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EE0214

SCADA(Supervisory Control and Data Acquisition)

1 GSV PAVAN KUMAR 2 D. VAMSI KRISHNA REDDY

Abstract:

SCADA (Supervisory Control and Data Acquisition) plays an important role in most of theindustries like petrochemical, cement and sugar & process industries. And is mainly used tomonitor or to control a chemical, physical or transport process, integrated with power systemmanagement application functions.

The basic of SCADA lies in automation majorly done by PLCs (programmable logiccontroller). Using this, a project can be done with effective increase of speed, and meaningful

processing. Any channel failures can be detected automatically by the use of SCADA with out anyhuman interaction. It will control a complete site. The bulk of the site control is actually done by aremote terminal unit (RTU). Data acquisition begins at the RTU or PLC level. This paper willexplain the working of SCADA in control process and applications. Any SCADA system usesadvanced linear electronic components for its working. A state of embedded controller technologywill be much suitable to achieve SCADA function in all instrumentation environments.

Key words:

SCADA, PLC, Remote terminal unit, Embedded controller technology, Geographical

information system.

Conclusion:

SCADA is a giant leap in automating the total process of electricity management. Itintegrates geographical information system (GIS), Distribution management system (DMS) andSAP operations. To improve the reliability and quality of power supply, the automated SCADA andGIS systems have been put in place. The entire network is being mapped through GIS.Theintegrated outage management system running over GIS, it helps to identify the affected areas ongeographical and will provide network details for faster response.

1. IIB.Tech EIE, 2. IIB.Tech EIE,Hi-tech college of Engg& Tech. Hi-tech college of Engg&Tech

vamsidega@gmail.com

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INDEX:

AbstractIntroduction

What is SCADA?

Benefits

Block Diagram.

Main parts.

What does SCADA do?

Practical Approach.

Real Time Applications.

Future Scope

Conclusion.

References.

Introduction:

SCADA basically originated in 1993. Since there was need of monitor the campus electrical supply

and distribution systems. Many researchers took place on SCADA and finally resulted in

automation of status with out man power.

1994 installation took place and presently finds multiple opportunities in different departments.

when comes to working, the signal is trapped in between source and destination (termed as set

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points) and error is detected if any.SCADA automatically generates alarms in case of any

disturbances or any occurrence of errors.

Its remote system for power management promises to reduce fault restoration time by over 60%.

SCADA is a giant leap in automating the total process of electricity management. It integrates

geographical information system (GIS), distribution management system (DMS) and SAP

operations.

What is SCADA?

SCADA systems, a branch of instrumentation engineering, include input-output signal hardware,

controllers, human-machine interfacing (HMI), networks, communications, databases, and

software.

The term SCADA usually refers to centralized systems which monitor and control entire sites, or

complexes of systems spread out over large areas (on the scale of kilometers or miles). Most site

control is performed automatically by remote terminal units (RTU) or by programmable logic

controllers (PLC). Host control functions are usually restricted to basic site overriding or

supervisory level intervention. For example, a PLC may control the flow of cooling water through

part of an industrial process, but the SCADA system may allow operators to change the set points

for the flow, and enable alarm conditions, such as loss of flow and high temperature, to be

displayed and recorded. The feedback control loop passes through the RTU or PLC, while the

SCADA system monitors the overall performance of the loop.

Benefits of SCADA:

Benefits of SCADA system include monitoring and control from one place. The

various trends and reports can be generated from the SCADA system

Single view of entire network.

Remote monitoring.

Reduced outage down time.Better voltage quality.

Pinpointing and isolation of faults.

More accurate information.

Reduced technical losses.

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We give input through the sensors and transducers and this is converted using a signal

conversion and conditioning circuit. The filtered out put is given to the embedded controller from

which the control outputs are taken. The hardware connected to the remote PC.There is a two way

transmission between the remote PC and the master PC. Two way communications is done using

an external RS-232-C.

Working of SCADA depends on PLCs which consists of simplification of rungs

Simple example of rungs.

And, or rungs.

Main Parts:

Human-Machine Interface:

HMI is the apparatus which presents process data to a human operator, and

through which the human operator controls the process.

The SCADA system gathers information from the PLCs and other controllers via some form of

network, and combines and formats the information. An HMI may also be linked to a database, to

provide trending, diagnostic data, and management information such as scheduled maintenance

procedures, logistic information, detailed schematics for a particular sensor or machine, and

expert-system troubleshooting guides. Since about 1998, virtually all major PLC manufacturers

have offered integrated HMI/SCADA systems, many of them using open and non-proprietary

communications protocols.

