1 UTTAR PRADESH POWER CORPORATION LIMITED, LUCKNOW ABOUT UPPCL Uttar Pradesh Power Corporation Limited uses microwave communication system fortransmitting and receiving data at its SLDC located at Shakti Bhawan in Lucknow. U.P. Power Corporation Limited, incorporated under the companies Act 1956, was incorporated in 2004 with the main objective to acquire, establish, construct, take over, erect, lay, operate, run, manage, hire, lease, buy, sell, maintain, enlarge, alter, renovate, modernize, work and use electrical transmission lines and/ or network through extra high voltage, high voltage and associated sub-stations, cables, wires, connected with transmission ancillary services, telecommunication and telemetering equipment in the State of Uttar Pradesh, India and elsewhere. Uttar Pradesh Power Transmission Corporation Ltd. (UPPTCL) has a very large network ofhigh voltage transmission lines in whole UP (about 24,000Km). Transmission lines transferpower from power houses to substations and fro m one substation to many other substations or
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work and use electrical transmission lines and/ or network through extra high voltage, high
voltage and associated sub-stations, cables, wires, connected with transmission ancillary
services, telecommunication and telemetering equipment in the State of Uttar Pradesh, India
and elsewhere.
Uttar Pradesh Power Transmission Corporation Ltd. (UPPTCL) has a very large network of
high voltage transmission lines in whole UP (about 24,000Km). Transmission lines transfer power from power houses to substations and from one substation to many other substations or
vice versa. Power is generated at low Voltage (of the order of 3.3KV to 25KV) and is
stepped-up to high voltage (765KV, 400KV, 220KV & 132KV) for evacuating power into
the grid network through transmission lines.
33/11KV Substations of distribution companies (DISCOMs) draw power from transmission
substations through 33KV lines and distribute that to consumers (at 0.4KV, 11KV or in few
cases at 33KV). Distribution companies have industrial, rural and domestic load, which
varies from time to time of the day and from season to season of the year. Sometimes, large
variations in load cause over/under loading of lines, transformers or generators. Variations
beyond limits and breakdowns cause fluctuations in voltages & grid frequency of the
network. Control Centers, in hierarchical form, are set up for smooth functioning of the grid.
Each generating unit or substation has its own Control Centre. These are also named as Unit
Control Board (UCB)/Main Control Board (MCB)/Control Room. These Control Centres
report to Area Load Dispatch Station (ALDS). ALDS report to Central Load Dispatch Station
(CLDS at State Level), CLDS reports to Regional System Coordination & Control Centre(RSCC at regional level having a group of States and Central sector units of that region) &
finally on top is National Load Dispatch Centre (NLDC) which is being set-up.
These control centers need real time information about generation, power flow, voltage,
frequency, etc. of generators & substations. This information is exchanged in data or voice
form. For exchange of such information, a reliable and dedicated communication system is
required. Substations or power houses, situated at both ends of transmission line, need
information in voice form. Trip commands (also called protection signal) are transmitted
from one substation to the other substation, through transmission line. When 'earth' or 'over-current' fault is sensed by one end of the transmission line, a trip command is generated,
which travels through communication system and opens circuit breaker (switchgear) of the
other end. Dedicated communication system is required for transmission of protection signal.
In the above Fig. National Load Dispatch Centre (NLDC) has been shown at the top. Its
control center is in construction stage at New Delhi and will be operational by the time all
India grids are combined. Below this, five nos. regional level Load Dispatch Centers have
been shown. Presently, except for southern region, grids of all other regions areinterconnected and are running in combined form. This way, Northern Regional Load
Dispatch Centre (NRLDC) Is now part of All India Grid or say „ National Grid’ .
The role of the NRLDC is to monitor and supervise the grid and power generation of the
region. It focuses attention on the regional interconnected network. By using „Energy
Management System‟ (EMS) and advanced application programs, NRLDC coordinates
with all inter-region and inter-state power exchange.
Below NRLDC, State level SLDCs and Central Project Coordination & Control Centre
(CPCC) have been shown.
The primary role of SLDCs is to monitor, Control and coordinate the generation,transmission and distribution of power within the state while ensuring safety and
continuity of its transmission and sub-transmission power networks. CPCC (North)
coordinates with all central sector projects of northern region such as thos of NTPC,
NHPC, Power grid, Tehri, etc. CPCC gets data from central sector projects and the data is
added at regional level.
