Supervisory Control and Data Acquisition (SCADA) is an acronym that stands for Supervisory Control and Data Acquisition. You should be able to conjure up a variety of images when thinking about this term.
A SCADA system is a collection of software and hardware components that allow for local and remote plant supervision and control. In addition, the SCADA examines, collects, and processes data in real time.
Human Machine Interface (HMI) software allows users to interact with field devices such as pumps, valves, motors, sensors, and so on. The SCADA software also includes the ability to log data for historical purposes.
A standard SCADA system's structural design begins with Remote Terminal Units (RTUs) and/or Programmable Logic Controllers (PLCs) (PLCs). RTUs and PLCs, as you may know, are microprocessors that communicate and interact with field devices such as valves.
Prior to SCADA, plant personnel had to monitor and control industrial processes using analog signals via selector switches, push buttons, and dials. This meant that plants needed to keep personnel on-site during production to control the processes.
Relays and timers were used to assist in the supervision and control of processes as manufacturing grew and sites became more remote in nature.
With these devices in place, fewer plant personnel were needed on-site to oversee and control operations. While relays and timers provided some level of automation, the panels required for these devices took up valuable real estate, troubleshooting was a nightmare, and reconfiguring was at best difficult.
These issues, combined with the need to build larger industrial plants, aided to facilitate the birth of automation.
Role of SCADA
SCADA (supervisory control and data acquisition) is a software and hardware-based system that enables industrial organizations to:
- Control industrial processes locally or remotely.
- Real-time data monitoring, collection, and processing
- Interact directly with devices such as sensors, valves, pumps, motors, and others using human-machine interface (HMI) software.
- Create a log file to keep track of events.
SCADA systems are critical for industrial organizations because they help to maintain efficiency, process data to make better decisions, and communicate system issues to help reduce downtime.
PLCs or remote terminal units serve as the foundation of the basic SCADA architecture (RTUs). PLCs and RTUs are microcomputers that communicate with a variety of objects such as factory machines, HMIs, sensors, and end devices before routing the information from those objects.
Current SCADA situation
Modern SCADA systems have adapted to changing technologies and have a significant advantage over older SCADA systems. Today's SCADA allows for real-time plant information to be accessed from anywhere in the world thanks to the adoption of modern IT standards such as SQL and web-based applications.
The ability to respond to SCADA system queues based on field collected data and system analysis is facilitated by having this data at the operator's fingertips.
These operator interactions can take place anywhere in the world, from a computer on the plant floor to an office building in another country. The advancement of technology has indeed made the world appear to be a very small place, in relative terms.
Furthermore, because current SCADA system software has typically used the SQL database model, historical data may be logged and used in trending applications to further improve plant processes as well as creating mandated record keeping for some of the industries out there.
Supervisory Control and Data Acquisition (SCADA) is essentially a collection of hardware and software components. This set of components starts with real-time data collected from plant floor devices like pumps, valves, and transmitters.
These components do not need to be from a specific vendor; they simply need to support a communication protocol that the processor can use. Data gathered from field devices is then routed to processors such as PLCs. Data is distributed from the processor to a networked device system.
HMIs, end-user computers, and servers are examples of such devices. Graphical representations of operator interactions, such as running pumps and opening valves, are available on the HMI and end-user computer. This information can also be analyzed and used to improve plant production and troubleshoot problems.
Functions
Scada System Functions
- Collection of data.
- Display of information.
- Supervisory Control (CBs ON/OFF, Generator OFF/ON, RAISE/LOWER command).
- Data storage and display of results.
- Acquiring the sequence of events.
- Processing of remote terminal units.
- Routine maintenance.
- Verification of runtime status.
- Economic modeling.
- Remote start and stop.
- Economic load matching.
- Load shedding.
Functions Of Control
- Control and monitoring of switching devices, tapped transformers, and auxiliary devices, among other things.
- Bay-wide and station-wide interlocking.
- Dynamic Bus bar coloring based on their current operational status.
- Sequences of automatic switching.
- Load shedding, power restoration, and high-speed bus bar transfer are all automatic functions.
- Radio and satellite clock signals are used to synchronize time.
Functions Of Monitoring
- Current, voltage, frequency, active and reactive power, energy, temperature, and other parameters are measured and displayed.
- Alarm functions are available. Time stamped events are saved and evaluated.
- Trends and measurement archiving.
- Data collection and analysis for maintenance.
- Recording and analyzing disturbances.
- Monitoring events such as start, trip indication, and relay operating time, as well as setting and reading relay parameters, are all part of substation protection functions.
- Protection for bus bars. Transformers, line feeders, and generators
- Monitoring of security (status, events, measurements, parameters, recorders)
- Adaptive protection via active parameter set switch-over.
Technologies Of Communication
Telemetry is the type of communication required for SCADA. Telemetry is the measurement of a quantity in such a way that it can be interpreted at a distance from the primary detector. The nature of the translating means distinguishes telemetry, which includes provision for converting the measure into a representative quantity of another kind that can be conveniently transmitted for measurement at a distance.
The actual distance is unimportant. Telemetry can be either analog or digital. In analog telemetry, a voltage, current, or frequency proportional to the quantity being measured is generated and transmitted over a communication channel to the receiving location, where the received signal is applied to a meter calibrated to display the quantity being measured.
Variable current, pulse-amplitude, pulse-length, and pulse-rate are all examples of analog telemetry, with the latter two being the most common.
The quantity being measured is converted to a code in digital telemetry, and the sequence of pulses transmitted indicates the quantity.
One of the benefits of digital telemetering is that data accuracy is not lost while being transmitted from one location to another.
As shown, digital telemetry necessitates analog to digital (A/D) and possibly digital to analog (D/A) converters.
Twisted pair wires were the first type of signal circuit used for SCADA telemetry; while simple and economical for short distances, they suffer from reliability issues due to breakage, water ingress, and ground potential risk during faults.
Improvements over twisted pair wires came in the form of what is now the most common type of wire.
Telemetry mediums based on leased wire, power-line carrier, or microwave are the most common and traditional types.
These are voice grade forms of telemetry, which means they represent communication channels suitable for the transmission of speech, either digital or analog, with a frequency range of approximately 300 to 3000 Hz.
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