Signalling & Telecommunication Installations Quiz
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Questions and Answers

What type of signal system is generally used in double line electrified sections?

  • Light-emitting diode signals
  • Colour light signals (correct)
  • Digital signals
  • Analog signals

Which factor does NOT influence the induced voltage in metallic items parallel to the electrified track?

  • Temperature of the cables (correct)
  • Soil conductivity
  • Current carried by the OHE
  • Length of parallelism

Which method is employed to mitigate electrostatic induction in S&T circuits?

  • Employing high-voltage transformers
  • Using ceramic insulators
  • Transferring circuits to underground cables (correct)
  • Increasing cable lengths

What is a consequence of electrostatic and electromagnetic induction on S&T equipment?

<p>Development of currents and voltages in metallic items (A)</p> Signup and view all the answers

What precautions must be taken to address induced voltages in the S&T department?

<p>Implementing proper shielding for circuits (B)</p> Signup and view all the answers

What effect can OHE masts and fittings have on signalling?

<p>Interfere with the visibility of signals (C)</p> Signup and view all the answers

Which of the following is NOT a factor affecting induced voltage according to the content?

<p>Weight of the signals (D)</p> Signup and view all the answers

What factors are considered when determining the location of signals on curved tracks?

<p>Visibility of the signal (D)</p> Signup and view all the answers

What committee is responsible for deciding the location and height of signals?

<p>Signal Siting Committee (D)</p> Signup and view all the answers

What type of voltage can affect wires and point rods in AC electrified sections during an OHE fault?

<p>Induced voltage (D)</p> Signup and view all the answers

What is the primary purpose of using insulators on wires and point rods?

<p>To insulate from rail potentials and induced voltages (A)</p> Signup and view all the answers

Which of the following equipment requires earthing in sections electrified with 25 kV AC 50 Hz single-phase systems?

<p>Block instruments and surge arresters (C)</p> Signup and view all the answers

Why is it important to earth cables properly at both ends?

<p>To achieve the screening effect against induced voltages (C)</p> Signup and view all the answers

What is included in the earthing requirements of signal posts?

<p>Protective wire-mesh screens (A)</p> Signup and view all the answers

Which of the following statements is true regarding earthing of lever frames?

<p>They must be earthed to prevent electrical faults. (A)</p> Signup and view all the answers

What should be done where the electrical conductivity of joints in rail staging is questionable?

<p>The members should be bonded at the joints. (C)</p> Signup and view all the answers

What is the primary reason for replacing overhead telecommunication lines with underground cables in ac electrified sections?

<p>To protect against induced voltage exceeding 60 volts. (D)</p> Signup and view all the answers

How much more attenuation does a speech signal experience when transmitted through underground cables compared to overhead lines?

<p>Approximately five times the attenuation. (B)</p> Signup and view all the answers

Who has the control over the utilization of traction power center circuits?

<p>The Chief Electrical Engineer. (A)</p> Signup and view all the answers

Which of the following locations is NOT typically provided with tappings from traction power circuits?

<p>Commercial railway headquarters. (A)</p> Signup and view all the answers

What should be taken into account when providing capacities on circuits for electric traction?

<p>Current and future requirements. (D)</p> Signup and view all the answers

What is the maximum resistance allowed for an individual earth?

<p>10 ohms (C)</p> Signup and view all the answers

When the cable is laid at a depth greater than 0.5 m, what is the minimum distance it should maintain from the nearest edge of the traction mast foundation?

<p>3 m (C)</p> Signup and view all the answers

What precautions must be taken for cables laid in the vicinity of traction substations and feeding posts?

<p>Cables must be laid at least 1 m away from any metallic parts. (B)</p> Signup and view all the answers

What is the minimum distance required between the cables and the station earthing system at switching stations?

<p>5 m (B)</p> Signup and view all the answers

How far should cables be laid from the metallic structure of a switching station?

<p>1 m (C)</p> Signup and view all the answers

If traction masts/structures are along the cable route, what is the minimum distance the cable trench should be from the center of the track?

