15.2.0 General Requirements October 30, 2008

15.2.0  General Requirements         

15.2.1  The Contractor shall provide  Control & Instrumentation systems   PLC based control systems for station auxiliaries equipment mounted/local instruments and transmitters including sensing elements as required,  Local instrument enclosures/racks, Local gauge boards/racks, Process Connection and Piping, Sample lines, Electric Power Supply System, Actuators for valves, Instrumentation Cables etc. as identified in the specification.

15.2.2  The Contractor shall provide all material, equipment and services so as to make a totally integrated Instrumen­tation and Control System together with all accesso­ries, auxiliaries and associated equipments ensuring operability, maintainability and reliability. The work shall be consistent with modern power plant practices and shall be in compliance with all applica­ble codes, standards, guides, statutory regulations and safety requirements in force.

15.2.3  The Contractor  shall include in his proposal all instruments and devices, which are needed for the completeness of the system. Same shall be subject to approval of the purchaser during detailed engineering. All instruments and control equipments like primary and secondary instruments etc. shall meet the functional requirements . In addition, all electrical instrument  solenoid valves which are located in the field/hazardous locations shall be provided with explosion proof enclosure             suitable for hazardous areas described in National Electric Code (USA), Article 500, Class-I, Division-I. All field wiring should be through conduits. All fittings, cable glands etc .shall be strictly as per NEC recommendation article, 500 to 503.,

15.2.4  All instrumentation and control equipment, instruments, instrumentation support steel work for gauge board, cabinet, local remote instruments and pipe work shall be suitable for guaranteed performance at the ambient, humid, dusty and corrosive conditions prevailing at site and specified elsewhere.   Environmental test for all electronic items shall be carried out as per IS: 2106 or equivalent standard acceptable to the owner.  All indoor equipment shall be suitable for continuous safe operation at ambient of 50 degree centigrade and also during periods of air conditioning failure without any loss of function, or departure from the specification requirements covered under this specification. The panels/desk/cubicles located in air conditioned area and indoor shall comply with the requirement of protection class IP-42 and panels located in outdoor areas shall be IP-65 as per IS: 2147.  All outdoor instruments and control devices shall be suitable for ambient of 80 Degree centigrade and humidity of 95%.  Degree of protection for outdoor equipment shall be minimum IP-65 as per IS: 2147.

15.2.5  The equipment offered shall be of proven make and design, ensuring reliability, safety, efficiency and long continuous trouble-free service with high economy and low maintenance costs.  The C&I system offered shall meet the operation requirements in all regimes, control philosophy, design concepts, sizing and design criteria as indicated in various sections of this specification.  The equipments/devices offered shall be suitable for satisfactory operation at ambient temperature specified with dusty, humid and corrosive conditions faced in thatl area and their design principles shall take into account but not be limited to the following :-

a)         Interchangeability and expandability

b)         Malfunction identification

c)         Maintainability

d)         Shock and vibration proofing

e)           Short circuit proofing

f)            Over-voltage protection

g)           Easy access to all components

h)           Highest class workmanship general finish

i)            Adequate space availability for connecting external cables.

j)         Noise immunity including immunity against radio frequency interference and electromagnetic interference to be provided with opto/galvanic isolation.

k)         Avoidance of overheating of electronic components

l)         Fail safe operation: It shall be ensured by the bidder that failure of any sensor, transmitter, controller, final control element, power or control supply shall not cause a hazardous condition. Further, such a failure should provide audio and visual alarms.

m)        Surge protection for electronic components as per IEEE-472.

n)         Selection of high quality equipments/material.

 

15.2.6  All equipment/systems covered under the specification shall be subject to inspection and tests as per the relevant standards including any additional tests considered necessary by the purchaser during manufacture, erection and on completion of the work.   The approval of the purchaser on passing of such inspection of test will not, however, prejudice the right of purchaser to reject the equipment if it does not comply with specification requirements when erected or does not give satisfactory performance in service.

 

15.2.7  The responsibility for safe, efficient and reliable operation of the equipment/system supplied shall rest with the bidder.  Approval of the drawings by purchaser/consultant shall not in any way relieve the bidder of his obligation/responsibility in this respect.

 

15.2.8  Contractor  shall include in his bid a detailed Bill of Material (BOM) for each of the systems.

 

15.2.9  All panels, desks, cabinets shall be provided with a continuous bare copper ground bus. The ground bus shall be bolted to the panel structure on bottom on both sides. The contractor shall submit with the offer recommended grounding scheme required for control system. The exact grounding scheme shall be finalized during detailed engineering.

 

15.2.10 The control system and various equipment shall conform to the requirements specified in the section -6 of BTG package, which are not specifically covered herein

15.3.0 Programmable Logic Based Control System October 30, 2008

15.3.0  Programmable Logic Based Control System :

15.3.1    PLC Processor : The processor unit shall be capable of executing the following functions :-

a          Receiving binary and analog signals from the field and operator initiated commands from OWS/ control panel.

b          Implementing all logic functions for control, protection and annunciation of the equipment and systems.

c          Implementing modulating control function for certain application as specified elsewhere in the specification.

d          Issuing control commands.

e          Providing supervisory information for alarm, various types of  displays, status information,  trending,  historical  storage of data etc.

f           Performing self-monitoring and diagnostic functions.

 

15.3.1.1           The controller shall provide all basic functions for binary gating operations,                      modulating controls, storage, counting, timing, logging, transfer operations and comparison functions.  The Contractor in his bid shall submit full details  regarding various functions along with expansion capability.

15.3.1.2           The programmable system shall be delivered completely programmed for the complete and reliable operation of the plant.

15.3.1.3           Each PLC unit shall be provided with two processors (Main processing unit and memories) one for normal operation and one as hot standby.  In case of failure of working processor, there shall be an appropriate alarm and simultaneously the hot standby processor shall take over the complete plant operation automatically. The transfer from main processor to standby processor shall be totally bumpless and shall not cause any plant disturbance whatsoever. In the event of both processors failing, the system shall revert to fail safe mode.  It shall be possible to keep any of the processors as master and other as standby. The standby processor shall be updated in line with the changes made in working processor.

15.3.1.4           The memory shall be field expandable. The memory capacity shall be sufficient for the complete system operation and have a capability for at least 20% expansion in future.  Programmed operating sequences and criteria shall be stored in non volatile semi conductor memories like EPROM. All dynamic memories shall be provided with buffer battery back up which shall be for at least 360 hours. The batteries shall be lithium or Ni-Cd type.

15.3.1.5           The PLC system shall be provided with necessary interface hardware and software for dual fibre optic connectivity & interconnection with  station wide LAN ( In Purchaser’s Scope)for two – way transfer of signals for the purpose of information sharing. The plant information shall be made available through an OPC compliant Ethernet link following TCP/IP standard. The exact data structure shall be as decided during detailed engg.  All required plant data shall be transferred to/from through this ensuring complete security. The exact number of points to be transferred through the above communication link and the format of the data shall be finalised during detailed engineering.    

15.3.1.6                   Two (2) nos latest version of  PC based Operator Work Stations each with 19” color CRT’s and key boards shall be provided for control & monitoring and programming function.  One no. number heavy duty A3 size color inkjet printer shall be provided along with operator work station.

PC based OWS (Operator Work Station, Spec. as provided at the end of this chapter) shall perform control, monitoring and operation of all auxiliaries/ drives interacting with PLC based control system. It shall be possible to use the same as programming station of the PLC. It shall basically perform the following functions. In case the PC based OWS can not be used as programming station of the PLC, then a separate PC based programming station shall be provided.

A         Operator interface for PLC based control system. Operator functions shall as minimum include local/ remote selection, A/M selection, open/ close operation, sequence auto, start/ stop selection, ON/OFF, bypassing criteria etc.

b          Supervisory functions like:-

Mimic displays, which shall depict the process in graphical form and shall cover all the process areas being monitored.

            Alarm monitoring/reporting, generation of logs, calculations, printing of logs & reports etc.

c          Suitable Interface with stations wide LAN ( In Purchaser’s Scope) for two-way transfer of data.

15.3.1.7           Programming station shall have access to the processor of the control system for programming. Programming shall not require special computer skills. On the programming console, it shall be possible to do the programming, self-diagnostics, testing of sequence, simulation and any sequence modification.

 

Programming shall be possible in any of the following formats :
a)	Flow-chart or block logic representing the instructions graphically.
b)	Ladder diagrams.
A forcing facility shall be provided for changing the states of inputs and outputs, timers and flags to facilitate fault finding and other testing requirements. It shall be possible to display the signal flow during operation of the program.  Programming shall be possible OFF line.
A NORMAL / TEST / PROGRAM / OFF lockable selector switch shall be provided.  In case of test mode of operation, all outputs should be blocked.

15.3.1.8           Provision shall be made for erasing and duplicating the user program and             longterm storage facilities shall be provided with the help of mag. tape cartridge or EPROM.

15.3.1.9           Priority of different commands shall be as follows :

15.3.1.10         Manual intervention shall be possible at any stage of operation. Protection commands shall have priority over manual commands and     manual commands shall prevail over auto commands.