Remote terminal Unit:

The RTU connects to physical equipment, and reads status data such as the

open/closed status from a switch or a valve, reads measurements such as pressure, flow, voltage

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or current. By sending signals to equipment the RTU can control equipment, such as opening or

closing a switch or a valve, or setting the speed of a pump.

The RTU can read digital status data or analog measurement data, and send out digital commands

or analog setpoints.Important to know that quality SCADA RTUs must have three important

characteristics: Data Networking, Data Reliability and Data Security.

Master Station:

The term "Master Station" refers to the servers and software responsible for

communicating with the field equipment (RTUs, PLCs, etc), and then to the HMI software running

on workstations in the control room, or elsewhere. In smaller SCADA systems, the master station

may be composed of a single PC. In larger SCADA systems, the master station may include

multiple servers, distributed software applications, and disaster recovery sites. To increase the

integrity of the system the multiple servers will often be configured in a dual-redundant or hot-

standby formation providing continuous control and monitoring in the event of a server failure.

What does SCADA do?

A SCADA system is used to monitor or control a chemical, physical, or transport process.

Integrated power system management application function, it provides an integrated distributed

management systems to improve the reliability of power supply, manage load effectively, reduce

restoration time and increase the utilization efficiency of the network equipment.

There are many functions of SCADA. Few of them are

Data exchange

Data processing

Supervisory control

Switching order

Load shedding and restoration

Any abnormality in the system is immediately flagged and corrective action is taken. The

term SCADA usually refers to the central system that monitors and controls a complete site. The

bulk of the site control is actually performed automatically by a remote terminal unit (RTU).Host

control functions are almost always restricted to basic site over ride or supervisory level capabili ty.

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Data acquisition begins at the RTU or programmable logic control (PLC) level and equipment

status that are communicated to the SCADA are required. Data is then compiled and formatted

such that a control room operator using the human machine interface (HMI) can make appropriate

supervisory decisions that may be required to over ride normal RTU or PLC controls.SCADA

system includes all the PCs, HMI, controllers, in put out put devices, network, software etc

SCADA Practical Approach:

The project SCADA is subdivided in to five modules. There are

Data Acquiring:

Data acquiring is acquiring the variable status like temp pressure flow, level etc. And main data

acquisition components are from simple thermocouple to complex gas analyzers transducers are

classified in to two types there is active transducer, passive transducer

Data Processing:

Data processing is much essential in field instrumentation techniques for save and secured

operations of process industries. It plays a major role and data acquisition systems.

Data processing circuits accept input from the transmitter or transducer directly and convert as per

the ADC standards.

Signal Conditioner:

Signal received from the field may not be suitable directly for ADC and further processsing.In such

case, the signal may need amplification or to remove unwanted frequency so that the signal

required is achieved.

Data conversion:

Data conversion means, converting analog data in to computing data, computing data means, and

the old data must be like BCD, data bus or logic level signals.

Data converters are used to convert the unknown field variables in to known datas, which can be

manipulated with a computer by using computing languages.

Data Manipulation:

Data manipulation is a simple calculation between real value and ADC value. The real value must

be sent to record files, graph file, controller setting a transmission file

Manipulation value must be compared with set points and controller actions

Data Transmission:

Data transmission is to form a bridge between master control room and sub system area. The

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distance between master control room and sub system area may dependent on the transmission

medium.

Real time Applications:

OFC failure

Coaxial cable failure.

RDX bomb detection.

Intruder Sensing.

UPS voltage Monitoring.

Floor Temperature Monitoring.

Flame detection.Power quality improvement.

Paralleling operations in industries.

Emergency Generator and Power management.

Medical services.

Many more.

Future Scope:

In many cases the applications that run at that level are becoming more important than the user

interface stuff. The user interface is an area where there is lots of competition. A spreadsheet can

even provide a decent user interface for some situations. However applications like batch tracking

and leak detection are a SCADA vendor's advantage. Those applications are becoming

modularized and contain many man-years of experience. And they usually run only on a SCADA

system. In a world of "economic rationalism" SCADA vendors become a pool of experience from all

of their customers. Not that trade secrets are being passed around, it's just that no one wants to, or

should, fund a new application 100%. A large SCADA vendor can play a role in reducing the cost

of a application that in turn provides cost saving benefits to the customer. Meanwhile many utilities

are looking more to their marketing side to get the advantage over the competition than the

operations side so sharing resources (informally) isn't perceived as a problem.