SCADA Types, Functions, SCADA System Architecture, Benefits and Applications

SCADA Types, Functions, SCADA System Architecture, Benefits and Applications


SCADA is the short abbreviation of Supervisory Control and Data Acquisition.
As the name suggests SCADA mainly does three operations
  • Supervise real-time data in the form of graphical presentation
  • Control industrial processes locally or through Remote locations
  • Acquire real-time data as well as logs data
SCADA system is an important factor of the industrial organization as they help to monitor process data as well as control the processes and easily detect any issue within the process thus reduce downtime.
Generally, SCADA is completely a software package that helps to monitor the entire area of the plant. The basic architecture of the SCADA begins with a Programmable Logic Controller(PLC) or Remote Terminal Units(RTUs).
As we know, PLC or RTUs are microprocessors that communicate with the field devices such as valves, pumps, sensors, HMIs, other end devices, etc. These devices route all this collected data from end devices to SCADA computers.
Then SCADA software processes distribute and display the data on the monitor to better understand the operator about the field condition.

Objectives of SCADA

There are many objectives of SCADA System.
  • Improved overall System efficiency (capital & energy)
  • Increased penetration energy sources including renewable energy sources.
  • Reduced Energy Requirements in both the Transmission and Generation
  • Increased Relativity of sequence to essential loads.


Furnishes status information & measured data to operator
Allows the operator to control the devices e.g. ckt breakers, Xmer, tap changer etc. from a remote centralize location.
Includes data quality & integrity check, limit check, analog value processing etc.
Operator identifies any specific device & subjects to specific operating restrictions to prevent from unauthorized operation
Alerts the operator of unplanned events & undesirable operating conditions in the order their severity & criticality
Logs all operator entries, alarms &selected entries
Plots measurements on selected scale to give information on the trends e.g. one minute, one hour etc.
To save & analyze the historical data for reporting, typically for a period of 2 or more years & to archive.

Types of SCADA System

SCADA systems are classified into four types which include the following.
  • Monolithic SCADA Systems
  • Distributed SCADA Systems
  • Networked SCADA Systems
  • IoT SCADA Systems

Monolithic SCADA Systems

Monolithic SCADA systems are called as early or first-generation systems. In these types of systems, minicomputers are used. The development of these systems can be done when common network services are not available. The designing of these systems can be done like independent systems without any relation to other systems.
The data can be gathered from all RTUs using a backup mainframe. The main functions of these first-generation systems are restricted to flagging processes in crisis cases &to monitor the sensors.

Distributed SCADA Systems

Distributed SCADA systems are called second-generation systems. The distribution of the control functions can be done across numerous systems by connecting with a local area network. The control operations can be performed by sharing real-time data & command processing.
In these types of systems, the size and cost of each station are reduced however there were no consistent network protocols. As the protocols were proprietary, fewer people understand the SCADA system security while installation & this factor were ignored largely.

Networked SCADA Systems

The networked SCADA systems are also known as third-generation systems. The networking and communication of present SCADA systems can be done using the WAN system through data lines or phones. The data transmission among two nodes can be done with the help of Ethernet or Fiber-optic connections.
This type of SCADA system uses PLC to adjust and monitor the flagging operations simply once there is a necessity for main choices.

IoT SCADA Systems

IoT SCADA systems are fourth-generation systems. In these systems, the system’s infrastructural cost is reduced by implementing IoT through cloud computing. Maintaining as well as integrating these systems is easy as compared with others.
In real-time, the condition of these systems can be reported through cloud computing. Therefore the implementation of algorithms like intricate control can be done that are frequently used on usual PLCs.

SCADA System Architecture

Generally, the SCADA system is a centralized system that monitors and controls the entire area. It is a pure software package that is positioned on top of the hardware. A supervisory system gathers data on the process and sends the commands control to the process. The SCADA is a remote terminal unit which is also known as RTU.
The SCADA system utilizes a WAN and LAN networks, the WAN and LAN consist of internet protocols used for communication between the master station and devices.
The physical equipment like sensors connected to the PLCs or RTUs. The RTUs convert the sensor signals to digital data and sends digital data to the master.
Centralize System
Monitor and control entire area
SCADA is a remote terminal unit
SCADA system utilizes a WAN and LAN network
Used communication between master station and devices

Level 0 (Sensors/ Actuators)

The ground-level/ field level devices that actually interact with the physical environment or work as technicians in a supervision system. Different types of sensors and actuators come under this level. A sensor is a device that can sense the physical changes around it and generate appropriate electrical or electronic signals. For, an example we can measure the temperature using a thermostat. Flow sensor, pressure sensor, LDR, and many more sensors are used in a SCADA system.
The actuator is a device that makes physical changes when an electrical or electronic signal is applied to it. For, example if we want to control the flow of a liquid using an electrical method we can use a solenoid. Same as there are so many different types of actuators are used in SCADA System.

Level 1 (Programming Devices)

Level first is used different types of programming devices such as PLC(Programmable Logic Controller), RTU(Remote Terminal Unit) are come under this level. These are the devices that directly control the ground-level devices such as sensors and actuators. A SCADA system can be built with only local area networks or a combination of both local and wide area networks. The PLC helps to build the SCADA system with local area network only whereas the RTU system helps to build the SCADA system with the wide-area network. Here, in the above block diagram, we have used both devices for better understanding.

Level 2 (Local Control and HMI)

Level second is used the supervisory computers are come under this level. All the programming devices that operate the ground-level devices are connected to these computers. Supervisory computers are those from where the SCADA software starts working. From these computers, the actual instructions and commands are given to do the operations. The supervisory computer may be connected to a particular machine or multiple same types of machines or a whole manufacturing plant. These computers are operated by machine operators, plant supervisors, and technicians of a manufacturing plant. The main functions of these computers are to observe and control the production, errors, etc.

Level 3 (Coordination)

Level third is used coordinating computers are comes under level. Generally, these computers are connected to multiple plants. So, it can help to gather data from different plants from one place. At this level, the production planning, scheduling, event timing management are done by the plant in charge, managers, etc.

Level 4 (Central Control)

It is top-level of the SCADA System. At this level, a central computer is connected to all the plants and machinery. Generally, this is operated and controlled by the management team. All the data and information are collected and stored here. Using these data and information they can take any decision. From this computer, the management team can see all the actions and operations, etc.

Benefits of SCADA for Power Systems

  • Improved quality of service
  • Improved reliability
  • Reduced operating costs
  • Maintenance /Expansion of customer base
  • Ability to defer capacity addition projects
  • High value service providers
  • Improved information for engineering decision
  • value added services
  • Flexible billing option
  • Improved customer information access
  • Reduced system implementation costs
  • Reduced manpower requirements

Applications of SCADA

  • Comprehensive operational planning and control
  • Fuel resource scheduling
  • Optimum power flow
  • Network security
  • Economic dispatch
  • Generation dispatch control

Leading SCADA software providers 

  • Honeywell
  • Schneider Electric
  • GE Grid Solutions
  • ABB
  • Siemens Energy