OVER VIEW, ARCHITECTURE MAIN COMPONENTS

OVER VIEW, ARCHITECTURE

MAIN COMPONENTS

T Srinivas, Chief Manager, SRLDC

SCADA SYSTEM

1

SCADA SYSTEM

OVER VIEW

ARCHITECTURE

MAIN COMPONENTS

2

SCADA :Supervisory Control and Data Acquisition

It is the system responsible for gathering, processing, and displaying information about the state of a monitored system.

From a SCADA control center, operators and application programs can oversee and change the operating state of monitored devices.

3

Southern Regional Load Despatching Facilities

CDP

Bangalore

10 Sec

2 Sec

2 Sec

RTU

INT SCADA

Chennai SCC UTPSLDC

Sub LDC

RLDC

RTU

WGL TVMVIJ

RTU RTU

GTR LGR

RTU RTU RTU

TVM

RTU

MDI

RTU

ERD

RTU RTU

Bangalore Hyderabad Kalamassery

5

TYPICAL SCADA SYSTEM

SCADAH/W &S/W

MEDIA

C TXO RX M EM QN P T

C TXO RxM EM QN P T

R

T

U

T PR AA NN ES LDUCER

C & R

PANEL

CONTROLCENTRE SUBSTATION / GEN STATION

COMMNMEDIA

FIELD UNIT / RTU

Scada System - Overview

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Scada System - Architecture

• First Generation – Monolithic

• Second Generation – Distributed

• Third Generation – Networked

7


MONOLITHIC SCADA SYSTEM8


MONOLITHIC SCADA SYSTEM

Computing Centered with Main Frame

Non existant of Networks

Centralised System

Standalone sytem

9


DISTRIBUTED SCADA SYSTEM10


DISTRIBUTED SCADA SYSTEM

• Advantage of developments andimprovement in system miniaturization and Local Area Networking (LAN)

technology to distribute the processing across multiple systems.

• Multiple stations, each with a specificfunction, were connected to a LAN and shared information with each other in real-time

11



• Communications processors, primarilycommunicating with field devices such

as RTUs.

• operator interfaces, providing the human-machine interface (HMI) for system operators.

• calculation processors or database servers.

12



• Network-connected systems served not only to increase processing power, but also to improve the redundancy and reliability of the system as a whole.

• Distributed architecture often kept allstations on the LAN in an online state

all of the time.

13


NETWORKED SCADA SYSTEM 14


NETWORKED SCADA SYSTEM

• The major improvement in the thirdgeneration is that of opening the system

architecture, utilizing open standards and protocols and making it possible to distribute SCADA functionality across a WAN and not just a LAN.

• There are still multiple networked systems, sharing master station functions. There are still RTUs utilizing protocols that are vendor-proprietary. 15



• Utilization of off-the-shelf systems makes it easier for the user to connect third party peripheral devices (such as monitors, printers, disk drives, tape drives, etc.) to the system and/or the network.

• Because of “open” or “off-the-shelf” systems, SCADA vendors have gradually gotten out of the hardware development business.

16



• Advantage of the use of WAN protocols such as the Internet Protocol (IP) for communication between the master station and communications equipment.

• Advantage brought about by the distribution of SCADA functionality over aWAN is that of disaster survivability.

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Control Room Hardware

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IT application servers (DMZ)

CFE Servers 2 No.

Serial Cards (including 8 pair of modems) /Splitters

RTUs on 60870-5-101 Protocol

Router cum Firewall 2 Nos.

RTU on 104/ PMU 0n

C37.118/ other IP devices

DATA ACQUISITION VLAN

SCADA NAS Storage SCADA ServersLCD / Video Projection

GPS , Time and

Frequency DisplaysDatabase Servers

ICCP ServersRouter cum Firewall 2 Nos.Routers at RLDCs and SLDC Dual Monitor Training ConsolesDTS Server

UPS, CMC, RD, PDS, ISR, NMS / Management LAN

Developmental Workstation

Programmer Development Server (1 Nos.) NMS Servers Printers

(B/W & Color)

Replica ServersCMC

ISR Servers2 No.

