The document discusses control systems and distributed control systems (DCS). It defines a control system as using feedback to maintain or alter quantities according to a desired state. A DCS uses distributed controllers and communication networks to control large, complex industrial processes. Key components of a DCS include field devices, input/output modules, controllers, human-machine interfaces, and control engineering software. DCS are suitable for large chemical plants, refineries, and other industrial applications where centralized control is not feasible.

1. PRESENTATION ON

2. Contents

3. The control system is that means by which any quantity of interest in a
machine, mechanism or other equipments is maintained or altered in
accordance with ad-desired manner.
CONTROLLER
CONTROLLED
ELEMENT
REFERENCE
INPUT
ACTUATING
SIGNAL
CONTROLL
ED OUTPUT
Examples-Traffic Light Controller, Electric Washing Machine ,Bread Toaster
etc.

4. CLOSE LOOP CONTROL SYSTEM
CONTROLLER
CONTROLLED
ELEMENT
Feedback
Element
Input Error Signal
Reference Signal
Example-Missile Launching System, Human Respiratory System,
Autopilot System etc.
Feedback Signal
Desired
Output

5. ANALOG CONTROL SYSTEM
Signal
Conversion
I/P
Transmitter 1 to 5V DC
Operational Amplifier
4-20 mA DC
Final Control Element
Examples- Volume Control of Radio, Room Temperature Control With
Thermostat etc.
Set Point

6. DIGITAL CONTROL SYSTEM
Examples-PLC, DCS, SCADA, Embedded System etc.

7. Centralized
Processing
Unit
CPU
PV2
PV3
PV1
PV4
PVn
MV1
MV2
MV3
MV4
MVn
SV1 SV2 SV3 SV4 SVn
Drawbacks of CCS:
•If the CPU fails the entire plant gets affected.
•Redundancy concept is not available.
TYPES OF DIGITAL CONTROL
Centralized Control System Distributed Control System

8. Distributed Control System is a specially designed control system used to control
complex, large and geographically distributed applications in industrial processes. In
this, controllers are distributed throughout the entire plant area. These distributed
controllers are connected to both field devices and operating PCs through high speed
communication networks.
Example scenarios where a DCS might be used include:
• Chemical Plants
• Petrochemical (Oil) And Refineries
• Pulp And Paper Mills
• Boiler Controls And Power Plant Systems
• Nuclear Power Plants
• Environmental Control Systems
• Water Management Systems

10. 1. Field devices
2. Input/output modules
3. Controllers
4. Human machine interface (HMI)
5. Control Engineering

11. Field devices control local operations such as opening and closing valves ,
breakers, collecting data from sensor systems and monitoring the local
environment for alarm conditions.
Examples- Transmitter, Electrical Drives etc.

12. I/O modules are building blocks of industrial control system used in end
equipments such as PLC, PAC, DCS. Digital input modules measure and
capture digital input signals from a wide variety of sensors like proximity
switches, limit switches and push button switches. Input typically are 0-24V with
tolerances up to 30V.
It is a versatile method for interconnecting real world analog and digital
signals to data acquisition, monitoring, or control systems. All modules provide
an optically isolated barrier between sensitive microprocessor or digital logic
circuits and field power devices.
Types of Module :
• Digital Input Module
• Digital Output Module

13. • Digital Input Module-
Digital input modules are used to monitor the status of a load or a sensor (such as a limit
switch, pressure switch, or temperature switch). The output of these modules is a logic
level signal which corresponds to the status of the device being monitored. A high level
output signal indicates the load is off (the switch is open). A low level output signal
indicates the load is on (the switch is closed)
• Digital Output Module-
Digital output modules are used to switch AC and DC loads such as solenoids, motors,
or lamps from logic signal levels.

14. It can be placed near to field devices (sensors and actuators) or certain
location where these field devices are connected via communication link. It
receives the instructions from the engineering station like set point and other
parameters and directly controls field devices.
It can sense and control both analog and digital inputs / outputs by I/O
modules. These modules are extendable according to the number of inputs
and outputs. It collects the information from discrete field devices and sends
this information to operating and engineering stations.
A controller is a comparative device that receives an input signal from a
measured process variable, compares this value with that of a predetermined
control point value (set point), and determines the appropriate amount of output
signal required by the final control element to provide corrective action within a
control loop.

15. Existing Cabinet
and Field Terminations
Redundant
Ovation
Controller
Q-line I/O
Redundant Fast
Ethernet Network (100 mB)
Controllers Setup

16. The user interface (UI), in the industrial design field of human–machine
interaction, is the space where interactions between humans and machines
occur. The goal of this interaction is to allow effective operation and control of
the machine from the human end, whilst the machine simultaneously feeds
back information that aids the operators decision making process.
Generally, the goal of user interface design is to produce a user interface
which makes it easy (self explanatory), efficient, and enjoyable (user friendly) to
operate a machine in the way which produces the desired result. This generally
means that the operator needs to provide minimum input to achieve the desired
output, and also that the machine minimizes undesired outputs to the human.

17. Real Time HMI

18. Control engineering or control systems engineering is the engineering
discipline that applies control theory to design systems with desired behaviors.
The practice uses sensors to measure the output performance of the device
being controlled and those measurements can be used to give feedback to the
input actuators that can make corrections toward desired performance.
Electrical circuits, digital signal processors and microcontrollers can all be
used to implement control systems.

19. • DCS’s are designed to control processes.
• DCS are made available to the user in a
way that only configuration in form of a
Functional Block has to be carried out.
• Scan time of the DCS is comparatively
higher.
• A DCS has inherently multiple processor
capability thus Engineer has to put in less
efforts for intercommunication of the
processors.
• A DCS takes much longer to process data,
so it’s not the right solution when response
times are critical. In fact, safety systems
require a separate controller.
• Highly redundant.
• PLC is in discrete control of manufacturing
processes.
• In PLC complete programming has to be
implemented using any one of the different
languages available in the system.
• Scan time of the PLC is lower.
• This is possible now in PLC but more efforts
have to be put in.
• Response times of 1/10 of a second
make the PLC an ideal controller for near
real time actions such as a safety shutdown
or firing control.
• Redundancy is not possible at greater levels.