Telecom Cable Laying and Termination
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Questions and Answers

What is the recommended method for laying cables in busy areas?

  • Trenching method
  • Open-cut method
  • Horizontal Directional Drilling (HDD) method (correct)
  • Micro-tunneling method

    • Where can telecom cables be laid in a station section?

  • In a large size duct with signalling cables (correct)
  • In a PVC pipe with other services
  • In a small size duct with power cables
  • In a separate concrete duct

    • What type of termination method is approved for PIJF cables?

  • Mechanical termination
  • DP Box of approved type (correct)
  • Direct termination
  • Thermo shrinkable termination

    • Who should perform the jointing of PIJF cables?

    <p>A skilled and experienced person</p> Signup and view all the answers

    What is the purpose of video recording in cable laying work?

    <p>To ensure quality of laying and jointing</p> Signup and view all the answers

    What type of jointing material is recommended for armoured PIJF cables?

    <p>Thermo shrinkable material</p> Signup and view all the answers

    What is the name of the jointing kit used for quad cables?

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

    What is the purpose of the RDSO code of practice?

    <p>To ensure quality of jointing</p> Signup and view all the answers

    Why is close supervision of telecom staff necessary during cable laying?

    <p>To ensure quality of laying and jointing</p> Signup and view all the answers

    What is the recommended method for submitting video recordings of cable laying work?

    <p>In a DVD format</p> Signup and view all the answers

    What type of cable is not suitable for underground laying?

    <p>Paper as well as polythene insulated copper quads</p> Signup and view all the answers

    What is the recommended size of conductor for subscriber's connections up to 5 km?

    <p>0.5 mm cond. Dia. twisted Pair PIJF</p> Signup and view all the answers

    What type of cable is used for local subscriber's connections in a building?

    <p>0.5 mm Annealed Tinned Copper (ATC) cable</p> Signup and view all the answers

    What is the specification for a 50 pair telephone exchange cable?

    <p>0.63 mm cond. dia. armoured polythene insulated polythene sheathed jelly filled armoured cable</p> Signup and view all the answers

    Why should RE cables containing paper as well as polythene insulated copper quads be replaced?

    <p>They are outdated and should be replaced at the earliest</p> Signup and view all the answers

    What type of insulation is used in jelly filled armoured cables?

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

    What is the purpose of armouring in cables?

    <p>To provide mechanical protection</p> Signup and view all the answers

    What is the recommended cable size for trunk connections?

    <p>2.52 kg/km cable</p> Signup and view all the answers

    What is the purpose of jelly filling in cables?

    <p>To prevent water ingress</p> Signup and view all the answers

    What is the significance of specifying the size of the telephone exchange cables?

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

    What is the primary reason for inspecting the bedding and armouring of the cable before laying?

    <p>To check for damage during transit or in storage</p> Signup and view all the answers

    What is the recommended method for laying out cables when cable-wheels are not available?

    <p>Mounting the drum on an axle at one end of the trench</p> Signup and view all the answers

    What is the primary purpose of twisted pairs in telephone cables?

    <p>To minimize electro-static and electro-magnetic induction between different pairs of conductors</p> Signup and view all the answers

    Who should be present during the excavation of earth for trenches or making other pits necessary for installation of cable junction boxes?

    <p>A Permanent Way Inspector or his representative</p> Signup and view all the answers

    What is the purpose of testing the cable for insulation and continuity of the cores before laying?

    <p>To verify the cable's insulation and continuity</p> Signup and view all the answers

    What is the primary consideration for laying telecom lines in railway departments?

    <p>To provide spare capacity for future extensions</p> Signup and view all the answers

    What is the typical diameter of the conductor used for control circuits and block interfaces?

    <p>0.9 mm</p> Signup and view all the answers

    What should be done to prevent the cable from being damaged or bent unduly during laying?

    <p>Guide the cable from the road into the trench carefully</p> Signup and view all the answers

    Why should the cable not be rolled off onto the road for laying purposes?

    <p>It may cause the cable to be damaged or bent unduly</p> Signup and view all the answers

    What type of cable is used for exchange subscriber lines or branch cables?

    <p>Multi pair Cable</p> Signup and view all the answers

    What is the purpose of providing spare capacity in telecom lines?