Direct data transmission does not take place between SLDC of one state with SLDC of
Due to narrow speech band in PLCC, voice of poor quality is available in comparison to
wideband communication system.
In this system, signal travels on the transmission line from one end to other end.
Transmitter output (Radio Frequency signal) is fed to the transmission line through a
Coupling Capacitor or CVT. RF power output is in frequency band from 70 KHz to 500KHz.
Inductors, called 'Wave Traps' are used at the ends of the transmission lines, before
transformers, to pass 50Hz a.c. power but block radio frequency signals.
UPPTCL has a wide network of PLCC links. Presently, its number of PLCC links are
about 550.
SCADA SYSTEM
In SCADA system measured values, i.e. analogue (measured value) data (MW, MVAR,V, Hz Transformer tap position), and Open/Closed status information, i.e. digital data
(Circuit Breakers/Isolators position i.e. on/off status), are transmitted through
telecommunication channels to respective sub-LDCs.
For this purpose Remote Terminal Units (RTUs) at 400KV, 220KV and few important
132KV sub-stations have been installed.
System values & status information below 132 KV have not been picked up for data
transmission, except for 33KV Bus isolator position and LV side of generators.
Secondary side of Current Transformers (CT) and Potential Transformer (PT) are
connected with 'Transducers'. The output of transducers is available in dc current form (inthe range of 4mA to 20mA).
Analogue to digital converter converts this current into binary pulses. Different inputs are
interleaved in a sequential form and are fed into the CPU of the RTU. The output of RTU,
containing information in the form of digital pulses, is sent to subLDC through
communication links.
Depending upon the type of communication link, the output of RTU is connected, directly
or through Modem, with the communication equipment. At subLDC end, data received
from RTU is fed into the data servers.
In general, a SCADA system consists of a database, displays and supporting programmes.In UPPTCL, subLDCs use all major functional areas of SCADA except the 'Supervisory
Control/Command' function.
The brief overview of major 'functional areas' of SCADA system is as below:
1. Communications - Sub-LDC's computer communicates with all RTU stations under its
control, through a communication system. RTU polling, message formatting, polynomial
checking and message retransmission on failure are the activities of 'Communications'
2. Data Processing - After receipt of data through communication system it is processed.
Data process function has three sub-functions i.e. (i) Measurements, (ii) Counters and
(iii) Indications.
' Measurements' retrieved from a RTU are converted to engineering units and
linearised, if necessary. The measurement are then placed in database and are checkedagainst various limits which if exceeded generate high or low limit alarms.
The system has been set-up to collect 'Counters' at regular intervals: typically 5 or 10
minutes. At the end of the hour the units is transferred into appropriate hour slot in a
24-hour archive/history.
' Indications' are associated with status changes and protection. For those statuses that
are not classified as 'alarms', logs the change on the appropriate printer and also enter
it into a cyclic event list. For those statuses, which are defined as an 'alarms' and the
indication goes into alarm, an entry is made into the appropriate alarm list, as well as
in the event list and an audible alarm is generated in the sub-LDC.
3. Alarm/Event Logging - The alarm and event logging facilities are used by SCADA data
processing system. Alarms are grouped into different categories and are given different
priorities. Quality codes are assigned to the recently received data for any 'limit violation'
and 'status changes'. Alarms are acknowledged from single line diagram (or alarm lists)
on display terminal in LDCs.
4. Manual Entry - There is a provision of manual entry of measured values, counters and
indications for the important sub-station/powerhouse, which are uncovered by an RTU
or some problem is going on in its RTU, equipment, communication path, etc.
5. Averaging of Measured Values - As an option, the SCADA system supports averagingof all analogue measurements. Typically, the averaging of measured values over a period
of 15 minutes is stored to provide 24 hours trend.
6. Historical Data Recording (HDR) - The HDR, i.e. 'archive', subsystem maintains a
history of selected system parameters over a period of time. These are sampled at a pre-
selected interval and are placed in historical database. At the end of the day, the data is
saved for later analysis and for report generation.
7. Interactive Database Generation - Facilities have been provided in such a way that an
off-line copy of the SCADA database can be modified allowing the addition of new
RTUs, pickup points and communication channels.
8. Supervisory Control/Remote Command - This function enables the issue of 'remote
control' commands to the sub-station/powerhouse equipment e.g. circuit breaker trip
command. Though, there is provision of this function in this system, yet it is not used in
U.P. As such, related/associated equipment have not been ordered.