15.3.1.11         In PLC controller, memory should exist as to where the sequence was             aborted due to power supply failure so that further operation from that point can restart after power supply restoration. This restart after recovery of the power supply shall be through operator intervention so as to enable verification of readiness of other related equipments.

15.3.1.12         All necessary software required for implementation of control logic, operator station displays / logs, storage & retrieval and other functional requirement shall be provided. The programs shall include high level languages as far as possible. The contractor shall provide sufficient documentation and program listing so that it is possible for the Purchaser to carry out modification at a later date.

15.3.1.13         The Contractor shall provide all software required by the system for meeting the intent and functional/parametric requirements of the specification.

a.         Industry standard operating system like UNIX/WINDOWS NT etc. to ensure openness and connectivity with other system in industry standard protocols (TCP-IP/ OPC etc.) shall be provided.  The system shall have user oriented programming language & graphic user interface.

b.         All system related software including Real Time Operating System, File management software, screen editor, database management software. On line diagnostics/debug software, peripheral drivers software and latest versions of standard PC-based software and latest WINDOWS based packages etc. and any other standard language offered shall be furnished as a minimum.

c.         All application software for PLC system functioning like input scanning, acquisition, conditioning processing, control and communication and software for operator interface of monitors, displays, trends, curves, bar charts etc. Historical storage and retrieval utility, and alarm functions shall be provided.

d.         The Contractor shall provide software locks and passwords to Purchaser’s engineers at site for all operating & application software so that Purchaser’s engineers can take backup of these software and are able to do modifications at site.

 

15.3.2        Input/Output Modules :

15.3.2.1           The PLC system should be designed according to the location of the input/output cabinets as specified

15.3.2.2           Input Output modules, as required in the Control System for all  type of field input signals ( 4-20 mA, RTD, Thermocouple, non change over/change over type of contact inputs etc.) and outputs from the control system (non change over/change over type of contact, 24/48 VDC output signals for energising interface relays,4-20 mA output etc.) are to be provided by the Contractor.

15.3.2.3           Electrical isolation of 1.5KV with optical couplers between the plant input/output and controller shall be provided on the I/O cards.  The isolation shall ensure that any inadvertent voltage or voltage spikes (as may be encountered in a plant of this nature) shall not damage or mal-operate the internal processing equipment.

15.3.2.4           The Input/output system shall facilitate modular expansion in fixed stages.  The individual input/output cards shall incorporate indications on the module front panels for displaying individual signal status.

15.3.2.5           Individually fused output circuits with the blower fuse indicator shall be provided.  All input/output points shall be provided with status indicator.  Input circuits shall be provided with fuses preferably for each input, alternatively suitable combination of inputs shall be done and provided with fuses such that for any fault, fuse failure shall affect the particular drive system only without affecting other systems.

15.3.2.6           All input/output cards shall have quick disconnect terminations allowing for card replacement without disconnection of external wiring and without switching of power supply.

15.3.2.7           The Contractor shall provide the following monitoring features:

a          Power supply monitoring.

b          Contact bounce filtering.

c          Optical isolation between input and output signals with the internal circuits

d          In case of power supply failure or hardware fault, the critical outputs shall be automatically switched to the fail-safe mode.  The fail-safe mode shall be intimated to the successful Contractor during detailed engineering.

15.3.2.8           Further, keying-in of individual wire connectors shall be provided to ensure that only the correct card is plugged on the I/O module. It shall be possible to remove I/O module without disconnecting wiring from field inputs or outputs.  There shall be atleast 20% spare capacity available on input, output and memory modules, over and above the system requirement.

15.3.2.9           Binary Output modules shall be rated to switch ON/OFF coupling relays of approx. 3 VA at 24 VDC. Analog ouput modules shall be able to drive an load impedance of 500 Ohms minimum.

15.3.2.10         Output module shall be capable of switching ON/OFF inductive loads like solenoid valves, auxiliary relays etc. without any extra hardware.

15.3.2.11         Only one changeover contact shall be provided in MCC for control and interlock requirement.  Further multiplication, if required ,shall be done by the contractor in PLC system.

15.3.2.12         All input field interrogation voltage shall be 24V DC or 48 V DC.

15.3.2.13         In case of loss of I/O communication link with the main processing unit, the I/O shall be able to go to predetermined fail safe mode (to be decided during detailed engineering) with proper annunciation.

15.3.2.14         Contractor shall provide for 20% spare I/O modules in each system cabinet to take case of any further addition.

15.3.3        Printer

One number A3 size color inkjet printer per PLC shall be provided as a part of the supervisory system.  It shall print out all alarm/trip conditions and event changes in plant status alongwith date and time of occurrence.  The time least count for event recording shall not be more than 100 milliseconds.

 

15.3.4        Data Communication System (DCS)

The DCS shall include a redundant System Bus with hot back-up and other applicable bus systems like cubicle bus, local bus, I/O bus etc.

The DCS shall have the following minimum features :

 

a          Redundant communication controllers shall be provided to handle the communication between I/O Modules (including remote I/O) and PLCs and between PLCs and operator work station.

b          The design shall be such as to minimise interruption of signals. It shall ensure that a single failure anywhere in the media shall cause no more than a single message to be disrupted and that message shall automatically be retransmitted.  Any failure or physical removal of any station/module connected to the system bus shall not result in loss of any communication function to and from any other station/module.

c          If the system bus requires a master bus controller philosophy, it shall employ redundant master bus controller with automatic switchover facility.

 

d          Built-in diagnostics shall be provided for easy fault detection. Communication error detection and correction facility (ECC) shall be provided at all levels of communication.  Failure of one bus and changeover to the standby system bus shall be automatic and completely bumpless and the same shall be suitably alarmed/ logged.

e          The design and installation of the system bus shall take care of the environmental conditions as applicable.

f           Data transmitting speed shall be sufficient to meet the responses of the system in terms of displays, control etc. plus 25% spare capacity shall be available for future expansion.

g          Passive coaxial cables or fibre optic cables shall be employed.

 

The Contractor shall furnish details regarding the communication system like communication protocol, bus utilisation calculations etc.

 

15.3.5        System Reaction Time

The reaction time of the programmable control system from input signals at the input cards to output of the associated signals or commands of the output card inclusive of programmed logic processing, comprising a mixture of logic gates, arithmetic operations and other internal operations shall be less than 100 milli seconds under the most arduous control system operating conditions.

15.3.6        Operator Interface Displays/Logs

Suitable displays and reports for control operation & monitoring shall be provided. The details shall be finalised during detailed Eng. stage.

 

15.3.7        Control & Power Supply Scheme

15.3.7.1           For PLC system, redundant 24 V DC  power supply shall be provided by the contractor. Necessary redundant transformers and redundant chargers with 24 V DC battery back-up shall be provided by the Contractor to derive power supply from 415 V, 3-phase redundant incomers of 415V MCC. The Contractor shall, however, furnish all required hardware/ equipment/ cubicles for conversion and/or stabilisation of the power source to all other levels which may be necessary for meeting the individual requirements of equipments/ systems furnished by him within the Contractor’s quoted lumpsum price. For separately mounted I/O racks, separate power supplies shall be provided. Power supply module shall be of ample capacity to supply all modules. In addition 20% spare capacity for future shall be provided.  All the drives      shall be switched ON/OFF through 24V DC coupling relays to be provided in HT/LT SWGR panels. Complete power supply scheme above with  power supply distribution cabinets shall be in the scope of Contractor. The exact power supply scheme shall be as approved by Purchaser during detailed Engineering stage.

15.3.7.2           Each set of PC along with CRT shall be provided with smart type line interactive UPS with software & hardware for remote management along with features of surge suppression & AVR facility by the Contractor. The UPS shall be of sufficient capacity of at least 30 minute at machine  load.

15.3.7.3           The battery shall be sealed maintenance free Ni-Cd type or Plante type Lead Acid batteries with long life and shall be able to provide a back-up for one hour at full load requirement of the complete control system.

15.3.8        Annunciation System

15.3.8.1           Contractor shall provide annunciation system as integral part of PLC system. Field contacts shall be acquired through PLC only. The annunciation sequence logics shall be implemented as a part of PLC controllers. The annunciation window lamps mounted on control panel shall be driven through contact output modules of PLC. It shall be preferable to have each window as mosaic compatible. The lamp box shall have removable impact polystyrene window shall be 50 mm x 50 mm or 48mm x 48mm with 5 mm size inscription in black lettering on white background. Each annunciation window shall be back lighted with two long life LED lamps The changing of lamps shall be conveniently done from the front by single removal of window. Redundant audible devices for alarms shall be cone type or metallic horn type and shall be driven by electronic tone generator of adjustable width and sound level. The trip alarm audible & ring back            audible shall be differentiated from other alarms.

15.3.8.2           The annunciator sequence shall conform to ISA sequence ISA-2A. The number of annunciation facia windows and the provision for original input will be on as required basis. However, the minimum number of facia windows, signal input to the annunciation system shall be 50 nos.

