NATIONAL ALUMINIUM COMPANY LIMITED - Rites

The LDBs shall be fabricated from CRCA sheets with 2 mm thickness for all members except
the doors of the modules, the rear covers, the covers of cable chambers and busbar chambers
which may be of 1.6 mm with adequate stiffeners to prevent buckling. Non Non-load bearing
partition walls may be of 1.6 mm thick sheet steel.
The cubicles shall be made up of bolted sheet steel members and side panels of pressed sheet
steel with neoprene gasket at all joints and openings including doors.
Bus bars shall have same cross cross-section section throughout the length. Rating of the neutral bus ba bar
shall be 50% of the main bus bar. Earth bus bar shall run in bottom chamber throughout the
length of the panel.
The LDBs shall have necessary provision at either end for future extension by bolting
additional section.
The busbar shall be supported wi with high quality non-hygroscopic, hygroscopic, insulating, self extinguishing
and fire retardant insulating material, of adequate mechanical strength so as to withstand,
without damage, effects of available short short-circuit circuit current. The busbars shall also be properly
spaced d of facilitate taking vertical connections to individual units. The connections to
individual units shall be taken by taped busbars. The busbars shall be of uniform cross cross-section
and the main busbars shall run throughout the length of the board. Similarly vertical droppers
shall extend for the full height of the panel except the bottom chamber. The connection
between busbars of different metals as well as their connection with the terminals of the
equipment shall be made in such a way to prevent corrosion and local heating.
Liberal space shall be provided for cabling and to accommodate any conventional type of cable
glands for PVC insulated and PVC sheathed armoured aluminum conductor cables.
The cables compartment shall have provision for clamping of ccables
ables inside compartment on
perforated sheet steel sections.
The LDB shall have following meters in each of the two incoming feeders:
• One no. digital type voltmeter with accuracy class of 1.0
• One no. digital type ammeter with accuracy class of 1.0
• One no. digital energy meters with accuracy class of 1.0
Suitable CTs with accuracy class of 1.0 shall be provided in the incomer modules for the above
metering.
Moulded Case Circuit Breakers
LDBs shall have moulded case circuit breaker triple pole, air break type with independent
manual quick make and quick break type. MCCB shall be capable of breaking rated current at
0.3 pf at rated voltage. MCCB shall withstand the fault current envisaged for 415V system and
shall be current limiting type. All outgoin outgoing g feeders shall have earth fault protection.
Technical Specification:Sec-6, Electrical
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