9. Fail-over - A 'Fail-over' subsystem is also provided to secure and maintain a database of
devices and their backups. The state of the device is maintained indicating whether it is
'on-line' or 'failed'. There is a 'backup' system, which maintains database on a backup
computer and the system is duplicated.
SLDC Lucknow has a large and active 'Mimic Board' in its Control room. This mimic board displays single line diagram of intra State transmission system i.e. grid network of
400KV, 220KV and important 132KV sub-stations, transmission lines, thermal & hydro
powerhouses.
Outgoing feeders, shown in the mimic board, have 'achieve' (LED display) colored
indications, of three different colors, to show the range of power flow at any moment i.e.
'Normal', 'Nominal' or 'Maximum' of its line capacity. UPPTCL's transmission network is expanding rapidly and thereby number of RTUs is
also increasing. For new substations and lines, displays in active and passive forms are
required to be made in the Mimic diagram. But, Mimic Board has a limitation that it
cannot incorporate/add large volume of displays for substations/power
houses/transmission lines in 'active' form due to space constraint and congestion. Due to
this Mimic Board is going to be supplemented with a Video Projection System (VPS) at
SLDC, Lucknow in near future. Also in SLDC & subLDCs, displays of single line
diagrams of RTU sub-stations/power house are viewed on VDUs of large size (21").
C) ENERGY MANAGEMENT SYSTEM (EMS)
For energy management of the power system, control personnel and application software
engineers use SCADA data available in the database by using EMS software. The software
functions are based on the Energy Management Platform (EMP). All servers have 'Open
VMS' operating system. All Personal Computers (PCs) have 'Window NT' operating system.
Important features are as below:
1. The Data Base Compiler provides a consistent source of data usable for the applications
in an efficient form. The Data Base Compiler does final checking for completeness andconsistency of the entries for a specific application and prepares those special tables
which are needed for the efficiency of specific application programmes.
2. Recording of 'Sequence of Events' (SOEs) is the most innovative feature provided in this
system. A RTU has the ability to accurately time tag status change and report this
information to sub-LDC. All RTUs in the system are 'time synchronised' with the master
station. Global Positioning System (GPS) system has been used at all subLDCs & SLDC.
In the event of any tripping, sequence of events can be well established on time scale with
a resolution of 10 milliseconds.
3. Normally, 'Automatic Generation Control' (AGC) function issues control commands togenerating plants using the concept of Area Control Error (ARE). It is base on deviations
in 'standard frequency (50 Hz)' and 'scheduled area interchanges' from that of the 'actual
frequency' and 'actual area interchanges'. The scope of AGC function for UPPTCL has
been limited to open loop operation i.e. the software provides the desired corrective
actions for each plant, but the actual command are not issued. It is left to 'System Control
Officer' to take necessary action as divided by AGC Controller. In the event of
unavailability of sufficient generation to satisfy the AGC requirement, the System Control
Officer can enforce required quantum of load shedding.
4. For 'Operation Scheduling' the application software has 'short-term' and 'long-term'
'System Load Forecasting' functions to assist dispatching Engineer/control Officer in
estimating the loads that are expected to exist for one to several days in advance. This
function provides a scientific and logical way of scheduling of resources in a very
effective manner.
Under 'Short-term Load Forecasting' function, application software engineers are able
to forecast weekly peak demands and load duration curves for several months into the
future.
Under 'Long-Term Load Forecasting' function, forecasting of monthly peak demands
and load duration curves for several years into the future can done for the use of
'Power System Planner'.
5. The other functions like economic dispatch, reserve monitoring, production costing,
inter system transactions scheduling, etc. are available to guide System Control Officer
to optimally use available resources.
6. Power System Control Officer/Analyst would be able to use contingency analysis
function to assess the impact of specified contingencies that would cause line (s)overloads, abnormal voltages, and reactive limit violations.
7. The EMS software system may have many other applications for use, which include
network topology, performing of state estimation, optimal power flow (OPW)
programme, stability programme, power flow displays, help and instructional displays,
tabular displays, single line diagram displays, etc.
