Track Circuits Overview

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Questions and Answers

What is the primary purpose of quarterly interchanging DC track relays?

To prevent permanent magnetisation.

List three visual checks that must be conducted on track relays during inspections.

Movement of armature, wiping of contacts, and arcing of contacts.

What action should be taken if a defective track relay is found during inspection?

The defective relay should be replaced immediately, and a report on the defects must be submitted.

How often should plug-in type track relays be replaced?

Every 12 years, or earlier if warranted by the condition or usage. Signup and view all the answers

What is the importance of having components ready before opening an insulated rail joint?

It ensures a smooth and efficient replacement process without unnecessary delays. Signup and view all the answers

What must be done if there is no gap at the insulated rail joint when replacing an end-post?

Loosen the rail fastening, pull back the rail, and insert the end-post between the rail ends. Signup and view all the answers

Why is it imperative to properly pack at least three sleepers on either side of an insulated rail joint?

To maintain track stability and integrity throughout the joint area. Signup and view all the answers

What maintenance procedure must be followed regarding fish bolts?

Fish bolts must be kept tight. Signup and view all the answers

Why is it important for the track circuit rail to be series bonded?

To ensure that defective bonding cannot cause a wrong side failure of the track circuit. Signup and view all the answers

What is a major consideration regarding traction return in rail bonding?

The traction return rail cannot be series bonded to avoid disconnection risks that may lead to loss of train shunt. Signup and view all the answers

What occurs if there is a break in the uninsulated rail of a single rail track circuit?

Very heavy current will flow through the track relay and equipment at the feed point. Signup and view all the answers

How should uninsulated rails be bonded to prevent excessive current flow?

The uninsulated rails of adjacent tracks should be cross bonded at intervals of no more than 100 meters. Signup and view all the answers

What type of wire is provided on traction masts in single line track circuited sections?

A continuous earth wire capable of carrying full traction return current. Signup and view all the answers

What must be done to connect uninsulated rails to traction masts?

Structure bonds must be riveted at both ends to connect uninsulated rails to each traction mast. Signup and view all the answers

What should not be connected to the running rails in double rail track circuits?

No structure bonds, cross bonds, or connections to earth wires or return conductors should be made. Signup and view all the answers

What is a potential installation method for double rail circuits when necessary?

An impedance bond must be specially installed to provide a neutral point for necessary connections. Signup and view all the answers

What are the two modes in which an Audio Frequency Track Circuit can operate?

Local fed and remote fed modes. Signup and view all the answers

List the components of an Audio Frequency Track Circuit.

Tuning unit, transmitter, receiver, power supply, track connections, and impedance bond. Signup and view all the answers

What precautions should be taken regarding the connection of the rail and tuning unit during installation?

Ensure the tightness of the connection. Signup and view all the answers

What is prohibited at the terminal junctions on insulated joints within the same frequency?

Connecting track circuits with the same frequency. Signup and view all the answers

Why is circuit pairing important when wiring and installing track circuits?

Circuit pairing prevents significant cross talk levels in adjacent circuits. Signup and view all the answers

What protective measures should be installed to safeguard electronic equipment from atmospheric voltage surges?

Protection against both common mode and differential mode voltages. Signup and view all the answers

How should the transmitter, receiver, and power supply be mounted for maintenance?

In a standard relay rack allowing maintenance staff to view the track relay. Signup and view all the answers

What should the design and installation of field equipment consider?

Requirements for mechanised track maintenance and safety for personnel. Signup and view all the answers

What is the primary purpose of locating the Relay End and Feed End at the boundaries of a track circuit?

To ensure effective monitoring and control of the track circuit boundaries. Signup and view all the answers

Why should all contacts of the track relay be loaded as much as possible?

To enhance reliability and minimize the risk of false detections in the track circuit. Signup and view all the answers

How should jumper connections be arranged to ensure they are effective?

They should be made in series and protected from damage while considering rail creep. Signup and view all the answers

What minimum cross-section should galvanized iron wire used for short jumpers be?

The cross-section should not be less than 8 SWG. Signup and view all the answers

What type of conductor is recommended for the lead wires connecting feed sets to junction boxes?

Copper conductor with a minimum cross-section of 2.5 sq.mm. Signup and view all the answers

What is the maximum resistance of rail and bonding per 1000 meters for track circuits longer than 700 meters?

