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Indian Railways Telecom Manual - 2021 Section XI
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Indian Railways Telecom Manual - 2021 Section XI

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Questions and Answers

What is the maximum end-to-end loss allowed at 1310 nm?

  • 0.30 dB/Km
  • 0.25 dB/Km
  • 0.40 dB/Km (correct)
  • 0.50 dB/Km

    • Which tool is used to measure the tension in a fibre optic cable during laying?

  • Tension meter (correct)
  • Reopening device
  • Cable grip
  • Pulley

    • What is the purpose of a Branch Joint Closure in fibre optic cable termination?

  • To connect multiple fibre cables (correct)
  • To test fibre optic cables
  • To terminate a single fibre cable
  • To joint two fibre cables

    • Which equipment is used for drilling during trenching and backfilling?

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

    What is the purpose of a Measuring cord for strain gauge in fibre optic cable laying?

    <p>To measure the tension in the fibre cable</p> Signup and view all the answers

    Which of the following is NOT a tool required for trenching, cable laying, and backfilling?

    <p>Branch Joint Closure</p> Signup and view all the answers

    What is the purpose of a Phawarah in fibre optic cable laying?

    <p>To mark the fibre cable route</p> Signup and view all the answers

    Which equipment is used for protecting the fibre optic cable during splicing?

    <p>Blank dark coloured cloth</p> Signup and view all the answers

    What is the frequency of measuring the earth resistance in the Telecommunication maintenance of Indian Railways?

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

    Which gang is responsible for maintaining the equipment in the Telecommunication maintenance of Indian Railways?

    <p>Equipment maintenance gang</p> Signup and view all the answers

    What is the frequency of checking the integrity of the fibre cable route in the Telecommunication maintenance of Indian Railways?

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

    What is the purpose of OTDR measurement in the Telecommunication maintenance of Indian Railways?

    <p>To measure the optical power loss</p> Signup and view all the answers

    What is the frequency of performing the protective works on bridges and culverts in the Telecommunication maintenance of Indian Railways?

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

    What is the purpose of earthing the sheath of the cable in the Telecommunication maintenance of Indian Railways?

    <p>To prevent electrical shock</p> Signup and view all the answers

    What is the frequency of measuring the temperature in the Telecommunication maintenance of Indian Railways?

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

    What is the purpose of cable markers in the Telecommunication maintenance of Indian Railways?

    <p>To mark the route of the fibre cable</p> Signup and view all the answers

    Who is responsible for maintaining the OFC in each section?

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

    How often should the removal of dust from the equipment and cards be done?

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

    What is the purpose of the joint test report of important parameters for all fibres?

    <p>To verify the quality of the fibre optic system</p> Signup and view all the answers

    What is the primary responsibility of the Sectional Supervisor?

    <p>Overseeing the maintenance gang</p> Signup and view all the answers

    How often should the measurement of battery voltages be done?

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

    What is the purpose of the OEM manuals and warranty certificates?

    <p>To provide guidance for maintenance and repair</p> Signup and view all the answers

    What is the purpose of the spare materials?

    <p>To provide replacement parts for maintenance and repair</p> Signup and view all the answers

    What is the primary purpose of the maintenance schedule for fibre optic systems?

    <p>To provide a checklist for maintenance and repair</p> Signup and view all the answers

    What is the primary purpose of the Duct Integrity Test (DIT)?

    <p>To test the integrity of the duct before OFC cable blowing</p> Signup and view all the answers

    Which of the following equipment is not related to fibre optic cable splicing?

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

    What is the purpose of the HDPE pipe pieces in the given list of equipment?

    <p>For trenching and backfilling</p> Signup and view all the answers

    Which of the following equipment is used for testing the fibre optic cable?

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

    What is the purpose of the Portable generator in the given list of equipment?

    <p>For providing power to the equipment in the field</p> Signup and view all the answers

    Which of the following equipment is not a type of fibre optic tool?

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

    What is the purpose of the Crow bar in the given list of equipment?

