64594914 NE Railway Training Report

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TABLE OF CONTENTS

Acknowledgement

Preface

Introduction To Indian Railways.

Module 1: Microwave Communication.

Module 2: Railway Signalling And Signal

Workshop.

Conclusion

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Acknowledgement

Behind the completion of any successful work there lies the

contribution of not one but many individuals who may have directly or

indirectly contributed to it.

First and foremost I am grateful to the management of NORTH

EASTERN RAILWAY,GORAKHPUR for providing me the opportunity

to undertake my Summer Industrial Training in the organization.I

specially convey my thanks to all the staff members for their precious

guidance during our training and in completion of this project. I feel

priviledged to express my deep regards and gratitude to all the Engineers

and staffs of MICROWAVE CENTRE,N.E RLY,GORAKHPUR and

SIGNAL WORKSHOP,N.E RLY,GORAKHPUR.

I am thankful to all my teachers who have best owed upon me their

knowledge and have been guiding light through out my course. They have

cast an indelible impression on my existence.

I am much indent to my friends whose moral support alwaysinspired me to come out with the best.Its great pleasure to extend my

heartfelt thanks to everybody who helped me through the successful

completion of my training.

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The acknowledgement would be incomplete if I fail to express deep

sense of my obligation and reverence to my parents without whom this

work would not have seen the light of the day.

Akhilesh kumar

singh

Preface

Engineering students gain theoretical knowledge only through books.

Only theoretical knowledge is not sufficient for absolute mastery in any

field. Theoretical knowledge in our books is not of much use without

knowing its practical implementation. It has been experienced thattheoretical knowledge is volatile in nature; however practical knowledge

imparts solid foundation in our mind.

The practical industrial training is a part of four year degree

course.Practical industrial training mainly aims at making one aware of

industrial environment which means that one gets to know the

limitations,constraints and freedom under which an engineer works.

To accomplish this aspect Gautam Buddh Technical University

(GBTU), Lucknow(U.P.) has included 4 weeks summer training for

B.Tech 3rd Year students in our curriculm.

This report is infact a summary of, what I have learnt and seen during my

training in N.E Railways. It simply summarizes the Microwave

communication, signaling and signal workshop as carried out in Indian

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railways.The training mainly involves industrial and complete knowledge

about designing,assembling and manufacturing of equipments.Thus it is

very necessary before becoming a professional engineer.

INDIAN RAILWAYS

FOUNDED - 16TH APRIL,1853

HEADQUARTER - New Delhi,India

AREA SERVED - India

INDUSTRY - Railway and Locomotives

SERVICES - Rail Transport

REVENUE - Rs. 107.66 billion

EMPLOYEES - 1,406,430

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INDIAN RAILWAYS(BHARTIYA RAIL) abbreviated as IR,is a state

owned railway company of India,which owns and operate most of the

countrys rail transport.It is overseen by Ministry of Railways and

Government of India.

Indian Railways has one of the largest and busiest rail networks

in the world,transporting over 18 million passengers and more than two

million tones of freight daily.It is the worlds largest commercial or utility

employer,with more than 1.4 million employees.The railways traverse the

length and breadth of the country,covering 6,909 stations over a total route

length of more than 63,327 kms (39,350 miles).As to rolling stock,IR owns

over 20,000 freight wagons, 50,000 coaches and 8,000

locomotives.Railways were first introduced to India in 1853.By 1947,the

year of Indias independence,there were 42 rail systems.In 1951,the

systems were nationalized as one unit,becoming one of the largest networks

in the world.IR operates both long distance and sub-urban rail systems on a

multi-gauge network of broad,meter and narrow gauges.It also owns

locomotives and coach production facilities.

As the economy of India improved,almost all railway production

units were Indigenized(produced in India).By 1985,steam locomotives

were phased out in favour of Diesel and Electric locomotive.The entire

railway reservation system was streamlined with computerization between

1987 and 1995.

In 2003,the Indian Railways celebrated 150 years of its

existence.Various zones of the railways celebrated the event by running

Heritage trains on routes similar to the ones on which the first trains on the

zones ran.The Ministry of Railway commemorated the event by launching a

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special logo celebrating the completion of 150 years of service.Also

launched was a new mascot for the 150 th year celebrations,named

Bholu,the Guard Elephant.

