Railway Track Circuits Overview

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Questions and Answers

What must be strictly followed according to the frequency assignment scheme for track circuits?

The same frequency must be assigned to all track circuits.

Use of multiple frequencies for the same track circuit.

A prior decision on frequency assignment. (correct)

Installation of additional insulated bonds.

What is prohibited regarding terminal junctions on insulation joints?

Using frequencies from the same pair. (correct)

Installation of track circuits in a single location.

Connection of multiple track circuits.

Use of different frequency pairs.

What should be considered for the design and installation of field equipment?

Minimizing materials used.

Enhanced features for automation.

Provision for separate power sources.

Requirements for mechanised track maintenance. (correct)

Why should circuit pairing be observed when wiring track circuits?

To reduce crosstalk in adjacent circuits. Signup and view all the answers

How far must TUs and ETUs be mounted from the near rail for safety?

Minimum distance of two meters. Signup and view all the answers

What must not be done in case of a track circuit failure?

Adjust the gain of the receiver. Signup and view all the answers

What kind of protection must be installed on each pair of conductors connected to the outside?

Protection against atmospheric voltage surges. Signup and view all the answers

Which statement is true regarding the bonding of fish plated joints?

They must be bonded with jumpers of adequate thickness. Signup and view all the answers

What action should be taken when rusty rails are present in track circuited areas until axle counters are installed?

Restrict sectional route release to essential areas Signup and view all the answers

What is a distinct advantage of Audio Frequency Track Circuits?

Does not require Insulated Rail Joints (IRJs) except in Point Zones Signup and view all the answers

Which of the following is NOT a component of the Audio Frequency Track Circuit?

Automated signaling unit Signup and view all the answers

What must be ensured about the operation of Audio Frequency Track Circuit?

Only approved types must be used Signup and view all the answers

What is one of the features of an Audio Frequency Track Circuit?

Built-in time delay, eliminating the need for a slow relay Signup and view all the answers

Which type of configuration can Audio Frequency Track Circuits be used in?

End or centre-fed configuration Signup and view all the answers

What should be strictly followed during the installation of track circuits?

Instructions specific to that type of track circuit Signup and view all the answers

Which condition prevents the installation of axle counters in relation to rusty rails?

Axle counters cannot be used in parallel with rusty rail track circuits Signup and view all the answers

Study Notes

Rusty Rails

Rusty rails in track circuits require zig-zag welding using steel wire.
P-Way staff perform this work.
Axle counters are required in these locations to ensure proper shunting.
Until counters are available, working instructions require physical verification of complete train arrival by ASM.
Sectional route release is restricted only when essential.
Axle counters are not installed in parallel with Rusty Rail Track circuits.
Maintenance schedule for DC Track Circuits is in Annexure 17-MS2.

Audio Frequency Track Circuits (AFTC) - General

Audio frequency track circuits define track limits via tuned short circuits between rails, instead of insulation.
IRJs (except point zones) aren't necessary for these circuits.
This saves impedance and offers advantages for high-speed, high-axle-load traffic.
Built-in time delay; QSPA1 relay (TPR) is not required.
Usable in AC, DC electrified, and non-electrified areas.
Single rail mode operation isn't allowed for these circuits.
Operated locally or remotely.

Audio Frequency Track Circuit Components

Tuning unit
Transmitter
Receiver
Power Supply
Track Connections
Impedance Bond (if applicable)

Installation and Maintenance of AFTC

Installation follows specific instructions for the type of circuit.
Tuning areas must be free of check rails, level crossings, and insulated bonds.
Each fish-plated joint must be bonded.
Special care to ensure connection tightness of rails and tuning units.
Frequency assignment scheme is crucial.
Terminal junctions on insulation joints with the same frequency are prohibited.
Cable cores for transmitter and receiver should be from the same pair. Incorrect wiring can cause cross-talk interference between circuits.
Field equipment design for track maintenance should prevent hazards.
Lightning protection, and protection against both common-mode and differential-mode voltage surges are essential.
Transmitter, receiver, and power supply are mounted on standard relay racks for easy maintenance and testing.
Equipment should be placed at least two meters from the nearest rail for staff safety.
When the track circuit fails, investigating the cause of receiver voltage drift before adjusting gain is necessary.
Impedance bond tuning ensures the frequency matches the track circuit.

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Description

Explore the fundamentals of railway track circuits, including the maintenance and operation of rusty rails and audio frequency track circuits. Learn about the tools and procedures essential for ensuring the safety and efficiency of train movements. This quiz covers the technical aspects of track circuits and their implications in railway operations.