The document discusses analog and digital control systems. Analog control systems use operational amplifiers and current signals to control final elements like valves. Digital systems use AD/A converters to convert signals and microprocessors to compare values and control elements. Distributed control systems have control and monitoring distributed across multiple CPUs for redundancy compared to centralized control systems. The Yokogawa Centum VP system is an example of a distributed control system.

1. DISTRIBUTED CONTROL SYSTEM

2. PROCESS CONTROL SYSTEM
• ANALOG CONTROL SYSTEM
• DIGITAL CONTROL SYSTEM

3. ANALOG CONTROL SYSTEM
• Transmitter generate 4-20mA current according to 0% to 100% process
value.
• 4-20mA current converted into 1-5 V d.c and given as input to op-amp.
• Operational amplifier is used in analog control system.
• This act as process value(P.V) & other leg is given as set value(S.V) of om-
amp.
• Manipulated value(M.V)=S.V-P.V.
• I/P converts 4-20 mA into 3-15 psi.
• 3-15 psi goes to final control element(control valve).

5. DIGITAL CONTROL SYSTEM

6. DIGITAL CONTROL SYSTEM
• Transmitter generates 4-20mA current according to 0% to
100% process value.
• A/D converter converts analog signal to digital signal.
• Microprocessor process signal & compare with set value(S.V)
and produce manipulated value(M.V).
• D/A converter converts digital signal into analog signal.
• I/P converts 4-20 mA into 3-15 PSI.
• 3-15 psi goes to final control element(control valve).

7. ADVANTAGE/DISADVATAGE
• Advantage of digital over analog:
• Data anaysis is easy.
• Fast processing of data.
• Less effect of noise.
• Advantage of analog over digital:
• Less costly.
• A/D & D/A converter hardware is not required.

8. DIGITAL CONTROL SYSTEM
• Digital control system is further classified as:
1.CENTRALISED CONTROL SYSTEM(C.C.S)
2.DISTRIBUTED CONTROL SYSTEM(D.C.S)

9. CENTRALISED CONTROL SYSTEM

10. • CCS have centralized control and centralized monitoring.
• All field inputs (P.V),set value (S.V),manipulated value (M.V)
processed in single C.P.U .

12. DISADVANTAGE
• If C.P.U fails, then whole plant got effected.
• No Redundancy.

13. DISTRIBUTED CONTROL SYSTEM

14. • It have distributed control but have central monitoring.
• Field inputs (P.V),respective set points (S.V) and corresponding
manipulated value (M.V) goes to different C.P.U.

16. ADVANTAGE
• Redundancy is present, so more reliable system
• Maintenance is easy.
• Field wiring is less.
• Instrument signal and interlock are created by software.
• Modification of interlock are simple and flexible.

17. CENTUM VP System Capacity
• Maximum number of stations per domain : 64 stations
• Maximum number of HIS per domain : 16 stations
• Station number for HIS : 1 to 64 in descending order
• Station number for FCS : 1 to 64 in ascending order
• Maximum number of domains: 16 per system
• Numbering of domains: 1 to 64
• Maximum number of stations per system: 256 per system

18. IFFCO AONLA
• Ammonia-I : Domain No.1
• Urea-I : Domain No.2
• Ammonia-II : Domain No.3
• Urea-II : Domain No.4
• Power plant : Domain No.5
• Terminal Server (A-II) : Domain No.6
• DM plant : Domain No.7
• Ammonia storage : Domain No.8
• PGR unit : Domain No.9

19. CENTUM VP SYSTEM
• The basic components of a DCS are:
Field Control Station
Human Interface Station
Communication Bus

20. FCS (Field Control Station):
• The Field Control Station is used to control the process.
• All the instruments and interlocks created by
software reside in the memory of the FCS.
• All the field instruments like transmitters and control valves
are wired to the FCS.

21. The Engineering / Operator Station (ENG / HIS)
• The operator station or the Man Machine Interface (MMI) is
called the Human Interface Station(HIS) in Centum VP system.
• The Human Interface station is used to monitor the process
and to operate various instruments.
• The component used for configuration is called the
Engineering station(ENG).
Communication Bus:
• Communication bus is used to communicate between the
Field Control Station and the Operator Station.

22. FIELD CONTROL STATION
• ALL FIELD INPUTS,INTERLOCK SOFTWARE RESIDES IN THE
MEMORY OF F.C.S.
• IT IS AN INTERFACE BETWEEN HIS AND FIELD INSTRUMENT.
• DATA PROCESSING DONE BY F.C.S.

23. • Two Power Supply Modules : PW 481
• Two CPU Modules : CP451
• Six I/O Modules: AAB841,AAV141,ADV561 etc..
• Two ESB Bus Coupler Module : EC401
F.C.U CONSISTS OF :-

24. I/O Modules
• The following I/O Modules are frequently used:
• AAB841 : Analog I/O module(8 channel I/P & 8 channel O/P)
1-5 V I/P & 4-20 mA O/P
• AAV141 : Analog Input module(16 channel I/P,1-5 V)
• ADV151 : Digital Input module (32 channel,24V DC)
• ADV161 : Digital Input module (64 channel,24V DC)
• ADV561 : Digital Output module (64 channel,24V DC)
• ADV551 : Digital Output module (32 channel,24V DC)

25. • ALR121 : Serial Comm. Module (RS422/485)
• EC401 : ESB Bus Coupler Module
• SB401 : ESB Bus Interface Module
• EB401 : ER Bus Interface Master Module
• EB501 : ER Bus Interface Slave Module
* ESB : Extended Serial Back board
* ER : Enhanced Remote

28. Network

31. Vnet/IP Communication
• In Vnet/IP, a duplex bus is configured with independent
subnets of bus 1 and bus 2.
• Bus 1 is used for control communication, and bus 2 is used for
open communication.
• If a communication error occurs in bus 1 for some reason,
control communication is performed using bus 2.
• In this case, because open communication is also performed
using bus 2, control communication and open communication
coexist.
• Therefore, to secure the band for control communication, the
band for open communication will be restricted.

32. Features of V-net/IP
• Real time control bus (Dual redundant possible)
• Cable :50 ohm coax. cable with BNC connector(1000 Base T )
• Communication speed : 1 Gbps
• Std. max. length : 100 m
• Max. length : 1.6 Km (with optical repeater)

33. ETHERNET
• Inter communication between HIS and Engineering Station.
• Data base equalization.
• Speed 100 Mbps.
• IEEE 802.3 protocol.

34. IP Address
• For Vnet/IP Bus1 : 172.16.<domain no>.<stn no>
For HIS 0262 : 172.16.2.62
• For Vnet/IP Bus2 : 192.168.<128+domain no>.<129+stn no>
For HIS 0262 : 192.168.130.191
• For Ethernet : 172.17.<domain no>.<stn no>
For HIS 0262 : 172.17.2.62

45. Queries ?