15.3.9       Software Documentation and Software Listings

15.3.9.1           All technical manuals, reference manuals, user’s guide etc., in English required for modification/editing/addition/deletion of features in the  software of the PLC System shall be furnished. The Contractor shall furnish a comprehensive list of all system/application software documentation after system finalisation for owner’s review and approval.

15.3.9.2         All The software listings including Source code for application software, All special-to-project data files etc. shall be submitted by the Contractor:

15.3.9.3         SOFTWARE LICENCES

The Contractor shall provide software license for all software being used in control system. The software licenses shall be provided for the project) and shall not be hardware/machine-specific. That is, if any hardware/machine is upgraded or changed, the same license shall hold good and it shall not be necessary for owner to seek a new license/renew license due to upgradation/change of hardware/machine  at site. All licenses shall be valid for the continuous service life of the plant.

15.3.9.4         Software Upgrades

As a customer support, the Contractor shall periodically inform the designated officer of the owner about the software upgrades/new releases that would be taking place after the system is commissioned so that if required, same can be procured & implemented at site.

15.3.10                    Specifications of  PC

 

The minimum requirement for PC shall be as below:
CPU	Latest with adequate no. of Ethernet/ LAN connectivity port
Main memory	256 MB SD RAM -  expandable to 512 MB
Drives	3 1/2″ floppy drive, 48 x CD ROM drive
Hard disk	19 GB
Monitor	19″ multi-sync colour monitor, 0.26 mm dot pitch, Resolution  1600 x 1280 non-interlaced, refresh rate min 85 Hz
Graphic accelerator	8 MB
Communication port	2 serial plus one parallel, 1 USB port
Expansion slots	5
Other Features	101 Keys Keyboard and Mouse
Intelligent UPS(on-line) with remote monitoring	1 no. with 30 mins. battery backup on full load(for PC & its printer)
Accessories	Industrial grade furniture (computer table & chair) for PC & its printer, as approved during detailed engineering
Software	a	General MS Windows’ NT, MS office, VISUAL C ++ VISUAL BASIC, RDBMS, anti-virus, etc.
	b	Application specific – to suit specific requirement

 

15.4.CONTROL PHILOSPHY October 30, 2008

15.4     SPECIFIC control system REQUIREMENTS

 

15.4.1  CONTROL  PHILOSPHY OF COAL HANDLING PLANT

 

 

a.         The control & instrumentation shall be through microprocessor based PLC system for the entire Coal handling plant covering the total functional requirement  of sequence control, interlock and protection, monitoring, alarm , data logging etc.

 

b.         The design of the control system and related equipment shall adhere to the principle of  Fail safe operation of all system levels i.e  the failure of signal, failure of power or failure of any component should not cause a hazardous condition and at the same time prevent occurrence of false trips and provide reliable and efficient operation of the plant under dynamic conditions.

 

c.         The system shall provide an integrated control & monitoring of coal handling plant equipment from a Main CHP Control Room. The control Room operator shall be provided with color graphic displays of the Coal handling plant and with sufficient details to allow proper            control and monitoring of the plant function.

 

d.         The entire Coal handling plant will be controlled from the following control points.

 

i)         The overall operation and control of the entire Coal Handling Plant, with acontrol desk and suitable control panel will be provided at the Main CHP Control Room .

 

The main Control Room of CHP shall have control desk in which the operating station along with CRT and keyboard will be mounted and control panel shall have the CHP mimic, indicating lamps, push buttons meters, totalizer etc. and the alarm fascia windows at the top. CHP main Control Room will house system cabinets in addition to control desk.

 

The main switchgear will be housed in the main control room building for CHP and located near the crusher house, the I/O cards and the relays for drives and the equipments which are around the crusher house shall be mounted in the system cabinets which are located in the main control room building.

 

ii)        The traveling Trippler and its associated drives shall be controlled from local panel located near the bunker floor MCC room .The system cabinet for remote I/O cards relays and interfacing equipment etc. for the Traveling Trippler drives and equipment shall be located in its MCC room to provide status indication /alarms for traveling Tripler operation in the main CHP control room. The system cabinets shall be suitable for protection class IP-65 .

 

iii)       Similarly Coal unloading operation for wagon rakes near track hopper area shall be controlled from control panel located in the control room with in building near track hopper. The ON/OFF operation of paddle feeders shall be controlled from this panel apart from its local Control Panels.  The control room in this building shall be provided with glass panel to  have full view of rakes unloading operation

 

The integrated weigh bridges shall be provided for the measurements of weight for each wagon at wagon trippler complex. Each weighing bridge shall have built in diagnostic and weight measurements software .The weigh bridges shall be controlled from the panel located in control room at Tripler complex..

 

The remote I/Os relays, interfacing equipment etc. will be located in system cabinets in building at Tripler complex to provide status indication/alarm of the unloading operation in the main control room.

 

iv)       Stacker Reclaimer shall be provided with PLC system. The remote   I/O and relays will be provided on operator’s cabin of stacker –re-claimer to indicate Stacker re-claimer operation in the main control room.

 

e.         Following Equipment will come under sequential interlock scheme and can be started / stopped from control desk in the main CHP control room with indication on CRT and mimic panel with fault annunciation facility:

 

i.          All belt conveyors.

ii.         Vibrating feeders.

iii.       Screens

iv.        Crushers

v.         Flap Gates.

 

The sequential control system shall provide stream selection from under ground conveyor of track hopper, from crusher conveyor to stacking yard conveyor, from stacker –re claimer to staking yard conveyor during reclaim mode etc.

                       

However, all the above mentioned equipment will have its local control panels/ station for start / stop and /or any other function required with suitable lockable type local / remote selector switch shall be housed in local panel and placed near drives

 

f.          Following equipment will not generally come under interlock scheme and can be started / stopped / controlled from its local panels shall be provided with status indication and alarms on mimic at control panel in main CHP control room:

 

            i.          Belt Weigher               :          

            ii.         Bunker Level Indicator:         

            iii.       Paddle Feeder :          

      iv.        Stacker/Reclaimer:

v.         Coal Sampling System.

vi.        Mobile Trippler          :          

vii.       Magnetic Separator in line.

viii.     Ventilation system

ix.        Dust extraction System.

x.         Dust suppression System.

xi.        Vibration monitoring system( for coal crushers)

 

g.         Following equipment will be operated from its local panels without any indication in control desk and mimic.

 

i.          Electric Hoist.

ii.         Sump pump

iii.       Suspended magnets

 

h.         All equipment systems and accessories supplied shall be from the latest proven product range of a manufacturer.

           

One communication gateway  shall be provided for hooking-up  CHPcontrol system with DDCMIS control system located in central control room of power plant.

15.4.2  CONTROL PHILOSPHY OF ASH HANDLING SYSTEM.

 

15.4.2.1           Control Philosophy.

 

The control & instrumentation shall be through microprocessor based PLC system for the entire Ash handling plant covering the total functional requirement of sequence control, interlock & protection, monitoring, alarm data logging etc.

 

The PLC system shall be an integrated control and data acquisition system for providing control & monitoring of Ash handling plant from a Main AHP Control Room.  The control room operator shall be provided with colour graphic displays of the Ash handling plant and with sufficient details to allow proper control & monitoring of the plant function.  The operation of ash handling plant will be possible in Auto / Semi-auto / manual mode .

 

            The entire Ash Handling plant will be controlled from the following control points:

 

For overall operation and control of entire Ash Handling Plant with fly ash system, bottom ash system, ash water and slurry pumping system and ash disposal system, a control desk along with control panels mimic will     be provided at the Main AHP Control Room.

 

i)         In order to have ease of operation and maintenance, the Central Control        Room of AHP shall have control desk in which the operating station along with CRT and keyboard will be mounted and the control panel shall have the AHP mimic, indicating lamps, push buttons, control switches, indicating instruments/recorders etc. the alarm facia windows.  AHP Central Control Room will house system cabinets in addition to control desk.

 

Following Equipment will come under interlock scheme and can be started/stopped from control desk with indication on CRT and mimic panel with fault nnunciation facility:

 

a.                All Pumps/Blowers and Compressors .

b.               Bottom Ash system.

c.                Fly ash system, comprising of ash extraction from ESP’s & duct hopper to buffer hopper located near ESP’s and fly ash transportation system from buffer hopper to storage silos.

d.               Ash slurry disposal system.

e.                Bottom ash over flow system comprising of bottom ash over flow water storage tanks, settling tank, ash over flow water pumps, sludge pumps etc.

f.                 Silo system.

g.                All Motorized valves

h.                All pneumatic operated valves.

 

For local operation in the Bottom Ash area one (1) no. Bottom ash control panel/cubical is provided for each unit .this panel shall provide control for clinker grinders, bottom ash discharge valves, jet pumps for ash slurry transport etc.

 

ii)        A control panel/cubicle shall also be provided in MCC room near  silo area for fly ash collection system. The panel shall provide control for dry pneumatic ash extraction transportation and unloading system

 

iii)       The system cabinet associated with various local controls shall be located near the local control panels. These cabinets shall accommodate I/O cards, relays, interfacing equipments etc. To provide status indication/ alarms etc. for various drives/ valves /equipments in main AHP control room.

