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					                         DICTIONARY OF OVERHEAD CONTACT SYSTEM TERMS
                   IEEE OVERHEAD CONTACT SYSTEMS COMMITTEE FOR RAIL TRANSIT

     DICTIONARY FOR OVERHEAD CONTACT SYSTEMS WITH PANTOGRAPH AND TROLLEY POLE OPERATIONS

                                                                 REVISED DRAFT   FEBRUARY 14, 2005




     IEEE SUPPLEMENTARY DICTIONARY OF TERMS FOR OVERHEAD
                       CONTACT SYSTEMS


Terms given in this dictionary are presently not given in the IEEE Standard Dictionary of
Electrical and Electronic Terms, (IEEE Dictionary), or are not defined in it with reference to
Overhead Contact Systems (OCS). Some terms given here are defined in the IEEE
Dictionary, and are so annotated.

The purpose of this dictionary is to provide uniform terminology and definitions for technical
terms used in OCS that supply electrical power to electric light rail vehicles (LRV) and
streetcars with pantographs or trolley poles and to electric trolleybuses (ETB) with trolley
poles.

Terms used only in OCS for trolley pole operations are in italics.

Terms, which in OCS are synonymous, are shown (Syn).
Where synonyms exist the NON- PREFERRED term has an asterisk (*).

OCS style can be either „Catenary‟ where the contact wire is supported from a messenger
wire by hangers, or „Direct Suspension‟ where the contact wire is directly supported by a
cross-span, bridle, trapeze, pendulum, resilient arm, bracket arm or cantilever.
Either style can be either „Fixed Terminated‟ or „Auto-Tensioned‟.
Terms that are exclusively to one style, are referenced FT or AT respectively.

All ETBs use swivel collector shoes to allow the trolleybus to deviate up to 12 or so feet each
side of the trolley wires.

LRVs and streetcars with trolley poles use „fixed‟ collector shoes, which allow them to track
the correct trolley wire at turnouts without the use of electric frogs.

For proprietary names see Suppliers Catalogs.
.
This dictionary does NOT define terms for ac-electrification OCS, but refers the reader to
AREMA Chapter 33, which are recommendations prepared by the American Railway
Engineering and Maintenance Association.




                   Dictionary of Terms for Overhead Contact Systems                       1 of 40
                             DICTIONARY OF OVERHEAD CONTACT SYSTEM TERMS
                       IEEE OVERHEAD CONTACT SYSTEMS COMMITTEE FOR RAIL TRANSIT

      DICTIONARY FOR OVERHEAD CONTACT SYSTEMS WITH PANTOGRAPH AND TROLLEY POLE OPERATIONS

                                                                      REVISED DRAFT   FEBRUARY 14, 2005




1. Acceptance Measurements                Final definitive records of the installed contact wire heights and
                                          staggers at OCS support and registrations, and at midspan.

2. Accessible Voltage*                    See “Step Potential”

3. Actual Span Length                     See “Span Length”

4. Adjustments, Final adjustments         Placing the conductors to the correct wire heights and staggers.

5. Airbreak; Half-tension Airbreak        See “Sectionalizing”

6. Alignment
7. Track alignment                        The centerline or other reference line of the track or tracks in
                                          both plan and profile.
8. OCS alignment                          The position of the OCS relative to the (superelevated) centerline
                                          of the track.

9. Along Track Feeder*                    See “Parallel Feeder”

10. Along-Track Movement (ATM)            The migration of catenary induced by BWs or tensioners due to
11. (AT Systems)                          thermal expansion or contraction of the conductors

12. Ambient Temperature                   The weather related temperature of an OCS, which excludes
                                          temperature effects due to current in the conductors.

13. Anchor
14. Anchor Base Pole*                     See “Bolted-Base Pole”.

15. Anchor Bolt                           See “Foundation”

16. Anchor Bracket                        An attachment to the face of a civil structure (tunnel soffits,
                                          bridge deck, tunnel portal, boat section, retaining wall, parapet,
                                          etc.) for anchoring OCS.

17. Anchor Plate or Dead-Man              See “Foundation”

18. Deadend                               See “Fixed Termination Assembly”

19. Pole Base Anchor                      A pole which provides the ground level anchorage at its base or
                                          base-plate for a down guy from an adjacent anchor pole.