<p>5.50 m (B)</p> Signup and view all the answers

Where cables must cross the track, which material must be used for the crossing?

<p>Concrete or GI pipes (A)</p> Signup and view all the answers

In what situation can the distance of 5 m from the earthing system be reduced to 1 m?

<p>When cables are laid in concrete pipes (D)</p> Signup and view all the answers

What is the recommended distance for cables from an independent earth for an OHE mast or structure?

<p>At least 1 m away (C)</p> Signup and view all the answers

What specification typically governs the main signalling & telecommunication cable used in AC electrified sections?

<p>IRS Specification No. S-35 (D)</p> Signup and view all the answers

What is prohibited within 300m from the feeding post?

<p>Galvanized iron pipes (B)</p> Signup and view all the answers

Which type of cables are used to replace overhead communication lines?

<p>PVC insulated quads (D)</p> Signup and view all the answers

What is the maximum induced voltage allowed in a circuit within 3.5 km of parallelism?

<p>120 volts (A)</p> Signup and view all the answers

Which type of track circuits can be used on AC electrified sections?

<p>Voice frequency circuits (A)</p> Signup and view all the answers

What must be done if the parallelism of a circuit exceeds 3.5 km?

<p>Insert a relay to break the physical continuity (B)</p> Signup and view all the answers

What type of conductors replace overhead lines due to electromagnetic induction concerns?

<p>Underground cables (D)</p> Signup and view all the answers

What is necessary when feeding two circuits from a common power supply source?

<p>Separate batteries for each circuit (C)</p> Signup and view all the answers

Which of the following is NOT a type of track circuit mentioned for AC electrified sections?

<p>AC track circuits at 50 Hz (A)</p> Signup and view all the answers

What additional equipment is provided at both ends of block circuits for safety?

<p>Special protective devices (C)</p> Signup and view all the answers

What modification is required for track bonding in track circuited zones?

<p>Specific adjustments mentioned in Appendix 11 (D)</p> Signup and view all the answers

What type of change-over switch is required at unmanned IBHs?

<p>Two-position automatic switch (A)</p> Signup and view all the answers

Which component provides power supply from the AT to the ASM's room?

<p>2 x 25 MM2 aluminium cable (D)</p> Signup and view all the answers

What is the minimum required electrical clearance for signals in electrified sections from live conductors?

<p>2m (D)</p> Signup and view all the answers

What additional circuit is provided to ensure emergency lighting at way-side electrified stations?

<p>Dedicated circuit fused at proper rating (B)</p> Signup and view all the answers

Which precaution is mandatory when a signal post is located within 2m of live OHE and non-technical staff are involved?

<p>A protective screening mesh must be provided (C)</p> Signup and view all the answers

What should be done if tools or equipment might enter a 2m zone near live equipment?

<p>Implement a power block (D)</p> Signup and view all the answers

How long should the 80 Ah battery capacity at each cabin be sufficient for during supply failures?

<p>Two hours of supply failure (D)</p> Signup and view all the answers

What is the recommended distance between a signal post and a traction mast when positioned in front of each other?

<p>30m (C)</p> Signup and view all the answers

What type of equipment will be provided in the relay room for signal and relay supplies?

<p>Integrated power cubicles (A)</p> Signup and view all the answers

What height should a caution board be placed at when a protective screen is not provided?

<p>3m above rail level (A)</p> Signup and view all the answers

Which personnel are advised to follow special protective measures when working near signals without protective screens?

<p>Technical personnel only (C)</p> Signup and view all the answers

How should signal posts be positioned in relation to traction masts to maximize visibility?

<p>Opposite to traction masts (A)</p> Signup and view all the answers

What is the maximum resistance allowed for an individual earth connection?

<p>10 ohms (D)</p> Signup and view all the answers

What is the minimum distance required between the main S&T cable and the traction mast foundation when laid at a depth greater than 0.5 m?

<p>3 m (B)</p> Signup and view all the answers

In the vicinity of feeding posts, how far must the cable be laid from any metallic parts of the OHE?