Server Management Console

UPS Monitoring

SystemIdentity Server

PD

S, IS

R, N

MS

LA

N

RD

, CM

C, U

PS

& S

ER

VER

MA

NA

GEM

EN

T L

AN

CORPORATE LAN

Web Servers

S C A D A / E M S VL A N (DMZ)

NETWORK

Renewable

Control / mon

RTUs on Other Protocol

Fig 1

Control center Architecture

WorkStation LAN

Remote WorkStation for Boss

(Single monitor

No controls)

SO WorkStation

(Dual Monitor)

SO WorkStation

(Dual Monitor)

SO WorkStation

(Dual Monitor)

SO WorkStation

(Dual Monitor)

Historian

ABT Scheduling, Poc & Market Operation

Energy accounting FTP Server

Redundant Internet from different service provider

Secure VPN

Report Generation

EMS Servers

PCPCPCPCPCPC

Corporate NAS Storage

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Scada System – Main Components

• Field Data Interface Devices

• Communication Network

• Central Host Computer

• Operator Workstations and Software Components

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• "eyes, ears and hands" of a SCADA system

• Before any automation or remote monitoring can be achieved, the information that is passed to and from the field data interface devices must be converted to a form that

is compatible with the language of the SCADA system.

Field Data Interface Devices

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• To achieve this, some form of electronic field data interface is required – RTU

• RTU - primarily used to convert electronic signals received from field interface devices into the language (known as the Communication protocol) used to transmit the data over a communication channel.


23


• Sensors/transducers that convert physical parameters to electrical signals.

• Signal conditioning circuitry to convert sensor signals into a form that can be converted to digital values.

• Analog-to-digital converters• A Scada system to process this

digital data.


24

HARDWARE CONNECTIVITY DIAGRAM FOR SCADA AT SUBSTATION / GEN.STATION

MAINCPU

BOARDPSU

COMMNBOARD

ANALOG

I / P

DIGTAL

I / P

CONTROLO/P

TERMINALBLOCK

TERMINAL BLOCK

TERMINALBLOCK

REMOTE TERMINAL UNIT

TRANSDUCER O/P TERMINAL

MVAR VOLTMW

TRANSDUCER I/P TERMINAL P TSEC

110VAC

CT SEC1 AMPS

FROM

SWITCHYARD-FIELD

EVENT LOGGERPANEL

DRIVER

RELAY

TRANSDUCER PANEL

RS232 PORT

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Basic Data Acquisition

TRANSDUCER

RTU Ang In

CB

RTU Dig In

Field

DAS

CT

PTPotential Free Contact

NO Coil for Close

NC Coil for Trip

Close

Trip

RTU Dig out

Pannel control

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TRANSDUCERS

CLASSIFICATION SELF POWERED/AUXILARY POWERED

INPUT VOLTAGE/CURRENT

OUTPUT 0-10mA, 4-20mA, 0-5mA 0-5v,0-10v

OUTPUT IMPEDANCE 500Ω,1000Ω,2000Ω

ACCURACY 0.2 CLASS, 0.5 CLASS, CLASS 2 AND ABOVE

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A/D CONVERSION AT RTU LEVEL(16 BIT ADC).

FOR MW / MVAR TRANSDUCER:INPUT: PT SEC PHASE TO PHASE : 110VAC CT SEC TWO PHASE CURRENT (R & B): 1 A.

OUTPUT : 4 – 20mA(TRANSDUCER OUTPUT)

IN ADC:

AT 4mA = 6553 CountAT 20mA = 32767 Count12mA IS THE CENTRE POINT.

(+/- 0.1% IS THE ACCEPTABLE RANGE OF ERROR ON FULL SCALE) 28

TELEMETRY FOR SCADATELEMETRY FOR SCADA

P Q

V

O

SS

DS

DC

MW MVAR

VOLTAGE

TAP POSITION

SINGLE STATUSISOLATOR POSIITION, PROTECTION,

LOSS OF VOLTAGE

DOUBLE STATUS CIRCUIT BREAKER POSITION

DIGITALCONTROLCIRCUIT BREAKER CONTROL

F FREQUENCY

THE PARAMETERS ARE MONITORED FOR FOLLOWING STATIONS :

•Substations 220 KV and above

•132/110KV AC Interstate Tie lines and in loop of 220 KV transmissions system

•Generating Station above 50MW capacity.

•Significant stations identified by constituents

P Q

DS DC

SS

SS

V F

DS

SS

SS

O

P Q

SS

DS

P Q

P Q

DS

DS

SS

SS

SS

SS

Q

DS

V F

SS

SS

SS

SS

SSSS

SS

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• Intended to provide data transfer between the central host computer servers and the field-based RTUs

• The Communication Network refers to the equipment needed to transfer data to and from different sites. The medium used can either be cable, telephone or radio.

