1. PLC & DDCMIS

2. What is PLC? Programmable Logic Controller
… a nice replacement for electromechanical relay controls

3. What is PLC?
A PLC is an industrially hardened computer-based unit that performs discrete or continuous control functions in a variety of processing plant and factory environments.
Originally intended as relay replacement equipment for the automotive industry, the PLC can be found in some part of virtually every type of industry imaginable.
The primary reason for designing such a device was eliminating the large cost involved in replacing the complicated relay based machine control systems.

4. What is inside a PLC? SOLENOIDS MOTOR STARTERS ETC
PROGRAMMING DEVICE
POWER SUPPLY
CPU
MEMORY
I/O BUS
I/O SYSTEM MODULES
OUTPUT DEVICES
INPUT DEVICES
SOLENOIDS MOTOR STARTERS ETC
SWITCHES PUSH BUTTONS ETC

5. What is inside a PLC? Power Supply
It converts Power Line voltages to those required by electronic components of PLC.
It may be Integral or separately mounted.
It provides the isolation necessary to protect electronic components from most high-voltage line spikes.
It is rated for heat dissipation requirements for plant floor operation.

6. What is inside a PLC? Input Systems
Inputs are defined as real-world signals giving the controller real-time status of process variables.
These signals can be analog or digital, low or high frequency, maintained or momentary.
They are presented as a varying voltage, current or resistance value.
Signals from thermocouples and RTDs are common examples of analog signals.
Pushbuttons, limit switches & electromechanical relay contacts are familiar examples of digital, contact closure type signals.

7. What is inside a PLC? Outputs
There are three common categories of outputs:
Discreet: Pilot lights, solenoid valves, annunciator windows (lamp box)
Register: Panel meters or displays
Analog: Variable speed drives or I/P converters (control valves)
Most I/O systems are modular in nature; that is, a system can be arranged by use of modules that contain multiples of I/O points.These modules can be composed of 1, 4, 8, or 16 points and plug into the existing bus structure.
The bus structure is really a high-speed multiplexer that carries information back and forth between the I/O modules and the CPU.
One of the important functions of I/O is its ability to isolate real-world signals from the low signal levels in the I/O bus

8. What is inside a PLC? Central Processor Unit
It performs the tasks necessary to fulfill the PLC function. Among these tasks are
Scanning
I/O bus traffic control
Program execution
Peripheral & external device communications
Self Diagnostics
One important factor which rates a PLC is scan time. It is roughly defined as the time it takes for the PLC to interrogate the input devices, execute the application program and provide updated signals to the output devices.

9. What is inside a PLC? Memory Unit
It is the library where the application program is stored.
It is also where the PLC’s executive program is stored. An executive program functions as the operating system of the PLC. It is the program that interprets, manages and executes the user’s application program.
It is the part of PLC where process data from the input modules and control data for the output modules are temporarily stored as data tables.
Memory can be volatile or nonvolatile. Volatile memory is erased if power is removed. Battery backup is provided for most units with volatile memory to avoid loss of program in the event of power outage.

10. What is inside a PLC? Programmer Unit
It provides an interface between the PLC and the user during program development, start-up and troubleshooting.
The instructions to be performed during each scan are coded and inserted into memory with the programmer.
Programmers vary from small hand-held units the size of a large calculator to desktop stand-alone intelligent CRT-based units.
Programmers come complete with documentation, reproduction, I/O status & on-line and off-line programming ability.
Many PLC use a PC as the programming tool using the serial interface and a Programming Software.

11. How a PLC Operates?
Step 1-CHECK INPUT STATUS-First the PLC takes a look at each input to determine if it is on or off. It records this data into its memory to be used during the next step.
Step 2-EXECUTE PROGRAM-Next the PLC executes your program one instruction at a time using the input data obtained in previous step and decides about the states of output. It will store the execution results for use later during the next step.
Step 3-UPDATE OUTPUT STATUS-Finally the PLC updates the status of the outputs using the results obtained in previous step.
After the third step the PLC goes back to step one and repeats the steps continuously.