20. Screw Anchor                          A specialty device with a helical cutting blade that is
                                          „corkscrewed‟ into the ground as an anchorage for a down-guy

21. Self Supporting Anchor (pole)         An anchor pole without a down-guy.




                     Dictionary of Terms for Overhead Contact Systems                          2 of 40
                          DICTIONARY OF OVERHEAD CONTACT SYSTEM TERMS
                    IEEE OVERHEAD CONTACT SYSTEMS COMMITTEE FOR RAIL TRANSIT

      DICTIONARY FOR OVERHEAD CONTACT SYSTEMS WITH PANTOGRAPH AND TROLLEY POLE OPERATIONS

                                                                   REVISED DRAFT   FEBRUARY 14, 2005


22. Arcing                             When associated with commutation between pantograph and
                                       contact wire, arcing is the sparking at the interface point when
                                       the pantograph is drawing current at speed. Arcing typically
                                       does more harm to the pantograph carbons than to the contact
                                       wire, weakening the surface of the carbon and causing it to be
                                       eroded. With metalized carbons, erosion of the carbon releases
                                       metal (commonly copper) often in minute globules the size of
                                       ground coffee. These settle onto the underside of the contact
                                       wire up to 10 feet from the arc, where they now act as a rasp on
                                       the carbon causing more erosion - this time mechanically.

                                       Arcing is typically caused at “hard spots” along the contact wire.
                                       See “Hard Spots”

                                       Arcing can be minimized by trains powering down before
                                       reaching known hard spots, and by avoiding getting into
                                       regeneration mode, which can be a source of current equal, if
                                       not greater, than normal traction current values.

                                       Arcing is preventable by avoiding designing hard-spots into the
                                       system due to the use of section insulators, direct push-off
                                       registrations, resilient arms and sharp changes in gradient.

23. Assembly
24. OCS Assembly                       A discrete configuration of components used in an OCS,
                                       and identified in combination for ease of reference. See
                                       “Assembly Reference”
                                       Assemblies such as trolley wire switches, frogs, crossings
                                       and curve segments are usually referred to as “Special
                                       Work” in the industry.

25. Assembly Reference                 An alphanumeric code assigned to a discrete group of
                                       components, and that describes the materials list for one
                                       standard configuration, in which only the lengths of pipes or
                                       wires can vary.

26. Auto-Tensioned (AT) Equipment      OCS conductors terminated with balanceweights, springs or
                                       hydraulic tensioning devices to maintain constant tension over a
                                       specified range of conductor temperatures by compensating for
                                       conductor thermal expansion and contraction.

27. Autotransformer (AC)
28. System                             See AREMA Chapter 33.
29. Substation
30. Auxiliary Messenger or             A third conductor typically installed with hangers above the
    Auxiliary*                         contact wire and beneath the messenger wire of a catenary
                                       system and forming „Compound Catenary Style‟




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                             DICTIONARY OF OVERHEAD CONTACT SYSTEM TERMS
                       IEEE OVERHEAD CONTACT SYSTEMS COMMITTEE FOR RAIL TRANSIT

      DICTIONARY FOR OVERHEAD CONTACT SYSTEMS WITH PANTOGRAPH AND TROLLEY POLE OPERATIONS

                                                                      REVISED DRAFT    FEBRUARY 14, 2005


31. Backbone                              A span guy or along track span-wire between structural
                                          supports used primarily to align contact/trolley wires around a
                                          curve using a series of pull-offs attached along the backbone.

32. Backguy*                              See “Guy”.

33. Balanceweight Assembly (BWA)          The tensioning gear with weights that are installed at each end of
                                          a tension section of an auto-tensioned OCS.
                                          See “Tension Section” and “Half Tension Section”

34. Balanceweight Stops, or               Mechanical means for preventing further movement of
    Temperature Stops*                    balanceweights beyond a specified range of movement.

35. Barn Hanger                           A support more commonly used with trolley wire than with
                                          contact wire, that is usually fixed directly to the underside of the
                                          protective troughing or sheeting that is customarily attached to
                                          the trolley barn roof.

36. Basic Impulse Insulation Level        See IEEE Dictionary.
    (BIL, bil)
37. Bent                                  See “Bridge Bent”

38. Blow-off                              Lateral displacement of the contact /trolley wire due to wind.

39. Boat section                          Civil engineering term for an open concrete structure that is
                                          below the general ground level.