Snapshots:-

It encompasses 6,909 stations over a total route length of

more than

63,028 kilometres of route length and a track length of 111,600

km .

It is one of the world's largest commercial or utility

employers, with more than 1.6 million employees.

It grossed a revenue of ` 88,355 cr and bagging a netincome of ` 951 cr in

the financial year 2009-10 .

It moves 2 million tons of freight & 20 million people daily

across the

county with the help of 200,000 (freight) wagons.

7,000 passenger trains across the country services 20

million people to

their destinations .

Vivek Sahai is the current Chairman of Railway Board .

Organizational Structure-:

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Indian Railways is a department owned and controlled by the Government

of India, the Ministry of Railways . IR is administered by the Railway

Board, which has a financial commissioner, five members and a chairman.

Railway zones:-

IR is divided into zones, which are further sub-divided into divisions. The

number

of zones in Indian Railways increased from six to eight in 1951, nine in

1952, and finally 16 in 2003. Each zonal railway is made up of a certain

number of divisions, each having a divisional headquarters. There are a

total of 67 divisions under 16 zones , presently operating in the country .

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Each of the 16 zones, is headed by a General Manager (GM) who reports

directly to the Railway Board. The zones are further divided into divisions

under the control of Divisional Railway Managers (DRM). The divisional

officers of engineering, mechanical, electrical, signal and

telecommunication, accounts, personnel, operating, commercial and

safety branches report to the respective Divisional Manager and are in

charge of operation and maintenance of assets.

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Further down the hierarchy tree are the Station Masters who control

individual stations and the train movement through the track territory under

their stations' administration.

Practical Training under NER:-

We've received the scheduled Summer Practical Training, as a part of our

curriculum, from June 22, 2010 July 12, 2010 under Divisional Railway

Manager,NER,Gorakhpur.

.

We've studied about the following operational technologies in the IR-

1. Microwave Communication & Links.

2. Railway Signalling.

3. Signal Workshop(Automatic track changer,Electronic point machines

and relays)

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MODULE I

MICROWAVE COMMUNICATION

Microwaves are electromagnetic waves whose frequencies range from 1

GHz to 1000 GHz. Microwaves are so called since they are defined in

terms of their wave -length.There are large number of bands in microwave

region. Microwaves are used for controlling of trains.It is necessary to give

correct running and stopping of the trains and there should be a single train

on a single track.

Microwaves help the railway staff to communicate for this purpose.Stations

on average of 40km can communicate with each other by microwave.there

are large number of bands in microwave region.Before the advent of fiber

optics, these microwaves formed the heart of the long distance telephone

transmission system.

In its simplest form the microwave link can be one hop,

consisting of one pair of antennas spaced as little as one or two

kilometers apart, or can be a backbone, including multiple hops,

spanning several thousand kilometers.

A single hop is typically 30 to 60 km in relatively flat regions

for frequencies in the 2 to 8 GHz bands. When antennas areplaced between mountain peaks, a very long hop length can be

achieved. Hop distances in excess of 200 km are in

existence.

The "line-of-sight" nature of microwaves has some very

attractive advantages over cable systems. Line of sight is a term

which is only partially correct when describing microwave paths.

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Microwave Transmitter and Receiver-:

Below figure shows block diagram of microwave link transmitter andreceiver section --

The voice, video, or data channels are combined by a technique known

as

multiplexing to produce a BB signal. This signal is frequency modulated to

an IF

and then up converted (heterodyned) to the RF for transmission through the

atmosphere.

The reverse process occurs at the receiver. The microwave transmission

frequencies are within the approximate range 2 to 24 GHz.

The frequency bands used for digital microwave radio are recommended

by the

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CCIR. Each recommendation clearly defines the frequency range, the

number of

channels that can be used within that range, the channel spacing the bit rate

and

the polarization possibilities.

Microwave Transmitter and Receiver.

Application Of Microwave In Indian Railways -:

Microwaves are used for controlling of trains.

It is necessary to give correct running and stopping of the trains and

there should be a single train on a single track.