Communications Network

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• Historically,SCADA networks have been dedicated networks

• With the increased deployment of office LANs and WANs as a solution for interoffice computer networking, there exists the possibility to integrate SCADA LANs into everyday office computer networks.


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The foremost advantage of this arrangement is that there is no need to invest in a separate computer network for SCADA operator terminals.

In addition, there is an easy path to integrating SCADA data with existing office applications, such as spreadsheets, work management systems, data history databases.


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Lingasugur

Communication System

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Network of computer servers that provide a man-machine operator interface to the SCADAsystem.

The computers process the information received from and sent to the RTU sites and present it to human operators in a form that the operators can work with.

Central Host Computer

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Operator terminals are connected to the central host computer by a LAN/WAN so that the viewing screens and associated data can be displayed for the operators.

SCADA systems are able to offer high resolution computer graphics to display a graphical user interface or mimic screen of the site.

Central Host Computer

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Operator workstations are most often computer terminals that are networked with the SCADA central host computer.

The central host computer acts as a server for the SCADA application, and the operator terminals are clients that request and send information to the central host computer based on the request and action of the operators.

Operator Workstations and Software Components

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An important aspect of every SCADA system is the computer software used within the system.

The most obvious software component is the operator interface or Man Machine Interface/Human Machine Interface (MMI/HMI) package

Many SCADA systems employ commercial proprietary software upon which theSCADA system is developed


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Central host computer operating system

Operator terminal operating system

Central host computer application

Operator terminal application


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Communications protocol drivers

Communications network management software

RTU automation software


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HMI -DAC -UI -DMC -ALARM EVENTS -ICCP -TDS

DAC MODULE (FOR SR ULDC)

Scans the RTUs cyclically or on demand by the user

The periodicity of scan can be defined

Analog Data – 10 SECONDS Status Data – By Exception /

Integrity check every 10 min

SOE Data processing

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Data types

SCADA processes and stores three different types of data:

Analog Measurement, Status (CircuirtBreakers and

Isolators Positions), and Count data (Like energy, Rainfall

during the day etc).

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Data Type

Analog Data : Analogs are numeric values representing the

state of variable-state devices, such as power lines, transformers etc

In the monitored system a physical variable is usually measured by a transducer, and the output of the transducer is passed through an analog-to-digital (A/D) converter in the RTU .

Status Data : Status values represent the state of devices,

such as circuit breakers, tap changers

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Data polling method

Analogs are defined as periodic/Cyclic data .

The periodicity varies from 10 seconds to 15 seconds depending upon the quantity of data and available bandwidth .

Digital input state changes are to be reported spontaneously .

The Digital input data have higher priority than Analog values.

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Data Flow

NLDC 4545

Digital Data Potential free contacts are used to transfer switch

position to control centre.

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Sequence Of Events

Sequence of events provides milli secs accurate time of status changes for devices monitored by Remote Terminal Units .

The RTU clock is synchronized periodically by the control center clock .

Reading its internal clock when a SOE status point changes state .

Time stamped digital data stored in RTU buffer and transferred as file or Digital data with time stamped is transferred for SOE

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UI & DMC

The UI subsystem facilitates interface to the User

It is through this module, the display, the real time status of the power system are viewed by the user.

The status of the hardware & logical devices, the communication with the RTU etc .. are closely monitored and failures are reported.

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RSCC, BANGALORE CONTROL CENTRE

APPLICATION PROCESSOR

WORK

STATIONS

FRONT END PROCESSORS

DUAL LAN

RAID

WS1 WS2 WS3 WS4 WS5

FE-1 FE-2

AP-1 AP-2 AP-4 AP-5 AP-6

SCADA AGC

DATA

SERVER

AP-3

BACKUP

SERVER

PNA/ICCP

SERVER

COPS

SERVERBACKUP

SERVER

Switch

AP-7

DTS

SERVER

AP-8

DTS

SERVER

WS6 WS7

DTS SYSTEM

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PNA:POWER NETWORK ANALYSIS

COPS: COMPREHENSIVE OPERATION PLANNING AND SCHEDULING

ICCP: INTER CONTROL CENTRE COMMUNICATION PROTOCOL

RAID:- REDUNDANT ARRAY OF INDEPENDENT DISKS49

Fig 2.41

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Alarm/Events & Log Subsystem

