing thing system accordingly.
Technical Specification:Sec-6, Electrical
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