The maximum resistance should not exceed 0.5 ohm. Signup and view all the answers

What methods can be employed for securing bond wires near fish plates?

Bond wire clips and securing them with channel pins or by brazing/welding. Signup and view all the answers

Why is it recommended to use duplicated jumper connections?

To provide redundancy and minimize the risk of connection failures. Signup and view all the answers

What applications may benefit from the use of Axle Counters instead of conventional track circuits?

Applications include Intermediate Block Stop Signaling, Automatic block signaling, poor drainage stations, Block Section Proving of Clearance, rust-prone tracks, and tunnels or bridges. Signup and view all the answers

Why might Digital Axle Counters be preferred on girder bridges?

Digital Axle Counters may be preferred due to their improved accuracy and reliability in detecting train presence in challenging conditions. Signup and view all the answers

What is the purpose of trolley suppression in the context of Axle Counters?

Trolley suppression is designed to prevent Axle Counters from incorrectly counting the wheels of motorized trolleys, ensuring accurate train detection. Signup and view all the answers

What installation guidelines must be followed for Axle Counters?

The installation must follow the OEM's prescribed guidelines and an approved pre-commissioning checklist. Signup and view all the answers

In what scenarios can trolley suppression provision be omitted during installation?

Trolley suppression can be omitted in sections using non-metallic wheels or in point zone portions with approved circuits. Signup and view all the answers

What role does the installation of trolley suppression arrangements play in Axle Counter operation?

Trolley suppression arrangements ensure that insulated trolleys do not trigger the Axle Counter, thereby maintaining system accuracy. Signup and view all the answers

List one specific location type where the installation of Axle Counters is beneficial.

Axle Counters are beneficial in flood-prone sections due to their effectiveness in such challenging environments. Signup and view all the answers

What aspect of Axle Counter technology is expected to improve in future models?

Future models are expected to include an inbuilt provision of trolley suppression, enhancing their functionality. Signup and view all the answers

What should the Station Master do after an Axle Counter failure?

The Station Master should verify the clearance of the block section with the Assistant Station Master by exchanging private numbers and recording it in the Train Signal Register. Signup and view all the answers

How is the reset operation of the Axle Counter controlled between stations?

The reset operation must be initiated cooperatively between the ASMs of both the dispatching and receiving stations, preventing independent resetting. Signup and view all the answers

What must happen before the Axle Counter can be reset?

The block section must be verified as clear of any obstructions or vehicles before initiating a reset. Signup and view all the answers

What role does the reset box play in the Axle Counter system?

The reset box, operated by a locked key, allows for controlled resetting of the Axle Counter while being monitored by a non-resettable counter. Signup and view all the answers

What should be checked by Signal and Traffic Inspecting officials during station inspections?

Officials should check and ensure that the exchange of private numbers between ASMs is being followed meticulously. Signup and view all the answers

What is the importance of the Line Verification box (LV box) in this context?

The LV box is utilized for the physical verification of a failed track section to ensure it is free from obstruction before receiving a train. Signup and view all the answers

What is documented in the Train Signal Register during the reset process?

The Train Signal Register records each operation of the reset button, noting the movement of trains before and after resetting. Signup and view all the answers

What established rules govern the procedure for resetting the Axle Counter?

The Station Working Rules clearly lay down the procedure for resetting and the verification of clearance. Signup and view all the answers

What indication should be displayed on the panel when a track line is unoccupied?

Yellow/white Light Signup and view all the answers

What is the maximum excitation limit for QBAT Relays according to the specified guidelines?

235% Signup and view all the answers

In what scenario should plug-in type track relays exclusively be used?

Future installations in both Non-RE & RE areas. Signup and view all the answers

What should be the minimum excitable voltage for a DC Track Relay as per the regulations?

125% of its rated pick up voltage. Signup and view all the answers

What should be the maximum length of track circuits as per different track parameter conditions?

Specified in the provided table, adhering to conditions. Signup and view all the answers

What is the minimum ballast resistance required for track in the block section?

4 ohms per km Signup and view all the answers

How often must the track circuited portion of the track be inspected jointly by S&T and Permanent Way Inspectors?

At least once every six months. Signup and view all the answers

What should be done if abnormal readings are noted during track circuit tests?

Suitable remedial action shall be taken. Signup and view all the answers

What is the significance of maintaining the percentage of missing insulated liners for the track circuit length?

It should not exceed 3%. Signup and view all the answers

What specific attention must be given to track drainage during rainy conditions?