12. How a PLC is Programmed? Ladder Diagrams
Ladder diagrams are one traditional method of describing control circuits.
There are a few basic symbols that are used to express the meaning and purpose of a control circuits. They are
Normally Open Contact
Starter/Relay/ Solenoid Coil
Normally Closed Contact
(T.O.) (Time to Open)
Time Delayed Contact
Normally Open Push Button
Normally Closed Push Button

13. Example PLC Program
Let us consider a simple example. In the given circuit, the coil will be energized when there is a closed loop between the + and - terminals of the battery(When both the switches SW1 & SW2 are closed).
This simple circuit is represented in a ladder Diagram as below.
A ladder diagram consists of individual rungs just like on a real ladder. Each rung must contain one or more inputs and one or more outputs. The first instruction on a rung must always be an input instruction and the last instruction on a rung should always be an output (or its equivalent).
Some PLC require that every ladder diagram include an END instruction on the last rung.

14. Advantages of PLC
Compared with electromechanical relay systems, PLCs offer the following advantages:
Ease of programming and reprogramming in the plant.
A programming language that is based on relay wiring symbols familiar to most plant personnel
High reliability and minimal maintenance
Small physical size
Ability to communicate with computer systems in the plant
Moderate to low initial investment cost
Rugged construction
Modular design

15. PLC Applications at Our Project
Some of the areas using PLC are:
Coal Handling Plant Stage-II
Ash Handling Plant Stage-II
DM Water Plant Stage-II
Condenser Tube Cleaning System Stage-II
Generator Stator Water Conductivity/Flow Protections Stage-I
Boiler Feed Pump Delta-T Protection in Unit-II

16. DISTRIBUTED DIGITAL CONTROL, MONITORING & INFORMATION SYSTEM
WHAT IS DDCMIS ?
DISTRIBUTED
DIGITAL
CONTROL,
MONITORING &
INFORMATION
SYSTEM
Distributed means there is no centralized control and control is spread across multiple units
Digital means processing of process information is done in digital form using micro-processor based hardware
MIS interfaces the human with process using computers

17. DDCMIS – TECHNOLOGICAL BACKGROUND
PROGRESS OF INSTRUMENTATION USED TO IMPLEMENT AUTOMATIC PROCESS CONTROL
LOCAL PNEUMATIC CONTROLLERS
MINIATURIZED AND CENTRALIZED PNEUMATIC CONTROLLERS AT CONTROL PANELS AND CONSOLES
SOLID-STATE CONTROLLERS
COMPUTERISED CONTROLS (SUPERVISORY)
DIRECT DIGITAL CONTROL(DDC)
DISTRIBUTED MICROPROCESSOR BASED CONTROL

18. Why DDCMIS? Disadvantages of earlier Systems
Analog instrument panels required huge space, lot of wiring and are less user friendly for monitoring of large number of parameters.
Accuracy obtained with solid-state controls is not good and they tend to drift with time.
Supervisory controls are inflexible as changing of control configuration requires change in routing of wires.
Use of centralized control leads to complete failure during shutdowns.

19. Components of DDCMIS
MAN MACHINE INTERFACE & PROCESS INFORMATION SYSTEM
DATA COMMUNICATION SYSTEM
( DATA HIGHWAY)
CONTROL SYSTEM

20. DATA COMMUNICATION SYSTEM
Components of DDCMIS
DATA COMMUNICATION SYSTEM
LOCAL SYSTEM BUS – It is just lines on the backplane of control panel to which all the modules are connected directly. It serves as communication medium between the modules.
INTRAPLANT BUS(IPB) – It is a coaxial cable which runs through all the panels of control system and interconnects them.
LOCAL AREA NETWORK(LAN) – It is a network of computers which are connected to a single point(HUB).
SOME FORM OF REDUNDANCY IS PRESENT

21. Components of DDCMIS CONTROL SYSTEM FUNCTIONAL DIVISION SG-C&I SYSTEM
TG-C&I SYSTEM
BOP-C&I SYSTEM
HARDWARE COMPONENTS
POWER SUPPLY
CONTROL PANEL
ELECTRONIC MODULES

