i want to explore the topic of Scada , very difficult not easy to understand by graduate student. it will be helpful to understand about SCADA

1. SCADA
Supervisory Control Data
Acquisition
By
Asadullah Khan

2.  SCADA refer to a system that collect data from various plants or other remote
devices and then send this data to control computer which Manage and control
this data.

 SCADA USES
 Electric power generation, transmission and distribution
 Water, wastewater and sewage
 Buildings, facilities and environments
 Manufacturing
 Mass transit
 Traffic signals
 Oil and Gas
 Food and Beverage Production

SCADA
Supervisory Control Data Acquisition

3. SCADA Architecture

4.  There three basic Components of SCADA
Architecture.
 Control Centre
 Field Site
 CommunicationLink
SCADA Architecture

5. Control center is responsible to communicate with field component
It has main Function
 together data in real time
 To record System events into a log file
 Information Storage and report for analysis
 Presentation of information in graphic and text form to operator
It consist of the following Components
 SCADA Server or MTU
 HMI Human Machine Interface
 Engineering Workstation
 Data Historian
 Communication router
 All these components are linked by Local area Network
Control Centre

6. Master Terminal Unit
 The MTU is the Heart of Control Center. MTU issues command to RTU/PLC’s/IED ( in field sites) and
asked the desired information from RTU.
 It communication through communication link
Human Machine Interface
 The HMI is hardware and software which enable human operator to control process data
 It provide tool for configuration and
 It also display information that required to supervise the field devices
 It can run on CMS (Central Monitoring System)
 The decision of action of any fault is taken in here
Data Historian
 This is database placed at control center for recording and storage information for any analysis
Engineering Workstation/Programming
 It helps to manage Logistic information and trouble Shooting guide
Control Centre

7. Communication Link
 There is usually long distance between control center and field site. The effective communication is
necessary for effective flow message to and from the MTU and PLC/RTU/IED’S
Link can either be
 Phone
 Cellular network
 Satellite
 Fiber optics

 Remote Terminal Unit
 It support to SCADA System remotely
 Its primary task to controlled collect data from processing equipment and send back to this data to
MTU through communication network
 Occasionally PLC are deployed as field devices to replace RTU’s
Control Centre

8.  Field site consist of Modem and PLC which connect to the
sensors and other field devices through bus network.
 The processed data fro the PLC passes through modem
where it is modulated transmitted through the
communication Modem to control center .
 PLC (Programmable Logic Controller
 It execute Logical function using electrical hardware such
as switches, counter and timer
 It is also responsible for supervisory and data acquisition
through sensors and convert data received from sensors to
digital format
Field site-1

9.  Field site -2 has both WAN card and Intelligent Electronic
devices connected directly to Modem there is no need of
PLC. It is enough intelligent to handle data.
 IED ( Intelligent Electronic Devices)
 It is the basic components of substation perform
protection, Monitoring, controlling and data acquisition
function
 IED are microprocessor based devices with the capability
to exchange data and control signals with another devices
i.e electronic meter, controller )over communication link
Field Site-2

10. The reason why you can see SCADA systems deployed
in many different industries is that these systems can
bring many benefits. Some of them are:
 Receiving real-time information to monitor
equipment
 Remote industrial control
 Storage of performance data for later analysis
 It allows for proactive maintenance and decreases
downtime
Advantage of SCADA