Block Diagram For Data And Speech Communication
Communication at Power Corporation is of two types, data communication and speechcommunication. Data is basically voltage, frequency, power, current etc. Speech is data in
A remote terminal unit (RTU) is a microprocessor-controlled electronic device that
interfaces objects in the physical world to a distributed control system or SCADA
(supervisory control and data acquisition system) by transmitting telemetry data to the
system, and by using messages from the supervisory system to control connected objects
An RTU monitors the field digital and analog parameters and transmits data to the Central
Monitoring Station. An RTU can be interfaced with the Central Station with different
communication media (usually serial (RS232, RS485, RS422) or Ethernet).
RTU can support standard protocols (Modbus, IEC 60870-5-101/103/104, DNP3, IEC
60870-6-ICCP, IEC 61850 etc.) to interface any third party software. An RTU can monitor analog inputs of different types including 4 to 20 milliamperes (4 –
20 mA), 0 –10 V., −2.5 to 2.5 V, 1 – 5 V etc.
Modern RTUs are usually capable of executing simple programs autonomously without
involving the host computers of the DCS or SCADA system to simplify deployment, and
to provide redundancy for safety reasons.
Comparison with other control systems
RTUs differ from programmable logic controllers (PLCs) in that RTUs are more suitable
for wide geographical telemetry, often using wireless communications, while PLCs are
more suitable for local area control (plants, production lines, etc.) where the system
utilizes physical media for control.
The IEC 61131 programming tool is more popular for use with PLCs, while RTUs often
use proprietary programming tools.
RTUs, PLCs and DCS are increasingly beginning to overlap in responsibilities, and many
vendors sell RTUs with PLC-like features and vice versa.
The industry has standardized on the IEC 61131-3 functional block language for creating
programs to run on RTUs and PLCs, although nearly all vendors also offer proprietary
alternatives and associated development environments
front bus. This protects the rest of the system in case any hazards occur in high
field circuitry.
LED indication is provided on the front panel for each channel. It lights on a high
input to the respective channel.
The processor can access any of the 16 channels through the front I/O bus.
3. Analog input card (AI)
The 16 channel isolated analog input module is a complete fully isolated input system
containing 16 different channels on a 6U Euro board. It is ideal for industrial
applications requiring measurement of non-isolated transmitter signals in the presence
of high common mode voltages and ground loop noise.
Each input channel consists of a highly reliable flying capacitor multiplexer utilizing
mercury wetter/ dry read relays. These inputs channels feed a stable instrumentationamplifier and conversion is accomplished by a 12 bit A/D converter. The result is an
input signal having noise immunity upto 100CMV (Common mode voltage)
The bard accepts 16 channel of analog signals as input. Depending upon the particular
channel selected, it provides an equivalent 12 bit digital data as output.
The signals are connected to the front D 37 female connector of the board.
When the board and the particular channels are selected, all the relays are actuated.
The capacitor, which was connected to the selected relay, will now be connected to
the input of the multiplexer ADG508.
The change over contacts thus provides necessary isolation during analog to digital
conversion.
The output of INA is fed to the input of ADC, which operate at 0-10V range. The
ADC converts this 0-10V to its equivalent digital value and store it in a buffer inside
ADC.
The software package delivered with S900 RTU allows handling both digital and
analog input/outputs.
The entities and related functions controlled by the S900 RTU include:
Transducer is a device, which provides a transformed output in
response to a specified measured value given as input.
The basic functions of transducer are:
1. To measure/ to sense the change in parameters.
2. To convert the measured values from one form into
another form, that is useful for further processing.
SIC has following types of transducers:
1) Power transducers (active power transducer, reactive power transducer)
2)
Voltage tranducer 3) Frequency transducer
4) OLTC (on load tap changer)
Output of current and 4 mA to 20 mA
Potential transformers current or
-10 to +10V
Output of transducer goes to the RTU panel
Working
The RTU is the supervision and control system for the unmanned operation of the electric -
power equipment. The SCADA-RTU read the analog value and the status value of breaker
status, power amount, voltage, power factor ratio and etc and it transmits their data to the
main system. The SCADA-RTU consists of a MODEM, a common control unit, a peripheral
unit, a power supply, a terminal unit and etc. The common control unit receives the control
orders of the RCC and decodes the received orders. And it supervises and controls the input-
output of the peripheral unit and performs the function, which transmit the results to RCC and
SCC. The peripheral unit is a unit, which controls the input-output of the field. It has a CPU
in itself and communicates with the common control unit. And it supervises and measures the
state of electric power equipment of the field. The terminal unit is a terminal block that is
able to combine physically the field and the peripheral unit and there is a line protection
circuit.