Microwave communication help the railway staff to communicate for

this purpose.

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Stations on average of 40 km can communicate with each other by

microwave.

Frequency Range In Microwave Region-:

BANDS FREQUENCY(GHZ)

L 1.1-1.7

LS 1.7-2.6

S 2.6-3.9

C 3.9-8.0

X 8.0-12.5

Ku 12.5-18.0

K 18.0-26.0Ka 26.0-40.0

How Terrestrial Microwave Transfer And Receive Data :

Terrestrial microwaves communication employs earth based

transmitters and receivers to transfer and receive data.

The frequencies used are in the low giga-hertz range,which limits all

communication to line of sight.

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Examples of terrestrial microwave equipment-Telephone relay

towers,which are placed every few miles to relay telephone signals

across country.

Antennas Are Used To Transfer Data -:

Microwave transmissions typically use a parabolic antenna that

produces a narrow,highly directional signals.

A similar antenna at the receiving site is sensitive to signals only

within a narrow focus.

Because the transmitter and receiver are highly focused,they must be

adjusted carefully so that the transmitted signal is aligned with the

receiver.

Role Of Microwaves In Passenger Reservation System -:

In PRS,the Gorakhpur Zone is connected to the main server

through communication lines and there is the need of non stop

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working of PRS in Indian Railways otherwise there will be

big loss to Indian Railways.

So to increase the reliability of PRS,the main server is also

connected to the zones through microwave links.In case if

there is a failure in the physical mediathen the PRS can be

operated by microwave.

Microwave Systems -:

There are two types of Microwave Systems.In first schematic processing is

in analog form and in second schematic processing is in digital form.

According to this there are two types of microwave systems as follows-:

1. Analog system.

2. Digital system.

The analog system is old system and digital system is new one.

Analog Systems -:

The analog system is simple and this system consists of

Transmitter,Receiver and communication media which is Microwave here.

Transmitter:

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The role of Transmitter is to send the signals and it consists of following

parts:-

Multiplexer(MUX):-

This is used to transmit various signals simultaneously.Here

there is many Input and there is only one output.The output of the

multiplexer is given to the Radio Equipment.

Radio Equipment:-

It receives the output of the multiplexer and then processes thesignals.This is the most important part of the transmitter and the

antenna is connected to the radio equipment directly.

Transmitting Antenna:-

This is a metallic object and this is used to transmit the signals in

free space.The antenna transmit the signals at 7 GHz in the

space.Here the antenna consists of a parabolic reflector and a Horn

antenna.The antenna is directional and directive.

Tower:-

The tower is a metallic and this is used only to give height to the

antenna.

Receiver:-

The role of receiver is to receive the signals.The receiver consists of

following parts:

Receiving Antenna:

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The receiving antenna receives the incoming signal and then it gives

the signals to the mixer.

Mixer:

Here in the mixer the frequency mixing takes place and now the

output frequency is different.And the output of the mixer is given to

the Discriminator.

Discriminator:

The Discriminator seperates the signals and the demodulationprocess is done here.This means that the carrier signal is removed

and only the

Message signals are taken.

Demultiplexer:

The demultiplexer has only one input and here the separation process

is done and the sent signals are recovered back.

Digital Systems :

This system has a large number of advantages over analog

system.This system is a new system and uses digital

technology.Digital system is more reliable and efficient.

Digital system consists of following parts:

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Transmitter-:

The transmitter of digital system is different from analog system.In

this transmitter two types of multiplexers are used which are as

follows:

Primary multiplexer:

This is the first multiplexer at the transmitter side.It multiplexes 30

voice signals and in the digital system sixteen multiplexers are used

of this type.The output of every primary multiplexer is 2.04 Mbps.

Higher order multiplexers:

This multiplexer is big and multiplexes the signal coming from the

primary multiplexers.The output of this multiplexer is 34.368 Mbps.

Radio Equipment:-

The output of the higher order multiplexer is given to the radio

equipment.Radio equipment process these signals and make them

able to be transmitted by antenna.

Antenna-:

The antenna is same as we are using in analog system.Here also we

use horn antenna and parabolc reflector.Horn antenna is at the focus

and it send the signals to the parabolic reflector surface.After striking

from the surface,the signals are parallel and it is transmitted in such

form.