<p>1 m (A)</p> Signup and view all the answers

What is the recommended action if it is difficult to maintain the specified distances for cable laying near traction mast foundations?

<p>Lay the cable in concrete pipes (C)</p> Signup and view all the answers

What is the minimum distance from any metallic structure at switching stations where the cable should be laid?

<p>1 m (D)</p> Signup and view all the answers

When laying cables in the vicinity of traction substations, what additional distance must be maintained from the station earthing system?

<p>5 m (B)</p> Signup and view all the answers

What is the result of laying cables at least 300 m in concrete pipes on either side of a feeding post?

<p>Prevent grounding issues (A)</p> Signup and view all the answers

What is the minimum distance that cables must be laid from an independent earth for an OHE mast or structure?

<p>1 m (D)</p> Signup and view all the answers

What precautions must be taken when cables have to cross the track?

<p>Use concrete or GI pipes (C)</p> Signup and view all the answers

What is the maximum length of a circuit length in a cable allowed to ensure the induced voltage does not exceed 120 volts?

<p>3.5 km (D)</p> Signup and view all the answers

What type of modifications needs to be made for track bonding in track circuited zones?

<p>Implementing specific changes as outlined in Appendix 11. (C)</p> Signup and view all the answers

What replaces overhead lines utilized for signalling and interlocking circuits due to high electromagnetic and electrostatic induction?

<p>Underground cables (C)</p> Signup and view all the answers

Which type of track circuit works effectively at frequencies other than 50 Hz to avoid interference?

<p>AC track circuits (C)</p> Signup and view all the answers

What action must be taken when the parallelism in excess of 3.5 km is due to feeding two circuits from a single power source?

<p>Provide separate batteries for each circuit. (A)</p> Signup and view all the answers

What is the main power supply method used at a station with a reliable local power source?

<p>Tapping the 25 kV catenary and installing a transformer (D)</p> Signup and view all the answers

How are auxiliary transformers utilized at stations with no local supply?

<p>Two transformers are connected to independent sub-sectors of the OHE (D)</p> Signup and view all the answers

Which among the following types of cables is suited for replacing block instruments working with overhead lines?

<p>PVC insulated quads (C)</p> Signup and view all the answers

What is the role of the manual three-position change-over switch at the CLS supply panel?

<p>To allow the ASM to control the power source manually (B)</p> Signup and view all the answers

What is required if parallelism of a circuit exceeds 3.5 km?

<p>Insertion of a relay to break circuit continuity. (C)</p> Signup and view all the answers

At what distance should an auxiliary transformer be installed near a traction switching post to treat the 240 V supply as the main supply?

<p>350 m (D)</p> Signup and view all the answers

What type of bonding systems are used to allow passage of traction current in track circuited zones?

<p>Resistance bonding systems (C)</p> Signup and view all the answers

What distance must cables maintain from the center of the track when traction masts are located along the cable route?

<p>5 m (B)</p> Signup and view all the answers

What is the minimum cable size required to connect the Auxiliary Transformers to the CLS supply panel?

<p>2 x 25 MM2 (C)</p> Signup and view all the answers

When should auxiliary transformers be provided at level crossings?

<p>When located more than 2 km from a railway station (D)</p> Signup and view all the answers

What is the purpose of special protective devices installed at both ends of block circuits?

<p>Protect instruments and operating staff. (C)</p> Signup and view all the answers

What configuration is ideal for providing power to several cabins at big yards?

<p>Two to three cabins grouped together with a set of two ATs (C)</p> Signup and view all the answers

What is the purpose of the CLS panel MCBs and neon indication lamps?

<p>To provide visual aid for incoming and outgoing supplies (A)</p> Signup and view all the answers

What alternative power source is integrated into the CLS supply panel when local supply is available?

<p>Third source from the local supply (C)</p> Signup and view all the answers

What additional infrastructure ensures power supply extension to other cabins from the CLS supply panel?