Responsible for processing alarm & event messages, updating the alarm/events, sending event messages to the log subsystem, acknowledging and deleting alarms and generating application trigger messages

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ICCP Responsible for data transfers between the control

centers The data includes real time data, interchange schedules,

application program results, operator messages, files and historical data

Data flows in a strict vertical direction. The data flows from a Sub-LDC to the SLDC The Sub LDCs attached to the SLDC do not communicate

directly with each other nor do they communicate with the RSCC, other SLDCs, the SCC or Sub-LDCs on another SLDC

Data flows from the SLDCs/SCC to the RSCC. However, data does not flow directly from SLDC to another SLDC or from a SLDC to SCC. The RSCC acts as an intermediary between the SLDCs and the SCC

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ICCP DATA FLOW

CLIENT SERVER

ANALOG/ STATUS POINT ANALOG/ STATUS POINT

ICCP POINT ICCP POINT

VAR LIST VAR LIST

DATA SET TRANSFER SET DATA SET TRANSFER SET

ASSOCIATION ASSOCIATION

DOMAIN DOMAIN54

PNA SYSTEM DATA FLOW

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TDS

Long term Storage of data in the system. The type of data include energy accounting data, telemetry from RTUs, schedules, operational planning data, random events such as system alarms, despatcher messages and activity logs.

Real time calculations

TDS ( Temporal database & archive database ) is built using the SYBASE relational database management

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TDS Archiving of the stored data – The archiving process copies data from the

Temporal database and stores it in a disk file. Archiving can be scheduled to occur or it can be done on demand. Once the disk file is created, it can be manually transferred to any type of off-line storage such as CD or cartridge tape.

Configurable Parameters Variable number Variable name Point Number Sample frequency ( 2 seconds – 1 year ) Storage frequency ( 2 seconds – 1 year ) Collection method ( maximum, minimum, summation,

average, integration, standard deviation ) Retention period ( 1 month to 1 year depending on the

storage frequency )

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ALARMS

65

ALARMS

ANALOG DIGITAL

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Alarms-Analogs

Normal limit-Range of limits which device is considers to be operating normally

Reasonability Limit-range of values that SCADA uses to determine whether the value retrieved for the analog is realistic.

Forbidden Limit-Range of values that SCADA considers violated when the analog point fall within that range

Dead band Limits-On a pair of low or high limits if it is violated the value must rise above the limit by at least the dead band amount before the SCADA consider s the analog to be back within normal limits .

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Normal Alarms-analogs

MW/MVAR/MVA/FREQ/VOLTAGE ALARM LIMIT-OPERATIONAL ALARM LIMIT-ALARMING ALARM LIMIT-EMERGENCY

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Alarm Limit -MW

ALARM LIMIT-OPERATIONAL+/- 1.05*(1.732*V*I*O.8) ALARM LIMIT-ALARMING+/- 1.10*(1.732*V*I*O.8) ALARM LIMIT-EMERGENCY+/- 1.15*(1.732*V*I*O.8)

V-NOMINALVOLTAGE I-NOMINAL CURRENT

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Priority Alarms Alarms are categorized in 8 category

Priority 1 -Emergency threshold overshoot and status point alarms of controllable switching devices, ICCP links and other ICCP data exchange related alarms)

• Priority 2 -Point alarms of non-controllable switching devices. • Priority 3 -Protection trips and substation alarms • Priority 4 -Alarms relevant to RTU’s, communication lines, and

alarms of “unreasonable” category • Priority 5 - “configuration management” alarms, i.e. hardware

failures (mimic board, printer, etc.) and software failures • Priority 6 –All Network alarms-state estimator , contingency

analysis) and the alarms detected by the generation applications (AGC and LF)

• Priority 7 -Scada topology alarms •Priority 8 -HDR, Tagging, Limit Replacement.

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Flags

Gives Source and Quality of data Source of data

RTU -----------Telemetered ENTERED-----Manually Entered EXTERNAL----Always to be entered manually INTERSITE-----Data from other site CALCULATED—Calculation tag

Quality of data GARBAGE-The data is unreliable. The flag appears when

data is uninitialized. SUSPECT-Data is labelled suspect when there is one or

more of this flag (OLD, BAD, OVER and RESUSP) REPLACED-Data is labelled replaced when MANREP,

ESTREPor REMPL) GOOD-Data is labelled GOOD when it is not GARBAGE,

SUSPECT and REPLACED. 71

Flags Unit: - uninitialized. Old:-Could not be retrieved in the last scan Telemetry failure:- communication with RTU failed BAD: - when RTU returns one or more standard test values in

the RTU outside the allowed limits. Either Transducer is faulty or there is an RTU malfunctioning.