22. SG-C&I SYSTEM CONSISTS OF BURNER MANAGEMENT SYSTEM (BMS)
SOOT BLOWER CONTROL SYSTEM (SBC)
SECONDARY AIR DAMPER CONTROL SYSTEM (SADC)
AUXILIARY PRDS CONTROLS (APRDS)
HP BYPASS SYSTEM(HPBP)

23. TG-C&I SYSTEM CONSISTS OF ELECTRONIC TURBINE PROTECTION (ETP)
AUTOMATIC TURBINE RUN-UP SYSTEM (ATRS)
AUTOMATIC TURBINE TESTING SYSTEM (ATT)
ELECTRO- HYDRAULIC TURBINE CONTROL SYSTEM (EHTC)
TURBINE STRESS CONTROL SYSTEM (TSC)
LP BYPASS SYSTEM (LPBP)
GLAND STEAM PRESSURE CONTROL
GENERATOR AUXILIARY MONITORING PANEL (GAMP)

24. BOP-C&I SYSTEM
CONSISTS OF OPEN LOOP CONTROL SYSTEM (OLCS) AND CLOSED LOOP CONTROL SYSTEM (CLCS)
OLCS - THE SEQUENCE CONTROL, INTERLOCK OF ALL THE PLANT SYSTEMS WHICH ARE NOT COVERED IN THE SG-C&I AND TG-C&I. THIS INCLUDES MAJOR AUXILIARIES LIKE FD/ID/PA FANS, AIR-PREHEATER, BFP/CEP/CWP/ BCWP , DMCWP/CLCWP AND ELECTRICAL BREAKERS.
CLCS - THE MODULATING CONTROL FOR VARIOUS IMPORTANT PLANT PARAMETERS, LIKE FW FLOW (DRUM LEVEL), FURNACE DRAFT, COMBUSTION CONTROL (FUEL FLOW AND AIR FLOW), PA HDR PRESSURE CONTROL, DEAERATOR/HOTWELL/HEATER LEVEL CONTROLS ETC.

25. CONTROL SYSTEM - HARDWARE
THE CONTROL SYSTEM USED IN STAGE-II IS PROCONTROL P13/42
PROCONTROL MODULES
INPUT
OUTPUT
PROCESSOR
DRIVE
BUS COMMUNICATION

26. CONTROL SYSTEM - HARDWARE
INPUT MODULE
It receives the process signal, convert them to digital form and communicate the value on local bus
ANALOG
Voltage(EA01) 4-channel
Current(EA02) 4-channel
RTD(EA03) channel
Thermocouple(EA04) 8-channel
DIGITAL
Voltage(EB01) 4-channel
Single contact(EB02) 16-channel
Change-over contact(EB03) 5-channel

27. CONTROL SYSTEM - HARDWARE
OUTPUT MODULES
They receive the value from localbus and give output to the process/field.
ANALOG
Voltage(AA01) 4-channel
Current(AA02) 4-channel
DIGITAL
Voltage(AB01) channel
Contact(AB02) channel

28. CONTROL SYSTEM - HARDWARE
PROCESSOR MODULE ( PR05)
IT IS RESPONSIBLE FOR THE EXECUTION OF ALL THE LOGICS THAT IS PROGRAMMED INTO IT
IT CAN BE USED IN REDUNDANT MODE
IT IS PROGRAMMED USING SK06 KIT, WHICH IS A COMPUTER BASED UNIT FOR INTERFACING WITH PROCESSOR
THE LOGICS ARE PROGRAMMED USING THE P10 LANGUAGE

29. CONTROL SYSTEM - HARDWARE
DRIVE MODULES
THESE ARE USED FOR CONTROLLING THE DIFFERENT TYPES OF PROCESS ACTUATING ELEMENTS
THEY HAVE PREDEFINED LOGICS BUILT INTO THEM
TYPES
ANALOG (AS06)
USED FOR DRIVING ANALOG CONTROL DRIVES SUCH AS VARIABLE SPEED DRIVES, CONTROL VALVES THROUGH I/P CONVERTER ETC
DIGITAL (AS04)
USED FOR OPERATING MOTORS, ELECTRICAL VALVES, SOLENOID VALVES ETC