    <p>To accommodate future extensions or extra connections</p> Signup and view all the answers

    What is the purpose of a lead or aluminium sheath in telephone cables?

    <p>To minimize electro-static and electro-magnetic induction between different pairs of conductors</p> Signup and view all the answers

    What is the significance of using 1.4 mm conductor dia cable in block sections?

    <p>It is more suitable for longer block sections</p> Signup and view all the answers

    How should the drum be mounted on the cable-wheel for laying out cables?

    <p>At one end of the trench</p> Signup and view all the answers

    What is the purpose of inspecting the cable's armour and screen before laying?

    <p>To ensure the continuity of the armour and screen</p> Signup and view all the answers

    What type of cable is used for underground laying and is suitable for control circuits and block interfaces?

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

    What is the primary purpose of using polythene insulated jelly filled cables?

    <p>To provide protection against moisture and corrosion</p> Signup and view all the answers

    What is the significance of using quad cables with different conductor diameters?

    <p>To provide flexibility for different types of applications</p> Signup and view all the answers

    What is the purpose of using twisted pair switch board cables?

    <p>To connect switch boards and equipment</p> Signup and view all the answers

    What is the primary consideration for selecting the type of cable to be used in railway departments?

    <p>Type of application</p> Signup and view all the answers

    What is the primary purpose of armouring in cables?

    <p>To provide mechanical strength to the cable</p> Signup and view all the answers

    What is the significance of specifying the size of the telephone exchange cables?

    <p>To maintain a consistent impedance</p> Signup and view all the answers

    Why is close supervision of telecom staff necessary during cable laying?

    <p>To monitor the quality of work</p> Signup and view all the answers

    What is the purpose of jelly filling in cables?

    <p>To prevent water ingress into the cable</p> Signup and view all the answers

    What is the recommended method for submitting video recordings of cable laying work?

    <p>Not specified</p> Signup and view all the answers

    What type of insulation is used in jelly filled armoured cables?

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

    Why should RE cables containing paper as well as polythene insulated copper quads be replaced?

    <p>Due to their vulnerability to moisture</p> Signup and view all the answers

    What is the primary consideration for laying telecom lines in railway departments?

    <p>Providing spare capacity for future extensions</p> Signup and view all the answers

    What is the purpose of inspecting the cable's armour and screen before laying?

    <p>To check for mechanical damage</p> Signup and view all the answers

    What is the significance of using quad cables with different conductor diameters?

    <p>To accommodate different types of telecommunication circuits</p> Signup and view all the answers

    What is the primary purpose of providing a lead or aluminium sheath in telephone cables?

    <p>To minimize electro-static induction between different pairs of conductors</p> Signup and view all the answers

    Why is it necessary to inspect the cable's armour and screen before laying?

    <p>To ensure the cable is not damaged during transit</p> Signup and view all the answers

    What is the recommended method for laying out cables when cable-wheels are not available?

    <p>By mounting the drum on an axle at one end of the trench</p> Signup and view all the answers

    What is the primary purpose of using thermo shrinkable jointing material in armoured PIJF cables?

    <p>To provide electrical insulation to the joint</p> Signup and view all the answers

    What is the primary purpose of testing the cable for insulation and continuity of the cores before laying?

    <p>To check for any defects in the insulation</p> Signup and view all the answers

    Why is it necessary to have a party of labourers follow the drum and guide the cable into the trench?

    <p>To prevent the cable from being damaged or bent unduly</p> Signup and view all the answers

    What is the recommended method for laying cables in busy areas?

    <p>Horizontal Directional Drilling (HDD) method</p> Signup and view all the answers

    What is the primary purpose of using twisted pairs in telephone cables?

    <p>To minimize electro-static induction between different pairs of conductors</p> Signup and view all the answers

    What is the purpose of using a jointing kit in PIJF cable jointing?

    <p>To provide a standardized jointing process</p> Signup and view all the answers

    What is the primary purpose of close supervision of telecom staff during cable laying and jointing?

    <p>To ensure quality of work</p> Signup and view all the answers

    Why should the drum not be rolled off onto the road for laying the cable?

    <p>To prevent the cable from being damaged or bent unduly</p> Signup and view all the answers

    What is the recommended method for terminating PIJF cables of various sizes?