Tower-:

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Here also the role of tower is to give height to antenna.In Microwave

station (Gorakhpur) of Indian railways,there are two towers ,one is

for analog and the other one is for digital communication.

Receiving Antenna-:

The receiving antenna is at the receiving side,receives the signals and

sends it to radio equipment.There is line of sight communication of

microwave in between transmitting and receiving antenna.

Radio Equipment-:

The radio receiver receives the signal coming from the antenna.Here

the signals are processed and then these signals are sent to higher

order demultiplexers.

Higher Order Demultiplexers-:

In this demultiplexer the signals are separated.And the output of this

multiplexer is given to the low level multiplexer.There is sixteen

outputs and every output has a bit rate of 2.048 Mbps.

Low level multiplexer-:

This multiplexer receives the output from the higher order

multiplexer.It has one input and thirty outputs.The output frequency

rate is 0-4 KHZ.This is the frequency range of human voice.Here the

original voice signals are obtained.

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Power Reqirement-:

Both systems require power for their operation.A dc current

is required for both systems.This dc current is provided by a

set of batteries.An extra set of battery is also kept for

emergency.

Analog System-:Analog system requires a dc voltage of -24v for its

operation.

Digital communication-:Digital system requires a voltage of 48 v

for its operation.

Essential Environment For Analog And Digital Systems-:

There are some requirements for these systems for there proper

functioning.Following are some of the requirements:-

1. Air Conditioning.

2.Dust Free Environment.

3.Uninterrupted Power supply.

4.Proper trained staff.

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Use Of Repeaters-:

After travelling some distance the microvave gets distorted.

The Repeater is a device which is used to obtain distortion free

microwave and this clean and distortion free microwave is

transmitted again in forward direction.

Repeaters are used at the average distance of 40 km.

Fault Control Procedure-:

In a typical Railway Telecom network Scenario,following types of

Telecom Network coexists:

Transmission-:

1.Microwave/UHF Network.

2.Optical Fibre Cable Network.

3.RE Telecom Cable Control Network.

4.Railways Overhead Wire Control Network.

5.DOT owned Overhead wire control Network.

Switching-:

1.Electronic Telephone Exchanges.

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2.Electromechanical Telephone Exchanges.

Others-:

1.Single Channel Duplex UHF/VHF Radio Systems.

2.Multiple Access Radio Relay.

3.Pair Gain System.

4.VHF/UHF Simplex Trans-receivers.

5.Talk Back systems for Major yards.

It is indeed very necessary to established well defined Fault Control

procedures for satisfactory maintenance of such diverse Railway

Telecommunication Networks so as to meet the demanding requirements

of Indian Railways in 21st century.

Typical Telecom Fault Control Setup-:

Typical telecom fault control setupon railway shall consist of

following-:

1. Zonal Telecom Fault Control Setup.

2. Divisional Telecom Fault Control Setup.

The Zonal Telecom Fault Control Setup shall be one for entire zonal

railway.

The Divisional Telecom Fault control setup shall be established in each

Division of the zonal railway.

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1.Zonal Telecom Fault control setup-:

It shall be manned by Section Engineer(Telecom) in a general

shift.Three section engineers(Telecom) shall be earmarked and should man

the zonal fault control setup round the clock in case of

emergencies.Following Telecom Network shall be monitored by zonal

Telecom fault control Room.

Microwave/UHF Network on the entire zonal Railway-:

The Zonal Telecom Fault Control room shall also function as an

emergency telecom control room in case of emergencies requiring

immediate telecom facilities/restoration.The emergencies may

consist of the following-:

Major rail accidents.

Cyclones.

Breaches.

When the Zonal Telecom Fault control room function as the Emergency

Telecom Control room,the divisional Telecom fault control rooms of theaffected Division(s)shall report their positions to the Zonal Telecom Fault

control room which in turn shall advice the Telecom officials at HQs of the

latest developments.

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The zonal Telecom Fault Control Room shall function under the direct

control of Dy. Chief Signal & Telecom Engineer(Microwave) or any other

officer designated by communication engineer of railway.