Over Range: - Raw Value Received from RTU is outside the expected Range.

Unreasonable:-The converted value has crossed the reasonability limit.

Anomalous:-Basically not a data quality Flag .State Estimator considers the above measurement not fit for the solution.

Manually replaced:-Replaced by operator

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Flags

State Estimator replaced:-Value for an analog is overridden, or replaced, by state Estimator on operator request.

Generalized Calculation: - Value replaced through generalised calculation.

Maintenance mode: - The Device has been placed in maintenance mode.

NIS:-device not in service. It will not allow scanning or calculation to update the record which is marked NIS

Alarm Inhibit: - Alarms for this device inhibited. Remote Suspect:-The value is suspect at source

control centre. Remote Replaced:-The value has been replaced by

source control centre 73

Historical DATA Recording

Historical Data Recording (HDR) function allows you to preserve a time series of any set of analog, status, and accumulator measurements . HDR functions

Saves the SCADA measurements in disk files called Historical files.

Keeps track of the Historical files that have been created and allows you to delete them.

The Database Reconstruction functions allow you to reconstruct or create a Data History listing from the data in the Historical files.

The reconstructed database can be moved to the network database for use by other applications.

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Trend Displays

Real Time Trend Display Digital, analog or counter value can be

viewed simultaneously in different displays. The information is usually sampled

cyclically, stored in memory on a circular buffer and plotted on a window against time.

Historical Trend Displays To trend the value (digital, analog counter)

with archived data

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Tagging Tags are free formatted text, which provide

critical information to next shift operator . Tags can be provided over digital, analog and

counters data-points. Operators can insert, edit or delete any number

of tags, if they have privileges to do so. Some operators may only be allowed to view

tags. These operations can be done from graphic

displays by selecting a dynamic object or from a system list of entities.

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EVOLUTION OF SCADA AT SRLDC

EARLY 90s : - Remote Console system i.e Getting Static Picture from Each SEB ,

displaying Limited values on cyclic telemetry.

- DOT dedicated Leased Circuit @1200 baud.

- No storage facility. - Operation Message transfer throu’ FAX

mile. - Remote Console Terminals used as MMI.

REMOTE CONSOLE78

Later 90’s : - Mini-SCADA system installed - One server & 3 MMI system ,Later Dual server system. - Data acquired from 17Nos of 400kV stations

by 8-bit Microprocessor based RTU. - Off Line studies. - Local Area Network - Storage on HDD & Backup done through DAT tapes.


MINI SCADA79


EARLY 2000 : - INSTALLATION & COMMISSION OF ULDC SCADA

SYSTEM. - MEASURANDS ACQUISION INCREASED FROM

FEW HUNDREDS TO FEW THOUSANDS. - STORAGE OF VOLUMINOUS DATA. - HIGH SPEED COMMUNICATION LINKS. - Used RISC based Servers & Workstations. - Time stamping at RTU as well as Control Centre

is possible with GPS. - Weather station used for EMS studies.

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SCADA SYSTEM EARLY 90’s AT SRLDC

REMOTECONSOLE

REMOTECONSOLE

REMOTECONSOLE

REMOTECONSOLE

MODEM

MODEM MODEM MODEM MODEM

MODEM MODEM MODEM

ND110TNEB

ND110APSEB

ND110KEB

ND110KSEB

DOT LEASEDLINE

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SCADA SYSTEM EARLY 90’s AT SRLDC (Contd …)

SRLDC CONTROL ROOM

APSEB KSEB TNEB KEB IOCC NLY TS 2 BANGL’RS/S

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HARDWARE CONFIGURATION OF MINISCADA AT SRLDC

MPCC

10

PORT

CARD

FRONT ENDPC

MPCC

MPCC

PENTIUMSERVER

PENTIUMSERVER

MMI MMI MMI

MODEM

MODEM

MODEM

MODEM

MODEM

MODEM

MONITOR

MPCC – MULTI PORT COMMUNICATION CARD

AP LD

TNEB LD

KEB LD

KSEB LD

IOCC

S’HALLI

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OVER VIEW, ARCHITECTURE MAIN COMPONENTS

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