A SEMINAR ON PRACTICAL TRAINING TAKEN AT

WESTERN CENTRAL RAILWAY, KOTA

SUBMITTED BY •NAME: AMIT MOORJANI•BRANCH: ELECTRONICS AND COMMUNICATION•ROLL NO.: 06EAREC012•ARYA COLLEGE OF ENGG. & IT

INDIAN RAILWAYSIndian Railways has one of the largest and busiest

rail networks in the world.The Indian Railways is the largest civilian

employer in the world at approximately 1.6 million employees.

Indian Railways is a department owned and controlled by the Government of India, via the Ministry of Railways.

The training of all the cadre is entrusted and shared between six Centralised Training Institutes.They are :

Indian Railway Institute of Transportation Management, Lucknow for officers of the Traffic department

Indian Railway Institute of Civil Engineering, Pune for civil engineers,

• Indian Railway Institute of Signal and Telecommunications Engineering, Secunderabad for engineers of S&T department,

Indian Railway Institute of Mechanical and Electrical Engineering, Jamalpur for mechanical engineers

Indian Railway Institute of Electrical Engineering, Nasik for Electrical Engineers,

RPF Academy, Lucknow for officers of the Railway Protection Force

TOPICS

1. Electronic Exchange

2. Axle Counter

3. Overhead Communication

Electronic Exchange

Supports large communication network of Railways.

Facilitates Internet, Fax etc.

Processing based on:-• Switching(provides bidirectional speech)• Signaling (establish connection)• Controlling

Easy fault diagnosis and smaller set up.

1.As soon as the intended caller picks the handset , DC starts flowing over the loop.2.Exchange returns the dialer tone to caller who then enters the unique sequence of digits of the other subscriber.3.Bursts of ringing tone are applied to the called party while the AC is flowing.4.When the called party picks up the phone, DC flows and a connection is set up by the exchange between the parties concerned.

NOTE: If the called party belongs to other exchange , the caller’s exchange sets the connection between the caller and the caller party’s exchange.Then ,the procedure repeats.

Working

Vitality of track circuiting:

• To ensure safety of train operators , track circuits are vital components of signaling system.

• They are recommended to safeguard against reception of trains on occupied lines.

Obstructions to track circuiting:

• Virtual scarcity of wooden sleepers.

• Prohibitive cost.

• Environmental consciousness.

Axle Counters

Advent of Universal Axle Counters:

• Initially , Axle counters were imported from Germany to judge their suitability.

•2 models namely:- a) Single entry/exit

b) Multi entry/exit

were bought up and the design was finalized and commercialized under certain conditions. Based on the feedback , Universal Axle Counter was developed by RSDO.

Axle Counters

Structure:

• It is an electronic device consisting of :-

a) A set of Track inductors that ‘counts in’ the number of axles passing over them. (Fitted at the entrance of length of track)

b) A set of Track inductors that ‘counts out’ the number of axles passing over them. (Fitted at the exit of the length of track)

c) An evaluator that registers ‘counts in’ and ‘counts out’.

• It shows ‘clear’ the line if ‘counts in’=‘counts out’

• It shows ‘occupied’ if the 2 counts are different.

Principle for counting axles:-

• The Magnetic Flux generated by 5KHz current flowing in the transmitting coil induces a voltage in the receiver coil on either side of running rail.

• When a wheel passes between these 2coils , the magnetic flux gets disturbed and the induced voltage in the receiver coil is substantially reduced.

• The reductions called ‘dip’ are processed in the evaluator.

• The system consists of:-

Track maintaining and track side equipment.

Central evaluator with EV relays and SUP relays as its output.

Reset box and Line verification box.

Advantages:

• Does not require wooden sleepers.

• Can cover a very long section of 15 kms.

• Not susceptible to flooding of tracks or poor maintenance of tracks.

• Does not require insulating joints , thus , rails can be continuously welded.

• Reduces track maintenance cost.

• Lowers wear and tear of tracks.

• Increases travelling comforts.

Applications of Axle Counters:

• Monitoring of berthing of tracks in station areas and yards.

• Monitoring of point zones in stations areas and yards.

• Automatic signaling systems using axle counters.

• Intermediated block signaling.

Overhead Communication

OPTICAL FIBRE:

EVOLUTION:

• Simple telephone wires formed the basis of communication in the earliest era of Indian Railways.

• Two stations were connected via telephone lines but the communication was subjected to the problem of limited channels.

NEW CONCEPT:

• Optical fiber cables were capable of carrying large number of channels.

•Under this system , many complex and sophisticated instruments exist.

•Optical fiber is delicate and requires a correct and fix approach as a mistake of 0.01% can fail the whole system.

CONSTRUCTION:

Optical fiber consists of 3 layers:

1. a core of highly pure glass with high refractive index.

2. a middle layer of glass with low refractive index namely Cladding that protects the core of glass from scratches and surface imperfections.

3. an Outer Polymer Jacket that protects the fiber from damage.

• To have a higher refractive index for core glass , it is doped with dopant (small and controlled amount of impurity).

• Dopant reduces the speed of light. The best dopant for pure glass Silica is Germanium because of same no. of outer electrons present in them.

DEMAND IN INDIAN RAILWAY:

• Mainly 6*4 OFC’S are used in Railways.

• 6*4 means that there are 6 groups , each containing 4 cables

or optical fibers so that there is total of 24 optical fibers in

each cable.

MAINTENANCE:

To prevent the malfunctioning of fibre - a)Isopropyl solution

b)Isopropane solution

are used to remove the dust from the tip.

Cleaning: Optical fibers are cleaned when 2 of them are fused.

• Identification through combinations: As

there are 6 groups having 4 fibers each, color combinations

are used to identify them. They are:-

1st combination

Blue

Orange

Natural

Natural

Natural

Natural

2nd combination

Blue

Orange

Green

Natural

Natural

Natural

• While fusing , wires of same color are connected.

• While making connections , DUMMY GROUPS are supplied for the sake of identification of counting and convenience.

Optical fiber communication Optical fiber connector

Splicer-the facilitator of fusing• Based on thermal energy , splicer helps to melt the

fibres and thus fuse them.

• Splice loss:- Loss introduced while splicing

process.

• Defects that can be seen after splicing are:-

a) Bubbling

b) Neck down/Not spliced

c) Thickening

d) Streak

DEFECTS POSSIBLE CAUSES Bubbling a) wrong fibre selection

b) faulty cleave

c) dirty fibre

d) degradation of electrodes

Not spliced a) wrong fusion

b) faulty cleave

c) excessive arc current

d) insufficient fibre feed

Thickening a) wrong fusion

b) excessive fibre feed

c) excessive arc current

Streak a) wrong fusion

b) weak arc

PRECAUTIONS :

To reduce the splice loss , tips of fibre must be cleaned with Isopropane and Isopropyl solutions.

Fibre ends must also be cleaned properly.

Base fibre must be wiped with tint free tissue soaked with denatured alcohol.

An arc in the machine can damage the retina of human eye , wearing a protection glass is recommended while operation.

OFC CENTER AT KOTA

Thank you