Railway Electrification Principles
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Questions and Answers

What is the purpose of regulating equipment in an overhead equipment system?

  • To support the suspension system at higher altitudes.
  • To prevent electrical current leakage between sections.
  • To increase the overall voltage of the overhead lines.
  • To maintain the tension of OHE conductors constant under varying temperatures. (correct)

    • What does the term 'stagger' refer to in the context of overhead equipment?

  • The angle at which the contact wire must be installed.
  • The vertical alignment of the traction mast to the catenary wire.
  • The distance between two adjacent supporting masts.
  • The horizontal distance of the contact wire from a specified vertical plane. (correct)

    • What is a section insulator used for in overhead equipment?

  • To regulate the voltage supplied to the contacting wire.
  • To insulate two electrical sections while enabling continuous pantograph operation. (correct)
  • To allow for the maintenance of the contact wire without affecting current flow.
  • To connect multiple feeding posts to a single overhead line.

    • What is the significance of 'setting distance' in overhead equipment installation?

    <p>It is the distance from the traction mast to the centerline of the track.</p> Signup and view all the answers

    What components are typically found in a supply control post?

    <p>Interruptors, isolators, potential transformers, and control gear.</p> Signup and view all the answers

    What defines the term 'suspension distance' in the context of catenary systems?

    <p>The horizontal distance from the catenary bracket eye to the mast face.</p> Signup and view all the answers

    What is considered a 'span' in an overhead equipment system?

    <p>The distance between the center lines of adjacent supporting masts.</p> Signup and view all the answers

    What is the maximum suspension distance for a bracket assembly designed without additional specifications?

    <p>3.5 m</p> Signup and view all the answers

    In which scenarios may the minimum setting distance of masts from the center line of the tangent track be reduced?

    <p>In special circumstances such as yards, cuttings, and bridges with approval</p> Signup and view all the answers

    What type of insulators should be utilized in heavily polluted areas such as tunnels and near chemical plants?

    <p>Long creepage path insulators</p> Signup and view all the answers

    What is the standard setting distance for mast placement on broad gauge tangent track?

    <p>2.50 m</p> Signup and view all the answers

    What should be added to the setting distance on curves to determine the minimum setting distance of masts?

    <p>Curve allowance and slewing allowance</p> Signup and view all the answers

    What is the wind pressure for structures in the yellow zone according to the specified standards?

    <p>112.50 kg/m2</p> Signup and view all the answers

    How is the total projected area for fabricated structures calculated for wind loading?

    <p>150% of the projected area</p> Signup and view all the answers

    What is the recommended method for measuring spans on a curve for an odd number of tracks?

    <p>Outer rail of the middle track</p> Signup and view all the answers

    What is the maximum allowed wind pressure for safety checks at 4 degree C temperature?

    <p>20% of the governing wind pressure</p> Signup and view all the answers

    Which diagram number corresponds with the standard spans for regulated tramway OHE?

    <p>Drg.No.ETI/OHE/G/04201</p> Signup and view all the answers

    How much are wind pressures for structures under 30 meters reduced as per the amendment issued in 1971?

    <p>25%</p> Signup and view all the answers

    What should be taken into consideration when determining the length of the span?

    <p>Permissible stagger and other factors</p> Signup and view all the answers

    What type of screens should be used for protection when clearance is not obtained?

    <p>Earthed metallic screens</p> Signup and view all the answers

    When calculating wind loading for conductors and other circular members, what area is considered?

    <p>2/3 of the projected area</p> Signup and view all the answers

    What type of masts can be used in lieu of K-series masts?

    <p>B-series masts</p> Signup and view all the answers

    In the context of masts for single OHE applications, what wind pressure level corresponds with Drg.No.ETI/C/0702?

    <p>Light wind pressure (75 Kgf/m2)</p> Signup and view all the answers

    What is used in lieu of 200x150 RSJ as specified in mast employment schedules?

    <p>200x200 BFB</p> Signup and view all the answers

    What should be considered when designing masts for locations such as turnouts and diamond crossings?

    <p>Load calculations specific to each location</p> Signup and view all the answers

    For heavy wind pressure, which drawing number is referenced?

    <p>ETI/C/0726</p> Signup and view all the answers

    What is the permissible bending moment for masts found in?