    <p>DP Box termination method</p> Signup and view all the answers

    Who should be present during the excavation of earth for trenches or making other pits necessary for installation of cable junction boxes?

    <p>The Permanent Way Inspector or his representative</p> Signup and view all the answers

    What is the primary consideration for laying telecom lines in railway departments?

    <p>Ensuring the reliability of the telecom system</p> Signup and view all the answers

    What is the purpose of using a video recording during cable laying and jointing?

    <p>To provide evidence of quality work</p> Signup and view all the answers

    What is the primary purpose of using a RDSO specified jointing kit in PIJF cable jointing?

    <p>To provide a standardized jointing process</p> Signup and view all the answers

    Why is it necessary to inspect the bedding and armouring of the cable before laying?

    <p>To ensure the cable is not damaged during transit</p> Signup and view all the answers

    What is the recommended method for laying telecom cables in a station section?

    <p>Laying in concrete large size ducts</p> Signup and view all the answers

    What is the purpose of using thermo shrinkable jointing technique in armoured PIJF cables?

    <p>To provide electrical insulation to the joint</p> Signup and view all the answers

    What is the primary purpose of using a skilled and experienced person for jointing PIJF cables?

    <p>To ensure quality of work</p> Signup and view all the answers

    What type of insulation is recommended for subscriber's connections up to 10 km?

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

    What type of cable is recommended for outdoor underground laying?

    <p>Armoured Polythene Insulated Cable</p> Signup and view all the answers

    What is the primary reason for specifying the size of the telephone exchange cables?

    <p>To determine the number of pairs</p> Signup and view all the answers

    What type of cable is recommended for local subscriber's connections in a building?

    <p>0.5 mm Annealed Tinned Copper (ATC) Cable</p> Signup and view all the answers

    What is the primary purpose of using armoured cables?

    <p>To provide mechanical protection</p> Signup and view all the answers

    What is the recommended size of conductor for trunk connections?

    <p>0.6 mm</p> Signup and view all the answers

    Why should RE cables containing paper as well as polythene insulated copper quads be replaced?

    <p>They are outdated and need to be replaced with newer technology</p> Signup and view all the answers

    What is the primary purpose of jelly filling in cables?

    <p>To prevent moisture ingress</p> Signup and view all the answers

    What type of cable is suitable for control circuits and block interfaces?

    <p>1.4 mm Conductor Dia Cable</p> Signup and view all the answers

    What is the primary reason for inspecting the cable's armour and screen before laying?

    <p>To check for mechanical damage</p> Signup and view all the answers

    Study Notes

    Cable Laying

    • In busy areas, HDD (Horizontal Directional Drilling) method should be used to lay all types of cables in DWC pipes or approved protection arrangements.
    • Where concrete large size duct is provided in the station section for laying signalling cables, the same may be utilized for telecom cables also, following due precautions.

    Cable Termination

    • Cables can be terminated in DP Box of approved type or through direct termination.
    • PIJF cable of various sizes shall be terminated through DP Box of approved type.

    Jointing of PIJF Cable

    • Jointing should be done by a skilled and experienced person using the correct RDSO specified jointing kit to ensure quality.
    • The entire cable laying and jointing to be done under close supervision of telecom staff.
    • Thermo shrinkable jointing material shall be used for jointing armoured PIJF cable with thermo shrinkable jointing technique using RDSO's code of practice.
    • The jointing material is readily available in the form of a jointing kit, and different kits are used for different sizes of cable (No. of pairs and cond. dia.).

    Testing Cable Before Laying

    • Before laying, the cable shall be tested for insulation and continuity of the cores.
    • Continuity of armour and screen of the cable need to be checked before laying.
    • Bedding and armouring of the cable shall also be inspected to see that there has been no damage during transit or in storage.

    Laying Out the Cable

    • For laying out cables, the cable drums shall be mounted on cable-wheels.
    • The drum on the wheel shall be brought to one end of the trench and the end of the cable freed and put into the trench.
    • A party of labourers shall follow the drum and guide the cable from the road into the trench carefully so that the cable is not damaged or bent unduly.

