signalling and ohte vs track
TRANSCRIPT
2
•INTRODUCTION
•Concept of “Track Vacancy Detection”
•Track Circuits
•How they work
•Some problems arising
•Addressing these problems
•Axle Counters
•How they work
•Problems
•New developments
•OHTE
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Track Vacancy Detection Equipment
• Track Circuits
• Axle Counters
Train Authorisation Technology
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Track Circuits
Track Vacancy Detection
Train Authorisation Technology
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Track Circuits
Basic Principles : Relays
N
a
b
c
a
b
c
Train Authorisation Technology
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Track Circuits
i
A
Basic Principles
Train Authorisation Technology
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Track Circuits
i
A
Basic Principles
Train Authorisation Technology
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Track Circuits
i
A
Basic Principles
Train Authorisation Technology
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Track Circuits
• Insulated Rail Joints used in Signal leg
• Traction return leg solid
• Rails insulated from ballast
• Sleeper insulated from rails.
Train Authorisation Technology
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Insulating Track Circuits
1 TR 2TR
i1 i2
Insulated Rail Joints
Train Authorisation Technology
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Insulated Rail Joints (Block Joint)
Train Authorisation Technology
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Ballast stone & Track Circuits
• Ballast resistance > 2,1 Ohm/km
• Contaminated ballast increases leakage currents
• Ballast MUST not touch rails.
Train Authorisation Technology
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TR
i1 i2 i3 i4
iB
Ballast stone & Track Circuits
Train Authorisation Technology
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Track Circuit Requirements
• Must shunt with 0,5 Ohm
• Operate safely and reliably
• Should not drop with ballast resistance of 2,1
Ohm/km
• Immune to environmental conditions
• Long as possible
• Cost effective.
Train Authorisation Technology
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Types of Track Circuits
• Jointed Track Circuits o Block Joints (Insulated Rail Joint)
required
o One Traction return leg
• Jointless Track Circuits o Simulated Block Joints
o Both rails available for traction return
d.c. (Old)
d.c. a.c.- Immune
a.c. 50 Hz
Jeumont
M.L.TI21
Train Authorisation Technology
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a.c. Track circuit
• 50 Hz Power supply
• Diesel and d.c. Traction areas
• No longer Purchased
50 hZ
Train Authorisation Technology
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Jeumont Track Circuit
• Specially shaped high voltage pulses
• Special receiver and relay
• Immune to 50 Hz interference
Train Authorisation Technology
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Points
TURNOUTS
Train Authorisation Technology
24
Straight
+
-
-
+
-
+
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Track Circuit Failures
Block Joints
Ballast stone
Train Authorisation Technology
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Train Detection
• Axle Counters
o Used instead of Track circuits
o Detects Completeness of trains
o Counts Wheels and
o Determines direction
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Axle Counters
Axle counter Heads
“Insert” “Insert” Evaluator
Communication Cable
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Axle Counter Heads
• Position is Critical
• Replacement requires Adjustments
• Two Frequencies to Heads
• Supervision Frequency
• Heads Detected in Position
• Presence of Wheel Changes Magnetic field &
Phase
• Pulses Correspond to Wheels.
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Results of the ballast and earth
returns not according to rules
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How a mast should be
installed
New ballast still
touching the rail
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