    <p>Drg.No.ETI/SK/C/122</p> Signup and view all the answers

    What should NOT be considered for masts on long bridges or near their abutments?

    <p>Reduction in wind pressure</p> Signup and view all the answers

    What is the tension in each conductor for Composite OHE masts?

    <p>1000 Kgf</p> Signup and view all the answers

    Which drawing number is used for medium wind pressure applications?

    <p>Drg.No.ETI/C/0717</p> Signup and view all the answers

    What type of wire is mentioned for use in standard mast applications?

    <p>Copper contact wire</p> Signup and view all the answers

    What is the minimum distance that masts should be located from a signal post?

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

    Where should masts not be located according to safety regulations?

    <p>In front of station entrances</p> Signup and view all the answers

    What type of support is recommended for overhead equipment in tunnels?

    <p>Supports on both sides of the tunnel</p> Signup and view all the answers

    What materials are specified for the cantilever bracket assembly?

    <p>Galvanized steel tubes</p> Signup and view all the answers

    What should be done if masts need to be located in areas of bad formations?

    <p>Prefer the side with better stability</p> Signup and view all the answers

    What is the role of the distance between masts and level crossings?

    <p>It should not normally be less than 10 m</p> Signup and view all the answers

    What should be done with core holes on piers that are not used for foundation?

    <p>Fill them with dry sand covered with a concrete slab</p> Signup and view all the answers

    What is the minimum distance for the location of masts on bridges?

    <p>Core holes should be provided</p> Signup and view all the answers

    What is a necessary condition for providing independent masts on multi-track sections?

    <p>If adequate track centres are available</p> Signup and view all the answers

    What should be considered when arranging cantilevers on platforms?

    <p>The arrangement as per specified guidelines</p> Signup and view all the answers

    What is the primary function of the 10 KVA LT supply transformer in substations?

    <p>To supply power for lighting and operation of sub-station equipment</p> Signup and view all the answers

    How are LT supply transformers protected on the primary side?

    <p>By 25 kV Amp. Dropout fuses</p> Signup and view all the answers

    In the context of mast and rail bonds, what bonding is required for traction masts?

    <p>Bonding to a non-track-circuited rail only</p> Signup and view all the answers

    What type of wiring is specified for the 63 A fuse on the secondary side of LT supply transformers?

    <p>20 SWG tinned copper wire</p> Signup and view all the answers

    What transformer capacity is specified for providing power to filtration plants at substations?

    <p>100 KVA</p> Signup and view all the answers

    What is a characteristic feature of a regulated OHE system?

    <p>Constant tension of conductors under varying temperature conditions</p> Signup and view all the answers

    What is the main function of a sectioning and paralleling post (SP)?

    <p>Providing sectioning capabilities midway between two feeding posts</p> Signup and view all the answers

    How is 'span' defined in the context of overhead equipment?

    <p>Horizontal distance between adjacent supporting masts</p> Signup and view all the answers

    What does the stagger of the contact wire directly influence?

    <p>The wear on the pantograph surfaces during operation</p> Signup and view all the answers

    Which of the following accurately describes 'suspension distance' in a catenary system?

    <p>The distance from the catenary eye to the mast face</p> Signup and view all the answers

    What distinguishes a supply control post from a regular post?

    <p>Inclusion of interruptors and transformers for power management</p> Signup and view all the answers

    What does the term 'setting distance' specifically refer to during installation?

    <p>The horizontal distance from a mast to the track centerline</p> Signup and view all the answers

    What percentage reduction in wind pressures applies to structures under 30 meters in height according to amendments issued in 1971?

    <p>25%</p> Signup and view all the answers

    When calculating wind loading, what percentage of the projected area is considered for fabricated structures?

    <p>150%</p> Signup and view all the answers

    What is the designated wind pressure in the red zone for structural design?

    <p>150 kg/m²</p> Signup and view all the answers

    Which condition must be checked for the safety of masts during wind loading calculations?

    <p>At 35 degree C and full wind pressure</p> Signup and view all the answers

    For what purpose should spans be accurately measured using a steel tape?

    <p>To ensure proper clearance for overhead equipment</p> Signup and view all the answers

    What type of wind load is applied in the yellow zone for structural safety?