<p>2x25 mm2 cables laid by the Electric Department (B)</p> Signup and view all the answers

Flashcards

Effects of 25kV Traction on Signaling Equipment

Electrostatic and electromagnetic induction from overhead lines (OHE) impacts signaling circuits near electrified tracks. Electrostatic induction is mitigated by underground cabling. Electromagnetic induction creates voltages in parallel metallic items like rails and cable sheaths.

Electromagnetic Induction

The generation of voltage in a conductor due to a changing magnetic field near the conductor.

Electrostatic Induction

The transfer of charge to an object through an electric field.

Signal Types in Electrified Sections

Colour Light Signals (CLS) are typically used in double line electrified railway sections.

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Overhead Line Equipment (OHE) Visibility

Signal visibility might be reduced when OHE masts and parts block the view.

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Track Circuits

Part of a signalling system that detects the presence or absence of a train on a section of track.

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Signal Siting

Process of determining the best signal placement in areas with obstructions (like curves, buildings, etc.)

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Signal Siting Committee

A committee, including an electrical representative, that examines signal visibility before placement decisions.

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Wire and Point Rod Insulation

Insulators are necessary on wires and point rods in AC electrified areas to protect them from induced voltages.

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Induced Voltage

Voltage generated by OHE faults (Overhead line equipment) that could affect wires and point rods.

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Rail Voltage

Another name for induced voltage. It transmits through wires to lever frames.

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Earthing of S&T Equipment

Essential process for AC electrified sections, using prescribed instructions, for signal posts, lever frames, metallic sheaths, cables, block instruments, telecommunication equipment, and surge arresters.

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Protective Wire-Mesh Screens

Used on signal posts to enhance safety and prevent electrical hazards in AC electrified sections.

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Cable Earthing

Critical earthing of the cable sheath and armouring at both ends of underground cables to achieve screening from induced voltages.

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Block Instruments

Instruments used in signalling systems, which often use earth return circuits through block filters

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Telecommunication Equipment

Equipment used for communication within a section, and its components need to be earthed as prescribed.

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Cable Laying Distance (Traction Masts)

Cables near traction masts must be at least 1 meter from the mast foundation edge, but a minimum of 3 meters if deeper than 0.5 meters; concrete pipes may reduce this distance.

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Cable Laying Distance (Substations)

Cables near substations must be at least 1 meter away from metallic parts and the substation earthing system. A 300m length requires concrete pipes.

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Cable Laying Distance (Switching Stations)

Cables near switching stations must be at least 1 meter from metallic structures, and at least 5 meters from the earthing system; concrete pipes reduce this to 1 meter.

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Cable Laying Distance (Independent Earths)

If an overhead line mast has a separate earth, cables must be kept at least 1 meter from it.

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Cable Laying Distance (General)

Ideally, cables should be laid on the opposite side of the track to feeding posts, and a minimum of 5.50 meters from the track center.

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Cable Crossing Tracks

When cables cross tracks, concrete or GI pipes for the crossing are necessary.

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Earth Resistance Limit

Earth resistance should not exceed 10 ohms.

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Cable Insulation Type

Main signaling cables in electrified sections are usually made from PVC insulated, screened and armoured type materials.

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GI pipe prohibition near feeding posts

Metallic pipes, like galvanized iron pipes, are not allowed within 300 meters of a feeding post.

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Pipe prohibition near switch stations

Galvanized iron pipes are forbidden near switching station grounds and traction masts.

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Block instrument cable transfer

When overhead communication lines are replaced with cables, block instruments using earth return are moved to insulated special PVC underground cables.

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Track circuit types

Different types of track circuits can be used on electrified sections, including DC single rail, AC at different frequencies, and electronic voice frequency circuits.

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Track bonding modifications

Track bonding for traction current needs adjusting in areas where track circuits are employed.

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Signalling cable replacement

Overhead lines used for signalling and interlocking are replaced by underground cables due to electromagnetic interference.

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Cable circuit length limit

Cable circuits are limited to prevent induced voltages exceeding 120 volts (3.5 km parallelism).

