INTRODUCTION TO SCADA SYSTEMS
SCADA- (Supervisory control and data acquisition) is the monitoring and/or control technology that enables the operator of a controlled industrial process, equipment, or plant to obtain data from one or more of its distant facilities and send limited control instructions to those facilities.
Originally used for remote monitoring
Now used for any control system in both In-plant and remotely.
Major application areas include energy, oil and gas refining, telecommunications, water and waste control, and transportation
These systems include the transfer of data between a SCADA Master Terminal Unit (MTU) and a number of Remote Terminal Units (RTUs) and/or Programmable Logic Controllers (PLCs), and the MTU to the operator workstation.
Components of SCADA
SCADA systems consist of:
One or more field data interface devices which are usually termed as RTUs or PLCs
A communications system (means of telemetry) utilized to transmit data between field data interface devices and control units and the computers in the MTU of SCADA.
A central host computer server or collection of servers, sometimes called a SCADA Center, master station, or Master Terminal Unit (MTU)
A collection of standard and/or custom software, sometimes called Human Machine Interface (HMI) software
SCADA Application
This example shows how SCADA is implemented to monitor the process at a water treatment plant. It provides an overview of tank levels and current operations flow.
SCADA Architecture
This is a visual representation the architecture of SCADA as processes are monitored from the control center and commands and monitoring information are relayed through the communication network between the field instruments and the control center.
SCADA Systems Capabilities
Access quantitative measurements of important processes, both immediately and over time.
Detect and correct problems as soon as they begin.
Discover and eliminate bottlenecks and inefficiencies.
Control larger and more complex processes with a smaller, less specialized staff.
A SCADA system performs four functions:
1. Data acquisition – sensors (digital or analog) are used to capture the data.
2. Networked data communication (connection from RTU to Computer system)
3. Data presentation – present to human in a form that we can digest
4. Control
These functions are performed by four kinds of SCADA components:
Sensors and control relays
Remote terminal units (RTUs)
SCADA Master Units / RCC (Region Control Center)
The data telecommunications network
Different uses for SCADA systems
Mass transit: regulate electricity to subways, trams and trolley buses; to automate traffic signals for rail systems; to track and locate trains and buses; and to control railroad crossing gates.
Manufacturing: manage parts inventories for just-in-time manufacturing, regulate industrial automation and robots, and monitor process and quality control.
Electric power generation, transmission and distribution: Electric utilities detect current flow and line voltage, to monitor the operation of circuit breakers, and to take sections of the power grid online or offline.
Buildings, facilities and environments: Facility managers use SCADA to control HVAC, refrigeration units, lighting and entry systems.
