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</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</p> Signup and view all the answers

    What effect can OHE masts and fittings have on signalling?

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

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

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

    What is included in the earthing requirements of signal posts?

    <p>Protective wire-mesh screens</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.</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.</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.</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.</p> Signup and view all the answers

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

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

    What is the maximum resistance allowed for an individual earth?

    <p>10 ohms</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</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.</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</p> Signup and view all the answers

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

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

    What is prohibited within 300m from the feeding post?

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

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

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

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

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

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

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

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

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

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

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

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

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

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

    <p>10 ohms</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</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</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</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</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</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</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</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</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</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.</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</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</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.</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</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</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</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</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.</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</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</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</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</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</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.</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</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</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</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</p> Signup and view all the answers

    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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    Related Documents

    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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