RTU is a system that continuously monitors status data & analog data. This data s transmitted
to a mater station. It also receives and executes control commands from the master station to
open and close output relays and operate controls on any connected IEDs.
The RTU is essentially a computer which can store and process data in digital form. RTUmaintain its own local database of all the points, which are to be measured and controlled and
continuously updates the information. The RTU sends data to the master in response to
queries sent by the master (poll response method). Typically only information that changes
since the last query is sent to the master.
Analog information are received from current and voltage transformers. The output of thecurrent and voltage transformers are then sent to transducers. The output of these transducers
(4mA - 20mA) is sent to the analog card of RTU. A/D converter converts these analog
signals to digital form for use in the microprocessor of RTU. On the other hand status signals
are taken from voltage free contacts of CB(52a) to status card to monitored status of CB.
After processing RTU transmit this digital data to master station through Power Line carrier
(PLC) & microwave communication. The RTU sends data to the master in response to
queries sent by the master (poll-response method). Typically only information that has
changed since the last query is sent to the master.
2. Communication front end (CFE)
CFE is the hardware of SCADA. This has ports of each data.
The communication equipment and software that links the computer to RTUs is referred
as communication front end. One RTU is located at the site and the other at the remote
station.
Function of CFE: It drives the serial communication lines connected to the RTUs. The
CFE hardware configures consists of Ethernet controller‟s card several serial
communication cards. The number of communication cards depends on the number of
RTUs connected to where each card can support up to 16 communication lines withRTUs.
As shown in the figure below; there are main, modem, and stand by in CFE.
A 3/7 connector is used to connect the DM2 with computer. It connects to micro Sd card,
so we can access all the channels.
Functions of DM2
In the Receive Direction are:
Convert the input signal complying with ITU-T rec. G.703 to agree with equipment logic
sections, disassembling the line code, generate the R X direction clock signal.
Synchronous to the incoming signal frame.
Control the demultiplexing occurring in the channel units.
Monitor the error ratio of the received signal and recognize AIS
Recognize Alarm Indication Signal (AIS)
In the transmit direction are:
To generate TX Direction clock Frequency of 2048 Kbit/s
Control the TDM occurring in the channel units.
Form the output signal frame
Generate the interface signal complying with ITU-T recommendation G.703, as HDB3
line coded.
Applications
The DM2 equipment has been designed for multiplexing analogue speech and signaling aswell as data channels of different bit rates into a common 2 Mbit/s frame. It can be used:
As a traditional PCM multiplexer in subscribe and junction line networks.
In corporate networks to provide full range of voice and data services
As one-way branching equipment to enable efficient use of channels in rural areas or in
private networks.
For efficient data multiplexing, e.g., X.58, V.110 and Ethernet.
DB2 (Digital Branching in Networks of small capacity)
This is used for dropping the data. So this is also called Insert Drop Mutiplexer.
Digital branching equipment the DB2 is a member of the Nokia Dynanet Family of
access network products. The DB2 performs the functions of branching equipment that
can be controlled dynamically, using the Dynanet channel unit selection.
The DB2 branching equipment forms a 2 Mbit/s bi-directional branch to the main line signal.The branch and the main line signal have the same speed and frame structure. Individual
channels are connected through or branched and the operation is completely digital.
Dynamic branching
Dynamic branching makes it possible to change branching configurations during normal
operations. This unique feature makes it possible to fully and flexibly use the transmission
network capacity.
The various branching alternatives are stored in each DB2 in the network. The network
reconfiguration can be done manually through the service interface or it can be triggered
automatically, based on e.g. alarms or the time of day. Changes in banching do not disturb
traffic on those channels that remained unchanged.
The four main DB2 configurations are:
DB2B, basic branching equipment
DB2P, protected branching equipment
DB2T, terminal(change-over) equipment
DB2B-LP loop protected branching equipment
The DB2T selects the faultless signal in the receive direction and duplicates the signal in the
transit direction.
Channel units
Dynanet channel units can be connected to all DB2 configurations. The VF and data interface
units are connected directly to the internal 2Mbit/s bus of the equipment.
Each unit and channel can be programmed for any time-slot. The DB2, the DM2 multiplex
equipment and the DN2 cross-connect equipment all use the same Dynanet channel units.
