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| Type | Commercial Circular |
|---|---|
| Topic | reservation |
| Currency | Currency not verified |
A)less length of Track Section B) more length of Track Section
Track circuits ,
Axle counters , Points and crossings
CLI -02
Role of signaling dept
To maintain
safety in train
working.
To help in train
operations to
maintain
punctuality of the
trains.
To help railways
in earnings by
increasing the
section capacity.
To provide
passenger
amenities.
➢ To detect the presence of a vehicle on a particular portion of track is
known as train detection.
➢ Basically there are two means to detect the presence of a train over a
track are
A)Track Circuits (DC-TC, AC-TC & AFTC)
B)Axle Counters (SSDAC, HASSDAC & Digital)
TRAIN DETECTION SYSTEMS
Applications of
DC Track
circuits
Fouling
mark
Protection,
Speed
checking,
Direction
Proving,
Calling on
Signal
initiation,
Applications
of DC TC
Point
Zones ,
L.C Gate ,
Block
Section,
Automatic
sections,
Intermedia
te block
sections
etc…
D.C. Track Circuits
SUBJECT
IRISET- SECUNDERABAD
6
Double Rail D.C
Track circuits
Single Rail D.C
Track circuits
A DC-Track Circuit consists of
Track relay
Battery
Track feed Battery
Charger
TL JB
TL JB
RT
Block joint
Block joints
A closed type track circuit shall be provided to prove the clearance of rail
track.
Minimum Length: The length of a track circuit shall not be less than the
maximum wheel base of any vehicle. The Track circuits shall cover at least
two rail lengths (26 meters). Maximum is 750 meters in a PSC Yard.
Glued Joints or Insulation Joints shall be provided for defining boundary of
track circuit. Glued joint should be tested before insertion.
GLUED JOINT
. <= - कु .
Hitting by a hanging part of a
train to the TLJB boxes (will be
uprooted/Damaged ) causes a
track circuit failure sometimes.
==) ‘B' Type choke(R=3 and Z=120 at SOHz) “| =
R = 30 and Z= 1200
Metal- carbon -Relay
SUBJECT
IRISET- SECUNDERABAD
12
SUBJECT
IRISET- SECUNDERABAD
13
Track clear, Route set and Locked - White
AXLE COUNTERS
• Axle counter – axle counter is a system used to
detect presence of train on particular length of track
section consisting of entry & exit points.
• It is an alternate system to Track Circuit for detecting
the presence of the Train on a particular portion of
the Track.
• AXLE COUNTERS – Axle counter is a system used to detect presence of
train on particular length of track section consisting of entry & exit
points
Axle counters are
• A) Universal axle counter ( Analog axle counter )
• B) Digital axle counters ( SSDAC/ HASSDAC, MSDAC )
SE4-CAVACH VER-1.0
IRISET- SECUNDERABAD
16
1.Insulation Joints(IRJ)
•
Many Track circuit failures are caused due to Rail fracture/ failure of
welding, accumulation of iron filings/ chips on Insulated Rail Joint (IRJ).
•In yards the track circuit bonding becomes much complicated involving
large number of glued joints.
LIMITATIONS OF DC TRACK CIRCUITS
2. Concrete Sleepers
Both DC & AFTC require wooden / concrete sleepers. It is not feasible to
provide wooden sleepers and providing concrete sleepers at every track
section is also not feasible even on Straight portions (for example: on
Bridges).
# AFTC is a another type track detection method.
LIMITATIONS OF DC TRACK CIRCUITS
LIMITATIONS OF DC TRACK CIRCUITS
3.Ballast Maintenance
•Drainage problem exists at many stations and in rainy seasons
this causes Track Circuit failures due to water stagnation.
• No insulation joints are required.
• Monitors very long track sections.
• Last vehicle check is done automatically.
• No effect due to ballast resistance.
Advantages of Axle Counters
• Error free operation over large temperature range.
• Train detection on rusted, sanded & water logged rails.
• Immune to traction return currents.
• No special type of Track Relay is required.
Advantages of Axle Counters
At the boundaries of the section to be monitored, the detection points
to be provided which generates a sort of information while train
wheels passing over them, and sends that information to evaluator
for further proces
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