Track Circuits Overview and Requirements

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Questions and Answers

What is the maximum length of track circuit for QBAT relays with the appropriate choke?

750 meters (correct)

1000 meters

500 meters

1500 meters

What additional component is required for operating a track circuit with QBAT relays?

One booster transformer

One 'A' type choke

Four cells delivering 8.8 V (correct)

Two impedance bonds

Which current level allows retaining the existing length of DC track circuit on single-track sections?

800 Amperes (correct)

1200 Amperes

1000 Amperes

600 Amperes

What is the specified limit of stray DC current for track circuits less than 100 meters?

10 milli-amperes Signup and view all the answers

What should be used on sections where the catenary current exceeds 300 Amperes?

Audio Frequency Track Circuit Signup and view all the answers

What is required to protect equipment from the effects of rail voltage?

Choke coil of approved type Signup and view all the answers

Where should impedance bonds be provided in double rail track circuits?

At the rail joints (IRJs) Signup and view all the answers

What is the appropriate action if stray current exceeds the specified limits?

Use a different type of track circuit Signup and view all the answers

What is the first step maintenance staff must take before starting maintenance activities on Axle Counters?

Take proper disconnection and de-energize sections Signup and view all the answers

Which activities can be performed without disconnecting the Axle Counters?

Measurement of parameters that does not interfere with the system Signup and view all the answers

What should be checked during periodic preventive checks by maintenance staff?

That axle counters are properly fitted and connections are intact Signup and view all the answers

What action should be taken if damage or irregularity is noticed near the trackside?

Immediately attend to damages by disconnecting the track section Signup and view all the answers

What is highly desirable for monitoring the working of axle counters?

Monitoring through Dataloggers with suitable interface Signup and view all the answers

What is included in the Maintenance Schedules of Appendix I?

Maintenance Schedule of Digital Axle Counter (DAC) Signup and view all the answers

What type of measurements should be taken before the installation of DC Single Rail Track Circuits?

Measurement of Stray Direct Current Signup and view all the answers

What is required before reconnecting the Axle Counters after maintenance?

Physical clearance of the track section and checking parameters Signup and view all the answers

What should be done if an axle counter cannot be reset?

It should be treated as failed Signup and view all the answers

Which staff is responsible for advising if an axle counter fails?

Signalling maintenance staff Signup and view all the answers

According to the maintenance guidelines, what is crucial to prevent differential creep?

Anchor 4 rail lengths on either side Signup and view all the answers

What should be avoided when maintaining axle counters?

Disconnection of track devices during active systems Signup and view all the answers

What is a necessary procedure when performing maintenance on axle counters?

Use the manufacturer's technical manuals Signup and view all the answers

What is the role of the Permanent Way staff in axle counter maintenance?

To monitor track anchoring and prevent creep Signup and view all the answers

Why should Tie Tamper be avoided on sleepers adjacent to track devices?

It may disrupt the performance of axle counters Signup and view all the answers

What is a key factor when managing axle counters in a working system?

Ensuring no adjustments during active conditions Signup and view all the answers

What is the maximum rail resistance permitted per 1000 meters for track circuits less than 700 meters in length?

1.5 ohm Signup and view all the answers

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

At least 3 meters Signup and view all the answers

What should be ensured before installing an insulated rail joint?

Compliance with permanent way requirements Signup and view all the answers

Where should insulated rail joints be avoided as much as possible?

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

What is the minimum spacing allowed between tracks for existing yards?

4.265 meters Signup and view all the answers

What should happen when the track relays concerned are de-energized in cut section track circuits?

The track feed opens and shunts the circuit Signup and view all the answers

What is the purpose of using a bond press for impedance bond connections?

To fix lugs by pressing rivets into the rail Signup and view all the answers

Which department is responsible for installing glued rail joints?

Civil Engineering Department Signup and view all the answers

What type of track circuit configuration is required for the Audio Frequency Track Circuit?

Double rail track circuit Signup and view all the answers

What is used to balance the traction rail return current in an Audio Frequency Track Circuit when no provision exists?

Impedance bond Signup and view all the answers

What is the maximum continuous current an AC impedance bond should support?