VF and data interface units of the dynanet family are detailed in separate leaflets
Number of VF and data uni ts limited by sub rack space only
Applications
The DB2 equipment family offers a wide range of different branching and drop/insert
functions. Typically, the DB2 is used in private cahin, tree or ring-shaped networks. In applications where dynamic network structure is the optimum solution, the DB2 is he
key component
In public networks, dynamic branching can be used to establish semi-permanent or leased
speech and data lines. The DB2 is also well suited for data network applications.
Functions of DB2B B2 unit:
Provide 2 x 2 Mbit/s interfaces (Direction #1 & #2)
Perform the settings and control coming via service interface and command bus.
Controls equipment in fault condition.
Generate Master clock, synchronized t incoming signal (R x 1..3) or external.
Handles alarm indications using LED‟s & Rack alarm lam ps.
Any direction (1,2 or 3) can be set for „In use‟ or „Not in use‟ mode
Code data hybrid.
Monitor the error ratio of the received signal and recognize AIS.
Microwave radio is a data transmission method commonly used in the telecommunications
industry. Using a microwave radio relay, these service providers can transmit digital and
analog signals across long distances. Microwave radio is known as a “line of sight”technology. This is because microwave data is transmitted between two microwave radio
towers in different locations. Once a clear path has been established, transmissions between
directional antennas on two microwave radio towers can occur.
Digital microwave RF is a more technologically advanced microwave data transmission
method. The higher bandwidth of digital microwave RF provides for increased data
transmission by supporting more verbose protocols. Digital microwave RF is faster,
decreasing system poll time as well.
NOKIA DMR 2000
PROPERTIES OF NOKIA DMR 2000
The radio relay equipment DMR 2000 operates in the 1.7…..2.7 GHz frequency band,
and the maximum output power is 30 dBm
The DMR 2000 can transmit two, four, eight or sixteen 2 Mbit/s G.703 signals or one 34
Mbit/s signal. An 8 Mbit/s interface can be implemented by using an external (DM8 –
second order multiplexer.
The frequency allocation meets the recommendations by ITU-R. The use of the radio
frequency spectrum has been optimized at all transmission capacities.
In this project the radio relay equipment is used to transfer 4 signals at 2 Mbit/s each
(G703). By means of the integrated n x2 Mbit/s multiplexer, DMR enables the direct
access to 4 x 2 Mbit/s signals. Also drop/insert and cross-connection facility between any
2 Mbit/s bit streams can be executed.
There are two transmitter power options : 20 dBm and 30 dBm. These correspond to an
output of 0.1W and 1W respectively.
In addition, the output power may be adjusted either by manually or automatically by
means of ALCQ feature (Adaptive Level Control with Quality Measure) withi wide range
The dimensions of the cartridge are (including filter) 445 mm (height), 120 mm (width) and
305 mm (depth from front edge of cooling extension to rear edge of rack).
At equipment station , the cartridge is suspended by the brackets at its rear wall to the
equipment rack. It may be installed in a Nokia TM4 rack (CEPT-A slim rack)
Structure of antenna filter and loop mixer
In redundant set-ups, the two equipments are installed vertically, the lower bit equipment
upside down. The radio relay equipment may also be installed in a 19‟‟ rack, an M80 rack, anoutdoor cabinet or it may be mounted on the wall using the installation accessories. In
redundant set-ups, the two equipments are then installed side by side. In single use, the
equipment may also be installed horizontally.
The main channel interfaces (2Mbit/s) may be either balanced using Euro connectors or
unbalanced using coaxial connectors (SMB) at the 34 Mbit/s capacities, the main channel
interface is always implemented by means of coaxial connectors. The front connectors and
the power switch of the radio equipment are located behind the front case. The measurement
point connector MP is accessible without having to open the front case which provides
protection against interference. Only the cables for the repeater bus and protection bus , if anyare connected to the rear of the cartridge.
Functions of baseband unit:
The BBU multiplexes the 2 Mbit/s main channels so that each channel may be placed into
any time slot of the radio frame (by means of the Service Terminal Settings). At the repeater
station the Service Terminal may also be used to specify without restrictions which channels
shall be directed to the interfaces at the station for branching and which channels will
continue on the repeater bus to the next radio hop. In addition to the 2 Mbit/s main channels,
the following information is multiplexed into the frame structure.
As seen in diagram, there is used master and slave technique. In this technique master can
use both of it‟s TX and R X, but slave cannot use it‟s R X. To use the R X of slave , first
convert slave into master and then use both TX and R X.
There is a green light which glows on use of master.