40. Body Span Wire                        The center wire of a three-wire head span used mainly to carry
                                          the radial and wind loads exerted by the messenger wires.

41. Bolted Base Pole                      A pole with baseplate for use on a foundation with anchor bolts
                                          (as compared to a plain or planted pole which is directly
                                          embedded in stone or concrete).

42. Bond                                  An electrical connection between metal hardware (rails, poles,
                                          rebar, etc) that eliminates voltage difference

43. Impedance Bond                        An inductive device bridging an insulated rail joint that allows
                                          passage of traction return current while preventing passage of
                                          signaling current. An impedance bond is typically housed in a
                                          metal box 1ft. deep and up to 3ft. square, that is located close by
                                          or between rails and connected across an insulated rail joint.

44. Rail Bond (traction)                  Electrical connection between two rails in OCS return circuits
                                          and rated for the full traction return current.

45. Structure Bond                        An electrical connection between a structure and the rebar cage
                                          of the foundation and/or to a ground rod, or to a grounding
                                          circuit of a civil structure.




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                           DICTIONARY OF OVERHEAD CONTACT SYSTEM TERMS
                     IEEE OVERHEAD CONTACT SYSTEMS COMMITTEE FOR RAIL TRANSIT

      DICTIONARY FOR OVERHEAD CONTACT SYSTEMS WITH PANTOGRAPH AND TROLLEY POLE OPERATIONS

                                                                      REVISED DRAFT    FEBRUARY 14, 2005


46. Booster Transformer or Suction      See AREMA Chapter 33.
    Transformer (AC)

47. Bracket Arm or Mast Arm*            The frame usually supporting a direct suspension single contact
                                        wire or trolley wire directly from a pole without using a hinge.
                                        (A bracket arm, which is hinged to a pole, has the preferred
                                        term “cantilever”.)

48. Bracket                             See “Pole Bracket” or “Anchor Bracket

49. Break*                              See “Section break” or “Airbreak”

50. Bridge

51. Overpass                            See “Overpass”

52. Bent                                A Structural Engineering term for a portal frame or transverse
                                        framework, as used to support the deck of a bridge.

53. Bridge Barrier                      The name given to a permanent protective shield on an
                                        overbridge spanning over electrified tracks or over trolley
                                        overhead wires, for the purpose of shielding the overhead
                                        conductors from vandals, and/or protecting people from
                                        electrical danger. Also see „Construction Barrier”.

54. Bridging                            The act of connecting across sectionalization points by
                                        pantographs.

55. Bridle                              A span guy or wire between structural supports used primarily
                                        to provide support to a cross-span wire or pull-off attached
                                        approximately midway along the bridle.

56. Bridle Suspension                   A short (4 feet to 6 feet long) loop of wire that supports a single
                                        contact wire from a horizontal (cantilever) pipe or pulley.
                                        A short (6 feet to 8 feet long) loop of wire that supports a
                                        messenger wire from a pulley in AT equipment.

57. Building Attachment                 An eyebolt or other OCS mounting on a building.

58. Bull Ring                           A steel ring usually 2” to 4” in diameter to which two or more
                                        aerial (span) guys may be attached.

59. Bus Path                            The locus of the center point of the front axle of a trolleybus along a
                                        transitway.

                                                NOTE. Not necessarily the centerline of the transitway.




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                             DICTIONARY OF OVERHEAD CONTACT SYSTEM TERMS
                       IEEE OVERHEAD CONTACT SYSTEMS COMMITTEE FOR RAIL TRANSIT

      DICTIONARY FOR OVERHEAD CONTACT SYSTEMS WITH PANTOGRAPH AND TROLLEY POLE OPERATIONS

                                                                     REVISED DRAFT    FEBRUARY 14, 2005



60. BW                                    Balanceweight

61. BWA                                   Balanceweight Anchor or Balanceweight Assembly

62. Bypass Switch                         See “Switch”

63. Cable Outlet*                         See “Feeder Spout”

64. Cadweld                               A proprietary thermic welding operation

65. Cantilever                            A hinged bracket arm*
66.
67. Back-to-back cantilevers              Cantilevers mounted on opposite sides of poles which are located
                                          between tracks.