 

iv)       The system cabinets associated with other system/equipment being controlled from main control room shall be located in the main AHP control room. The various local control panels envisaged will be located/installed in different areas for ease of operation of different sub systems. Suitable alarm/annunciation system will be provided to warn of any mal-functioning g of the ash handling system.

 

v)         The control panel shall be provided with adequate nos. of facia type annunciation windows for audio-visual summary fault annunciation purpose. 

 

vi)       One communication gateway along with suitable cables shall be provided    for hooking up the ash handling control system with DDCMIS  control system located in the central control room of the power plant.

 

vii)      All instruments like vacuum/pressure switches, pressure gauges transmitter, level ontrollers, level switches/indicators, level probes, flow indicators and any other special instruments for remote measurements in the    main control room shall be provided by the contractors                

 

 

15.4.3  CONTROL PHILOSPHY OF PLANT WATER SYSTEM.

 

The control & instrumentation shall be through microprocessor based PLC system for the entire Plant water system covering the total functional requirement of sequence control, interlock & protection, monitoring, alarm data logging etc.

 

The PLC system shall be an integrated control and data acquisition system for providing control & monitoring of Plant water system from a            DM plant   Control Room.  The control room operator shall be provided with colour graphic displays of the entire system with sufficient details to allow proper control & monitoring of the plant function.  The operation of plant water system will be possible in Auto / Semi-auto / manual mode

 

            The entire Plant water system will be controlled from the following control points:

 

For overall operation and control of entire Plant water system  i.e.Raw water system, Chlorination plant for raw water system and DM plant system, a control desk along with control panels mimic will be provided at the DM plant Control Room.

 

i)         In order to have ease of operation and maintenance, the l Control      Room   of DM plant shall have control desk in which the operating station along with CRT and keyboard will be mounted and the control panel shall have the Plant water system  mimic, indicating lamps, push buttons, control            switches, indicating instruments/recorders etc. the alarm facia windows.  DM Control Room will house system cabinets to accommodate I/O cards ,drive cards, controllers etc. with the associated system.

 

ii)        The following local control panels are envisaged .which are  located near their associated system.

a)         Raw water system local control panel

b)         Chlorination plant local control panel for raw water treatment and  CW water treatment

c)         Chlorination plant local control panel for potable water system.

d)         CW treatment plant local control panel

e)         Transfer of acid/Alkali local control panel for DM plant

f)         Any other control recommended  by contractor 

 

iii)       The local control panel shall be provided with adequate nos. of  facia type  annunciation windows for audio-visual  annunciation to warn operator for any mal functioning. 

 

 

iv)       All instruments like vacuum/pressure switches, pressure gauges transmitter, level controllers, level switches/indicators, level probes, flow indicators and any other special instruments for remote measurements in the main control room shall be provided by the contractors

 

v)         The system cabinet associated with various local controls shall be   located near the local control panels. These cabinets shall accommodate I/O cards, relays, interfacing equipments etc. to provide status indication/ alarms etc. for various drives/ valves /equipments in DM Plant control         room.

           

vi)       The following minimum safety  inter locks shall be provided in the system for pumps and drives.

 

a)          water level in the sump——– very low

b)          Pressure at  pump discharge due to accidental closure of valve——- high

c)          Winding temp of  Motor(for HT drives)——–high

d)          Temperature of pumps thrust bearing (HT drives only)———-High

e)          Bearing vibration (for HT drives only)———-High

 

vii)      Emergency stop of drives has also been envisaged from the local push button (lockable stay put type) provided near the drive. This local push button will be directly wired to Switchgear/MCC. To monitor the HT/LT drives following  minimum signals shall be exchanged between  Switch gear/MCC and PLC system:

 

a.         Drive start/stop command.

b.         Drive status feedback (ON/OFF)

c.         Ready to start.

d.         Electrical trips (from SWGR/MCC).

 

viii)     DM plant PLC system shall be provided with suitable communication gateway for monitoring through DDCMIS in central control room

 

15.4.3.1           SYSTEM DESCRIPTION :

 

A)        RAW WATER SYSTEM CONTROL.

 

i)         The pre treatment plant is controlled from PLC, and the chemical dosing is envisaged only in manual mode from local. The Dosing pumps ,Tank  agitator, Sludge pumps and clarifloculator bridge pumps  can be   operated from remote (i,e.PLC) as well as local control panel.

 

ii)        Drives on the clarifier bridge i.e. rake  mechanism drive motor and floculator agitator motor shall be operated from local start/stop push     buttons to be located near it.

 

iii)       The clarified water storage sump level is controlled  by raw water inlet control  valve with respect to the  level in the clarified  water sump .

 

iv)      All the chemical dosing/solution tank shall be provided with local level indicator and low level switch ,which shall be interlocked with respective dosing pumps i.e the pump shall trip in case of the low level in the respective tank.

 

v)         The sludge sump shall be provided with low and high level switch and selected pump whichever in auto shall start automatically when sludge sump level is high and stop automatically when sump level is low.

 

B)        CHLORINATION PLANT CONTROL.

            ( control for CW water treatment, Raw water treatment)

 

i)         The chlorination plant shall be controlled manually from local control panel located in chlorination system main control building. The control of all the drives and auxiliaries shall be implemented from this panel. The control panel shall have operators interface devices as selector switches, indicating lamps, push buttons and other required indicators.

 

ii)        The control panel shall also provided control for absorption system to be     located in main chlorination building.

 

iii)       Provision shall also be given for local operation of pump/drives from control Box. Emergency trip push buttons shall be provided for all such    drives which needs immediate stopping due to any  mal- functioning of equipment or due to health/operator hazards. Provision shall be made to operate the booster pumps through selector switch.

 

iv)       Local starting shall be possible through remote/local selector switch on control panel or in MCC. Tripping of / emergency stop of dries motors locally shall be permissible irrespective of position of remote/local selector switch. provision for locking the local stop push buttons after tripping the motors from local push buttons shall be provided.

 

v)         A window based annunciator system shall be provided in local control panel for all major alarms/trip conditions. The annunciation system shall also include alarms for abnormal level conditions in caustic solutions            preparation cum recirculation tanks,

 

vi)       The chlorination of potable water system shall be separately carried out through chlorine cylinder .This arrangements is located near by DM plant building .The operation &control is similar to above and operated through a local control panel located there.

 

C)        D.M.  PLANT CONTROL.

 

i)         The operation and control of Dematerializing Plant shall be through a PLC in Auto/semi auto mode.  However, there shall be provision to changeover to manual operation.  The control operation philosophy shall include    sequential control like semi-auto/remote-manual/manual , facility like step numbering, step time elapsed time, hold/release push button through CRT, flow of control logic (sequence of various steps) for smooth operation of the entire plant .

 

ii)        DM plant control system shall be designed so that complete Operation, Control & monitoring, interlocks, logic etc. of  Raw Water system and associated clarified sump pumps, Raw water chlorination system, service water pumps, CT make up pumps, Potable water pumps control, DM feed pumps etc.shall be provided from DM plant control room

 

iii)       The operator will initiate the operation of regeneration/rinsing/backwashing of a particular ion-exchange unit/filter based on the criteria described below, but the change from one step of the sequence to the next will be automatic.  The system will employ a logical system, which will link the various steps such as closing/opening of different valves, starting/stopping of various pumps, which make a sequence.

 

iv)       Filters/lon exchange units will be automatically isolated from the system as follows:

 

Pressure Sand Filter                :           On passing predetermined volume of water or high

                                                                        Differential pressure across the filter bed.

 

Activated Carbon Filter          :           On passing predetermined volume of water or on                                                                                     reaching preset residual chlorine level of high

                                                                        Differential pressure across the filter bed.

 

Cation                                      :          On reaching high sodium leakage or on passing of

                                                                        Predetermined volume of filtered water whichever

                                                                        Occurs first.

 

Anion Unit                               :           On reaching higher conductivity & Silica at

                                                                        Outlet or on passing of predetermined volume of

                                                                        Decationised water, whichever occurs fist.

 

Mixed Bed Unit                       :           On reaching higher conductivity, pH at outlet or

                                                                        On passing of predetermined volume of deionised

                                                                        Water or on reaching preset silica level, whichever

                                                                        Occurs first.

 

v)         As state above, the isolation of the  exchanger unit from the system will be displayed on CRT.  The operator will then select the particular vessel to be regenerated through option and selected for regeneration.  On selecting     the option the regeneration cycle shall start automatically.  During regeneration, the progress of different sequence/sub-process shall be displayed to the operator in the form of step number as well as step description  which is in progress, the set time for that.

 

vi)       The progress of the sequence shall be displayed to the operator through suitable means.  The system will incorporate the  necessary safety systems, locking systems and manual emergency system.  On failure of logic system, in between , the failure shall be annunciated to the operator and all the valves corresponding to that unit, being regenerated shall close automatically.

 

vii)      A graphic depicting the complete plant process operations shall be   designed properly and be available on CRT. The graphic shall indicate the different filters, exchanger units, measuring tanks, opening/closing of      all valves (motorized and solenoid operated), ON / OFF of different pumps and blowers etc. Color coding shall be used to differentiate lines for different services such as normal water lines, backwash lines, Acid / Alkali lines etc.