As we study earlier that there is four 2 Mbps signals exists in Shakti Bhawan, thesesignals have ports in DMR. There are four connections in which each is of 2Mbps.
LEDs are also connected which glow when radio access.
Filter is used for frequency change purpose. Filters are connected with MDF (Main
Distribution Filter).
Motherboard is connected to BBU.
Output power is control by ACQL (Automatic Quality Control Level).
Methods of redundancy
i. Hot standby operation (HSB) ii. Warm standby operation (WSB)
iii. Hot standby operation with space diversity
iv. Frequency diversity
v. Polarization diversity
vi. Pace diversity with 2 TX
Technical Specifications
Frequency range 2.3 – 2.5 GHz
Interface connector SMB coaxial 75Ω
TX output power 1 W
Duplex frequency 95MHz
Capacity 4 x 2 Mbit/s
SCADA (Supervisory Control And Data Acquisition)
SCADA stands for Supervisory Control and Data Acquisition – any application that gets
about a system in order to control that system is a SCADA application.
A SCADA application has two elements:
1) The process/ system/ machinery you want to monitor a control – this can be a power
plant, a water system, a network, a system of traffic lights, or anything else.
2) A network of intelligent devices that interfaces with the first system through sensors
and control outputs. This network, which is the SCADA system, gives you the ability
to measure and control specific elements of the first system.
of 4 CTs (only R&B phases), 3PTs, 1 neutral point, 1 earth point, 2 points for dc supply (48
V, to energize the T/D), 2 points of Ms and 2 points for MVARs.
Potential Transformers (PTs) and Current Transformers (CTs)
Transformers used for the measurement of voltage are called potential transformers. The primary winding is connected to the voltage being measured and the secondary winding,
to a voltmeter. The PT steps down the voltage to the level of voltmeter specification used
in the project. Here this is 110 KV/ 110 V
Transformers used for the measurement of current are called Current Transformers. The
primary winding of a current transformer is so connected that current being measured
passes through it and the secondary winding is connected to an ammeter. The CT steps
down the current to a lower level. The current transformer is used with its primary
winding in series with the line carrying the current to be measured.
Modem
The term MODEM is an acronym for Modulator- Demodulator.
The primary modem function is to convert digital data into analog form, which is suitable
for transmission on common carrier circuits. Modulation is the D/A conversion in which
the digital data is placed on the transmission line by modulation of a tone or carrier.
Demodulation is the reverse process.
Three modulation techniques are commonly used:
i. Amplitude modulation
ii. Frequency modulation
iii. Phase modulation
Modems operate with one functioning as an originate unit and the other as an answer
unit.
The originate modem transmits on a low frequency channel, using 1.27 KHz for a mark
and a 1.07 KHz for a space. It receives on a high frequency channel using 2.225 and
2.025 KHz respectively for a mark and space.
The answer modem transmits on the high frequency channel and receives on the lower frequency channel.
The timing circuit provides the basic clocking information for both the transmission as
well as reception of signals.
A crystal oscillator to within about 0.05% of the normal value usually controls the
internal timing.
Modem is used to adjust the output level of data the computer data is converted to analog
waveforms as carrier and this composite signal passes through our common telephone
lines to reach the destination, where the carriers is removed and the original data is given
In the field of telecommunications, a telephone exchange or telephone switch is a system of
electronic components that connects telephone calls. A central office is the physical building
used to house inside plant equipment including telephone switches, which make telephone
calls “work” in the sense of making connections and relaying the speech information.
The exchange code or central office code refers to the first three digits of the local number
(NXX).
3 Types of exchange:
a) Local
b)
Tandemc) International
Local Exchange – connect to the customer (subscriber).
Tandem Exchange – A telephone central office switch that links Telco end offices
together and does not connect to the customer directly.
International exchange – connects exchange to entire country and oversea.
Switched calls are dialable (users dial a telephone number to make a connection).
People can reach anyone on public network by dialing a telephone number.
A network consisting of at least one switching system (exchange) and accommodatedtransmission lines (optical fiber microwave) is referred to as a telephone network.
Function of Exchange
Records customer‟s call meter.
Monitor switching process between exchange and
customer
Record customer‟s request (meter termination).
Provide supervision tone such as dial and busy tone.
Control conversation quality and exchange service.
Besides above cards there are computer, processor, power supply and internal buses.
Computer is used for control the whole system.
Processor is connected to the computer. It is P01 processor which has EPROM or
EEPROM.