2.Divisional Telecom Fault Control Setup-:

The Divisional Telecom Fault Control setup shall have two components:

For monitoring all telecom networks other than Microwave/UHF

called

Divisional Telecom Fault Control Room.

For monitoring Microwave/UHF networks called Divisional

Microwave Fault Control Room.

Each of these Contol rooms shall be headed by a Senior Section

Engineer(Telecom) in a general shift.Three section engineers

(Telecom)/Jr. Engineer(Telecom)shall man the fault control room

round the clock.

Following Telecom Networks shall be monitored by the

Divisional Fault control Room-:

Optical fibre Cable Network.

RE Telecom Cable Control Network.

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Railways Overhead wire control network.

DOT owned Overhead Wire Control Network.

Electronic Telephone Exchanges.

Electro-mechanical Telephone Exchanges.

Single channel Duplex UHF/VHF

MODULE II

Railway Signalling & Signal

Workshop

Introduction-:

Signaling is one of the most important aspects of Railway

communication. In the very early days of the railways there was no fixed

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signaling to inform the driver of the state of the line ahead. Trains were

driven on sight. But several unpleasant incidents accentuated the need for

an efficient signaling system. Earliest system involved the Time Interval

technique. Here time intervals were imposed between trains mostly around

10 mins. But due to the frequent breakdown of trains in those days this

technique resulted in rear-end collisions. This gave rise to the fixed

signaling system wherein the track was divided into fixed sections and each

section was protected by a fixed signaling. This system is still being

continued although changes have been brought about in the basic signaling

methods. Earlier mechanical signals were used but today block signaling is

through electric instruments.

When trains run on railway tracks they follow rules of operations

in which safety plays a very important role.The most important rule in

respect of safety is to ensure that two trains do not occupy the

sameposition on the track at the same time. To make this rule work

operation of trains uses signaling to controlmovement of trains on

tracks and divides tracks into several sections which are protected by the

signals.

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Fig shows a representation of a railway signaling arrangement. The

horizontal liner represents the railway track, the signals are depicted by the

symbol of the circle with a horizontal and vertical line to this circle and the

red rectangles are the trains. This representation is however to explain how

trains are run safely.

Locking-:

There are three types of locking

a) Direct

b) Approach

c) Route

Direct locking is available as long as a signal is clear or track is occupied or

a point is set. This is the most fundamental level of locking.

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When signal S1 is cleared the cleared condition of the signal locks other

signals which can cause trains to run on any part of the route over which S1

allows a train to run. Thus with S1 cleared allowing trains to move to track

T1 signal S4 cannot be cleared and willbe locked as the latter also allows

trains to occupy track T1. Other form of direct locking is the locking of the

point in the route for which signal S1 is cleared. If S1 is cleared to the

straight route T0 T1 T2 then the point P1 will be set and locked to allow

a train to move on the straight route over Point P1.Attempts to move point

P1 from this position will not be allowed and hence will be locked.

Conversly if the point P1 is not set for straight the signal S1 will be locked.

The occupation of a track also locks signals if T1 is occupied then signal S1

cannot be cleared. Signal S1 is therefore directly locked to the cleared

status of the track. Points are directly locked to track circuits over the point

zones. If the track circuit over a point zone is occupied the it is locked so

that it cannot move. This is the direct locking of the point.

Approach Locking -:

While ensuring safety for train running it is not only necessary to ensure

that safety is ensured over all portions of track for which signals have beengiven but also over portions over track which can get occupied due to trains

approaching a signal which protects these portions of track failing to stop at

this signal. Such protection is required under the condition when the signal

protecting had not been cleared.

Flank protection and isolation -:

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When a train is allowed to move by a signal it is also necessary to ensure

that no part of the train will be Involved in a side collision.

Protection in the overlap -:

When a train is approaching a signal a possibility exists that the train may

fail to stop at the signal where it is intended to stop due to mechanical

failure or due to human failure. While there is no absolute arrangement to

control against this eventuality a partial safety is ensured by providing a

small part of the track beyond the signal at which the train is to stop free of

any conflict or obstruction to the train if it fails to stop at the foot of the

signal. Typically when train TR1 is approaching S1 it will normally be

ensured that the track section onto T2 is free of any obstruction. This

includes possibility of any train from the opposite direction reaching T2.