30. CONTROL SYSTEM - HARDWARE
BUS/COMMUNICATION MODULES
BUS TRAFFIC DIRECTOR
IT CONTROLS THE COMMUNICATION PROCESS ON THE BUS
- THERE ARE TWO TYPES OF TRAFFIC DIRECTORS:
LOCAL BUS(BV05)
INTRAPLANT BUS(FV05)
BUS COUPLER(BK02)
IT CONNECTS THE LOCAL BUS TO THE IPB
BUS END MODULE(BA01)
IT IS USED FOR TERMINATING THE LOCAL BUS

31. LOCAL BUS – P42 IPB Local Bus AD CLK Analog Input Module Binary Input
PROCESSOR
Local Bus
Bus
Coupler AD
CLK
Analog
Output
Module
Binary
Output
Module
DRIVE
CONTROL
MODULE
LOCAL
BUS
TRAFFIC
DIRECTOR

32. CONTROL SYSTEM OVERVIEW
IPB - 1
IPB
TRAFFIC
DIRECTOR
BUS
COUPLER
BUS
COUPLER
WSPOSE
PANEL
Local Bus -1.0B
Local Bus
-1.0C,2.0C
BUS
COUPLER
SERVER
IPB - 2
IPB
TRAFFIC
DIRECTOR
BK 02
Local Bus -1.0C

33. PMS AND WSPOSE ARE EXAMPLES OF MMIPIS SYSTEM
Components of DDCMIS
MMIPIS – MAN MACHINE INTERFACE & PLANT INFORMATION SYSTEM
Functions
VPC OPERATION
OTHER OPERATOR INFORMATIONS THROUGH VARIOUS DISPLAYS
ALARMS, LOGS, HISTORICAL AND LONG TERM STORAGE.
PERFORMANCE AND OTHER CALCULATIONS
PMS AND WSPOSE ARE EXAMPLES OF MMIPIS SYSTEM

34. WSPOSE OVERALL VIEW LOCAL BUS STATIONS PS PR05 BK I /P O/P PR
IPB 1 & 2
WS POSE PANEL ( DDC – MMI INTERFACE PANEL )
SERVER 1
SERVER 2
LAN
OWS 1
OWS 5

35. PMS SYSTEM OWS -1 OWS -2 OWS -3 OWS -4 WORKSTATIONS PMS PANEL LAN
SERVER2
SERVER1
IPB
ACCESS
COUPLER
SG PACKAGE
TG PACKAGE
STATION
C & I
IPB - 1
IPB - 2
IPB - 3
IPB - 4

36. WHY DDCMIS ?
1. VERY HIGH FLEXIBILITY FOR MODIFICATION IN CONTROL STRATEGY
2. VERY HIGH SELF-DIAGNOSTIC
3. VERY LOW DRIFT (ONLY IN I/O CARDS) , HENCE NO NEED OF FREQUENT RE-CALIBRATION
4. MUCH HIGHER RELIABILITY (BASED ON MTBF)
5. BETTER LONG TERM SUPPORT DUE TO CHANGING TECHNOLOGY
6. MUCH BETTER OPERATOR INTERFACE

37. PLC & DDC - COMPARISION
DCS systems are used for large applications and closed loop controls, whereas, PLC are primarily used for small applications and sequential controls.
DCS systems are very costly for small applications, whereas, PLCs are much cost-effective for both small and large applications.
While DCS systems are superior in communication redundancy and data security, PLCs are better for logic, are faster and have more rugged I/O.
DCS systems are more difficult to design than PLCs.

