What is SCADA?

SCADA is an acronym for Supervisory Control And Data Acquisition, which is a computer system for gathering and analyzing real-time data. Such systems were first used in the 1960s.

The SCADA industry was essentially born out of a need for a user-friendly front-end to a control system containing PLCs (programmable logic controllers). SCADA networks enable remote monitoring and control of an amazing variety of industrial devices, such as water and gas pumps, track switches, and traffic signals.

One of the key processes of SCADA is the ability to monitor an entire system in real time. This is facilitated by data acquisitions including meter reading and checking statuses of sensors that are communicated at standard intervals depending on the system. Besides the data being used by the RTU, it is also displayed to a human that is able to interface with the system to override settings or make changes when necessary.

SCADA can also be seen as a system with many data elements called points. Each point is a monitor or sensor and these points can be either hard or soft. A hard data point can be an actual monitor; a soft point can be viewed upon as an application or software calculation. Data elements from hard and soft points are usually always recorded and logged to create a time stamp or history.

In essence, A SCADA application has two elements:

1. The process/system/machinery you want to monitor and control - this can take the form of a power plant, a water system, a network, or a system of traffic lights.
2. A network of intelligent devices that interfaces with the first system through sensors and control outputs. This network, which is the SCADA system, gives you the capability to measure and control specific elements of the first system.

Throughout this article, we will be answering not only answering the question of “What Is SCADA?” but also discussing other concepts related to the application of this system.

SCADA can be used to manage many kinds of equipment. Typically, SCADA systems are used to automate complex industrial processes where human control is impractical.Around the world, SCADA systems control are used in the following industries:

Manufacturing:SCADA systems manage parts inventories for JIT manufacturing, regulate industrial automation and robots, and monitor process and quality control.

Buildings, facilities and environments: Facility managers use SCADA to control HVAC, refrigeration units, lighting and entry systems.

Electric power generation, transmission and distribution: Electric utilities use SCADA systems to detect current flow and line voltage, to monitor the operation of circuit breakers, and to take sections of the power grid online or offline.

Water and sewage: State and municipal water utilities use SCADA to monitor and regulate water flow, reservoir levels, and pipe pressure.

Mass transit: Transit authorities use SCADA to 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.

Traffic signals: SCADA regulates traffic lights, controls traffic flow and detects out-of-order signals.

There are three main elements to a SCADA system:

• RTU's (Remote Telemetry Units),
• Communications
• HMI (Human Machine Interface).

Each RTU collects information at a site, while communications bring that information from the various plant or regional RTU sites to a central location, and occasionally returns instructions to the RTU.

Communication within a plant is conducted by data cable, wire or fiber-optic, while regional systems most commonly utilize radio. The HMI is fundamentally a PC system running powerful graphic and alarm software programs.

The HMI displays this information in an easy to understand graphics form; archives the data received, transmits alarms, and permits operator control as required.

Now that the initial question of “What is SCADA?” has been answered, the next step is to look at the way this system operates as a network.

A SCADA network consists of one of more Master Terminal Units (MTUs), which are utilized by operators to monitor and control a large number of Remote Terminal Units (RTUs). The MTU is often a computing platform, like a PC, which runs SCADA software. The RTUs are generally small dedicated devices that are hardened for outdoor use and industrial environments.

As we saw earlier, there are several parts of a working SCADA system. A SCADA system usually includes signal hardware (input and output), controllers, networks, user interface (HMI), communications equipment and software. All together, the term SCADA refers to the entire central system. The central system usually monitors data from various sensors that are either in close proximity or off site (sometimes miles away).

1. Data acquisition
2. Networked data communication
3. Data presentation
4. Control

These functions are performed by several kinds of SCADA components:

• Sensors (either digital or analog) and control relays that directly interface with the managed system.
• Remote telemetry units (RTUs). These are small-computerized units deployed in the field at specific sites and locations. RTUs serve as local collection points for gathering reports from sensors and delivering commands to control relays.
• SCADA master units. These are larger computer consoles that serve as the central processor for the SCADA system. Master units provide a human interface to the system and automatically regulate the managed system in response to sensor inputs.
• The communications network that connects the SCADA master unit to the RTUs in the field monitor at your remote sites

Your SCADA master should display information in the most useful way to human operators and intelligently regulate your managed systems.