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Relay insertion for large parallelism

If the parallelism is more than 3.5 km, using a relay interrupts the cable and reduces parallelism to within the 3.5 km limit.

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Parallelism and Multiple Battery Feeds

If a circuit exceeds 3.5km in parallelism due to it being fed from multiple batteries, it requires separate batteries for each section to limit the length to below 3.5km.

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Telecommunication Circuits (AC Traction)

Telecommunication lines running parallel to tracks on AC electrified sections should be replaced with underground cables to prevent induced voltage issues.

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Induced Voltage (Telecom)

Voltage created in a cable due to electrical fields/magnetic fields from the adjacent overhead lines.

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Isolating Transformers

Used to protect telecommunication equipment (way stations, subscribers' equipment, exchanges) from high induced voltages in underground cables.

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Underground Cables (Telecom)

Used to replace overhead lines in AC electrified areas because they're less susceptible to induced voltages.

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Attenuation (Telecom)

The loss of signal strength over a distance in a communication line.

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Repeaters (Telecom)

Used to boost signal strength in communication lines, especially those laid underground.

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Tapping (Traction Power)

Connecting to a circuit for use.

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Traction Power Control Circuit

A circuit used to regulate and control traction power systems.

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CEE Approval

Approval required by the Chief Electrical Engineer for tapping into specific traction power circuits.

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Signal Location in Electrified Sections

Signals must be placed for maximum visibility and with specific electrical clearances (at least 2m) from live conductors in electrified sections.

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Protection Screens for Signal Posts

Protective screens of wire mesh are needed when signal posts are within 2 meters of live overhead equipment (OHE) to safeguard non-technical staff.

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Signal Post and Traction Mast Spacing

Signal posts should be located as far as possible from traction masts to ensure driver visibility, with a minimum distance of 30m when the mast is in front.

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Signal Height for Visibility

Signal posts should be sufficiently tall for drivers to easily see them.

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Caution Boards for Signals

When protective screens are not feasible, caution boards must be placed on the signal post to alert personnel.

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Technical Personnel Precautions

Technical personnel working on signal posts need to take extra care when live equipment is nearby, potentially using power blocks.

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Staff and Equipment Safety

Prevent tools from getting too close to electrified equipment. Use power blocks as detailed in Chapter VI, near OHE and return conductors treated as live.

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GI pipe prohibition near feeding posts

Metallic pipes, like galvanized iron, are not allowed within 300 meters of a feeding post.

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Pipe prohibition near switch stations

Galvanized iron pipes are not allowed near switching station grounds and traction masts.

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Block instrument cable transfer

When overhead lines are replaced with cables, block instruments using earth return are moved to insulated PVC underground cables.

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Track circuit types

Different types of track circuits are used in electrified sections (DC single rail, AC at different frequencies, electronic).

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Track bonding modifications

Track bonding for traction current needs adjustment in areas with track circuits.

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Signalling cable replacement

Overhead signalling lines are replaced with underground cables to reduce electromagnetic interference.

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Cable circuit length limit

Cable circuits are limited to prevent induced voltages exceeding 120 volts (3.5 km parallelism).

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Relay insertion for large parallelism

If cable parallelism exceeds 3.5 km, a relay is inserted to break the physical continuity and reduce parallelism to within the limit.

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Parallelism and Multiple Battery Feeds

If a circuit exceeds 3.5 km in parallelism due to multiple battery feeds, separate batteries are needed for each section.

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Earth Resistance Limit

The maximum acceptable resistance of an earth connection, which should not exceed 10 ohms.

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Cable Laying Distance (Traction Masts)

Cables near traction masts must be at least 1 meter from the mast foundation edge, increasing to 3 meters if laid deeper than 0.5 meters; concrete pipes can reduce the distance.

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Cable Laying Distance (Substations)

Cables near substations require a minimum 1 meter distance from metallic parts and the substation grounding system, plus 300 m of concrete pipe.