68. Cantilever Assembly                   An OCS support frame typically for mounting a messenger
                                          support or suspension fitting and a contact wire registration
                                          assembly that is mounted on a pole or portal beam drop bracket
                                          using hinge fittings.

69. Long-Reach Cantilever                 A cantilever assembly whose reach (see below) typically exceeds
                                          13 feet.

70. Multi-Track Bracket Arm               A frame rigidly attached to a pole and serving three or more
                                          tracks.

71. Reach                                 The dimension between the face of the pole and the contact wire,
                                          or in the case of several contact wires, the furthest contact wire
                                          from the pole.

72. Reduced Height Cantilever             A cantilever where the system height of the OCS is (typically)
                                          more than one foot less than the standard system height, thereby
                                          requiring reconfiguration of the basic cantilever shape by
                                          lowering the messenger wire support.

73. Twin Cantilevers                      Two cantilevers installed side-by-side on spreaders on one pole,
                                          each supporting its own OCS, and both OCS serving the same
                                          track. Have application in overlaps and at crossovers where two
                                          catenaries will normally have differential along-track movement.

74. Two-Track Bracket Arm                 A frame rigidly attached to a pole that serves two adjacent
                                          tracks to one side of it from which the OCS for each track is
                                          supported.

75. Two-Track Cantilever                  A single OCS cantilever frame serving two adjacent tracks to
                                          one side of its supporting pole, and catering to the independent
                                          movement of the catenaries in AT systems.




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                           DICTIONARY OF OVERHEAD CONTACT SYSTEM TERMS
                     IEEE OVERHEAD CONTACT SYSTEMS COMMITTEE FOR RAIL TRANSIT

      DICTIONARY FOR OVERHEAD CONTACT SYSTEMS WITH PANTOGRAPH AND TROLLEY POLE OPERATIONS

                                                                      REVISED DRAFT   FEBRUARY 14, 2005



76. Catenary                            The combination of two or more OCS conductors, with hangers
                                        and in-span hardware, but not including supports and
                                        cantilevers.

77. Dictionary Meaning                  The curve assumed by a perfectly flexible cord of uniform
                                        weight and cross-section hanging freely between two fixed
                                        points.

78. Simple Catenary Style               Auto-Tensioned Simple Catenary (ATSC) and Fixed Terminated
                                        Simple Catenary (FTSC) styles each comprised of a contact wire
                                        supported from a messenger wire by hangers.

79. Compound Catenary Style             Comprising a contact wire supported by an auxiliary wire,
                                        which, in turn, is supported from a messenger wire by hangers.

80. Stitched Catenary Style             A two conductor catenary system to which a stitch wire
                                        (messenger bridle) has been added at the supports to improve
                                        catenary dynamics.

81. Inclined Catenary Style             An arrangement of OCS conductors, where the messenger
                                        carries the horizontal (radial) load of the contact wire (and
                                        auxiliary wire) on curved tracks, in addition to providing
                                        vertical support, and in which the contact wire closely follows
                                        the centerline of the track. Inclined catenary has excellent
                                        commutation performance, has great economy of OCS support
                                        structures, but is difficult to install and to replace.

82. Low Profile Catenary Style          A version of simple catenary with a small system height, (2ft. 0in.
                                        to 2ft. 6in. compared to 4ft. 0in. of standard simple catenary)
                                        which permits both conductors to be supported and registered
                                        from a single cross-span wire for improved aesthetics. As a
                                        consequence of the small system height the maximum span is
                                        typically limited to about 150 feet.

83. Chordal Catenary Style              A catenary system in which the messenger (and auxiliary) are
                                        installed vertically above the contact wire. Also known as
                                        Tangent-Chord style.

84. Contenary                           A twin contact wire system.

                                        OCS construction wherein the messenger of a simple catenary
                                        system is locally substituted with a contact wire, that can be
                                        installed alongside the primary contact wire to create a catenary
                                        system of extremely small system height which is a practical
                                        solution for wiring bridges with very low clearances.