    General

    • While excavating earth for trenches or making other pits necessary for installation of cable junction boxes, the Permanent Way Inspector or his representative shall be present.
    • In 'Quad' type of cables, conductors diagonally opposite shall form one circuit.
    • In telephone cables, electro-static and electro-magnetic induction between different pairs of conductors shall be minimized by a lead or aluminium sheath and by the provision of twisted pairs.

    Line Plant Systems - Underground Copper Cable

    • Railway departmental telecommunication lines are usually laid underground between railway offices in railway colonies, large workshops, station yards, and in the block sections alongside the track.
    • All telecom lines shall, as far as possible, be laid in a manner that due provisions are kept for any future extensions or extra connection which can be catered for without considerable alteration to the existing circuits or reconstruction of the entire alignment.

    Types of Cables Used

    • Quad Cable 0.9 or 1.4 mm conductor dia as per IRS specification No.IRS:TC 30/05 is used for control circuits and block interfaces.
    • Multi pair (from 10 pairs to 200) Multi Dia (0.5mm/0.63mm/0.9mm) PIJF (Polythene insulated Jelly Filled) Cable as per IRS specification No.IRS:TC 41/97 is used for exchange subscriber lines or branch cables branching off from the main Quad cable.
    • Twisted Pair Switch Board Cable of sizes 0.5 mm / 0.6 mm copper conductor dia as per IRS/TEC specification is used for indoor applications such as distribution to various telephone subscribers in a building, MDF to exchange wiring etc.
    • RE cable containing paper as well as polythene insulated copper quads should be replaced at the earliest.

    Testing Cable Before Laying

    • Cable must be tested for insulation and continuity of cores before laying
    • Continuity of armour and screen of the cable also needs to be checked before laying
    • Bedding and armouring of the cable must be inspected for damage during transit or storage

    Laying Out the Cable

    • Cable drums must be mounted on cable-wheels for laying out cables
    • Drum on the wheel is brought to one end of the trench, and the end of the cable is freed and put into the trench
    • Cable-wheels are then drawn along the road or track, and a party of labourers follows the drum to guide the cable into the trench
    • In case cable-wheels are not available, the drum is mounted on an axle at one end of the trench, and cable is laid out and carried by labourers

    General Guidelines

    • Permanent Way Inspector or representative must be present while excavating earth for trenches or making pits for cable junction boxes
    • In 'Quad' type of cables, conductors diagonally opposite form one circuit
    • Electro-static and electro-magnetic induction between different pairs of conductors in telephone cables must be minimized
    • HDD (Horizontal Directional Drilling) method should be used to lay all types of cables in DWC pipes or approved protection arrangement in busy areas
    • Concrete large size ducts provided in station sections for laying signalling cables can also be utilized for telecom cables

    Cable Termination

    • Cables can be terminated in DP Box of approved type or by direct termination
    • PIJF cable of various sizes must be terminated through DP Box of approved type

    Jointing of PIJF Cable

    • Jointing should be done by a skilled and experienced person using the correct RDSO specified jointing kit to ensure quality
    • Jointing should be done under close supervision of telecom staff, and video recording may be used to ensure quality of laying and jointing
    • Thermo shrinkable jointing material must be used for jointing armoured PIJF cable with thermo shrinkable jointing technique
    • Jointing material is readily available in the form of a jointing kit, and different kits are used for different sizes of cables

    Line Plant Systems – Underground Copper Cable

    • Railway departmental telecommunication lines are usually laid underground between railway offices, large workshops, station yards, and block sections alongside the track
    • Telecom lines should be laid in a manner that allows for future extensions or extra connections without considerable alteration to existing circuits or reconstruction of the entire alignment

    Types of Cables Used

    • Quad Cable with 0.9 or 1.4 mm conductor diameter is used for control circuits and block interfaces
    • Multi pair (from 10 pairs to 200) Multi Dia (0.5mm/0.63mm/0.9mm) PIJF Cable is used for exchange subscriber lines or branch cables
    • Twisted Pair Switch Board Cable of sizes 0.5 mm / 0.6 mm copper conductor diameter is used for indoor applications
    • RE cable containing paper as well as polythene insulated copper quads should be replaced at the earliest

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    Underground Copper Cable Systems PDF

    Description

    This quiz covers guidelines for laying and terminating telecom cables in various settings, including road and rail crossings, and station sections.

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