Hence if TR1 is allowed to approach S1 it will be ensured that the train

TR2 does not at the same time approach signal S2. Any point in this portion

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of the track also needs to be set and locked in the position allowing safe

movement through it. If TR1 is approaching signal S1 it will mean point

P2A must be set and locked for the straight route. The point P2A and track

T2 is referred to be in the overlap for signal S1 and locks the signal

allowing approach of a train to signal S1 if not found free. Conversely if

signal S1 is cleared any condition which can lead to the overlap from

failing to remain in the condition to maintain safety for train TR1

approaching S1 will be locked.

Release of locking -:

Signals indicate when a route which it checks is safe for a train to travel.

The safety is checked from different angles as explained above. After a

signal has been cleared for a train it is required to be put back to danger as

the train moves past it. There are two reasons for doing this-:

a) To ensure the safety of the train which has moved past.

b) To allow clearance of other signals which has been locked by it.

The release of locking is done automatically as a train moves along the

route a signal had cleared for it. The locking is released in stages-:

a) As the train moves past the signal the approach locking is brought back

to normal.

b) As the train clears the first track after the signal the direct locking gets

released.

c) As the train moves the route locking , flank or isolation protection for the

portions of the route cleared by the train is removed.

d) After the train has come to a stop at the next signal for sufficient time to

prove that it is not moving the overlap is released. This is the normal

release with the passage of train. There can however be occasions when it is

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required to cancel a signal which has been cleared and yet to be passed by

the train. When this is required the signal is canceled. When the signal is

canceled it is necessary to ensure that the locking it had enabled also get

canceled. Here again the cancellation starts from release of the approach

locking followed by release of the route locking, locking of flank and

isolation and finally the overlap. The release is done only after it is

established that a train which had been approaching the train has come to a

stopped at the signal before the locking to other signals are released.

Detection of trains -:

Signals control movement of trains. For it to effectively control movement

of signals there is a need to know the location of trains on the track. The

railway tracks are divided into short sections normally referred to as track

sections. At any time only one train can occupy one such a section. Track

circuits or axle counters are used for the detection of trains in these

sections. Only one train can occupy a

track section at any time. Normally the detector is fed with the signal from

the

source through the rails and as long the detector receives a signal it

concludes that the track section is not occupied. If a train occupies the track

section being monitored it short circuits the track cutting off the signal

from the source to the detector. When the detector fins loss of signal from

the source it concludes that the section is occupied by a train. Principles of

fail safety is also very well demonstrated in this arrangement. In case of a

failure like a broken wire, rail fracture, power supply failure, failure of the

source the detector will lose the signal and conclude the section is occupied

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by a train. This will allow the detection to maintain safety even under

failure condition and satisfy requirments of fail safety.

Control and drive to points -:

Points are driven by electrical motors. The motors are known as point

motors and moves point using a mechanism which including the motor is

referred to as point machine. A point machine mechanism moves switches

of a point through a mechanical arrangement of rods and gears.

Signal s-:

Signals indicate to the train drivers whether the route till the next signals is

reached is safe or not. Before a signal is cleared the signal control logic

verifies that everything is safe for a train which follows it. This will mean-:

a) All track sections over which the train will be routed is unoccupied. This

is checked by checking the status of the track circuit relays. Track proving

relays of all track sections which are clear will be picked up. By checking

the status of these relays which are referred as track relays the signaling

control logic can determine

that the route is clear.

b) Routes of any signals which conflict with the signal is not cleared andthat none of the signals have been approach locked.

c) There is not route set over a track section conflicting with the route of the

desired signal. This is proved by checking that all track circuits over which

the signal reads is clear of route locking.

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Implementation of Signaling Systems

Train running and signaling the drivers of the trains depends to a significant

extent on mechanized equipment. The technologies used for this application

ranges from very rudimentary systems to highly sophisticated equipment.

The technologies are based to a great degree on mechanical arrangement at

large number of installations. Advanced technologies are in use on sections

where train densities are high and

specially where Railway Electrification has already been done.