38. SALIENT FEATURES OF DDCMIS

39. SALIENT FEATURES OF DDCMIS
INTEGRATED PLANT CONTROL FOR SG, TG AND BALANCE OF PLANT CONTROL IT MAY BE REMEMBERED THAT HISTORICALLY THE TERM DDCMIS USED BE REFERRED TO FOR THE SO-CALLED “BOP-C&I” . THE SG-C&I, i.e. FSSS etc. TG-C&I i.e. ATRS, TURBINE PROTECTION etc. ORIGINALLY WERE NOT CONSIDERED UNDER DDCMIS OR DCS AS PER MANY SUPPLIERS. ONLY RECENTLY THE TYPE OF SYSTEMS FOR ALL THE SYSTEMS HAVE BECOME SIMILAR (WITH SOME DIFFERENCE WHICH WILL BE DISCUSSED LATER), WE TEND TO CONSIDER THESE SYSTEMS UNDER DDCMIS.

40. SALIENT FEATURES OF DDCMIS
INTEGRATED PLANT OPERATION THROUGH FULLY INTERCHANGEABLE OPERTAOR WORK STATIONS (OWS) FOR SG, TG AND BALANCE OF PLANT (SOMETIMES THIS MAY NOT BE POSSIBLE DUE TO PACKAGING CONCEPT)

41. SALIENT FEATURES OF DDCMIS
PROVISION OF EXTENSIVE SELF-DIAGNOSTICS
USE OF LARGE VIDEO SCREENS FOR PROJECTIONS OF VARIOUS PLANT MIMICS ETC.
PROVISION OF FAULT ALARM ANALYSIS TO GUIDE THE OPERATOR TO THE MOST LIKELY EVENT
PROVISION OF TREND ALARMS

42. SALIENT FEATURES OF DDCMIS
PROVISION OF SAFETY HARDWARE FOR BURNER MANAGEMENT SYSTEMS
PROVISION OF FAIL-SAFE HARDWARE FOR TURBINE PROTECTION SYSTEM
PROVISION OF ADEQUATE RELIABILITY AND AVAILABILITY WITH PROPER REDUNDANCY IN SENSOR, I/O AND CONTROLLER LEVELS.

43. DDCMIS CONFIGURATION maxDNA SYSTEM PROCONTROL SYSTEM
ENGG. STN
FOR HMI
HMI
PROCONTROL SYSTEM
MMI LAN
HMI
REDUNDANT
SERVERS
ENGG.STN.
FOR CONTROL SYS.
I.P. BUS Max. 4 nos. rdundant
Redundant F.G.Controllers
Measurement system / I/O subsystem

44. CONTROL SYSTEM

47. FUNCTIONAL GROUPS
SIGNIFICANT REDUCTION IN NUMBERS EXPECTED IN FORTHCOMING PROJECTS
COMBINING OF OLCS AND CLCS CONTROLLERS - HISTORICAL BACKGROUND
EXCEPT FOR CERTAIN SUPPLIERS, ALL HAVE VERY POWERFUL CONTROLLERS
TRANSPARENCY 6,7,8 FOR GROUP DRAWINGS

48. MMIPIS

49. MAN-MACHINE INTERFACE AND PLANT INFORMATION SYSTEM
LATEST STATE-OF-THE-ART WORKSTATIONS AND SERVERS BASED ON OPEN-ARCHITECTURE AND INDUSTRY STANDARD HARDWARE AND SOFTWARE TO ENSURE BETTER CONNECTIVITY.
e.g. HARDWARE FROM COMPAQ/DIGITAL, HP, SUN MICRO-SYSTEM OR OTHER MAJOR SUPPLIERS (LESS DEPENDENCE ON THE C&I SYSTEM SUPPLIER IN THE LONG RUN)
OPERATING SYSTEM WINDOWS-NT, OPEN-VMS OR UNIX.

