NATIONAL ALUMINIUM COMPANY LIMITED - Rites

Input power supply shall be fed through UPS system. However, PLC shall be capable of
withstanding power supply from electrical feeder. Alternate source of power supply
arrangement or second UPS shall be provided to take care of the situation when the original
UPS fails.
Built-in in power supply units
• Suitable for the e power supply system as specified above.
• Independent units for the following:
• CPU and associated electronic units
i) sensing the status of input devices
ii) driving outputs if outputs are relays
iii) Insulation level 2.5 kV for 1 minute.
• Protection against t surge protection & short circuit
• Electronic over current protection with feedback feature.
Central processor unit
• Modular and plug-in in type
• 32 bit microprocessor based
• Scan time 2 m sec per one K Words of instructions or better
• Provision to latch desired outputs.
• The processor shall have in in-built built provision for examining input conditions, compare,
compute, logical, conversion from/ to BCD, bit manipulation, block memory manipulation,
diagnostic, shift, sequencing, conditional jumping, subroutine instructions.
• In-built built PID instruction shall be preferred over separate PID hardware Module.
• Timer & counter modules shall be provided wherever required.
Memory units
Modular and plug-in type
• Word length 32 bit as per CPU
• Expandable in blocks of 4K Words
• Minimum size 16K Words
• EPROM/ RAM with battery back back-up
• Back-up up battery shall be as follows:
i) Rechargeable Ni-Cd Cd batteries with necessary charging circuit, Lithium or any other
internationally acceptable type.
ii) Able to retain memory for a minimum of 1 year with no power applied to the controller.
Input units
• High density (32/16 Channels), modular and plug plug-in type
• Insulation level of 1.5 kV
• Input interrogation voltage 24V DC
• Discrete input units shall l have the following:
i) Filter to take care of contact bounce
ii) Opto-isolation isolation to isolate the input device from the controller
Technical Specification:Sec-6, Electrical
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