    <p>For trenching and backfilling</p> Signup and view all the answers

    Which of the following equipment is used for emergency lighting?

    <p>Lighting arrangements and emergency lamps</p> Signup and view all the answers

    What is the primary tool used for splice loss measurement?

    <p>Optical Attenuation Measurement set</p> Signup and view all the answers

    Which equipment is used for trenching and backfilling?

    <p>Not mentioned in the content</p> Signup and view all the answers

    What is the tool used for cable laying and termination?

    <p>Fibre Optic Tool Kit</p> Signup and view all the answers

    What is the primary equipment used for optic fibre testing?

    <p>PCM Transmission Analyzer</p> Signup and view all the answers

    What is the tool used for cleaning optical fibre connectors?

    <p>Optical Fibre connector Cleaning kit</p> Signup and view all the answers

    What is the primary equipment used for cable maintenance?

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

    What is the tool used for measuring the signal strength of an optic fibre?

    <p>Optical power meter</p> Signup and view all the answers

    What is the primary equipment used for fibre optic testing?

    <p>Fibre Optic tool kit</p> Signup and view all the answers

    What should be done with the remaining portion of cable when part of the work is to be put off till the following day?

    <p>Wound it back on the drum, reducing the distance from already laid cable</p> Signup and view all the answers

    What is the importance of covering already laid cables?

    <p>To protect it from outside interference</p> Signup and view all the answers

    What type of drilling should be adopted for smaller culverts/bridges, if feasible?

    <p>Trenchless horizontal directional drilling (HDD) with DWC pipe protection</p> Signup and view all the answers

    Why should the drum be prevented from tumbling down or rolling away?

    <p>To prevent damage to the cable</p> Signup and view all the answers

    What is the purpose of providing separate troughs for laying 6 quad cable and OFC?

    <p>To prevent damage to the cable</p> Signup and view all the answers

    What is the minimum depth below the bed of culverts/bridges that the cable should be laid?

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

    What type of bridges/culverts require special protection arrangements?

    <p>Girder bridges and major culverts</p> Signup and view all the answers

    What is the purpose of protection of optic fibre cable routes and back filling of trenches?

    <p>To prevent damage to the cable and protect staff</p> Signup and view all the answers

    Where should the upper surface of the RCC concrete chamber be kept?

    <p>50 cm below the surface</p> Signup and view all the answers

    What should be done with the armouring of OFC in absence of earthing?

    <p>It should be properly wrapped with insulator tape to prevent electric shock</p> Signup and view all the answers

    How should the cable be secured on the wall/frame?

    <p>At two places within 1 m from the termination box</p> Signup and view all the answers

    What should be done after the cable is laid and splicing has been completed?

    <p>Measurements in the enclosed proforma have to be prepared</p> Signup and view all the answers

    What should be placed on all joint locations?

    <p>A suitable joint marker</p> Signup and view all the answers

    How much extra cable should be coiled in the pit for future use?

    <p>10 m of extra cable</p> Signup and view all the answers

    What should be kept inside the termination box?

    <p>Sufficient silica gel in bags</p> Signup and view all the answers

    In which system should the OF cable be installed in all future installations?

    <p>Fibre Distribution and Management System (FDMS)</p> Signup and view all the answers

    What is the recommended way to remove the inner sheath while stripping a cable?

    <p>Score the inner sheath twice on opposite sides of the cable</p> Signup and view all the answers

    How should the fibres be cleaned individually?

    <p>Using kerosene/suitable liquid to remove the jelly</p> Signup and view all the answers

    What is a common step in preparing a cable joint closure for splicing?

    <p>Joining the strength member of each cable to each other and/or the central frame of the joint closure</p> Signup and view all the answers

    What should be done with the armouring during splicing?

    <p>It should remain outside the gland and not be connected through</p> Signup and view all the answers

    What is the purpose of marking the loops on the cable coil?

    <p>To make it easier to install the cable later</p> Signup and view all the answers

    How should the cable be coiled on the pit wall?