Here's a down and dirty checklist of SCADA master essentials:

Flexible and programmable response to sensor inputs
Look for a system that provides easy tools for programming soft alarms (reports of complex events that track combinations of sensor inputs and date/time statements) and soft controls (programmed control responses to sensor inputs).

24/7, automatic pager and email notification
Why pay personnel to watch a board 24 hours a day? If equipment needs human attention, the SCADA master can automatically page or email directly to repair technicians.

Detailed information display
You want a system that displays reports in plain English, with a complete description of what activity is happening and how you can manage it.

Nuisance alarm filtering
Nuisance alarms desensitize your staff to alarm reports, and they can start to believe that all alarms are nonessential alarms. Eventually they may stop responding even to critical alarms. Look for a SCADA master that includes tools to filter out nuisance alarms.

Expansion capability
An SCADA system is a long-term investment that will last for as long as 10 to 15 years. So you need to make sure it will support your future growth for up to 15 years.

Redundant, geo-diverse backup
The best SCADA systems support multiple backup masters in separate locations. If the primary SCADA master fails, a second master on the network automatically takes over, with no interruption of monitoring and control functions.

Support for multiple protocols and equipment types
Early SCADA systems were built on closed, proprietary protocols. Single-vendor solutions aren't a great idea as vendors sometimes drop support for their products or even just go out of business. Support for multiple open protocols safeguards your SCADA system against unplanned obsolescence.

Reliability and robustness.
These systems are used for mission critical industrial processes where reliability and performance are paramount. In addition, specific development is performed within a well-established framework that enhances reliability and robustness.

Maximize productivity
Maximizes productivity and ensures continuous production. SCADA's design is centered on multi-level redundancy to ensure constant communication and operation of your system.

Improve product quality
Analyzes and controls the quality of manufactured products using standard SCADA functionality, such as Statistical Process Control (SPC). Advanced statistical alarms enable your personnel to perform predictive calibration of process parameters thus preventing out of limit deviations before they occur.

Reduce your operating and maintenance costs
Through the deployment of a centralized SCADA system you can signi?cantly reduce operating and maintenance costs; fewer personnel are required to monitor ?eld equipment in remote locations, resulting in increased operator effectiveness; and less maintenance trips are required, resulting in decreased maintenance and training costs.

Integrate with your business systems
A SCADA system can be easily integrated with your existing business systems, leading to increased production and pro?tability. In addition, this system implementation allows you to transform, analyze and present real-time information throughout the enterprise for prioritized decision-making.

Preserve your capital investment
When you spend money to improve operations, you need to ensure prolonged use; SCADA's open system design protects against control system obsolescence and can be easily scaled to meet growing demands on your operations.

There are five phases in creating a functional SCADA system:

Phase 1
The DESIGN of the system architecture includes the communication system. Also involved in this initial phase will be any site instrumentation that is not currently in existence, but will be required to monitor desired parameters.

Phase 2
The SUPPLY of RTU, communication, and HMI equipment, which consists of a PC system and the required powerful graphic and alarm software programs.

Phase 3
The PROGRAMMING of the communication equipment and the powerful HMI graphic and alarm software programs.

Phase 4
The INSTALLATION of the communication equipment and the PC system. The previous task is typically much more involved.

Phase 5
The COMMISSIONING of the system, where communication and HMI programming problems are solved, the system is proven to the client, and operator training and system documentation is provided.

It should be noted and appreciated that while a SCADA system can be complex to configure - it is generally much easier to operate.

SCADA systems are an extremely advantageous way to run and monitor processes. They are great for small applications, such as climate control, but they can also be effectively used in large applications such as monitoring and controlling a nuclear power plant or mass transit system.

SCADA can come in open and non-proprietary protocols. Smaller systems are extremely affordable and can either be purchased as a complete system or can be mixed and matched with specific components. Large systems can also be created with off-the-shelf components. SCADA system software can also be easily configured for almost any application, removing the need for custom software development.

As demonstrated in this “What is SCADA?” guide, building the right SCADA system for your business isn't simple. It's easy to spend more than you need, but there are also opportunities to save money and improve operational efficiency that you don't want to miss. It's hard to learn everything you need to know and still perform your daily job. DPS Telecom can help you plan your SCADA implementation, with expert consultation, training and information resources. DPS telemetry equipment is built with the capabilities you need and we are committed to helping you get the best SCADA system for your specific needs.

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