50. MAN-MACHINE INTERFACE AND PLANT INFORMATION SYSTEM
64-BIT SERVER/OWS WITH HIGH-SPEED AND LARGE MEMORY (256/512 MB RAM, 8 GB HDD FOR SERVER AND 128/256 MB RAM AND 4/6 GB HDD FOR OWS) TO ENSURE FAST RESPONSE
PROVISION OF LVS
CONNECTION TO OTHER SYSTEM THROUGH STATIONWIDE WAN
TRANSPARENCY NO 9 & 10

51. MMIPIS FUNCTIONALITIES
VPC OPERATION
OTHER OPERATOR INFORMATIONS THROUGH VARIOUS DISPLAYS
ALARMS, LOGS, HISTORICAL AND LONG TERM STORAGE.
PERFORMANCE AND OTHER CALCULATIONS

52. DCS

53. REDUNDANT DATA COMMUNICATION SYSTEM (DCS)
1. MAIN SYSTEM BUS
2. LOCAL SYSTEM BUS
3. LOCAL BUS OR I/O BUS
4. OWS LAN
5. STATION-WIDE WAN

54. DDCMIS CONFIGURATION maxDNA SYSTEM PROCONTROL SYSTEM
ENGG. STN
FOR HMI
HMI
PROCONTROL SYSTEM
MMI LAN
HMI
REDUNDANT
SERVERS
ENGG.STN.
FOR CONTROL SYS.
I.P. BUS Max. 4 nos. rdundant
Redundant F.G.Controllers
Measurement system / I/O subsystem

55. STATION-WIDE ON-LINE LAN
OFF-LINE LAN
GATEWAY
TO CORP.
CENTRE
STATION-WIDE ON-LINE LAN
UNIT C&I
SYSTEM
(TYP)
OTHER
UNITS
OFF-SITE C&I
SYSTEM
(TYP)

56. POWER SUPPLY SYSTEM
CONTROL SYSTEM POWER SUPPLY TWO SETS OF DC POWER SUPPLIES - ONE SET FOR SG/TG-C&I AND OTHER FOR BOP-C&I EACH WITH 2 X 100 % CHARGER AND 2 X 100 % BATTERY.
OTHER IMPORTANT AC LOADS LIKE MMIPIS, PANEL INSTRUMENTS, ANALYSERS ETC. SHALL BE POWERED FROM UPS COMPRISING OF 2 X 100 % CHARGER, 2 X 100 % INVERTER AND 1 X 100 % BATTERY.
HEAVY DUTY Ni-Cd BATTERIES HAVE BEEN ENVISAGED FOR LONGER LIFE & LESSER MAINTENANCE

57. CABLING & TERMINATION
EXTENSIVE GROUPING OF SIGNALS BY LARGE SCALE USE OF JBs AT STRATEGIC LOCATIONS
USE OF CABLES WITH HIGHER NO OF PAIRS
USE OF MAXI-TERMI CONNECTION FOR SYSTEM CABINETS, MARSHALLING PANELS & OUTGOING SIDE OF JBs, CJS BOXES etc.
USE OF PLUG-IN SOCKET AND CONNECTORS FOR TRANSMITTERS, SWITCHES, LS/TS etc.

58. IMPORTANT SG/TG RELATED C&I SYSTEM
FLAME MONITORING SYSTEM
COAL FEEDER C&I
ELECTROMATIC SAFETY VALVES
FURNACE TEMP PROBES
ACCOUSTIC PYROMETER FOR FURNACE TEMP PROFILE
BOILER FLAME ANALYSIS SYSTEM
COAL BUNKER LEVEL MONITORING SYSTEM
ELECTRONIC DRUM/SEPARATOR LEVEL MONITORING SYSTEM
TURBINE SUPERVISORY SYSTEM
TDBFP TURBINE SUPERVISORY SYSTEM
IN PACKAGED SYSTEM, THESE ARE UNDER SG & TG PACKAGES.