Defects must be reported to the SSE/JE(P-Way). Signup and view all the answers

How frequently should a Train shunt test be conducted?

Every quarter and every time the track circuit is adjusted. Signup and view all the answers

What is the minimum availability of insulated liners required when using PSC Sleepers?

A minimum level of 97%. Signup and view all the answers

What must be reported regarding defective valves of overhead water pipes in track circuited areas?

They must be reported to the Inspector of works SSE/JE(Works). Signup and view all the answers

What specific requirement must be met for both rails in an Audio Frequency Track Circuit?

Both rails must be balanced with respect to earth and current flow. Signup and view all the answers

Why are impedance bonds necessary in the design of Audio Frequency Track Circuits?

They are necessary to balance the traction rail return current where no other provisions are present. Signup and view all the answers

What is the maximum continuous current that AC impedance bonds should support?

AC impedance bonds should support a continuous current of 400 Amperes. Signup and view all the answers

What is the primary distinction between AC and DC impedance bonds?

AC impedance bonds are generally designed for lower traction current ratings than DC impedance bonds. Signup and view all the answers

What conditions must be considered in the design and installation of impedance bonds?

Design and installation must consider mechanized track maintenance and safety for personnel. Signup and view all the answers

What should be done to the leads between impedance bonds across IRJ on the same track?

They must be capable of carrying the traction current. Signup and view all the answers

What is the significance of examining Electric Traction Units for harmonics before service?

It is crucial to identify any potentially harmful harmonics that could affect overall performance. Signup and view all the answers

Why are impedance bonds designed for AC traction systems not suitable for DC traction systems?

They are not suitable because AC impedance bonds are typically rated for lower currents than necessary for DC systems. Signup and view all the answers

What is the maximum allowable resistance for rail bonding per 1000 meters for track circuits that are shorter than 700 meters?

1.5 ohms Signup and view all the answers

How far should track circuit termination be from the Fouling Mark?

At least 3 meters Signup and view all the answers

What should be ensured before the installation of an insulated joint?

Compliance with permanent way requirements in Para no. 17.1.2 Signup and view all the answers

Where should insulated rail joints ideally not be installed?

On the outer rail in curves Signup and view all the answers

What is the minimum spacing required between tracks in existing yards?

4.265 meters Signup and view all the answers

What's the main impact of incorrect installation sizes of insulated rail joint components?

It may lead to malfunction or safety hazards. Signup and view all the answers

What installation should be done by the Civil Engineering Department according to the text?

Installation of glued rail joints Signup and view all the answers

What happens to track relays when cut section track circuits are de-energized?

They open the track feed and shunt the track circuit. Signup and view all the answers

What minimum distance must be maintained between adjacent axle detectors, and why?

The minimum distance must be at least 2 meters to minimize mutual interference. Signup and view all the answers

What is the purpose of installing deflectors near axle detectors?

Deflectors are installed to protect axle detectors from damage caused by hanging parts of moving trains. Signup and view all the answers

How should cables between axle detectors and track side electronics be managed?

Cables should be terminated on a cable distribution board for testing, and transmitter and receiver coil cables must be laid in different pipes. Signup and view all the answers

What is the recommended ripple limit for input power supply to track side electronic equipment?

The maximum ripple limit for the input power supply shall be 50 mV peak to peak or 10 mV rms. Signup and view all the answers

Where should the evaluator be installed, and why is the location significant?

The evaluator should be installed in a relay room or inaccessible location to protect it from unauthorized access and environmental damage. Signup and view all the answers

What measures should be taken to avoid vibration of track devices under train movement?

A minimum of 400 mm sleeper spacing must be ensured, and proper packing of sleepers should be conducted. Signup and view all the answers

What type of power supply is recommended for track side electronic equipment in remote locations?

Separate power supply systems should be used for track side electronic equipment in remote locations. Signup and view all the answers

What precautions need to be taken regarding electromagnetic interference when installing electronic equipment?

Electronic equipment should be located away from sources of heavy electromagnetic interference like industrial machinery. Signup and view all the answers

What is a significant reason for the quarterly interchanging of DC track relays?

To prevent permanent magnetisation of the relays. Signup and view all the answers

Why should the defective track relay be immediately replaced without attempts to repair it?

Because unauthorized repairs can lead to further malfunctions or safety hazards. Signup and view all the answers

What condition must be ensured regarding the rail fastening during the replacement of an end-post?

