Introduction to SCADA

Supervisory Control and Data Acquisition abbreviated as SCADA is regarded as a complete system constituting of hardware and software components that helps allow industrial organizations to have control over the industrial processes either locally or at remote areas, monitor, gather (or capture) and thereby process real time data, have direct interaction with devices (like, valves, sensors, motors, pumps, etc.) via a software called human-machine interface (HMI) and at last record the events into log files.
The SCADA systems have got a paramount importance in industrial organizations as they are helpful in maintaining efficiency, processing data for making smarter decisions and communicating the system issues by mitigating downtime.
The most basic architecture of SCADA starts with the establishment of PLCs known as programmable logic controllers or RTUs known as remote terminal units. Both the PLCs and RTUs are denoted as microcomputers which communicate with a range of objects like, sensors, HMIs, factory machines and end devices, and then later transmit information from the objects mentioned to the computers holding SCADA software. SCADA software then processes, disseminates and displays data thereby helping the operators as well as rest of the employees analyze the data and help make critical decisions.
For example, a SCADA system would quickly notify an operator about a batch of product showing high error rates. The operator would then stop the operation and view the SCADA system’s data via HMI in order to zero down the actual cause of that issue. The operator would review data and then discover that machine 2 to be malfunctioning. Therefore, the ability of the SCADA system to notify an operator of any issue would help him in resolving it and preventing from further product losses.
The SCADA systems are mostly used by industrial organizations and companies (or enterprises) in both public as well as private sectors to help control and maintain efficiency levels, disseminate data in order to make smarter decisions and help communicate the issues in the systems so as to lessen the downtimes. The SCADA systems work pretty well in various types of enterprise establishments as they can possibly range from simple configurations to particularly large and complex installations. SCADA systems form the supporting structure or backbone of pretty much many of the modern industries such as; energy, oil & gas, transportation, food & beverage, power, water & waste water, manufacturing, recycling, etc.
Now in today’s world, one can find some or the other type of SCADA system being used in the background like; maintenance of the refrigeration system at a local supermarket, assurance of both production as well as safety at any refinery, achievement of quality standards at any waste water treatment plant or maybe even keeping a track of the energy usage at homes. Use of effective SCADA systems can bear results as in making significant amount of savings when it comes to both time as well as money.

Manual Inputs
Sensors

PLCs or RTUs

HMI/SCADA Panel View
HMI/SCADA Computer
Network

Basic SCADA Architecture

The figure above shows a basic structure of SCADA architecture. The sensors and manual inputs send data to PLCs or RTUs, which instead feeds data to SCADA system. The network connects SCADA through LAN or WAN. The HMI/SCADA computer helps supervise and control from a workstation while the HMI/SCADA panel view helps supervise and control from an operator terminal.
The birth of SCADA systems is quite easy to comprehend if we understand the problems faced by the industrial organizations at that time. During that era there was too much reliability on personnel so as to manually control as well as monitor equipments through use of push buttons and analog dials in many of the manufacturing floors, industrial plants and remote sites. But as and when the plants and remote sites started to scale out as per size basis, solutions were needed to be found out so as to have control over the equipments over distances that were too long. Along came along the concept of relays and timers to provide supervisory control by not having to send people to remote sites so as to have direct interaction with the devices. Though the relays and timers provided limited automation functionalities but then again the industries exponentially kept on increasing in size. It was difficult to configure and do fault finding in the relays and timers which indicated the introduction of a fully efficient as well as automated mode or system of controlling and monitoring. This slowly and steadily gave rise to the use of SCADA systems in major utilities, oil and gas pipelines and other huge markets during that time.
The usage of modern SCADA systems has made it possible to collect real time data from the industrial floors so as to be accessed anywhere outside in the world. The data so retrieved helps individuals, businesses, governments, etc make informed as well as data driven decisions so as to constantly make improvements in their processes. The new improvements or introduction brought about by the modern IT standards as well as practices like, use of SQL and other web based applications into this SCADA software has made greater and improved changes on the basis of efficiency, productivity, reliability and security of SCADA systems. One of the noteworthy advantages of making use of SQL databases with SCADA systems is that it becomes easier while integrating with the ERP and MES systems thereby helping the data flow flawlessly through the entire organization.

