Supervisory Control and Data Acquisition (SCADA) System: Definition & Components

Instructor: Kellie Moore

Kellie has over 25 years' experience in IT and holds a master's degree in business with IT emphasis.

SCADA systems are used in all different types of industry including utilities and manufacturing. In this lesson, we'll discuss what SCADA systems are and how they can be used.

What is a SCADA System?

A SCADA system is used to monitor all kinds of industrial systems. For example it can monitor parts of the electric grid in the United States, a local water utility company or equipment used at a manufacturing facility. SCADA is an abbreviation for Supervisory Control and Data Acquisition.

SCADA Functionality and Components

A SCADA system is like a manager. It supervises industrial systems but does not directly make changes to them. The system centers around a SCADA master, which is a large back-end component that collects incoming information such as water levels, equipment status or system discrepancies. The SCADA master will then provide information in a usable format to consoles or human management interfaces (HMIs). Information about current conditions or alerts based on current condition changes can be sent from the SCADA master to the consoles. People monitoring the consoles can then use the received data to make process or repair decisions.

If necessary, changes are then requested by the person monitoring the console through a production system that has the capability of making the requested change. These production systems are called remote terminal units (RTUs). Generally, there will be some sort of telecommunications link (i.e. a data line or a wireless tower) that provides the connectivity between the SCADA system and the RTU. In some cases, commands can be automatically issued by the RTU based on conditions or alerts. Remote terminal units issue commands to the systems by utilizing many different types of intelligent devices like programmable logic controllers (PLCs) or actuators. All of these components and their relationships are outlined in Figure 1.


Figure 1: SCADA System Layout
SCADA System


SCADA Examples

There are many examples of how SCADA systems can be used. Below are a couple helpful ones to better clarify how they work.

Electric Grid

A SCADA system can be used to monitor electric grid components in the United States. Because SCADA is a supervisory control system, people using this system don't implement changes, they simply watch the many parts of the electric grid via consoles. If something doesn't look right, they'll pick up the phone and call the utility that has access to control the affected systems.

The utility will then make changes to their production systems. When they make those changes, rather than driving out to a substation that may be far away from their main office, they will likely utilize a remote terminal unit that can communicate the commands to one or more devices to make the change or correction.

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