    <p>112.50 kg/m²</p> Signup and view all the answers

    Which drawing corresponds to the standard spans for composite OHE?

    <p>Drg.No.ETI/OHE/SK/375</p> Signup and view all the answers

    What is the influence of curvature on the length of the spans for overhead equipment?

    <p>Curvature limits the maximum span length</p> Signup and view all the answers

    What safety measure is required if clearance is not obtained?

    <p>To install earthed metallic screens or warning boards</p> Signup and view all the answers

    What is the minimum static clearance from an earthed structure for the return conductor?

    <p>150 mm</p> Signup and view all the answers

    In complicated track layouts, how should the route of the return conductor be determined?

    <p>Based on individual case merits.</p> Signup and view all the answers

    What is the minimum required vertical clearance between the return conductor and overhead equipment?

    <p>400 mm</p> Signup and view all the answers

    Where should the return conductor be connected to the buried rail?

    <p>At the midpoint between two consecutive transformers.</p> Signup and view all the answers

    What should be avoided when routing the return conductor in station areas?

    <p>Running over platforms.</p> Signup and view all the answers

    What is required at all booster stations for the return conductors?

    <p>A cut-in-insulator.</p> Signup and view all the answers

    What is the purpose of connecting the return conductor in series with the secondary winding of the booster transformer?

    <p>To ensure proper return current flow.</p> Signup and view all the answers

    What relationship does the return conductor have with subsidiary lines such as sidings or loops?

    <p>They do not have return conductors.</p> Signup and view all the answers

    What is defined as the mid-point of the return conductor?

    <p>The midpoint between two consecutive booster transformers.</p> Signup and view all the answers

    How should return conductors be terminated at masts?

    <p>They are connected to the rail.</p> Signup and view all the answers

    What is the recommended encumbrance for a 54.0 m span under an over-line structure?

    <p>0.75 m</p> Signup and view all the answers

    What is the largest permissible adjacent span for both 63.0 m and 58.5 m under over-line structures?

    <p>67.5 m</p> Signup and view all the answers

    If the encumbrance cannot be increased beyond 1.40 m from the value given for a 54.0 m span, what is the applicable condition noted?

    <p>This is applicable where the encumbrance cannot be increased to 1.40 m.</p> Signup and view all the answers

    What is the recommended encumbrance for a span of 36.0 m under an over-line structure?

    <p>0.40 m</p> Signup and view all the answers

    For a 31.5 m span, what is the recommended encumbrance under an over-line structure?

    <p>0.40 m</p> Signup and view all the answers

    What is the recommended encumbrance for a span of 49.5 m under an over-line structure?

    <p>0.60 m</p> Signup and view all the answers

    What is the discrepancy in encumbrance recommended between spans of 63.0 m and 58.5 m under over-line structures?

    <p>Both have the same encumbrance.</p> Signup and view all the answers

    What is the relationship between the span of a structure and its recommended encumbrance?

    <p>Longer spans generally require higher encumbrances.</p> Signup and view all the answers

    Which encumbrance value is recommended for spans shorter than 27.0 m under over-line structures?

    <p>0.30 m</p> Signup and view all the answers

    Across different spans, what is the maximum encumbrance value observed for spans ranging from 1 m to 63 m under over-line structures?

    <p>1.40 m</p> Signup and view all the answers

    Study Notes

    Principles for Layout Plans and Sectioning Diagrams for 25kV AC Traction

    • These principles standardize and guide railway electrification projects
    • Some principles are mandatory, others provide guidance for standardization and efficiency
    • Design prioritizes proper contact wire height for pantograph operation
    • Key terms have specific meanings defined in the traction manual unless otherwise specified

