Railway Automatic block signaling with Automatic Sectionsppt

It is about Automatic Block Signalling as provided in Railways

1. 1 AUTOMATIC COLOUR LIGHT SIGNALLING

2. 2In Automatic Block Working system train movements are controlled by
the automatic stop signals.

These signals are operated automatically by the passage of trains into and
out of the automatic signalling sections.

Essentials of Automatic Block System : Where trains are worked
on Automatic Block System: -

(a) the line is track circuited throughout its length and divided into a
series of automatic signalling sections each of which is governed by an
Automatic Stop Signal.

(b) the movement of trains is controlled by stop signals which are
operated automatically by the passage of trains past the signals.

(c) No Automatic Signal assumes 'OFF' unless the line is clear not only
upto the stop signal ahead, but an adequate distance beyond it. Introduction :

3. 3The automatic Signalling Section is defined as the portion of the
running road between any two consecutive automatic stop signals and
each of these sections is protected by an automatic stop signal.

The adequate distance also be termed as 'overlap' and not less than
120 M unless otherwise directed by approved special instructions.

4. 4Automatic Stop Signal General Description and numbering: Automatic Stop Signals are Multiple aspect colour light signals and are
either 3 aspect or 4 aspect.

These signals are numbered serially, ODD numbers in one direction and
even numbers in the other direction, for UP and DOWN lines or vice versa.

There is an attempt at numbering these signals according to their location
with respect to the kilometrage. This requires a code consisting of a group
of digits in which the last two digits indicate the telegraph or traction pole
and the first group of digits indicating the kilometres at which the signal is
located.

For example 2611 means the automatic signal located at 11th telegraph or
traction pole between 26th and 27th kilometre. For distinguishing UP and
DN signals the last digit can be made ODD in one direction and EVEN in the
other approximate to the nearest telegraph or traction poles.

5. 5Aspect Control Circuits for Signal No.1. Sometimes 3HR front contact is used in 1DR circuit as a direct
proof that 3 TR and A3TR are in pick up condition in addition to the
3 HECR and 3DECR contacts

6. 6 The aspect control and lamp control circuits for all signals are
same as for signal No.1 Sometimes, it is
customary to eliminate
the control relay HR
making use of the track
relays directly in the
lamp control circuit

7. 7CASCADING( Cutting in) Arrangements.
Whenever the lamp fuses with the signal displaying a particular aspect,
then it is likely that the signal becomes blank and there is a chance that
the driver may miss the signal and overshoot.
Even if the driver observes the signal, the signal with no light has to be
treated as a defective signal and GR 278, 279 will have to be observed.
This will have a deleterious effect on capacity, so if a lamp of clear aspect
fuses the signal should display a more restrictive aspect than no light
which is equivalent to 'Red'.
To avoid this conditions, an arrangement in the lamp control circuit can be
adopted in such a way that if a lamp fuses the signal can be restored to a
more restrictive aspect.
This arrangement is called the "cascading (cutting-in) arrangement".

8. 8 The cutting in arrangements
can also be provided by by-
passing the control relay
contacts by the lamp checking
relay contacts. This looks
simple, but requires more
number of ECR contacts.

9. 9Protection for Red Lamp Failure.
When red lamp in the automatic signal fails, the cutting in
arrangement cannot restore the signal to a more restrictive aspect.
Hence, the signal goes blank aspects not in a position to protect the
automatic signal section specially when a train occupies this section.
Under these conditions, the usual practice is to force the rear signal
to danger so that it assumes the protection of not only its section,
but also the section in advance and as a result the rear signal will
remain at red till the train clears two sections ahead.
The circuit arrangements required for this can be provided in three
different methods.

10. 10First Method

In this method, the red lamp checking relay 3 RECR front contact
is included in series with the 3TR front contact in the 'cut
section' arrangement between 3TR and A1TR
whenevertheaspectchanges,itbecomesblankduringwhichallECRsmay
dropcausingthedisconnectionoffeedtotherearberthtrackthus
replacingtherearsignaltodangerautomatically.Thisundesirableeffect
canbeeliminatedifECRsaremadeslowtorelease.

11. 11
theoverlaptrackrelayisshuntedwiththebackcontactsofRECR&A3TRso
thatwhenredlampfails3TRisshuntedandhence,itdrops.
ThiscausesdisconnectionoffeedtotherearberthtrackcausingA1TRto
dropwhichwillrestoresignalNo.1toredtillthetrainclearsadvancesection.
Thedisconnectionofthis
shortcircuitingloop
across3TReliminates
theredlampprotection
withoutanyindication.
Second Method

12. 12
Third Method
Inthisthefrontcontactof3RECRinserieswiththecutsection
arrangementasinthefirstmethodbut
A3TRfrontcontactisprovidedtobypassthe3RECRfrontcontactto
maintainthesupplytothereartrackwhentheadvancesectionisclearso
thatthesignalinrearcanchangeitsaspecttooff.
This method
eliminatesthe
undesirable
features of
firstandsecond
methods.

13. 13
Four-Aspect Automatic Signalling
Generallywhentheautomaticsignalsareprovidedwithdistancebetweenthe
signalsnotlessthanBDthen3-aspectsignalswillservethepurpose.
ButifthedistancebetweentwoconsecutivesignalsislessthanBDon
accountofstationsbeingverycloseortoimprovethesectioncapacityby
reducingtheheadwaybetweentrainsandreducingtheautomaticsignalling
sections,thentheautomaticsignalshavetobeprovidedwith4aspects.
Inthiscase,thesequenceofaspects,whenatrainpassesasignalisRed,
YellowdoubleYellowandGreenasthetrainoccupiesthesectionafter
passingasignalandclearingonesection,twosectionsand3sectionsahead
ofthesignalrespectively.
-

14. 14
Inthis,itiscustomarytoensurethatthedistancebetweenthesignal
displayingredandasignaldisplayingdoubleyellowisatleastequaltoB.D.
Ifthisdistanceisnotavailablethen,thedoubleyellowaspectsarerepeated
tillthelastsignaldisplayingdoubleyellowisatabreakingdistanceinrearof
thesignaldisplayingRed.

15. 15
Aspect control of Four -aspect automatic signals
Whenasignalis
displayingGreen,all
thecontrolrelays
arekeptenergised.
First Method

16. 16

17. 17
Second Method
Any one yellow up

18. 18
Thank you