How Does a SCADA System Work?


SCADA is the acronym for supervisory control and data acquisition. In basic terms, SCADA refers to a computerized system used to monitor, gather, and analyze data in real time. They are used to help monitor and control many processes that are critical to modern society such as traffic lights, transmission of electricity, and the flow of oil and gas through pipelines.

What Makes Up a SCADA System?

According to the website, a SCADA system performs four basic functions and is implemented using four types of components. The functions that are required are data acquisition, data presentation, data communication through a network, and control.

The components that perform these functions in the SCADA system are sensors and control relays, remote telemetry units (RTUs) and programmable logic controllers (PLCs), SCADA master units and the communication network that connects all of the other components.

The sensors and control relays interact directly with the system that is being controlled. The RTUs are small computerized units whose purpose is to be local collection points. They receive the data from sensors and send commands to control relays. SCADA master units are machines that provide a human interface to the system and can perform automatic regulation of the system based on sensor input. All of these components are tied together into a network where feedback is immediately available to the main controlling system.

The brains behind this conglomeration of electronic devices, computers, and network components is the SCADA software. The ability to create useful Human Machine Interfaces (HMIs) that empower operators to take the proper action to deal with events is a crucial feature of the underlying programming in any SCADA system. Automated responses to various situations that may be encountered by the controlling system are also put in place with this software.

A Brief History Of SCADA

The principles of SCADA arose in the search for solutions to the problems faced by the expansion of industrial organizations and utilities. Throughout the early 20th century industrial equipment was controlled by human operators who were required to be located near the hardware they were responsible for maintaining. Simple relays and timers were employed as the scope of the industrial enterprise expanded, allowing a level of remote control without sending human resources to visit each piece of equipment.

The advent of computers opened the doors to the development of truly automated control and monitoring systems. The 1950s and 1960s saw the adoption of supervisory control systems in the power utility fields and other industries. The term SCADA was introduced in the early 1970s and coincided with the rise of microprocessors and PLCs. These components enabled the construction of more advanced monitoring and control systems.

SCADA systems were initially comprised of self-contained, non-networked, mainframe computers. Local area networks and PC based HMI software led to the creation of distributed SCADA systems, but the use of proprietary protocols limited their interoperability. The next step was to use protocols that were not vendor specific in an open architecture, networked SCADA. This was a major step forward in the development of truly viable SCADA systems that can share information with other systems.

While some industrial SCADA systems are still hampered by enterprise level access of the underlying industrial data, steps are being made to alleviate these issues. Though slow to adopt the SQL standard of the IT industry, there are now SCADA software packages that take full advantage of the power and universality of SQL and other web-based principles. This makes the SCADA data more accessible to MES and ERP systems and adds value at the enterprise level.

What Does a SCADA System Actually Do?

Now that we know all about SCADA, let’s dig into the details of some SCADA systems to see how the components interact to create control systems that can handle some of the more complex industrial tasks that make modern life possible.

An example of a critical SCADA system would be the system that is utilized in power generating stations. Monitoring is of prime concern in the power generating business. The SCADA system monitors factors such as the speed of transmission, water treatment and fuel delivery across wide geographical areas, as well as load scheduling and turbine protection. This is accomplished through the use of PLCs, powerful and robust networks, and quality SCADA software. Without adequate control systems in place, power generation would be even more complex than it is and prone to problems and outages.

Industrial manufacturing facilities are prime customers for SCADA systems. The ability to monitor and control assembly lines from a centralized location not only leads to improved production but also results in savings in human resources. Properly tuned SCADA systems can greatly reduce the number of operators required to keep a plant running at peak capacity.

Food production is another industry where a SCADA system can lead to increased efficiency. Proper temperature monitoring by sensors and adjustment that can be automatically made by the system can reduce waste as problems will be resolved before spoilage occurs. The movement of raw materials through the plant can also be monitored and point to opportunities for more economical production.

Utilities in general benefit from SCADA systems as they need to closely monitor and control their lines which are spread over a large area. Water treatment facilities, power plants and telecom companies all need the type of oversight and control offered by SCADA systems.

Should My Company Look Into SCADA?

If you are involved in just about any industry or production facility then you can benefit from a SCADA system. The larger and more widespread your facility, the greater the advantage of automating your monitoring and control processes.

The gains will be seen in reduced manpower requirements, and the elimination of simple human errors as problem situations are addressed by the system. Additionally, the use of HMIs and analysis tools can allow better decision making as you fine-tune your facility and strive to become the industry leader in your chosen field.

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