    Definitions

    • Bond: An electrical connection across a rail joint, maintaining continuity
    • Bond, continuity: Maintains continuity of the rail circuit at crossings and junctions
    • Bond, cross: Connects together rails of a track or adjacent tracks
    • Bond impedance: A specific rail bond bridging insulated rail joints in AC track circuited sections
    • Bond rail: An electrical connection across a joint between adjacent rail lengths for the track return
    • Bond, structure: Connects track structures/bridges with the overhead equipment to the track return
    • Cantilever assembly: A structural member comprising steel tubes supporting the catenary system to facilitate current collection by the pantograph at all speeds
    • Stay arm: A component with diameter 28.4/33.7 mm, with an adjuster for bracket tube position, insulated from mast by stay arm insulator
    • Bracket tube: A component with diameter 40/49 mm (small) or 30/38 mm (standard), insulated by bracket insulator
    • Register Arm: A 28.4x33.7 mm tube for registering the contact wire's position with steady arm assistance
    • Crossings: Electrically live members/conductors passing over other live members without physical contact
    • Power line crossing: An overhead transmission/distribution line or underground cable across railway tracks, for electrical energy transmission.
    • Crossing OHE: Crossing of two OHE conductors without physical contact.
    • Dropper: A fitting supporting contact wire from catenary
    • Electrical Clearance: The air distance between live equipment and the nearest grounded part
    • Encumbrance: The axial distance on a vertical plane between catenary and contact wire at the support
    • Feeder: A conductor connecting substation with feeding post or feeding post with OHE
    • Height of contact wire: The vertical distance from rail level to the underside of the contact wire
    • Interruptor: A single-phase vacuum SF6/oil circuit breaker used in circuit closure in case of a fault
    • Bridging Interruptor: Provides connection between substations in emergencies
    • Sectioning Interruptor: Connects adjacent sectors for continuity of supply
    • Paralleling Interruptor: Joins overhead equipment of different tracks for voltage reduction
    • Jumper: A conductor providing electrical continuity between two conductors or equipment
    • Mast: A vertical post supporting overhead equipment (OHE) assembly
    • Neutral Section: Short section of insulated dead OHE separating sectors fed by two adjacent substations.
    • Overhead Equipment (OHE): Electrical conductors, fittings for overhead electrical systems
    • Overlap: OHE arrangement spanning a short distance to facilitate pantograph movement
    • Pantograph: Collapsible device on rolling stock for collecting current from OHE
    • Return Conductor: A conductor carrying current from tracks to substation
    • Regulating Equipment: Maintains constant tension in OHE conductors at varying temperature
    • Setting Distance: Horizontal distance from the traction mast to the track center line
    • Span: Horizontal distance between supporting masts for OHE
    • Stagger: Horizontal distance of a wire/catenary from a vertical plane through pantograph center
    • Section Insulator: In OHE, isolates sections to prevent current flow between sections
    • Sector: Part of an OHE energized by a feeder circuit breaker at the substation
    • Sub-sector: Smallest section of an OHE isolated remotely by interruptors
    • Elementary Section: Smallest section of an OHE isolated manually.
    • Tension Length: Length of conductor stretched between two anchor points
    • Versine: Maximum offset of the rail, relating to curved track's chord
    • Clearance: Minimum distance between live parts and earthed parts in various conditions
    • Span Measurement: Measuring spans accurately using a steel tape.

    Spans

    • Spans measurement guidelines: different methods based on the track configuration (single vs. multiple) and location
    • Standards for calculating spans: references to drawings, with variations for regulated/conventional OHE, and different OHE types.
    • Restrictions apply to different scenarios. These restrictions limit span lengths under various conditions (e.g., over-line structures or locations with restricted clearances)

    Masts, Portals, and Foundations

    • Mast types: various designs and materials (e.g., rolled sections, fabricated, concrete spun poles)
    • Descriptions of specific mast designs (150x150 BFB, 200x150 RSJ, K-series, B-series )
    • Selection of masts based on wind pressure zones

    Over-line Structures

    • Clearance considerations: clearance standards and required calculations based on various locations

    Contact Wire Height

    • Standard height: minimum 5.5 m above the track in all conditions
    • Reduced height permissible for over-line structures after clearance considerations
    • Special requirements near electric locomotives or inspection areas

    Stagger

    • Tangent and curved tracks: Different stagger values for different track types
    • Stagger at support and mid-span

    Droppers

    • Standard arrangement designs
    • Special dropper arrangements for unusual locations

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    Principles For Layout Plans And Sectioning Diagrams For 25kV AC Traction PDF

    Description

    This quiz covers the fundamental principles for layout plans and sectioning diagrams in 25kV AC traction systems. It delves into standardization, efficiency, and specific definitions crucial for maintaining the integrity of railway electrification projects. Participants will gain a better understanding of electrical connections and design priorities critical for pantograph operations.

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