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Cable Laying Distance (Switching Stations)

Cables near switching stations must be at least 1 meter from metallic structures and 5 meters from the station grounding system; concrete pipes can reduce the distance to 1 meter.

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Cable Laying Distance (Independent Earths)

If an overhead line mast has a separate earth, cables must be kept at least 1 meter away.

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Cable Laying (General)

Ideally, cables should be laid on the opposite side of tracks to feeding posts, and a minimum 5.50 meters from the center of the tracks.

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Cable Crossing Tracks

Where cables cross tracks, concrete or GI pipes must be used for the crossing.

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Cable Insulation Type

Signalling cables in electrified sections are usually made of PVC-insulated, screened, and armoured type material.

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Main Power Source (Electrified Stations)

At stations with reliable local power, the main power supply comes from the local source.

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Standby Power Source (Electrified Stations)

The backup power comes from a 25 kV/240 V auxiliary transformer connected to the catenary.

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Power Supply (No Local Source)

When no dependable local power exists, two 25 kV/240 V transformers are needed - each connected to the OHE (Overhead Line Equipment).

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Main Supply (Transformer Near Cabin)

If the auxiliary transformer is near the station cabin, the 240 V supply acts as the primary power.

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Standby Supply (Transformer Near Cabin)

A second 25 kV/240 V transformer is installed on another OHE section for a standby power supply where the auxiliary transformer is near the station cabin.

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Auxiliary Transformers (Wayside Stations)

Each wayside station needs two auxiliary transformers, one connected to the OHE for the up and down lines.

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Cable Connection (Auxiliary Transformers)

A 2 x 25 mm2 aluminum cable connects each auxiliary transformer to the control room.

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Control Supply Panel (CLS)

Power is received at the CLS panel, which also has local power if available, and a manual changeover switch.

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Level Crossing Power (2km +)

Two auxiliary transformers are required at each level crossing more than 2 km from a railway station.

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Big Yards Power Grouping

In big yards, multiple cabins are grouped and served by a set of two transformers connected to the OHE for up and down lines.

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CLS cable supply

The supply cable for Colour Light Signals (CLS) and the manual change-over switch

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Automatic change-over switch (IBH)

A two-position automatic switch for power supply at unmanned Isolated Block Huts (IBH).

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Single line CLS power

One Automatic Train (AT) connected to Overhead Line Equipment (OHE) is used for CLS supply in single line sections.

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LT supply extension

Low Tension (LT) supply from AT to ASM's room using 2x25mm2 aluminium cable.

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Wayside station power

Power supply arrangement for wayside stations, level crossings (beyond 2km from station) and IBHs, incorporating a change-over switch using local power if available.

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Emergency lighting

Emergency light points are provided at electrified wayside stations in ASM's room and cabins to ensure power in case of local supply interruptions, from AT via separate circuit with fuses.

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Non-electrified station lighting

Separate lighting circuits from the AT provide lights in ASM's room, platform, ticket window, waiting hall, and cable huts at non-electrified stations.

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S&T department works

The Signal & Telecommunication (S&T) department lays 2x25mm2 cable from ASM room to each cabin, along with signal control cables.

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Integrated power cubicles

Power cubicles with voltage stabilizer, inverter, and battery chargers are provided in relay rooms to supply signals and relays.

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Battery capacity (cabins/level crossings)

An 80 Ah battery backup is provided at each cabin and level crossing, sufficient for two hours of supply failure.

