NATIONAL ALUMINIUM COMPANY LIMITED - Rites

• Sequence module
• Zero speed/over speed monitor as applicable
• V/f control
• Current limiter
• Counter current/ regenerative braking unit as applicable
• active electronic components used shall be of industrial grade hermetically sealed
• Regulated power supply for reference setting:
Voltage variation of (+/-) ) 0.1 % with an input variation of +10% - 15%
Steady state regulation of (+/ (+/-)0.25% % guaranteed against 100 to 200 % load disturbance and +
3%, -6% 6% input supply frequency variation.
• Facility to accept speed reference from computer/ programmable controller
Construction features
• Floor mounted, free standing
• Dust and vermin proof
• Sheet steel clad
• Minimum 2.5 mm thick for panels.
• Minimum 2.0 mm thick for doors and side covers.
• Suitable to withstand vibrations to be encountered in steel plant application.
• Cubicles with illumination lamps, door switches, space heaters and adequate sockets
for soldering.
• All control blocks plug –in-type with necessary test sockets.
• Units shall be self contained and serviceable.
Enclosure and Ventilation
• Enclosure conforming to IP IP-52 or more with weather proof enclosures
• Units shall be provided with cooling fans and louvers at the bottom sides. All louvers shall
have fine mesh behind them.
• Ventilation through individual ventilation ducts, from bottom not acceptable.
4.9 RELAY PANELS
Relay panels (RP) housing aux. contactors, timers, relays, etc. shall be provided for equipment
control, sequential control, monitoring, safety alarm signals, annunciation signals, interlocking
of drives ,signal exchange, interface with future system etc. shall be provided. Constructional
features of R.P. shall be similar to MCC. At least 10 % spare auxiliary contactors, timers &relays
shall be provided in the relay panel whose contacts and coils shall be wired up to terminals. terminals.10
% spare terminals shall als also be provided. 10 % of auxiliary contactors, timer and relays shall be
provided as spares which will be wired upto terminals.
4.10 PROGRAMMABLE LOGIC CONTROLLERS (PLC)
Power supply system
Technical Specification:Sec-6, Electrical
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