Technologies used for this application are for two reasons :-

1) To ensure safety of train running.

2) To improve operational efficiency.

Basic Principles :

Safety of train running in practice means ensuring that two trains do not

occupy the same location at the same time. Since trains are bound onto

Railway tracks it means ensuring two trains do not occupy same location of

the track at the same time. This is ensured in two stages-:

1) By dividing the Railway track into sections.

2) Entry into each of these sections are controlled by suitable signaling

system which ensures through various means that when a train is signaled

to Basics of Railway Signaling.

3) The drivers controlling the train are signaled sufficiently in advance so

that they can stop the train before signals which are not cleared. Since trains

typically move at a speed of around 100 Km./Hr. it requires a braking

distance of 1 Km before a signal at which it is required to stop. Hence

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signaling system ensures that signals are conveyed to the Drivers

sufficiently in advance to bring the train to stop safely.

4)It should not be possible to move a point when a train is over the point or

is very near to the point having picked up signal allowing the train to move

over the point likely to be moved. In addition to above various other rules

are applied to

make a signaling system safe. These rules are results of experiences gained

after accidents. Thus one rule msays that if a passenger train has to run

through a line then this run through line should be isolated from other

connected lines in the station by suitable means. This rule has been

introduced to ensure that if there is a train standing on a connected line and

it starts rolling it cannot result in a devastating collision as it is kept isolated

from run through line on which high speed train has been signaled to go

through.

Basic Rules -:

The basic rules of safety in connection with train running is implemented

through various methods. The Railway Engineering is very old and,

therefore, implementation methods also are old. Availability of modern

electrical & electronic technology is gradually changing the implementation

of Railway signaling systems. The technologies used in Railway signaling

system depended on human element initially. Gradually mechanical

systems were introduced followed by electrical/electromechanical and now

electronics/electrical/electromechanical systems. The human element in

Railway signaling is getting reduced wore & more for improving safety and

efficiency of train operations.

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The Human element :

Signaling Systems exist where setting of the point and locking of the same

is entirely manual. The locking of the point is achieved through key and

lock system.

The signals are all hand Signals. A more mechanized arrangement is where

switches turning points are connected to levers and signals are given by

mechanical arms known as semaphore signals. In both the systems the

human element ensure that the routes a train will take is not obstructed. The

set person who is clearing the signals for passage of the trains achieves this

entirely visually. The oldest signaling Systems are entirely manual where

even the checking that a route has been properly is manual.

The 50 Hz & 83&113 Hz signal source is used in a manner similar to D.C.

voltage and requires no special mention as the detector is simply a relay. In

case of 83&1/3 Hz system normally 3 phase system is used and two phases

are used on any section. The feed end gives one phase and a second phase

is always fed to the detecting relay. When the track circuited section is free

the two phases create a rotary force as in a AC electric motor. Absence of

one of the phase via the rails due to presence of a train removes the rotating

force dropping the relay. The 83&1/3 Hz track circuits is a popular track

circuiting arrangement.

Electronics in Railway Signaling for improved

Safety-:

The audio frequency track circuit is the latest entrant in the field. This

arrangement feeds an Audio frequency signal which causes pick up of

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Relay via the detector. A simple Audio frequency generator is used and at

the detecting end a L.C. resonant circuit is used for picking up the desired

Audio frequency signal & rejecting others. Due to the use of high frequency

it is possible to use the Railway track as a

transmission line and use of physical insulating pieces electrically isolating

one section as "R' from 'A-B" is not required. By using resonant L.C.