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Study Notes

Signalling & Telecommunication Installations in Electrified Sections

  • Introduction: Important points regarding signalling, telecommunication, and permanent way installations in electrified railway sections are grouped. Rules are detailed in the Indian Railways Telecom Manual for signalling and telecommunication staff and in the Indian Railways Permanent Way Manual for civil engineering staff. Safety guidelines for S&T and civil engineering departments are detailed in Chapter IV, Volume 1 of the manual.
  • Effects of 25 kV Traction on S&T Equipment: Circuits near overhead lines (OHE) are influenced by electrostatic and electromagnetic induction. Electrostatic induction is mitigated by using underground cables with metal sheaths. Electromagnetic induction creates currents and voltages in trackside metallic components (rails, return conductors, cable sheaths, S&T circuits) causing potential gradients. Voltage magnitudes depend on factors like length of parallelism, soil conductivity, cable sheath efficiency, return current paths, mutual inductance, and OHE current. Precautions must be taken by the signalling and telecommunications (S&T) department to mitigate effects of induced voltages.
  • Types of Signals: In double-line electrified sections, colour light signals (CLS) are commonly used, though semaphores might be used on single-line sections.
  • Signal Locations: Signals must provide maximum visibility to drivers with the signal structures clear of moving equipment. In electrified sections, signals must be at least 2 meters from live conductors. Precise locations are issued by the S&T department. Screens or caution boards may be required when signal posts are near OHE for safety of personnel, particularly if non-technical staff are required to work on them. Special care must be taken to protect personnel from live equipment. Visibility is a key consideration in locating signal posts, especially with respect to traction masts. Decisions need to be based on detailed instructions.
  • Signal Insulation: Wires and point rods are generally eliminated in ac electrified sections due to induced voltage risks. Where these components exist, insulators are installed for protection from induced voltages and rail voltages. Detailed instructions are provided in the Indian Railway Signal Engineering Manual (Chapter XXII).
  • Earthing of S&T Equipment: Earthing is essential on electrified sections. Signal posts with protective wire-mesh screens, lever frames, metallic sheaths of underground cables, block instruments, and telecommunication equipment must be earthed. Earthing resistance should not exceed 10 ohms.
  • Cable Specifications and Installation: Overhead signalling/telecommunication cables are usually PVC insulated, screened and armoured, laid according to S&T department instructions. Factors like distance from traction masts, overhead lines, sub-stations, and switching stations must be observed during cable installation. Cable trenches should be located at least 5.5 meters from the center of the track.
  • Block Instruments and Circuits: Block instruments working with overhead lines are transferred to underground cables with special protective devices.
  • Track Circuits: Several types of track circuits suitable for ac electrified sections include dc single rail track circuits, ac track circuits, and voice frequency/electronic track circuits. The track bonding used in track circuits requires specific modifications for traction current passage. Modifications are detailed in Appendix 11.
  • Signalling and Interlocking Circuits: Overhead signalling and interlocking circuits in electrified sections are replaced with underground cables to reduce electromagnetic/electrostatic induction. Cables should be sectioned and earthed to prevent induced voltage exceeding 120 volts. If parallelism exceeds 3.5 km, a relay is inserted to maintain maximum 3.5 km limits per segment.
  • Telecommunication Circuits: Overhead telecommunication lines running parallel to tracks must be replaced by underground cables, particularly for circuits where induced voltage might exceed 60 volts in electrified sections. Isolated transformers may be used for protecting wayside stations and subscriber equipment from the effects of induced voltage. Underground cables have higher attenuation than overhead lines affecting speech transmissions. Repeaters are required for longer transmission distances.
  • Tapping Principles: Special electrical circuits are installed for electric traction, including power control, traction loco control, emergency circuits, and telephones. These have specific responsibilities, locations, and capacities.
  • Major Track Maintenance: Authroized OHE staff should be present for work on track. Structure bonds, cross bonds, and return feed lines must not be disturbed. Safety clearances should be upheld for personnel doing track maintenance in electrified regions.
  • Principles of Tapping: Specific traction power, control, and emergency circuits are installed for electric traction. Detailed plans are laid out concerning location and capacities, and it is the responsibility of the Chief Electrical Engineer to oversee installations.

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Indian Railways AC Traction Manual Volume 11 Part 1 PDF

Description

This quiz covers key concepts related to signalling and telecommunication installations in electrified railway sections, as outlined in the Indian Railways manuals. It delves into the effects of 25 kV traction on S&T equipment, including issues of electrostatic and electromagnetic induction. Test your knowledge on safety guidelines and installation rules crucial for railway operations.

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