What Is SCADA
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Joined: Feb 2011
17-02-2011, 11:08 AM
Section 1: What is SCADA, andwhat can it do for you?
SCADA is not a specific technology, but a type ofapplication. SCADA stands for Supervisory Controland Data Acquisition — any application that gets dataabout a system in order to control that system is aSCADA application.A SCADA application has two elements:1. The process/system/machinery you want to monitora control — this can be a power plant, a watersystem, a network, a system of traffic lights, oranything else.2. A network of intelligent devices that interfaceswith the first system through sensors and controloutputs. This network, which is the SCADA system,gives you the ability to measure and controlspecific elements of the first system.You can build a SCADA system using several differentkinds of technologies and protocols. This whitepaper will help you evaluate your options and decidewhat kind of SCADA system is best for your needs.
Where is SCADA Used?
You can use SCADA to manage any kind of equipment.Typically, SCADA systems are used to automatecomplex industrial processes where human controlis impractical — systems where there are morecontrol factors, and more fast-moving control factors,than human beings can comfortably manage.Around the world, SCADA systems control:
• Electric power generation, transmission anddistribution: Electric utilities use SCADA sys- tems to detect current flow and line voltage, tomonitor the operation of circuit breakers, and totake sections of the power grid online or offline.
• Water and sewage: State and municipal waterutilities use SCADA to monitor and regulate waterflow, reservoir levels, pipe pressure and other factors.
• Buildings, facilities and environments: Facilitymanagers use SCADA to control HVAC, refrigerationunits, lighting and entry systems
.• Manufacturing: SCADA systems manage partsinventories for just-in-time manufacturing, regulateindustrial automation and robots, and monitorprocess and quality control
• Mass transit: Transit authorities use SCADA toregulate electricity to subways, trams and trolleybuses; to automate traffic signals for rail systems;to track and locate trains and buses; and to controlrailroad crossing gates.•
SCADA regulates traffic lights,controls traffic flow and detects out-of-order signals.As I’m sure you can imagine, this very short list barelyhints at all the potential applications for SCADAsystems. SCADA is used in nearly every industry andpublic infrastructure project and implimentation — anywhere whereautomation increases efficiency.What’s more, these examples don’t show how deepand complex SCADA data can be. In every industry,managers need to control multiple factors and theinteractions between those factors. SCADA systemsprovide the sensing capabilities and the computational power to track everything that’s relevant to your operations.
What’s the Value of SCADA to You?
Maybe you work in one of the fields I listed; maybe you don’t. Butthink about your operations and all the parameters that affect yourbottom-line results:• Does your equipment need an uninterrupted power supplyand/or a controlled temperature and humidity environment?• Do you need to know — in real time — the status of many differentcomponents and devices in a large complex system?• Do you need to measure how changing inputs affect the outputof your operations?• What equipment do you need to control, in real time, from adistance?• Where are you lacking accurate, real-time data about keyprocesses that affect your operations?
Real-Time Monitoring and Control Increases Efficiencyand Maximizes rofitability
Ask yourself enough questions like that, and I’m sure you can seewhere you can apply a SCADA system in your operations. But I’mequally sure you’re asking “So what?” What you really want toknow is what kind of real-world results can you expect from usingSCADA.Here are few of the things you can do with the information andcontrol capabilities you get from a SCADA system:• Access quantitative measurements of important processes,both immediately and over time• Detect and correct problems as soon as they begin• Measure trends over time• Discover and eliminate bottlenecks and inefficiencies• Control larger and more complex processes with a smaller, less specialized staff.A SCADA system gives you the power to fine-tune your knowledgeof your systems. You can place sensors and controls at everycritical point in your managed process (and as SCADA technologyimproves, you can put sensors in more and more places). Asyou monitor more things, you have a more detailed view of youroperations — and most important, it’s all in real time.So even for very complex manufacturing processes, large electricalplants, etc., you can have an eagle-eye view of every eventwhile it’s happening — and that means you have a knowledge basefrom which to correct errors and improve efficiency. WithSCADA, you can do more, at less cost, providing a direct increasein profitability.
Section 2: How SCADA Systems Work
A SCADA system performs four functions:1. Data acquisition2. Networked data communication3. Data presentation4. ControlThese functions are performed by four kinds of SCADA components:
1. Sensors (either digital or analog) and control relays thatdirectly interface with the managed system.
2. Remote telemetry units (RTUs). These are small computerizedunits deployed in the field at specific sites and locations.RTUs serve as local collection points for gathering reportsfrom sensors and delivering commands to control relays.
3. SCADAmaster units. These are larger computer consoles thatserve as the central processor for the SCADA system. Masterunits provide a human interface to the system and automaticallyregulate the managed system in response to sensor inputs.
4. The communications network that connects the SCADAmaster unit to the RTUs in the field.