NATIONAL ALUMINIUM COMPANY LIMITED - Rites

• The communication subsystem between PLC processor and I/O subsystem shall be dual
redundant.
• The communication munication subsystem between processor subsystem and PLC console shall be dual
redundant, consisting of two separate communication interfaces and two buses, each one
configured in redundant mode.
• No hardwired alarm system is required. All the alarms are to be displayed in OWS of PLC
with multi tone buzzer and with alarm history provision.
• The software provided at the time of supply should be of latest version.
• Necessary license to be provided along with the software.
• The OS (Operator Station) desk and opera operator tor chair to be supplied by the bidder.
4.11 UNINTERRUPTIBLE POWER SYSTEM (UPS)
General System Description
The required kVA, 50 Hz, single phase UPS system shall provide continuously operating
uninterrupted power supply to critical AC loads such PLC PLC, , instrumentation, etc.
The capacity of UPS shall be suitable to feed power requirement of the PLC which shall control
and monitor all the drives/mechanism of proposed additional coal handling system.
The UPS system shall include but not necessarily limited to the following equipment:
• One 100% rated battery bank
• One set of Float Charger (FC) and one set of Float cum Boost Charger (FCBC) complete
with associated incoming AC switchgear.
• Two nos. 100% capacity inverter banks.
• One no. DC switchgear, cconnecting
onnecting above and also inverter banks stated above
• One no. 3 phase to 1 phase transformer and associated AC switchgear, 230V, 1 phase
voltage stabilizer and backup source static switch.
• One no. 240 V UPS ACDB
• One no. four way manual bypass switch
• Static switches
• All inter connecting cables/wiring with connection accessories and other required items
to make the system complete.
Mode of Operation
Normal Mode
During the normal operation the UPS shall be used to provide power to the critical loa loads. The
primary AC source shall be used to supply power to the rectifier charger. Two (2) no. chargers
shall feed regulated DC power to their individual inverter banks and simultaneously float
charge the backup batteries.
Emergency Mode
Technical Specification:Sec-6, Electrical
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