36250202 railway signalling

7/31/2019 36250202 Railway Signalling

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BY

SHAHNAWAZ HAQUE

DEPT. OF ELECTRICAL ENGINEERING

GURU NANAK INSTITUTE OF TECHNOLOGY

RAILWAY

SIGNALLING

RAILWAY

SIGNALLING


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Principles of SignallingPrinciples of Signalling

The Time Interval System

Fixed Signalling

Distant Signals

Interlocking Blocks

The Track Circuit

Multi-Aspect Signals

Four-Aspect Signalling A Safe Braking Distance

The Overlap

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Track Unoccupied

Track Occupied


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Automatic Warning System(AWS)Automatic Warning System(AWS)

An alarm sounds in the driver's cab whenever a train approachesa caution or stop signal. If the driver fails to acknowledge thealarm, the train brakes are applied. The system is called AWS.

A form of a track mounted, non-contact inductor.

The AWS "ramp" as the inductor is known, is placed about 185 m

on the approach side of the signal between the rails. AWS ramp contains a pair of magnets, the first permanent, the

second an electro-magnet linked to the signal to provide anindication of the aspect.

Operation is based on energising and denergising of the electro-

magnet. Enforcement-A very simple system called trainstop is used.

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Train Protection and WarningTrain Protection and Warning System (TPWS)System (TPWS) If a train approaches a stop signal showing a danger aspect

at too high a speed to enable it to stop at the signal, it willbe forced to stop, regardless of any action (or inaction) by

the driver.

Consists of two pairs of electronic loops are placed between

the rails. Each pair consists of, first an arming loop and

secondly, a trigger loop.

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TPWS Unit

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Automatic Train Protection(ATP)Automatic Train Protection(ATP)

It can be either mechanical or electronic.

Electronic ATP involves track to train transmission ofsignal aspects and (sometimes) their associatedspeed limits.

ATP Speed Codes-Gives two pieces of information

about the state of the line ahead - what speed can itdo in this block and what speed must it be doing bythe time it enters the next block.

ATP Speed Code includes an antennae on the train,

electronic track circuitry and generates codes The code data consists of two parts, the authorised

speed code for this block and the target speed codefor the next block.

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ATP Code TransmissionATP Code Transmission

ATP Signalling codes contained in the track circuits are transmitted to thetrain.

Data is passed to an on-board decoding and safety processor.

The permitted speed is checked against the actual speed. At the trackside, the signal aspects of the sections ahead are monitored

and passed to the code generator for each block.

The code generator sends the appropriate codes to the track circuit.8/22/2010


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Route SignallingRoute Signalling Junctions-Signals are provided at junctions.

The signal has to perform two functions -to confirm to the driver that the route is set and thepoints locked for the indicated route and that theblock ahead is clear.

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Route Locking -The section of track between the signal and the

points is "route locked.-Once this track circuit is occupied the point control is

locked and the points cannot be moved.

Track locking-the track circuit at the points is also interlocked withthe point operation system to prevent any movement taking place

while the train is passing through

Route SignallingRoute Signalling

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Automatic TrainAutomatic Train Operation(ATO)Operation(ATO) It is the non-safety part of train operation related to station stops

and starts. The basic requirement of ATO is to tell the train approaching a

station where to stop so that the complete train is in the platform

Use of beacon - originally a looped cable, now usually a fixedtransponder

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ANY QUESTIONS???ANY QUESTIONS???

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THANK YOUTHANK YOU

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36250202 railway signalling

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