 

viii)     Separate conductivity measurement, silica mesurement and pH measurements shall be employed for ensuring the various parameters in the effluent and in the rinse line of caution, anion and mixed bed exchanger units for normal and rinsing operation.  The conductivity cell in the rinsing line shall be automatically isolated during the first half of the rinsing cycle and shall be connected automatically during the second half of rinsing cycle when the conductivity is less than 100 micromhos/cm excess over the rinse water conductivity.

 

ix)        Discharge valves of all pumps of the entire plant, connected with semi-auto/remote manual operation shall be pneumatically operated: and all pumps, pneumatically operated valves, drive motors of all the other equipment and other accessories, pneumatic on-off valves, etc. shall be completely suitable  for remote manual operation from operating console/panel. All drive motor shall also be provided with arrangement of local stopping.  Tripping of drive motors from local panel shall be permissible irrespective of the position of local-remote selection option.  Local stop push-button shall be locked after tripping the motor from local.

 

x)         Although the basic demineralising process is semi-automatic in nature, following operations shall be performed manually.

 

Unloading and Transfer of Acid.

 

a.         Hydrochloric acid will be unloaded from the road tank-cars by operating     any one of the acid unloading pumps.  Opearation shall be controlled from local panel.

 

b.         Hydrochloric acid, stored in over ground tanks, will be led remote manually by gravity to the acid measuring tanks for cation, mixed bed units to fill up to the desired level.  Subsequent transfer of acid from the measuring tanks to the ion-exchanger units as required in regeneration operation is however  automatic.

 

Unloading, Preparation and Transfer of Alkali.

 

a.         Caustic solution will be unloaded from the road tank-cars by operating any one of the Caustic unloading pumps.  Operation shall be controlled manually from local panel.

 

b.         Caustic solution, stored in over ground tanks, will be led remote manually   by gravity to the caustic measuring tanks for anion, mixed bed units to fill up to the desired level.  Subsequent transfer of caustic from the measuring tanks to the ion-exchanger units as required in regeneration operation is however automatic.

 

c.         All operations in items (a) and (b) will be controlled manually from the local panel.

 

d.         Transfer of alkali to the respective measuring tanks for anion and mixed bed exchanger units will be done remote manually.  However, subsequent transfer of alkali to respective ion exchanger units will be automatic.

 

Neutralization of Waste from DM Plant.

 

a.         After completion of regeneration of one cation and one anion exchanger, the waste generated during regenerations will be thoroughly recirculated in the neutralizing pit and if necessary, acid/alkali solution will be added to make the waste slightly alkaline.

 

b.         When required pH of waste solution has been reached, the waste solution will be pumped to the effluent treatment plant area and the effluent shall conform to IS-2490.  The pump will automatically be tripped when the level in neutralization pit reaches very low.

 

c.         Priming of pumps operating under suction lift and operations as in (a) and    (b) will be done manually.  All pump operation shall be controlled from the       local panel.

 

D)        CW TREATMENT PLANT CONTROL

(for make up to condenser)

 

The operation and control philosophy of circulating water treatment plant shall be as below:

 

i)         Sulphuric acid shall be unloaded by two no. unloading pumps into over ground acid storage tanks. Acid shall be subsequently transferred to acid dosing tanks by using above unloading pumps.

 

ii)        The sulphuric acid dosing pumps operation shall be auto and  manual from local control panel. In the auto mode ,the rate of acid dosing shall be controlled by auto adjusting of the stroke of the pumps by sensing of ph of circulating water. However the starting and tripping of the dosing pumps shall be controlled by the level switches of the dosing tanks.

 

iii)       During normal operation sulphuric acid dosing pumps shall operate in the    auto mode and inject sulphuric acid to maintain the ph of circulating water at desired level so that alkalinity remains with in desired limits.

 

iv)       The operation of other chemical dosing pumps like anti scalant dosing pumps, anti corrosion dosing pumps and biocide dosing shall be  manual from local control panel operation of the pumps shall be guided through  the level of the respective tanks.

 

 

15.4.4    Control philosphy  for compressed air system

 

15.4.4.1  CONTROL PHILOSOPHY.

 

i)         Complete automation of the Compressed Air System and Air drying Plant     shall be based on dedicated microprocessor based PLC Control System.  The Control System shall be comprising a Processor Unit, Input./Output   modules, LCD screen display The PLC l will be housed in local control panel located in compressor room/compartment.  . 

 

ii)        The local control panel shall house PLC hardware (processors, I/O cards, relays, cables etc) LCD screen , Alarm annunciators configured in PLC. Indication lamps,  witches, Start/Stop push buttons, Auxiliary relays, Motor current etc.,through the local control panel, local, manual and automatic operation of the compressed air system shall be carried out for local operation of the system

 

iii)       Each compressor shall be suitable for individual and / or parallel operation with other compressors at any demand rate from zero to maximum capacity . Each compressor shall be suitable for start up and operation of a second or third operating with the first compressor in operation at all load with no instability in performance.

           

iv)       The operating compressor for units shall be on automatic mode .both service  air & instrument air is is fed from the same and common compressor. The compressors shall be utilized for On-off/load control as decided by the operator. All necessary instruments /controller and interlock /protection /monitoring and sequential logics controls shall be provided for implementation andare achieved by PLC.

 

v)         Each air dryer shall be provided with independent microprocessor PLC, heater, set of absorber . With a selector switch ,the particular air dryer is selected and then the operation is fully automatic. Start up and shut down permissive interlocks for compressor and air drying plant shall be provided for safe operation of the equipment.

 

vi)       Hooking up with central control room DDCMIS will be done through proper gateway  and communication cables.

 

vii)      All process connection and piping materials including pipes, valves, manifolds and fittings as required for connecting all field instruments shall be provided.

 

15.4.5  CONTROL PHILOSOPHY OF FUEL OIL  STORAGE AND HANDLING SYSTEM

 

i)         Two no  control panels (Local  control panel-1  & Local control panel-2) are envisaged for control and operation for fuel oil unloading, storage & transfer system. Local  control panel-1 shall be placed at fuel oil pump house for control and operation of HFO/LSHS & LDOunloading, storage and transfer operation.  & Local control panel-2 shall be located in Fuel oil pressuring and heating building for control and operation of HFO/LSHS & LDOday storage tank.

 

ii)     When the unloading header & the piping at the pump suction becomes filled with        oil and the steady supply is ensured  at the suction pipe the unloading pumps shall be started manually from push buttons in the local control panel-! located in the fuel oil unloading pump house.  These pumps shall,however, trip automatically in the event of high level in the respective oil (LDO or HFO/LSHS) storage tank. Standby pump shall start automatically whenever any operating pump trips due to any fault ( echanical / electrical) or discharge header pressure low. The differential pressure across the suction duplex strainer high initiates alarms to change the duplex strainer position.

 

iii)    The transfer pumps to day tank shall be started manually from push buttons in the above local control panel-1.  These pumps trip automatically when the level in the source storage tank goes low or the level of respective day oil tank goes high.  These pumps will also be prevented from starting in case of low level in the respective source storage tank, or  high level in respective day oil tank or high pressure drop across the respective suction strainer.  Stand-by pump shall start automatically whenever any operating pump trips due to any fault (mechanical/electrical) or discharge header pressure goes low.

 

iv)       The drain oil pump will start/stop automatically on high/low level initiation. Further there should be provision for alarm also.  The standby pump shall also operated automatically in case the operating pumps trip.

 

v)         Local emergency stop push button shall be provided for all electrical drives.

 

vi)       Steam  flow to HFO/LSHS storage and day tank floor coil heater shall be controlled by pneumatically operated control valve (ON-OFF type) to maintain the desired oil temperature.

 

vii)      Steam flow to suction heater of HFO/LSHS day tanks shall be regulated through pneumatically operated control valve on the steam supply line to the suction heater and the same shall be actuated from heater outlet oil temperature.

 

viii)     The Local  control panel-1  & Local control panel-2 panel shall include start/stop buttons for all drives, status indication etc. and shall also include complete annunciations (alarm & indication) with TEST/ACKNOWLEDGE/RESET push buttons.

 

ix)        One communication gateway shall be provided by hooking up the system with             DDCMIS for monitoring from central control room

 

x)         All the instruments shall be supplied as required with all necessary  accessories for safe and efficient running of the plant.