    <p>In the same position as required after the joint is complete</p> Signup and view all the answers

    What should be fixed on the wall of the pit?

    <p>Brackets to support the cable coil</p> Signup and view all the answers

    What is the purpose of staggering the removal of the outer and inner sheath?

    <p>To prevent damage to the fibres</p> Signup and view all the answers

    What is the recommended minimum bend radius for fibre optic cables during pulling?

    <p>20 times the diameter of the cable</p> Signup and view all the answers

    What is the purpose of attaching a swivel between the pulling line and pulling eye at the end of the duct?

    <p>To prevent twisting of the cable during pulling</p> Signup and view all the answers

    What should be done before handing over the cable drum to the contractor?

    <p>All of the above</p> Signup and view all the answers

    Why is it important to provide a nylon rope for pulling the cable when laying the cable in duct?

    <p>To prevent damage to the fibre</p> Signup and view all the answers

    What should be done to the lags of the drum before pulling out the cable?

    <p>Remove them carefully with a bar or other means</p> Signup and view all the answers

    What should be done to the cable grip/pulling eye if it is not already provided?

    <p>Fit it to the swivel and pull the wires by means of shackle</p> Signup and view all the answers

    What is the minimum bend radius under tension during pulling for armoured OFC used by IR?

    <p>30 times the diameter of the cable</p> Signup and view all the answers

    Why is it important to check the drum number and length of the cable before laying the cable?

    <p>To ensure that the correct cable is being used</p> Signup and view all the answers

    What is the primary purpose of laying cables in RCC/DWC ducts when crossing tracks or level crossing gates?

    <p>To protect the cable from damage</p> Signup and view all the answers

    What is the minimum depth required for cable crossing at any track crossing?

    <p>1.2 meters</p> Signup and view all the answers

    What is the purpose of providing cable markers at a distance of every 50 meters on the cable route?

    <p>To identify the location of the cable</p> Signup and view all the answers

    What type of material is used to cover the duct with riddled earth in the station yard?

    <p>B-class brick</p> Signup and view all the answers

    What is the purpose of providing a joint indicator at all joints?

    <p>To identify the location of the joint</p> Signup and view all the answers

    What is the standard type of cable marker and joint marker used?

    <p>Standard stone RCC type</p> Signup and view all the answers

    What is the purpose of laying cables in station yards and on embankments?

    <p>To protect the cable from damage</p> Signup and view all the answers

    What is the drawing number used for cable marker and joint marker provision in normal and rocky areas?

    <p>RDSO/TCDO/COP-22(a)</p> Signup and view all the answers

    Study Notes

    Fibre Optic Cable Installation and Maintenance

    Cable Loss and Distance

    • The end-to-end loss should not exceed 0.25 dB/km at 1550 nm and 0.40 dB/km at 1310 nm.

    Tools and Equipments for Installation and Testing of Optic Fibre Cable

    • Group-I Tools: cable jack, cable grip, reopening device, free hood hook, shackle free head hook, growling hook, pulling bolt, tension meter, pulley, anti-twist device, roller, flexible cable, pulling rope, brush, mandrel, chain, measuring cord, slip winch, wire rope, portable VHF set, measuring tape, phawarah, iron plate, loader backhoe, warning tape, caterpillar tractor, fork lifter, tool van vehicle, tachometer, portable generator, and tent type umbrella.
    • Group-II Tools: branch joint closure, termination box, equipment maintenance, digital multi-meter, optical fibre connector cleaning kit, sectional supervisor, portable BER & PCM test set, meager, optical attenuation measurement set, and fibre optic tool kit.

    Maintenance Schedule for Fibre Optic System

    • Equipment maintenance: power supply, battery maintenance, measurement of battery voltages, charger in/out voltages, checking of fuses and terminations, and earthing connections.
    • General maintenance: removal of dust from equipment and cards, and maintenance of pigtail, fibre distribution frame, etc.

    Staff Requirement and Maintenance Gang

    • OFC in each section should be maintained by a cable gang.
    • The staff strength should be as per the latest yardstick issued by Railway Board.
    • The maintenance gang should have provision for a vehicle where men and material can be loaded and comfortably reach the site.