Usage of SCADA in process automation

The SCADA is the zeroed down solution when we talk about collection as well as monitoring of data. The industry which encompasses multiple segments highly depends on SCADA as of today for executing automation of various industrial tasks or activities. So, to put in short and crisp terms, SCADA can be considered as the lifeline and soul of industrial (or process) automation thereby ensuring the flawless and smooth running of the business as well as maximizing profits.
The uninterrupted control over the applications as well as processes under consideration and maximization of power of the information collected is pretty easy with the successful use of SCADA. It takes control over the large scale processes which may to some extent incorporate very large distances along with multiple sites. Besides all the industrial and infrastructure processes in picture, SCADA also finds its place within the public as well as private facilities (that is; the buildings and the entire premises which is spread across huge areas) so as to monitor and hence control the consumption of energy along with automation of the electrical tasks or supporting activities.
The functions of SCADA which are listed under indicate it as a must incorporated addition when it comes to process automation;

  • Data acquisition
  • Collection, storage and accessing or retrieval of data
  • Monitoring over multiple cases such as; events, limits, status and trends
  • Having control over instructions as well as commands
  • Provisions set for the human operators in order to watch the processes that are being monitored as well as controlled and thereby intervene as and when required or necessary. In short it can be termed as human-machine interface abbreviated as HMI.
  • Electrical communication between the MTUs and RTUs, then among the RTUs and field or floor devices
    The calculations executed within RTUs
  • Generation of respective and specific, corresponding reports in relation to and on the basis of data collected as well as stored
  • Both large as well as small systems can be constructed or built by making use of the SCADA concept. Such systems under consideration can range from just incorporating tens to thousands of control loops in relation to or depending on the application. SCADA finds its implementation in multiple processes and fields of work such as; cement and fertilizer, automobile, food processing, petrochemical, oil and gas, water treatment, power generation, etc. The list below mentions the use of implementation or application of SCADA on the basis of above mentioned fields;

  • Electric power generation, transmission and distribution
    The electric related utilities make use of SCADA systems in order to detect flow of current as well as line voltage so as to monitor operation of the circuit breakers and to take the sections of a power grid either online or offline.
  • Water, waste water utilities and sewage
    State along with municipal water utilities make use of SCADA so as to monitor as well as regulate the flow of water, pipe pressure, reservoir levels and multiple other factors.
  • Buildings, facilities and environments
    The facility managers make use of SCADA in order to control HVAC, lighting, entry systems and refrigeration units.
  • Oil and gas transportation and distributions
    The SCADA systems help in oil or gas pipeline leak detection, well testing, tank monitoring, asset data management and maintenance management, fault finding in pipelines or equipments, optimizing the flow, etc.
  • Wind power generation
    Here the SCADA can be put to use for remote supervision as well as control over wind turbines and wind parks. The main features offered by SCADA include park overview, park control, turbine overview, turbine control, log viewer and report generator.
  • Industrial plans and process control
    The SCADA systems tend to be helpful in scenarios such as, fault finding or detection in devices carrying out respective processes, temperature control, starting or shutting down field or plant equipments, etc.
  • Manufacturing
    SCADA systems help manage the parts residing in inventories so as to execute just-in-time manufacturing, regulating the industrial automation as well as robots and monitoring processes and doing quality control.
  • Mass transit and railway traction
    The transit authorities make use of SCADA so as to regulate the electricity to subways, trams and trolley buses, to help automate traffic signals for the rail systems, to track as well as locate the trains and buses and help control the railroad crossing gates.
  • Traffics signals
    SCADA helps regulate the traffic lights, controls the flow of traffic and detects any sort of out-of-order signals if any.
  • SCADA finds its wide range applications in power systems that include comprehensive operational planning as well as control, scheduling of fuel resources, optimization of power flow, provision of network security, establishment of economic dispatch and generation of dispatch control.
    So, by inculcating the implementation of SCADA we are made available to accurate and timely data. This real time data captured can be put to use as to optimize the operations or processes in a plant. SCADA systems help in enablement of considerable amount of improvements in relation to efficiency and for sure data safety. This efficiency so achieved directly translates in significantly reducing the operating costs.