SCADA | Types, Block Diagram and Functions of SCADA System

SCADA

Supervisory Control and Data Acquisition (SCADA). A SCADA system is a collection of both software and hardware components that allow supervision and control of plants, both locally and remotely. Scada is a system that monitors and controls the complete system speed over long-distance.

Types of SCADA

SCADA systems are classified into four types which include the following.

1. Monotholic SCADA Systems(i.e First generation Architecture)
2. Distributed SCADA Systems(i.e Second generation Architecture)
3. Network SCADA Systems(i.e Third generation Architecture)
4. IoT/Web base SCADA Systems(i.e Fourth generation Architecture)

1. Monotholic SCADA Systems

Monotholic SCADA systems are called early or first-generation systems. Early SCADA system computing was done by large minicomputers. The first-generation SCADA System redundancy was achieved using a backup mainframe system connected to all the remote terminal unit (RTUs) sites and was used in the event of the failure of the primary mainframe system. No communication protocols are used at this time.

2. Distributed SCADA Systems

Distributed SCADA systems are called second-generation systems. SCADA information and command processing were distributed across multiple stations, which were connected through a LAN. Information was shared in real-time. Each station was responsible for a particular task, which reduced the cost as compared to first-generation SCADA. The network protocols used were still not standardized.

3. Networked SCADA Systems

The networked SCADA systems are also known as third-generation systems. In the case of a networked design, the system may be spread across more than one LAN network and separated geographically. Several distributed architecture SCADAs run in parallel, with a single supervisor. This type of SCADA system uses PLC to adjust and monitor different geographical areas using WAN networking data through the data lines.

4. IoT/Web base SCADA systems

IoT/Web-based SCADA systems are fourth-generation systems. The growth of the internet has led SCADA systems to implement web technologies allowing users to view data, exchange information, and control processes from anywhere in the world through a web connection. Web SCADA systems use internet browsers such as Google Chrome and Mozilla Firefox as the graphical user interface (GUI) for the operator’s HMI (Human-Machine Interface). This enables the users to access the system from various platforms with web browsers such as servers, personal computers, laptops, tablets, and mobile phones.

Functions of SCADA Systems

SCADA systems perform several functions that allow for proper management of remote facilities There are four core functions of a SCADA system.

1. Data Acquisitions
2. Data Communication
3. Information/Data presentation
4. Monitoring control

Sensors, RTUs, controllers, and a communication network perform these functions. The sensors are used to collect the important information and RTUs are used to send this information to the controller and display the system’s status. The user can give the command to other system components according to the system’s status. A communication network does this operation.

• Data acquisition: is the foundation of SCADA systems. The real-time system consists of thousands of components and sensors. It is essential to know the status of particular components and sensors.

• Data Communication: It uses a wired network to communicate between users and devices. Real-time applications use a lot of sensors and components, which should be controlled remotely. The SCADA system uses internet communications. All information is transmitted through the Internet using specific protocols. Sensors and relays can not communicate with the network protocols, so RTUs communicate sensors and network interfaces.
• Information / Data presentation: The normal circuit network has the same indicators, which can be visible to control, but in the real-time SCADA system, thousands of sensors and alarms are impossible to handle simultaneously. The SCADA system uses the human-machine interface to provide all of the information gathered from various sensors.
• Monitoring/Control: The SCADA system uses different switches to operate each device and displays the status of the control area. These switches can be turned on/off from the control station using any part of these switches. SCADA system is implemented to work automatically without human intervention, but in critical situations, it is handled by manpower.

Block Diagram of SCADA

The major components of this system are:

MTU (Master Terminal Unit)

It is also called the heart of this system. This system can be a dedicated computer or PC, a programmable logic controller(PLC), or a network server system that is used to communicate with a remote field unit. It also allows the user to perform control functions on many field devices like breakers, switches, and other actuators depending on the data type.

RTU (Remote Terminal Unit)

Its main function is to collect or gather information from various field sites in which they are placed. Each Remote terminal unit is connected to the various sensors and field devices to manage the progress. It collects the information from the various field devices and sends it to them to the MTU.

Communication Equipment

It is the link or channel between the RTU and MTU system. The communication can be done through the wire or it can be wireless. It is done by the Internet which provides bidirectional and unidirectional communication between Remote Terminal Unit and Master Terminal Unit.

Software

It is also an important part of the whole system. Without this system, we can not handle or operate the system. This software comprises a computer OS that controls the host computer system, communication network, and other things.

Advantages of SCADA

The advantages of the SCADA system include the following.

1. The quality of service can be improved
2. Reliability can be improved
3. Maintainance cost is less
4. Manpower can be reduced
5. it stores a large amount of data

Disadvantages of SCADA

The disadvantages of the SCADA system include the following.

1. It is complex in terms of dependent modules and hardware units.
2. It needs analysts, programmers, and skilled operators to maintain
3. High installation cost
4. Unemployment rates can be increased
5. This system supports hardware devices and restricted software

Frequently Asked Questions (FAQS)

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