SCADA DCS AND PLC

INTRODUCTIONSCADA DCS and PLC based automation

systems are available

Selection depends on factors like type of process industry, scale of production etc

PLC Programmable Logic Controller PLC is a digital computer designed for

multiple inputs and output arrangements, extended temperature ranges, immunity to electrical noise, and resistance to vibration and impact

Speed and accuracy of the operation can be greatly enhanced using plc.

PLC INPUTS AND OUTPUTSprocess can be automated using a PLC.

Proximity Sensors Motor Limit Switches Actuators Pressure Switches Pumps

PLC APPLICATIONS Robots manufacturing and control Car park control Train control station system Food processing Materials handling Machine tools Conveyer system etc.

PLC ADVANTAGESReliability.Flexibility in programming and

reprogramming.High speed of operation.

PLC DISADVANTAGES

Limited design

Fixed Circuit Operations.

SCADASCADA stands for Supervisory Control And Data

Acquisition As the name indicates, it is not a full control

system, but rather focuses on the supervisory level

purely software package that is positioned on top of hardware to which it is interfaced, in general via Programmable Logic Controllers (PLC's), or other commercial hardware modules

I/O channels of several 100 thousands I/O's

Distributed control system (DCS)DCS is a system of dividing plant or process

control intoseveral areas of responsibility, each managed by

its owncontroller, with the whole system connected to

form asingle entity, usually by means of

communication buses.

The entire system of controllers is connected by networks for

communication and monitoring.

The entire system of controllers is connected by networks

for communication and monitoring.

The DCS is a control system which collects the data from the field and decides what to do with them. Data from the field can either be stored for future reference, used for simple process control, use in conjunction with data from another part of the plant for advanced control strategies

DCS ADVANTAGESControl function is distributed among

multiple CPUs (Field Control Stations). Hence failure of one FCS does not affect the entire plant.

Redundancy is available at various levels.

Information regarding the process is presented to the user in various formats

SCADA & DCS APPLICATIONS Electrical power grids and electrical

generation plants

Manufacturing

Oil and Gas Industry

PLC AND DCSPLC DCSUsed for low loop

countTypical performance

100 PID loops/secManual

documentation

Large engineering effort required in case of expansion

Used for high loop count

Typical performance 1000 PID loops/sec

Automatic documentation

Less engineering effort required in case of expansion

PLC DCSSimple operating

interfaceLadder logic used

to configureValue of individual

component manufactured very less

Sophisticated operating interface

Use function block diagram to configure

Value of individual component manufactured not very less

PLC DCSDown time results in

loss of productionReturn to steady

state production after an outage is short

Operators primary role is to handle exceptions

Down time results in loss of production and can results damage of process equipment

Return to steady state production after an outage is not short

Operators role is to keep process in target performance range

DCS AND SCADADCS SCADADistributed control

systemsCostly Used in control

levelDCS is process

state drivenchoice for

installations that are limited to a small locale,

Supervisory Control And Data Acquisition

Less CostlyUsed in supervisory levelis event drivenpreferred when the

entire system isspread across a much

larger geographic location

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