 

15.5 MONITORING INSTRUMENTATION October 30, 2008

15.5     MONITORING INSTRUMENTATION

 

15.5.1  All the instruments required for safe, efficient and reliable operation of plant shall be supplied along with all necessary usual accessories as a system. The Bidder along with the Bid shall submit list of instruments (Quantity, type, make, model, rating etc.) and it shall be subject to approval by the purchaser during electrical engineering. Monitoring instrumentation shall include but not be limited to the following :

 

i)         Pressure gauges, temperature gauges, level gauges, flow gauges etc. shall have dust and weatherproof enclosures

ii)        Switch devices for protection/interlock/alarm purposes viz. pressure switches, temperature switches, level switches etc. shall have dust and weather proof enclosures and shall be of suitable rating.

iii)       Thermocouples and RTDs for temperature measurements and temperature transmitters

iv)      Flow elements viz. orifice plates, nozzles,  venturies, etc.

v)       Pressure/Differential pressure/level/flow transmitters.

vi)       Receiver indicators & Recorders

vii)      All special  instruments, measuring instrument for water analysis system and waste water disposal system,

viii)     Complete erection hardware as required including impulse pipes, fittings,    valves, cables, cable glands, junction boxes, supporting and protective arrangements etc. for erection of above instruments.

ix)        Adequate redundancy (1 out of 2 or 2 out of 3) for switches/transmitters shall be provided for critical controls and protections.  The same shall be     subject to approval during detailed engineering. 

 

15.5.2 Local Gauges :

 

i)         Pressure gauges shall conform to IS:3624 or equivalent and employ stainless steel movement. Stainless steel bourdon tube type pressure gauges shall be supplied.  Diaphragm/bellow shall be used for vacuum and low pressure applications. All pressure gauges shall be glycerin filled.  Accuracy of pressure gauges shall be ±1% FSD or better.  Dial size shall be minimum 150 mm.  Standard accessories like snubbers, chemical seal diaphragms, siphon, 3 way valves, drain valves etc. shall be included in the scope of the bidder.  Connection size of pressure gauges shall be M20×1.5.

 

ii)        Temperature gauges shall be filled thermal system with mercury in steel type with sufficient length of the capillary tube.  Accuracy of temperature gauges shall be ±1% FSD or better.  These shall employ stainless steel movement and dial size shall be 150 mm minimum. Mercury in glass thermometer is not acceptable.

 

iii)       Level gauges shall generally be transparent or reflex type with illumination arrangement as required and protection cage.

 

iv)       Local gauges shall not be mounted directly on pipeline or  equipment where vibrations or other disturbance is expected.

 

v)         Explosion proof construction shall be provided for all hazardous area applicable in accordance with area classification requirements.

 

vi)       All temperature elements shall be of duplex type.  For all RTD/thermocouple or any other sensor, secondary instruments along with associated cables shall  be provided and mounted on the  control Panel.

 

vii)      Thermocouples shall be stain less steel sheathed, compact magnesium oxide insulated type.

 

15.5.3  Local Switches:

 

i)         Non-indicating type switches shall be supplied and mounted on local enclosures/racks as required.  The switches shall be used for alarm, interlock and protection purposes. The switches shall have plug in type connection. Contacts of these switches shall be changeover type and suitably rated for the application.  Accuracy and repeatability of these switches shall be ± 1% and ± 0.5% respectively.

 

ii)        Pressure switches and differential pressure switches shall be diaphragm/bellow/bourdon tube/piston actuated.

 

iii)       Temperature switches shall be filled thermal system type and shall be provided with thermo well of SS:316 or suitable material for handling corrosive materials.

 

iv)       Level switches shall be  of the following type;-

 

a)         Static head devices for vessels exposed to atmospheric pressure ,.

b)         Differential type for high-pressure and high-temperature

c)          Displacement float type for enclosed vessels

d)         Moving float type for open tank and sumps.

e)         Capacitance or radio frequency based for bulk material applications like solids, slurries etc.

f)         level switches for different  chemical solution tanks of DM plant/effluent treatment plant shall be  capacitance/conductivity  type.

 

v)         Flow switches shall be variable area or differential pressure type actuating element for low flow and low pressure applications.

 

vi)       Positive displacement type transmitter for oil flow application and the size and flow range shall be suitable for application.

 

vii)      Connection sizes for local switches and gauges shall be as follows:

a) Pressure switches and gauges         M20 x 1.5

b) Temperature switches and gauges   M33×2

c)  Level switches and gauges             25 mm NB

 

viii)     All thermo wells shall be provided with sealing plugs that shall be screwed on whenever the temperature element is not inserted.  The plug shall be of stainless steel and be fastened to the boss with a chain.

 

15.5.4  Transmitters for pressure, differential pressure, level flow etc.  

 

i)         Smart type electronic transmitters (for pressure/differential pressure) employing diaphragm, bellow or bourdon tube as sensing elements shall be supplied. The transmitters shall be capacitance type or inductance type.  Output signal of the transmitters shall be 4-20 mA dc and circuit shall employ two-wire transmission.   Measurement accuracy of all types of transmitters shall be ± 0.25% with least long term drift and maintenance.

 

ii)        Transmitters shall be provided with enclosure having a degree of protection IP-65 as per IS: 2147.

iii)       Range elevation/suppression facility shall be provided in all the transmitters.

iv)       Level transmitter shall be of the following type :

 

a)         Differential pressure or displacement float type for enclosed vessels

b)         Moving float type for fuel oil storage tanks.

c)         Radio frequency type for ash hopper ,coal feeder sand  ash slurry applications.

d)         Strain gauge type load cells for coal hoppers.

 

15.5.5 Receiver Indicators and Recorders

 

i)         Following general requirement of indicators and recorders shall be complied with :

 

a)         Indicators/recorders shall be suitable for flush mounting on the panel and shall be provided with a bezel of colour that matches the panel colour and shall have semi gloss finish.  Instruments shall be capable to withdrawal from the front.

b)         Connection to the instruments shall be by means of individual plug and sockets arrangement.

c)         Instruments shall be provided with transparent non-reflex type front covers.

d)         Visual indication shall be provided on instruments front to indicate failure of supply to the instrument, wherever applicable.

e)         Instrument scales shall be in metric units and shall be linear with respect to measurement variable.

f)         Facility for zero and span adjustment shall be provided.

g)         Signal monitor cards shall be used to initiate alarms where 4-20 mA signal is available.  Solid state relays may be suitably incorporated in the amplifier circuit when the signal is directly connected to the receiving indicator/recorder to generate alarm contacts.  Alarm contacts generated by pointer movement shall not be acceptable.

 

ii)        Indicators

Vertical Bargraph indicator with four digital display on top or bottom of the indicator shall be provided.

Indicators shall be with multi-channels and shall accept universal input signal (TC/RTD) 4-20ma,Voltage range shall be configurable and programmable with measurement accuracy ± 0.2% of span or ± count.   Requisite mounting accessories and mounting bins shall also be provided.

 

iii)       Recorders

The recorders shall be microprocessor based, chart less recorders with multi-channels shall be provided.   The recorders shall have accuracy of ± 0.2%

 

iv)       Integrators/Totalisers :

The integrator unit shall accept an input signal of 4-20 mA/1-5 V DC.  It shall indicate the quantity of flow with minimum 6 digit displays and 4 mm height and provided with manual reset facility.  The indicator shall be suitable for 240 volts A.C. supply and accuracy of indication shall be +/- 0.5%.  It shall be provided with plug-in type current to pulse rate converter and shall have adjustable pulse rate compatible with the process measured values.

15.6 Control Cabinets / Panels / Desks October 30, 2008

15.6     Control Cabinets / Panels / Desks

i)         The cabinets shall be IP-22 protection class. The Contractor shall ensure that the packaging density of equipment in these cabinets is not excessive and ab­normal temperature rise, above the cabinet tempera­ture during normal operation or air-conditioning failure, is prevented by careful design. This shall be demonstrated to the Purchaser during the factory testing of the system. The Contractor shall ensure that the temperature rise is limited to 10 deg. C above ambient and is well within the safe limits for system components even under the worst condition  Ventilation blowers shall be furnished as required by the equipment design and shall be sound proof to the maximum feasible extent.  If blowers are required for satisfactory system operation, dual blowers with blower failure alarm shall be provided in each cabinet with proper enclosure and details shall be furnished with proposal. Suitable louvers with wire mesh shall be provided on the cabinet.

ii)        The cabinets shall be designed for front access to system modules and rear access to wiring and shall be designed for bottom entry of the cables.

iii)       The cabinets shall be totally enclosed, free standing type and shall be constructed with minimum 2 mm thick steel plate frame and 1.6 mm thick        CRCA steel sheet or as per supplier’s standard practice for similar applications, preferred height of the cabinet is 2200 mm. The cabinets shall be equipped with full height front and rear doors. The floor mounting arrangement for other cabinets shall be as required by the owner and shall be furnished by the Contractor during detailed engineering.

iv)       Cabinet doors shall be hinged and shall have turned back edges and additional braking where required ensuring rigidity. Hinges shall be of concealed type. Door latches shall be of three-point type to assure tight closing. Detachable lifting eyes or angles shall be furnished at the top of each separately shipped section and all necessary provisions shall be made to facilitate handling without damage. Front and rear doors shall be provided with locking arrange­ments with a master key for all cabinets. If width of a cabinet is more than 800 mm, double doors shall be provided.

v)         Two spray coats of inhibitive epoxy primer-surface shall be applied to all exterior and interior surfaces.  A minimum of 2 spray coats of final finish colour shall be applied to all surfaces.  The final finished thickness of paint film on steel shall not be less than 65-75 micron for sheet thickness of 2 mm and 50 microns for sheet thickness of 1.6 mm.  The finish colors for exterior and interior surfaces shall conform to following shades:

            a) Exterior:- As per RAL 7032 or as finalised and specified during detailed engineering.

            b) Interior:- Same as above.