Exchange has 48V DC power supply and it has 250 mA current. Power supply system
generates +5V or +12V power.
Internal buses can access 2Mbps data at a time.
Every card has 8 ports in which two ports are TX, two ports for RX, two ports for TX
signaling and remaining two ports for RX signaling.
There is a stand by (i.e. copy) of above card system. If any card fails then copy of that card is
used.
Block diagram of exchange:
Exchange is divided into three parts. These are called as COPY0, COPY1 and POWER
SUPPLY. Every copy has one PFC and ports such as P0, P1,P2 and so on. Power supply is
48V DC which is used to generate +5V r +12V power.
Telephone Number
A telephone number is a sequence of digits used to call from one telephone line to another ina public switched telephone network. When telephone numbers were invented, they were
short- as few as one, two or three digits – and were given orally to a switchboard operator. As
phone systems have grown and interconnected to encompass the world, telephone numbers
have become longer. In addition, they access other devices, such as computers and fax
machines.
There are 9 numbers in a phone number. In these 9 numbers first is STD code of country,
then two digits are for Area code (area such as Delhi, U.P. etc.) , then tree digits for
Exchange ID and last three digits are directory numbers.
By means of inter-modular load current distribution the total current is delivered in equal
parts by each rectifier module. The circuits for system monitoring detect abnormal voltages,
short circuitry, mains failure and overheating by means of a comparison with preset values.
Alarm signals are generated according to type and/ or importance of this failure. LEDs
performs the display at the rectifier modules and on the controller display.
1) AC- source Mains, 230V AC, 3 – phase
2) Rectifier module protection Magnetic circuit Breakers(MCB)
3) Rectifier modules SMPS 48V – 1900 W
4) Relay Low voltage disconnection LVD of the battery
5) Battery Battery or battery group
6) DC – output 48 V
7) Controller Overall system controller PSC 1000 evaluation
Power stack battery
The power stack batteries are maintenance free type and work on oxygen recombination
principle. The oxygen gas generated at the positive plate, is transported in the gas phase
through a highly absorbant and porous glass separator to the negative plate. The micro porous
glass separator is not completely saturated with electrolyte and the void space thus available
allows an unimpeded access of oxygen to the negative plate. The oxygen gas gets reduced at
the negative plate surface, thereby effectively suppressing the evolution of hydrogen.
Consequently, power stack cell do not lose any water under normal operation and therefore
no toping up is required.
Voltage: Power Stack cells are 2V units, which are assembled, in modular racks to get 2V,
6V and 12V modules. These racks are mounted horizontally and can be stacked one above
the other. For maximum service life, the recommended float voltage is 2.23 volts per cell.
Power stack cells are normally rated to an end cell voltage of 1.76 volts per cell where it is
necessary to terminate discharge at higher end cell voltage due to reason of equipment
compatibility , it can be done providing higher rated capacities.
Chargers: Power stack cells should be charged with constant potential charges. The charging
current should be limited maximum of 0.2 C10. The widely accepted charging methods use acurrent of 0.1 C10. Float charging is at 2.23 VPC. If the charger does not have a float-cum-
boost mode, it is important to switch over to float either after boost not later than 24 hours
under steady current conditions.
Applications: Power stack cells are designed especially for stand by applications. The deep
discharge cycle performance combined with excellent float characteristics make Power Stack
the ideal choice for a wide range of industrial applications like telecom, power generating
stations and sub- stations, uninterrupted power supplies , railways and solar photo voltaic.
Modern economies are dependent on reliable and secure electricity services. Electricitymakes an essential contribution to economic performance, international competitiveness and
community prosperity. The society‟s dependence on electricity shall intensify as the world
moves ahead in the twenty- first century.
A knowledge of electricity and its principles and the means through which they are directed
to the service of mankind should be a part of the mental equipment of everyone who pretends
to education in its truest sense.
The project is based on the dedicated machinery, technology, equipments and manpower
working to ensure smooth functioning of the grid. The project will benefit those who haveinterest in the instrument and will provide the reader with the deeper knowledge of the topic.
It is matter of great prestige to be a part of well & highly organized UPPCL. After being a
part of such organization one has the chance to learn a lot about a successful organization.
Besides this it also imparts the opportunities to strengthen the particular‟s professional skills.
This department helps in all possible ways to guide the functions, working process, units
prepared of the organization. One can learn a lot if he takes the proper interest.