400 Amperes Signup and view all the answers

Which statement is true about impedance bonds used for AC traction systems compared to DC traction systems?

AC impedance bonds are not suitable for use on DC traction systems. Signup and view all the answers

Which department is responsible for the provision and maintenance of connections between rail and impedance bonds?

S&T department Signup and view all the answers

What is the designed peak loading capacity of an AC impedance bond for a short duration?

1000 Amperes for 5 minutes Signup and view all the answers

How should leads between impedance bonds be designed across the Insulated Rail Joints (IRJ)?

By using PVC sheathed cables Signup and view all the answers

What is a critical examination required for Electric Traction Units before service?

Examination for harmonics generated Signup and view all the answers

What is the minimum distance required between two adjacent axle detectors of different axle counters?

2 meters Signup and view all the answers

What is the purpose of deflectors provided near axle detectors?

To protect against damage from moving trains Signup and view all the answers

What is the recommended maximum ripple in the power supply for track side electronic equipment?

50 mV peak to peak Signup and view all the answers

Where should the evaluator typically be installed?

In a relay room or inaccessible area Signup and view all the answers

What should be done to the cable distribution board connected to the incoming cables from axle detectors?

It should provide a facility for testing. Signup and view all the answers

What distance should be maintained for sleeper spacing between the track device and adjacent components?

400 mm Signup and view all the answers

Which of the following describes a suitable location for installing track side electronic equipment?

Above the flooding level and away from heavy electromagnetic interference Signup and view all the answers

What is the purpose of laying transmitter and receiver coil cables in different pipes?

To minimize mutual interference Signup and view all the answers

What is the correct maximum excitation limit for QBAT relays?

235% Signup and view all the answers

Which track relay design is required for future installations in both Non-RE and RE areas?

Plug in type track relays (9 ohm) Signup and view all the answers

How should track circuits be indicated when the line is occupied?

Red Light Signup and view all the answers

What is the purpose of the Q series slow to pick up relay in conjunction with the Q series track relay?

To act as a repeater relay Signup and view all the answers

What feature must limiting resistance of DC track circuits possess?

It must be adjustable and of an approved type Signup and view all the answers

What is a typical application for Axle Counters in railway signaling?

Intermediate Block Stop Signaling Signup and view all the answers

In which scenario should trolley suppression not be implemented with axle counters?

On sections with non-metallic wheels Signup and view all the answers

Which factor does not affect the requirement for using digital axle counters?

Type of signal systems used Signup and view all the answers

What is a recommended installation guideline for axle counters?

Follow the OEM installation guidelines Signup and view all the answers

Which scenario is least likely to require the use of axle counters?

Section with excellent drainage Signup and view all the answers

What specific wheel type should axle counters avoid counting?

Four spoke wheels of push trolleys Signup and view all the answers

When is it permissible to eliminate trolley suppression arrangements?

In areas without trolley operation Signup and view all the answers

What feature should be included in axle counters for specific trolley operation scenarios?

Inbuilt trolley suppression Signup and view all the answers

What is the primary purpose of series bonding in track circuits?

To prevent wrong side failures due to defective bonding. Signup and view all the answers

Why is bonding disconnection to the traction return rail particularly risky?

It minimizes the risk of train shunt loss. Signup and view all the answers

When cross bonding uninsulated rails, how frequently should bonds be installed?

At intervals of not more than 100 meters. Signup and view all the answers

What must be ensured when tuning the impedance bond within a track circuit?

The resonating capacitor should match the frequency of the track circuit. Signup and view all the answers

What is a primary factor that affects the maximum length of a track circuit?

The ballast resistance and track layout. Signup and view all the answers

In single line track circuit sections, what role does the continuous earth wire play?

It carries the full traction return current. Signup and view all the answers

What is strictly prohibited in double rail track circuits regarding structural connections?

Connecting structure bonds or earth wires to running rails. Signup and view all the answers

Which precaution should be taken if a track circuit failure occurs?

Investigate the reason for voltage drift before making any adjustments. Signup and view all the answers

In single rail DC track circuits, what is the characteristic of the uninsulated rail?

It carries the traction return current. Signup and view all the answers

What should happen in the case of a break in the uninsulated rail during a single rail track circuit operation?