            Paint films which show sags, checks or other imperfections shall not be acceptable.

vi)       Cabinets shall be designed for a grounded installa­tion on the building structure. Any isolation from the building ground which is required by equipment design shall be provided internal to the cabinet.

vii)      The mimic shall be configured on the OWS/CRTs and it shall be possible to control, monitor and operate the plant from the same.

viii)     Ammeters will be provided on control panel for All motors  rated 30KW and above. Further, HT/LT switchgear voltmeters shall be provided on control desk for HT/LT feeders. Ammeters and voltmeters shall be suitable for 4-20 mA DC signals derived from Analog Output cards of PLC.

ix)        Mosaic based control desk type for mounting push     buttons/meters etc. with door at the rear shall be provided by the contractor. The mosaic grid tiles shall be of 24mmx48mm (or 25 mmx50 mm) size, made of heat and flame retardant, self extinguishing and non hygroscopic material with flat-matt finish without glare and non reflecting type. PC based OWS(operator Work Station) of PLC shall be mounted on table type control desk to house PC/ keyboards/ mouse etc. The profile and dimension shall be decided during detailed engineering and shall be subject to Owner’s approval.

 

15.6.1  Panels and wiring

 

i)                Interconnecting wiring shall be provided between all electrical devices mounted in the panels, desks, consoles etc.   The equipment outside the panel shall be connected through terminal blocks only, except for other special circuits.

ii)              Wiring to each control switch shall be individually bunched and shall be installed with a “drop loop” of sufficient length (not less than 750 mm) to allow the item to be removed from the panel for maintenance without disconnecting the wiring.

iii)            Wire sizes for various applications shall be finalized during detailed engineering. However, the wire sizes shall be limited to 0.5,1,and 2,5 sq. mm cross section, stranded copper.

iv)             Color code/size etc. for control & instrumentation cable shall be finalised during detailed engineering..

v)               Common connections must be limited to two wires per terminal.

vi)             All panels/desks/consoles internal wiring shall be tinned copper, stranded conductor, flame retardant cross linked polythylene (XLPE) insulated as per relevant standards.

vii)           Panel, desk console wires shall be identified with wire number at each termination by means of split sleeve or indelible tubing markers.  The ferruling system shall be finalised during detailed engineering.

viii)         Terminal lugs furnished must be of the compression, insulated sleeve, ring tongue type.  Open-ended terminal lugs will not be accepted.  Wires shall not be looped around the terminal screws or studs.

ix)             Wires shall not be tapped or spliced between terminal points.

x)               Instrumentation wire shield connection shall be individually terminated on terminal blocks.  Shield termination shall be made on terminal blocks adjacent to the enclosed wire terminations.

xi)             Contractor shall group the internal wiring so that all out-going wiring to each particular remote location is terminated on adjacent terminal blocks.

xii)           Panels, desks, consoles will be provided with removable gasketted cable gland plates and cable glands for all floor slots used for cable entrance.  All openings at the bottom shall be sealed to stop the entry of vermins in the panels.  There shall be sufficient space provided for easy fixing and removing of all external cables.  Sufficient space must be provided between the terminal blocks and cable leads for easy replacement

 

7.Power Supply System October 30, 2008

Power supply system:

 

All AC/DC power supplies required for the completeness and successful operation of C&I  system  shall be fed from the system  LT Distribution boards to be  arranged by the bidder.  However, the arrangement shall be subject to consultant/owner’s approval.

 

15.7.1 UPS System

 

The UPS system shall be supplied to cater the following minimum load requirement of C&I system:

 

a.         Un-interruptible power supply (UPS) system consisting of 2X100% static inverters, 1X100% stationary batteries, 2X100% chargers static switches, manual by-pass, step down transformers, 2X100% AC distribution board.

b.         The bidder shall also provide all other required stable and reliable power supplies/packs as required for various C&I equipment /devices/system offered to ensure reliable operation of various C&I equipment/devices under all conditions

c.         The capacity and rating of each of the system shall be adequate to meet their respective load requirements and spare capacity margin of at least 25%.The capacity of UPS shall have one hour  back up time The bidder shall furnish exact load calculation for each of the systems and subject to purchaser/consultant approval.

d.         All the power supply equipment/system shall have surge withstand capability (SWC) to meet the requirement of relevant latest ANSI standard.

e.         All non-interrupting components of the electric power supply system shall be capable of withstanding all possible short circuit currents without damage. Additionally, all circuit interrupting components shall be capable of withstanding and interrupting all encountered short circuits current without damage.

f.          The bidder shall decide the KVA rating of UPS based on the KVA rating of various loads to be fed from UPS. Further a spare capacity margin of not less than 25% shall be provided. The loads considered critical and required to be fed from UPS shall be decided during detailed engineering stage keeping in view the recommendation of sub-system supplier etc.

g.         Complete 24V DC power supply system shall be supplied to meet the requirements of PLC based control system.

 

15.8 ERECTION HARDWARE October 25, 2008

15.8     ERECTION HARDWARE:

 

i)                The contractor shall furnish installation practices and erection procedures proposed to be followed for erection of sensors, transmitters, local instruments etc. which shall be subject to the approval of purchaser.  Complete erection hardware and accessories as required, shall be deemed to be included in the scope of the bidder.

 

ii)              All tools, tackles and test equipment required for erection, testing, commissioning and maintenance shall be provided.  A list of such items shall be furnished with the bid.

 

iii)       Impulse pipes roots valves and fittings shall conform to ASME code for pressure piping ANSI-B31.1 or any other equivalent standard.

 

iv)       Instrument valves and valve manifolds, root valves as well as blow down valves etc. shall be provided as required according to the approved erection drawings. The valves shall generally be globe type with preferably stainless steel drop forged body rated to the test pressure of line/equipment where these are to be used.

 

v)         All cable trays shall be in bidder’s scope.

15.9 INSTRUMENTS AND CONTROL CABLES October 25, 2008

15.9     INSTRUMENTS AND CONTROL CABLES

       

15.9.1  All interconnecting cabling required for C&I systems/equipment, inter-panel cabling, power supply cabling etc.) shall be included in the scope of this specification.  The cables supplied shall include but not be limited to the following :

 i)        Control cables (1.1 kV, multi-core, 1.5 sq. mm) stranded copper conductor, PVC insulated, steel wire armoured and PVC sheathed, flame retardant low smoke.

ii)        Instrumentation cables

iii)       Pre-fabricated cables

iv)       All special cables i.e. screened, twisted pair co-axial, heat resistant, etc. required for C&I system.

v)         Power supply cables. These shall be Red, Yellow, Blue, Black coloured for three phase with neutral system.  For DC these shall be coloured Red & Black.

vi)       Compensation cable for Thermocouples.

vii)      Any other required for C&I systems not specifically brought out above.

 

15.9.2  Laying, termination and ferruling of all cables covered in this specification shall be included in the tenderer’s scope.  Requisite wiring schedules and cable schedules shall be prepared by the successful bidder and shall be subject to approval by purchaser.  All cables shall be terminated with proper lugs.  At external terminals inside the panel, there should be sufficient space so as to ensure easy replacement and fixation of external cables.

 

15.9.3  The cables in hot zone shall be fire and heat resistant type and be laid in insulated heat proof conduits upto junction boxes located far away from hot zone.

 

15.9. 4 Special earthing requirements of the system, earthing details etc. should be brought out by the bidder for the equipment being supplied.  All earthing shall be done with green coloured leads to have proper distinction.  Two copper earth bases of 75×5 mm should be provided in each panel.

 

15.9.5  The philosophy of termination of various type of filed instruments/designs shall be submitted in advance for the approval of the owner.

 

15.10 Actuators for Valves October 25, 2008

15.10   Actuators for Valves

 

15.10.1            Wherever required, valves shall be provided with actuating gear  for remote operation. All actuators with complete assemblies shall be included in the Bidder’s scope.  Isolating and remote manual regulating valves shall generally be provided with electrical actuators. 

 

The power supplies for electrical actuators for regulation duty shall be provided with solid state reversal facility and shall be mounted in separate panels near respective control cabinets.  All actuator motors shall be suitable for 415 V, 3 phases, 4 wire supply.    All motors shall be suitable for voltage variation of ± 10 % and frequency variation of ± 5 %.  Actual selection of voltage level will be decided during detailed engineering.

 

Each actuator shall be provided with sufficient sets of independent position operated adjustable limit switches each for open and close position for signaling, interlocking etc.  In addition, two numbers torque limit switches (one for fully open position and the other for fully closed position) and space heater shall be provided in case of ;regulating actuators, provision shall also; be made for suitable two numbers position transmitters for remote position indication .  In case two position transmitters are not available suitable single sharing arrangement shall be provided.

