Podcast
Questions and Answers
What must be strictly followed according to the frequency assignment scheme for track circuits?
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?
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?
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?
Why should circuit pairing be observed when wiring track circuits?
How far must TUs and ETUs be mounted from the near rail for safety?
How far must TUs and ETUs be mounted from the near rail for safety?
What must not be done in case of a track circuit failure?
What must not be done in case of a track circuit failure?
What kind of protection must be installed on each pair of conductors connected to the outside?
What kind of protection must be installed on each pair of conductors connected to the outside?
Which statement is true regarding the bonding of fish plated joints?
Which statement is true regarding the bonding of fish plated joints?
What action should be taken when rusty rails are present in track circuited areas until axle counters are installed?
What action should be taken when rusty rails are present in track circuited areas until axle counters are installed?
What is a distinct advantage of Audio Frequency Track Circuits?
What is a distinct advantage of Audio Frequency Track Circuits?
Which of the following is NOT a component of the Audio Frequency Track Circuit?
Which of the following is NOT a component of the Audio Frequency Track Circuit?
What must be ensured about the operation of Audio Frequency Track Circuit?
What must be ensured about the operation of Audio Frequency Track Circuit?
What is one of the features of an Audio Frequency Track Circuit?
What is one of the features of an Audio Frequency Track Circuit?
Which type of configuration can Audio Frequency Track Circuits be used in?
Which type of configuration can Audio Frequency Track Circuits be used in?
What should be strictly followed during the installation of track circuits?
What should be strictly followed during the installation of track circuits?
Which condition prevents the installation of axle counters in relation to rusty rails?
Which condition prevents the installation of axle counters in relation to rusty rails?
Flashcards
Track Circuit Tuning Area
Track Circuit Tuning Area
The area where track circuits are tuned for optimal performance, free from interference sources.
Fish-plated Joint Bonding
Fish-plated Joint Bonding
Each fish-plated joint in the tuning area must have adequate thickness jumpers installed for bonding.
Track Circuit Frequency Assignment
Track Circuit Frequency Assignment
A pre-determined scheme for assigning frequencies to track circuits to prevent interference.
Terminal Junction Restrictions
Terminal Junction Restrictions
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Track Circuit Cable Core Separation
Track Circuit Cable Core Separation
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Track Cable Circuit Pairing
Track Cable Circuit Pairing
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Field Equipment Safety
Field Equipment Safety
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Atmospheric Surge Protection
Atmospheric Surge Protection
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Rusty Rail Track Circuits
Rusty Rail Track Circuits
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Axle Counters
Axle Counters
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Audio Frequency Track Circuits (AFTC)
Audio Frequency Track Circuits (AFTC)
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IRJs (Insulated Rail Joints)
IRJs (Insulated Rail Joints)
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AFTC Time Delay
AFTC Time Delay
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Track Circuit Configuration
Track Circuit Configuration
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AFTC Power Supply Types
AFTC Power Supply Types
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AFTC Components
AFTC Components
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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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