    Duct Integrity Test (DIT)

    • Duct Integrity Test (DIT) is to be carried out before OFC cable blowing.
    • The test ensures the integrity of the duct before cable installation.

    Cable Laying and Protection

    • When laying one piece of cable, keep the remaining portion of cable wound on the drum, reduce the distance of the drum from already laid cable, and ensure the drum is prevented from tumbling down or rolling away.
    • Already laid cable shall be fully covered to avoid outside interference.

    Protection of Optic Fibre Cable Route and Back Filling of Trenches

    • This chapter covers protection arrangements for preventing damage to the cable and protection to staff.
    • It also covers arrangements for back filling of cable trenches to provide protection to the cable.

    Protection of Cable Route

    • Typical arrangements for protection for bridges/culverts include cable troughs and channels for girder bridges and major culverts.
    • For smaller culverts/bridges, trenchless horizontal directional drilling (HDD) should be adopted with DWC pipe protection and ensuring the cable is minimum 2 m below the bed of culverts/bridges.

    Cable Crossing Bridges/Culverts

    • The termination box should be placed and the nuts inside the base box shall be tightened.
    • Sufficient silica gel in bags should be kept inside and the covers shall then be put on the termination box and closed.
    • Fibre Distribution Management System (FDMS) should be used in all future installations.

    Jointing/Splicing

    • The optic fibre placed in the joint should be safely protected in a RCC concrete chamber as per RDSO drawings.
    • The chamber should be filled with fine sieved sand, and the upper surface of the chamber should be kept 50 cm below the surface.
    • A suitable joint marker should be placed on all joint locations.
    • 10 m of extra cable should be coiled in the pit for future use.
    • Armouring must not be put through, and the armouring of OFC should be earthed at all locations with new/existing available telecom/signalling earthing arrangements.

    Fixing the Cable

    • The cable on the wall/frame shall be secured at two places within 1 m from the termination box, keeping in view the straight entry of cable into the termination box.
    • A pit length of 1 meter is sufficient for most of the cable and joint closures.
    • Bracket to support the cable coil is fixed on the wall of the pit.

    Stripping/Cutting of the Cable

    • The cable should be stripped of outer and inner sheath with each sheath staggered approximately 10mm from the one above it.
    • Proper care should be taken when removing the inner sheath to ensure that the fibres are not scratched or cut with the stripping knife or tool.

    Preparation of Cable Joint Closure for Splicing

    • The type of preparation work performed on the cable prior to splicing differs on the type of joint closure and fibre organizer used.
    • The strength member of each cable shall be joined to each other and/or the central frame of the joint closure.
    • The joint closure shall be assembled around the cable.

    Cable Marker and Joint Marker

    • The cable marker shall normally be provided at a distance of every 50 meters on the cable route and at places wherever the route changes.
    • A joint indicator shall be provided at all joints.
    • The cable marker and joint marker provision shall be as per Drawing No.RDSO/TCDO/COP-22(a) for normal and rocky areas.

    Cable Crossing Tracks and Level Crossing Gate

    • The cable shall be laid in RCC/DWC ducts keeping the depth same as in normal routes.
    • Minimum depth at any track crossing shall not be less than 1.2 meters with RCC/DWC duct.
    • In case the cable crosses the track, it may be ensured that it should not be bent less than 600mm radius.

    Preparation for Paying Out Cable

    • Check the drum number and length of the cable, etc.
    • Entrust cable drum to the contractor after testing the fibres with OTDR for attenuation and to ensure that no mechanical damage of the fibre exists while handing over the cable to the contractor.
    • The normal recommendation for fiber optic cable bend radius is the minimum bend radius under tension during pulling is 20 times the diameter of the cable.

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    Description

    This quiz is based on the Indian Railways Telecom Manual - 2021, Section XI, covering topics related to tools and equipment for inspecting and Maintaining fibre optic cables.

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