Heavy current will flow through the track relay. Signup and view all the answers

Which type of track circuit configuration is permitted when using electric separation joints?

It can only be a double rail circuit. Signup and view all the answers

What setup is required for impedance bonds in double rail track circuits?

They require a neutral point for safe connections. Signup and view all the answers

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

2 meters minimum. Signup and view all the answers

How are structured bonds on traction masts installed?

By riveting at both ends. Signup and view all the answers

What is crucial during the mounting process of track components?

To maintain a distance of at least two meters from nearby structures. Signup and view all the answers

What configuration is not permitted for track circuits with electrical separation joints?

Single rail track circuit. Signup and view all the answers

What is the first step that an ASM must take when an Axle Counter has failed?

Verify the clearance of the block section with the receiving station Signup and view all the answers

What ensures that the reset operation cannot be initiated independently at the dispatching or receiving stations?

The circuitry design of the Axle Counter system Signup and view all the answers

During inspection, which protocol must Signal and Traffic Inspecting officials specifically verify?

Systematic exchange of private numbers between stations Signup and view all the answers

What type of verification is required before the reset of an Axle Counter?

Manual clearance of the section ensuring no obstructions Signup and view all the answers

What is the physical device used for verifying the failed Track section?

Line verification box (LV box) Signup and view all the answers

How is the operation of the reset button recorded?

In the Train Signal Register by both SMs Signup and view all the answers

What mechanism must be followed after confirming that the block section is clear?

Start the cooperative reset operation between the ASMs Signup and view all the answers

Which of the following maintains a record of the movement before and after resetting the Axle Counter?

The Train Signal Register Signup and view all the answers

What is a suitable reason for placing track side electronic equipment close to axle detectors?

To minimize the length of cable used Signup and view all the answers

Why should the deflectors be provided near axle detectors?

To prevent damage from falling debris from trains Signup and view all the answers

What contributes to the need for a minimum sleeper spacing of 400 mm between the track device and other components?

To prevent vibrations from affecting device stability Signup and view all the answers

What is the maximum ripple allowed in the power supply for track side electronic equipment?

50 mV peak to peak Signup and view all the answers

Where is it preferable to install the evaluator in relation to other equipment?

In a relay room or an area inaccessible to unauthorized persons Signup and view all the answers

What is the requirement for the placement of transmitter and receiver coil cables?

To keep them in different pipes as prescribed by OEM Signup and view all the answers

What type of power supply is preferred for operating track side electronic equipment?

A central DC–DC converter with adequate battery backup Signup and view all the answers

What is essential to ensure the installation of the cable distribution board connected to axle detectors?

It should be accessible for frequent testing Signup and view all the answers

Study Notes

Track Circuits General

Closed-type track circuits are used to confirm rail track clearance.
Double-rail track circuits are required in non-RE areas. Single-rail DC and double-rail AFTC track circuits are used in RE areas.
Track circuit length must be at least the maximum wheel base of any vehicle and cover at least two rail lengths (26 meters).
Track sections should be connected in series.
Approved track relays are required.

Permanent Way Requirements of Track Circuits

Glued joints or insulated joints of approved types define track circuit boundaries.
Future track circuits should use glued insulated joints, tested before installation.
Staggered joints' spacing should not exceed minimum vehicle wheel base.
Rail ends of joints should be square, smooth, and the gap equal to end post thickness.
Fish bolts must be tight and sleepers firmly packed around joints.
Drainage is necessary to prevent flooding, especially in yards where coaches are watered. Washable concrete aprons are recommended at platform lines.
Ballast must be clean, and clearance from rail ends must be at least 50 mm.
Properly screened ballast shall be maintained up to formation level.

Location of Track Relays

Relays are placed at the entry point of the track circuit wherever possible.
If location in cabin/relay room is not possible, an approved location must be used.
Relays in vibration-prone areas should be mounted using shock absorbers like rubber or foam pads.
Electrical connections between relays and repeating relays must follow approved wiring diagrams and incorporate cross-protection and double-cutting arrangements.
Separate cables should connect the feed and relay ends.