 

 For hydraulically operated valves/dampers/vanes the bidder shall furnish all required equipment and accessories such as power cylinders, positions, position transmitters of approved design, pressure gauges, filter, pressure regulator, hydraulic piping solenoid valve, 4 nos. limit switches (2 nos. for open and 2 nos. for close position) and other requisite accessories.  Hook up diagram for each type of hydraulic operated valves shall be furnished for owner’s approval.  All actuators shall be stay put type both for failure of signal as well as failure of power (electric, pneumatic).  For certain cases, open/close fail safe positions may be necessary which shall be decided during detailed engineering.

 

Solenoid valve shall be Electromagnetic type 3 ways having !/4 NPT ports . Body shall be made from ss bar stock whereas trim shall be AISI ss-316 materials.

 

15.10.2            Electro-Pneumatic  converters

 

Electro pneumatic converter having 4-20 ma current input shall deliver 0.4 to 1kg/sq. cm output air to drive the final control element like control valve etc. This shall have all required accessories like Air filter regulator, air lock relay, isolating cock, mounting accessories cable gland etc. On loss of control signal the last set point pressure shall be maintained so that the associated control valve remain in stay put condition without any additional Solenoid valve. the allowable drift rate shall be +-2% of set point/hour maximum.

 

15.10.3            Air filter Regulator

 

Air filter regulator shall have filter element of size 5 microns and to have continuous adjustable output pressure from0to 2kg/sq.cmor oto7 g/sq.cm.All accessories like 2dial  size output pressure gauge and proper bowl (metallic or transparent poly carbonate)shall be provided.

15.11 Plant Communication System October 25, 2008

15.11   PLANT COMMUINICATION SYSTEM

 

 

15.11.1            The  system shall consists of electronic  private automatic branch exchange (EPABX ), public address for the complete power plant including  switchyard, coal handling areas, ash handling areas, CW and other off site areas.

 

            Electronic Private Automatic Branch Exchange (EPABX)

Plant communication system shall include a private telephone exchange.  The telephone exchange shall be 32 bit microprocessor base Electronic Pvt. Branch exchange (EPABX) for industrial telephone communication system.  The exchange shall have facility to connect D.O.T / truck lines

 

The EPABX shall be of approved technology of department of telecommunication, Government of  India.  It shall have fully non blocking architectural.

 

EPABX shall have `1 no. 200 lines, expandable to 256 lines including 8 P&T and digital lines.

 

15.11.2            The exchange shall be suitable for high speed digital data and voice communication and shall have the facilities to connect data terminals from fax machine  and personal computers along with telephone services.

 

15.11.3            The battery and battery chargers combination shall be such as to ensure continuity of D.C. supply to EPABX system at all times without even momentary interruption   of serviced.

 

15.11.4            The facility to be provided by EPBAX system shall include but not limited to the following:

 

            i.          Hold for enquiry

            ii.         Shuttle on enquiry calls.

            iii.       Call store and retrieve.

            iv.        Wait on busy

            v.         Pick-up

            vi.        Call transfers.

            vii.       Conference

            viii.     Automatic call back.

            ix.        Call diversion.

            x.         Music on hold.

            xi.        Auxiliary equipment assess.

            xii.       line lock out.

            xiii.      Howler tone alert.

 

15.11.5            Operator Console.

 

The operator console shall have PC base maintenance – cum-operation / Administration facilities along with necessary display (VDU), key board printer etc. and  include but not limited to the following features;-

 

i.          Subscriber calling.

ii.         Call hold.

iii.       Camp on ringing.

Iv,.       Camp on busy.

v.         Prevention of double cam on.

vi.        Serial calls.

vii.       Call monitoring.

viii.     Busy over right.

ix.        Abbreviated dialing.

X,        Answering priority

xi.        Call sequencing.

xii.       Paging access.

xiii.      Station busy display.

xiv.      Incoming call type display.

xv.       Trunk number and type display.

xvi.      Waiting call display.

xvii.     System alarm display

xviii.    Digital clock.

xix.      Listen in

xx.       Night / off duty service.

xxi.      Departmental calls.

xxii.     First party release.

xxiii.    On line package replacement.

xxiv.    Direct station selection.

xxv.     Direct  inward dialing.           

 

15.11.6   Telephone set.

 

            The telephone sets shall be of the following types :

 

Desktop push button operated decadic type with tone dialing (ordinary) –     Type ‘A’.

 

Desktop  push button operated decadic type with tone dialing and 10 nos.     memory storage type “B”

 

            Same as type ‘A’ but wall mounted type instruments type “C”

 

            Flamproof telephone instruments type “D”.

 

 

 

15.11.7            Telephone cables.

 

Telephone cable shall be 0.5 mm dia annealed electrolitic copper conductor both inner and outer sheet PVC insulated, color coaded twisted  pair, laid up , taped galvanized round / flat wire armoured conforming to IS-1554.

 

Cable sizes shall be standardized in terms of the no. of pairs , which shall    be 100 pairs, 50 pairs, 20 pairs, 10 pairs, and 5 pairs.

 

15.11.8   Junction boxes.

 

The telephone junction boxes shall be of MS steel / fibre having IP-52 degree of protection for outdoor duty and IP-42 for indoor duty.  It will be complete with jumper , terminal block, earthing , studs suitable for terminating OR looping telephone cables.

 

15.11.9   Public Address (PA) System.

 

Distributed PA system shall be supplied for the main plant, offsite areas and CHP areas.  PA system shall be micro-processor based and user programmable.  The system shall comprise of four (4) sub-groups, namely Sub-group-1 for Unit No.1.  Sub- group-2 for Unit No.2 , Sub-group-3 for Common Areas like Switchyard and Offsets, Sub-group-4 for CHP area. List of distribution of PA system Field Call Station (CCS) is given in Annexure-B.

 

15.11.10          The system shall have four (4) channel party and page system with facility  of inter connection among the sub-groups through Master Call Station (MCS). The  system shall be operative without interruption even on station AC supply failure.  Incoming supply shall be fed from main plant UPS.

 

15.11.11          The PA system for coal handling plant area, shall be suitable for heavily dusty atmosphere.  This system shall avoid use of handsets, as these are susceptible to pilferage in such areas.

 

15.11.12     System details

 

a)         PA system shall have four (4) channels party / channel page system. 

Following communication modes are possible:

 

i.          Between Field Call Station (FCS) in the same subgroup without the help of Master Call Station (MCS).

 

ii.         Between Master Control Station and any Field Call Station (FCS),

iii.       Between an EPABX subscriber  with the Field Call Station (FCS) through EPABX interface.

 

Individual system shall be expandable with maximum number of sets per system limited to 100 nos.

 

b)         each group shall consist of the following main equipment.

 

i.          Indoor/Outdoor, column/wall/desk-mounted Field Call Stations (FCS) with built –in-amplifiers of adequate output capacity. Extension amplifiers shall be provided for desktop mounted handset station wherever needed.

ii.         Horn type loudspeakers.

iii.       Indoor cone type loudspeakers.

vi.        Main junction boxes & distribution boards and junction boxes for handset station and for loudspeakers etc.

v.         Weatherproof canopy / box for outdoor handset stations.

vi.        Acoustic hoods.

vii.       Cables.

viii.     Conduits, if required.

ix.        Central Control Exchange.

x.         One desk mounted type Master Call Station (MCS).

 

c)         Desk mounted HS for unit control rooms shall have snap action self return micro switches for different functions such as PAGE, LOUDSPEAKER MUTE and SIREN, LED indicating lights, a built-in-loud speaker and dynamic, noise canceling microphone.

 

d).        Desk  mounted Master Control Station (MCS) shall have a multifunction key-board, a backlit display, a press to page switch, a gooseneck microphone with dynamic noise-canceling and a built in speaker.  The  communication from MCS to any field station is a hands-free voice switch duplex communication without requiring number dialing.

 

e)         Outdoor/Indoor FCS shall be provided at various locations of the plant and auxiliary buildings. In some areas for noisy areas such as turbine hall, mills etc. HS’s shall be provided with acoustic hoods to cut down the ambient noise for proper communication.

 

f)         Where cable trays are not available cables shall be laid directly along the wall.

 

g)         The outdoor LS shall be of weather proof die cast aluminum construction.

 

h)         All outdoor HSs shall be provided in the weatherproof boxes with canopies.

 

i)         For areas where false ceiling will be provided, cone type speakers shall be suitable for false ceiling mounting.

 

j)         All outdoor type handsets and speakers shall be provided with dust and weather proof, pilfer proof enclosure with locking facilities.

 

15.11.13          Walky Talky System

 

Walky Talky System shall be a two-way radio communication system with an effective reach of 5 km. Radius.  The system shall comprise of repeater, a VHF antenna and 20 Nos. talk-back  transreceivers.

 

Repeaters are special relay station which re-transmit one users transmission to another. If comprises of receive, transmitter, interface controller, power supply and duplexer.

           

            As soon as repeater receives a valid signal its transmitter turns on.  The receives audio is fed into the transmitter, which then retransmits the same.  Retransmission usually happens on a different frequency so that it does not load the receiver and create a loop.  The duplexer provides additional       isolation of  0-1000 dB.