The rail fastening should be loosened to allow the rail to be pulled back. Signup and view all the answers

What should be visually checked to ensure the integrity of the track relay contacts?

Wiping of contacts, arcing, and any pitting or charring. Signup and view all the answers

Which components must be prepared before opening an insulated rail joint?

The replacement components conforming to the rail section. Signup and view all the answers

What is the minimum distance recommendation for packing sleepers on either side of an insulated rail joint?

At least three sleepers should be packed properly. Signup and view all the answers

What are the main conditions for the maintenance of insulated rail joints according to the guidelines?

Components must match the rail section, and sleepers must be adequately packed. Signup and view all the answers

What role does the visual inspection play in the maintenance of track relays?

It helps identify defects that could affect relay performance and safety. Signup and view all the answers

Study Notes

Track Circuits General

Track circuits use closed-type systems to detect train clearance.
Double rail track circuits are used in non-RE areas, while single rail DC for RE and double rail for AFTC are used in RE areas.
Track circuits must cover at least two rail lengths (26 meters).
Minimum circuit length is determined by the maximum wheelbase of any vehicle.

Permanent Way Requirements of Track Circuits

Glued/insulated joints define track circuit boundaries.
Glued joints should be inspected before installation.
Staggered joint spacing should not exceed minimum vehicle wheelbase.
Rail ends of joints should be square and true.
Fish bolts at joints must be tight, and sleepers well-packed.
Proper drainage to avoid flooding during rain is essential in yards.
Ballast should be kept clean around rails and fastenings.
Clearance from rail foot to formation level should be at least 50mm.

Location of Track Relays

Locate relays at the entry end of track circuits, whenever possible.
If relays cannot be located in the cabin, use an approved location.
Mount relays on vibration-reducing surfaces (e.g., rubber pads, foam).
Wire connections follow approved diagrams, incorporating cross-protection and double cutting.
Use separate cables for feed and relay ends.

Track Circuit Terminations

For track circuited points or lines, terminations should be sufficiently before the Fouling Mark.
The distance from the termination to the Fouling Mark should not be less than 3 meters.
In cut section track circuits, track relays are de-energized to open track feed and shunt the circuit.
Insulated rail joints should be used in accordance with standard guidelines.

Track Indicators

Track indicators show no light when lines are unoccupied.
If action is initiated, indicators show yellow/white (for unoccupied routes) or red (for occupied lines).
Panel interlocking/route relay indicates track clearance until sub-route/route is released.
For berthing tracks, individual track circuit status indicators are desired.
Track indicators show yellow/white for unoccupied lines, and red for occupied lines.

Track Relays

Use DC track relays of approved design.
Plug-in type relays (9Ω) are preferred for new installations in Non-RE and RE areas.
Use Q series track relays together with Q series slow relay for repeaters.
Excitation of DC track relays shall not exceed 235% for QBAT and 300% for other plug-in type relays.
Maximum track circuit lengths depend on different parameters (table provided in the text).

Track Feed

Use approved secondary cells for track circuits, with battery chargers/solar panels.
Provide a separate feed for each track circuit.

DC Track Relays

Maintain pick-up and drop-away values within manufacturer's specifications.
Inspect track relays quarterly for armature/contact carriage movement, contact arcing, dust, corrosion, cracks, and fungus.
Defective relays should be replaced immediately, with a report submitted to authorities.
Replace plug-in type relays after 12 years, or as condition warrants.

Insulated Rail Joints

Follow RDSO instructions for insulated rail joint installation.
Use "J" type clips.
Avoid hammering fish bolts, maintain correct alignment.

Bond Wires/Rope Wires

Use approved bond wires/rope wires.
Duplicate wires should be close to fish plates.
Secure wires by clips, drilling holes or brazing.
Resistance per 1000 meters should not exceed 0.5 ohms (for tracks more than 700 meters), up to 1.5 ohms for tracks less than 700 meters.

Stretcher Bars and Point Rodding Connections

Conduct periodic checks of insulation for stretcher bars/point rodding.
Replace defective insulation.

Ballast

Ballast resistance per km should not be less than 2 ohms in station yards, 4 ohms in block sections.

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Description

This quiz covers essential concepts related to track circuits used in railway systems. Learn about the components of track circuits, including their requirements, types, and proper installation practices. Test your knowledge on the key aspects that affect train clearance and safety.