circuits at suitable points the AF signal can be made to stop beyond any

particular point without the need of any insulating joint. This feature is a

big advantage for this type of track circuit as there is no need to cut Rails &

insert insulating pieces. Indian Railways but considerable difficulties, faced

on account of loss of track side equipment due to theft has rendered the

system ineffective. As a corollary to this simple arrangement, systems of

continuous automatic control of trains are also available. Such systems

continuously control speed of trains through transfer of signals from the

track side to the engine. The system is quite elaborate consisting of a

receiver located in the engine and suitable transmitter coils located on the

sleepers between the track. A computer computes the required speed of

trains running on the track for ensuring safety as well as for ensuring that

trains run on time speeding as necessary or slowing when needed. Such a

system is being implemented on Metro Railway Calcutta in India for the

first time. Such systems are important for Metro Railway services where

time between two successive trains is are required to be kept very small toas much as one min or less. Even with such small interval between trains

complete safety & punctuality can be attained using the continuous

automatic train control and protection system. Use of Electrical/Electronic

Gadgets for ease of operation Over and above allowing higher levels of

safety by using sophisticated controls the use of electrical/electronic

gadgets for Railway Signaling is also made for ease of train operations and

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higher efficiencies. Systems known as Panel Interlocking and its

sophisticated variety known a Route Relay Interlocking are for control of

signals and points with higher efficiencies.

Design of Signaling Circuits -:

The design of signaling circuits is based on simple principles. Railway

Signaling being one of the oldest control engineering is based on very

simple methods

and principles. One of the main reasons of its simplicity lies in the fact that

technological aids for design were not very high till late 21st century and

complicated design principles and methods could not be supported. as a

result of this the circuits are drawn using very simple symbols and names

are kept short. If looked in the context of the fact that the circuits had to be

hand drawn in times where duplicating facilities were very primitive the

reason why they are so simple

can easily be understood. Signaling circuits are based on defining relays of

the

following types-:

a) Those signifying states in progress of a command

b) Those indicating steady state of the signaling functions.c) The last operation has been completed properly .All circuits of Railway

Signaling has to ensure safety. Hence both the type of relays defined above

also always ensure safety. This fundamentally means that in absence of any

voltage to the circuit the relays shall assume safe state which is the drop

state for all neutral relays and can be dropped or one of the latched state for

relays which are latched electrically or mechanically.

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Signal Workshop-:

In the signal workshop of Indian railways,following machine are

manufactured which are used as a part of signaling system-:

1. Electric point machine.

2. Relays.

Points are provided to divert the running trains from one track to another.

The points have movable switches which can be operated electrically by a

point machine. A point can be single-ended point or double-ended point

depending on whether the movable switches are provided at one end or two

ends of the point,

The two switch rails of the point are rigidly connected together by a cross

bar so that they can be moved from one position to the other position

together by the point machine. If the position of the switches is such that

the train is moved on to the main line as shown above, then the point is said

to be in its normal (N) position. If the switch rails are moved to the other

position as shown below so that the train is diverted to the loop line, then

the point is said to be in its REVERSE (R) position.

Solid State Interlocking -:

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Solid State Interlocking is a data-driven signal control system designed for

use throughout the British railway system. SSI is a replacement for

electromechanical interlockings---which are based on highly reliable relay

technology---and has been designed with a view to modularity, improved

flexibility in serving the needs of a diversity of rail traffic, and greater

economy. The hugely complex relay circuitry found in many modern

signalling installations is expensive to install, difficult to modify, and

requires extensive housing---but the same functionality can be achieved

with a relatively small number of interconnected solid state elements as

long as they are individually sufficiently reliable. SSI has been designed to

be compatible with current signalling practice and principles of interlocking

design, and to maintain the operator's perception of the behavior and appe

arance of the control system.

A schematic view of SSI processor.

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Conclusion

This report takes a pedagogical stance in demonstrating how results from

theoretical electronics may be applied to yield significant insight into the

behavior of the devices .Electronics & communication engineering practice

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seeks to put in place, and that this is immediately attainable with the present

state of the art. The focus for this detailed study is provided by the type of

solid state signaling and various communication systems currently being

deployed throughout mainline railways. Safety and system reliability

concerns dominate in this domain. With such motivation, two issues are

tackled: the special problem of software quality assurance in these data-

driven control systems, and the broader problem of design dependability. In

the former case, the analysis is directed towards proving safety properties

of the geographic data which encode the control logic for the railway

interlocking; the latter examines the fidelity of the communication

protocols upon which the distributed control system depends.

We have covered in this report the history ,latest developments in Railway

systems as well as related fields. We have studied the various uses of

electronics and communications in railways like microwave

communication,signaling,electronic point machines etc..

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64594914 NE Railway Training Report

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