NATIONAL ALUMINIUM COMPANY LIMITED - Rites

front design. The distribution board shall be suitable for cable entry from the bottom.
Devices requiring operation sh shall all be located in between 450 mm and 1900 mm from the floor
level .
The ACDB shall have indicating voltmeter with selector switch, PT, MPCB & MCB at the line
side of the distribution board. Ammeter with selector switch, CT, MPCB & MCB shall
also be provided. These instruments shall be flush type located on the front door of the
compartments. The sizes of ammeter and voltmeter shall be 96 mm x 96 mm. Phase
indicating lamps shall be provided vided at the bus side of incomer.
The ACDB shall be fabricated from minimum 2.0 mm thick CRCA sheet steel with load
bearing members comprising 2.5 mm thick CRCA sheet steel. The degree of protection
shall be IP:54.
A the outgoing feeders shall be of MCCB/MCB unit.
Power circuit isolation shall be possible without opening the front door and shall have
provision for padlocking in OFF position with the door closed. ON/OFF indications
shall be provided for a feeders by means of cluster LED lamps.
The main phase busbars and tappings shall be made of aluminium having cross sectional
areas to be substantiated during en engineering gineering but in no case the current density shall
be more than 80 A/sq cm. The busbars shall be suitably supported on non hygroscopic
moulded glass reinforced plastic insulators so as to be capable of withstand withstanding dynamic
forces due to 50 kA through fault short circuit. All joints shall be coloured PVC taped.
Temperature rise of busbars/joints while carrying the rated current shall not be more
than 45°C over maximum ambie ambient nt temperature of 45°C when measured by thermometer.
Tappings from the main busbars to individual feeder compartments shall be by means of
insulated single core copper cables with stranded conductor for feeders upto 100 A ratings
above which aluminium busbars shall be used. All copper to aluminium joints shall be
provided with bimetallic nuts/bolts/washers.
A continuous 50 mm x 10 mm aluminium earth bus shall be provided throughout the
length gth of the panels and shall be located in a separate chamber at the bottom with
removable front cover. Provision shall be kept for taking earth connections to external earth
mat. PVC insulated (Green coloured) copper wires shal shall l be used to connect all noncurrent
carrying metallic parts, doors, etc to the earth bus.
All relays, instruments, meters, pushbuttons, switches and other devices of any feeder
shall be located on the respective compartment only.
All operating handles, control switches, pushbuttons, indicating lamps, instruments, meters
etc shall be mounted on the front of the cubicles.
220 V DC Control Battery Bank
Battery bank shall consist st of plante type lead acid cells in transparent plastic containers
with sufficient quantity of electrolyte, acid level indicating floats, intercell connectors,
cell support insulators, cell number plates, properly ttreated
reated and acid resistant painted
wooden stand supported on porcelain insulators, terminal connectors for external
connections etc. as required to make the installation complete in all respects. The wooden
Technical Specification:Sec-6, Electrical
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