Jumper Connections

Jumper connections should connect the rails in series, except traction return rail. If parallel, connections must be effective and protected from damage.
Galvanized iron wire (at least 8 SWG) or cable (larger than 7.0750mm) is used for short jumpers, and cables for long jumpers.
Lead wires connecting feed/relay to junction boxes (JBs) must have a minimum cross-section of 2.5 sq.mm.
Track lead JBs must be clear of ballast.
Individual, paralleled 2.5 square mm cables are used for feed end and relay end connections.+ve and -ve leads.

Track Circuit Terminations

Track circuit termination at stations should be placed before the fouling mark to avoid vehicle infringement, with distance of at least 3 meters.
Cut-section track circuits should open the track feed and shunt the circuits when de-energized.
Insulated rail joints must comply with RDSO drawings and correct sizes/combinations.
Insulated rail joints shall, as far as possible, not be placed on the outer rail in curves.
Rail joints minimize dead zones (where no standing vehicle is detected)
Follow all permanent way guidelines in Para 17.1.2.
In the case of point track circuits, insulation joints should not be in the stock rail joint, rather in the rail joint ahead, where feasible.
Only "J" type clips should be used for glued joint track portions.

Track Indicators

Track indicators at panel-interlocked/route relay interlocked stations show no light for an unoccupied line.
When a route is set, the track indication shifts to yellow/white if unoccupied, or red if occupied.
The indicators show white/yellow when the track is clear after intended movement, and red when occupied.
It's desirable to have individual indicators per track in multiple-section configurations.

Track Relays

Use approved design DC track relays. Future installations should use plug-in type with 9 ohm value relays in Non-RE and RE areas.
Use Q-series relays with Q-series slow-to-pick-up relays as repeaters.
Track circuits' excitation voltage should be at least 125% rating and maximum 235% for QBAT and 300% for other plug in type relays.
Maximum track circuit lengths should not exceed permissible limits for different track parameter conditions.

Track Feed

Approved secondary cells are used for feeding track circuits.
Use battery chargers and/or solar panels.
One separate feed is required per track circuit.

DC Track Relays

Maintain pickup and drop-away values within manufacturer's specified limits.
Periodically inspect relays visually and address any issues.

Insulated Rail Joints (IRJ):

Follow RDSO guidelines/booklet No. STS/E/IRJ/IMI "Installation and Maintenance Instructions for Nylon Insulated Rail Joint."
Do not hammer in fishbolts.
Ensure end-posts are at rail table height.
Keep 3 sleepers on either side of the insulation joint packed well.
Keep fish bolts tight.
Address any metal flow/sharp burrs at rail ends.
Address brake block dust buildup on end posts.
Properly install, align, and secure all components.

Stretcher Bars/Point Rodding Connections:

Monitor insulation insulation for proper conditions and replace any defective insulation.

Bond Wires/Rope Wires:

Inspect and condition bond wires regularly.
Paint extensively corroded wires with aluminum paint.
Inspect bond wires every 15 rail lengths or less as needed, looking for variations in voltage readings or defective bonding.

Jumper Connections

Regularly inspect and maintain in good condition.

Ballast:

Maintain a minimum ballast resistance of 2 ohms/km at station yards and 4 ohms/km in blocks.
Minimum 97% insulated liner availability is required when PSC sleepers are used

Track Bonding

The objective is to provide a low-resistance path for traction return current, ensuring components do not exceed 25V to earth normally and 430V during short circuits.
Protective equipment function must not be compromised.
Track bonding plans, identifying positions of insulated joints, impedance bonds, etc., are required.
Maintain earth connections to traction system.

Axle Counters

Axle counters can function in place of track circuits in various applications.
Use of Digital Axle Counters may be preferable in certain applications, especially girder bridges.

Trolley Suppression

Ensure that axle counters do not register trolleys; specific procedures may need to be used in areas where trolleys are prevalent.

Axle Counter Resetting

Use a reset key kept in a separate box at the station master's office.
Operations must be recorded and verified.
Follow procedures for cooperative or main-line/run-through types resets.

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Description

This quiz covers essential aspects of track circuits, including their types and requirements for proper installation and maintenance. Learn about the various specifications that ensure safety and functionality in railway operations. Test your knowledge on track circuit designs and standards.