59. SCOPE OF SUPPLY OF C&I SYSTEM
DDCMIS (IN C&I PACKAGE, SG-TG C&I & ASSOCIATED MMI etc. EXCLUDED)
OTHER SG/TG C&I (ONLY FOR TURN-KEY PACKAGE)
MEASURING INSTRUMENTS
SWAS
CONTROL DESK/PANELS
ALARM ANNUNCIATION
ELECTRIC POWER SUPPLY
CONTROL VALVE AND ACTUATORS (ONLY FOR 500 MW PROJECTS, BEING DELETED FROM C&I IN RECENT PROJECTS)
MAINTENANCE & CALIBRATION EQUIPMENT
INSTRUMENTATION CABLES
PROCESS CONNECTION & PIPING
PA SYSTEM
OFF-SITE PLANT CONTROL SYSTEM (ONLY FOR TURN-KEY PACKAGE, ELSE IN RESPECTIVE MECH. PKG)

60. OPERATION PHILOSOPHY
CENTRALISED OPERATION OF MAIN PLANT THROUGH OWS & LVS
OFF-SITE PLANTS TO BE CONTROLLED FROM THEIR LOCAL STATIONS WITH STATION-WIDE LAN DATA LINK
MINIMUM BACKUP INSTRUMENTATION ( ORIGINALLY CONSERVATIVE, NOW REDUCED. CRITERIA - HANDLING EMERGENCY & SAFE SHUT-DOWN)
GEOGRAPHICAL DISTRIBUTION - ALTHOUGH NOT VERY USEFUL FOR POWER PLANTS AS COMPARED TO PROCESS/INDUSTRIES, BEING ADOPTED FOR FEW AREAS WHERE SIGNALS ARE CONCENTRATED (REDUCTION OF CABLING, MUCH LESS ERECTION & COMMISSIONING TIME)

61. REDUNDANCY IN CONTROL SYSTEM
ORIGINALLY THE CONTROLLERS
ALT-I - SINGLE LOOP NON-RED
ALT-II- MULTI-LOOP REDUNDANT
NOW ALT-I ABOLISHED. NOW 2 X 100 % OR 2 OUT OF 3.
I/O REDUNDANCY - CURRENT PROJECTS HAVE HIGH LEVEL OF I/O & DRIVE CONTROL MODULES REDUNDANCY DUE TO LOWERING OF BACK-UP AND INCREASE IN NO. OF CHANNELS. IN FUTURE PROJECTS, LIMITED TO SAFETY SYSTEMS AND CASES WHERE SENSOR REDUNDANCY IS THERE.
DATA COMMUNICATION SYSTEM % REDUNDANT
MMIPIS
- REDUNDANT SERVERS
MULTIPLE OWS (PRESENTLY 10 NOS, BEING REDUCED TO 6 NOS.)

62. DESIGN CRITERIA PROVENNESS RELIABILITY AVAILABILITY
SUPPLIER’S EXPERIENCE
SYSTEM EXPERIENCE
PROVENNESS VS OBSOLESCENCE
RELIABILITY AVAILABILITY
HARDWARE QUALITY (PUBLISHED MTBF etc.)
CONFIGURATION
REDUNDANCY
FAULT TOLERANCE
STANDARDISATION AND UNIFORMITY OF H/W
SAME SERIES & FAMILY OF H/W AS FAR AS POSSIBLE
DIFFICULTIES BECAUSE OF PACKAGING CONCEPTS & RESPOSIBILITY CENTRE & INTERFACES (EVEN IN TURNKEY PACKAGE)

63. DESIGN CRITERIA OPERABILITY MAINTAINBILITY OTHER CRITERIA
DESIGN CONCEPT - FAIL SAFE ETC.
FALSE TRIP VS SAFETY
OPERATOR CONVENIENCE DURING NORMAL RUNNING & EMERGENCY
MANAGEMENT REPORTING
MAINTAINBILITY
STANDARDISATION (AS INDICATED ABOVE)
MODULAR DESIGN AND EXPANDABILITY
DIAGNOSTIC, FAULT IDENTIFICATION AND FAULT TOLERANCE
GUARD AGAINST OBSOLESCENCE
AVAILABILTY OF SPARES
OTHER CRITERIA
UNIT OPERATION PHILOSOPHY
MARKET TRENDS AND EVOLUTION OF INFORMATION TECHNOLOGY
FEEDBACKS FROM EXISTING SYSTEMS