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                             DICTIONARY OF OVERHEAD CONTACT SYSTEM TERMS
                       IEEE OVERHEAD CONTACT SYSTEMS COMMITTEE FOR RAIL TRANSIT

      DICTIONARY FOR OVERHEAD CONTACT SYSTEMS WITH PANTOGRAPH AND TROLLEY POLE OPERATIONS

                                                                      REVISED DRAFT    FEBRUARY 14, 2005



85. Catenaries Dynamics                   The interactive relationship between “current collectors” and
                                          contact/trolley wires at operating speeds.

86. Chording of Curves                    On curved route the propensity of the contact wire to “cut the
                                          curve” between points of registration.

87. Clamp                                 A fitting with bolts and nuts that be fixed in position on a pire or
                                          conductor, and yet can be removed (unbolted) and re-used at
                                          another position.

88. Contact Swivel or Fixed Clamp         The fitting on the end of the steady arm or registration pipe,
                                          which attaches to the contact wire

89. Parallel Groove Clamp                 A piece of hardware used to clamp two or more parallel wires
                                          together.

90. Pipe Clamp                            A piece of hardware used to attach various types of components
                                          to a pipe.

91. Strain Clamp                          A piece of hardware used for deadending a wire or conductor
                                          under high tension.

92. Suspension Clamp                      A piece of hardware used to support a tensioned conductor or
                                          cable in a hanging arrangement, the greater part of the applied
                                          load being due to conductor weight.

93. Clipping In                           The sagging (regulating) of the OCS conductors to correct
                                          tension, and clamping at the supports and installing the hangers.

94. Collector Strip*                      See “Contact Strip”

95. Commutation*                          The act of picking up electrical power from an overhead contact
                                          wire by pantograph or trolley pole.

                                          See “Current Collection”. See also “Bridging”

96. Commutation Performance*              See “Catenary Dynamics”

97. Component (OCS)                       An item of OCS hardware as commonly supplied complete by
                                          manufacturers.

98. Compound Equipment                    See “Catenary”

99. Compression Type Fittings* or         Fittings that require a hydraulic press to crimp or otherwise
    Compression Fittings                  form a mechanical joint usually with one or more conductor
                                          using a sleeve or ferrule.
                                          Fittings that require the forcing of one or more pins into a solid
                                          conductor in order to effect a mechanical connection.




                       Dictionary of Terms for Overhead Contact Systems                         8 of 40
                           DICTIONARY OF OVERHEAD CONTACT SYSTEM TERMS
                     IEEE OVERHEAD CONTACT SYSTEMS COMMITTEE FOR RAIL TRANSIT

       DICTIONARY FOR OVERHEAD CONTACT SYSTEMS WITH PANTOGRAPH AND TROLLEY POLE OPERATIONS

                                                                     REVISED DRAFT    FEBRUARY 14, 2005


100.      Conductor Bar* or             See “Conductor Rail”
    Conductor Beam*
101.      Conductor Joints              OCS conductor joints carry full catenaries tension and full
                                        conductor current. Factory jointing of conductors is performed
                                        before final extrusion of the finished conductor, and joint
                                        between the individual „stock‟ bars may either be scarfed and
                                        braised or fusion butt welded.        Field joints are usually
                                        mechanical, being cone type couplings, or compressed sleeves.

102.        Conductor Rail              Various shapes of rigid bar, e.g. “double lobe bar”, used in
                                        maintenance shops and under bridges as an alternative to a
                                        contact wire or trolley wire. Not to be confused with third rail.

103.        Constant Tension OCS*       See “Auto-tensioned equipment”

104.        Construction Barrier        A temporary barrier serving the purpose of a bridge barrier
                                        during construction/reconstruction of an overbridge spanning
                                        electrified tracks.

105.        Construction Overlap        An OCS overlap without provision for sectionalizing. An
                                        “Uninsulated Overlap”

106.        Contact Bar* or Rail*       See “Conductor Rail”.

107.        Contact Strip               The wearing strip on the head of a pantograph that enables an
                                        electric vehicle to draw power from an OCS. Typically made of
                                        carbon or metalized carbon, the strip may be in one piece or in
                                        four or five abutting pieces, with an overall length not more than
                                        52 inches. The Pantograph head typically has two strips at
                                        approximately 13 inch centers. Each strip is either 40 cm. wide
                                        or 60cm. wide.
                                        In the past, other materials, such as copper and steel have been
                                        used with or without an integral greasing system.

108.        Contact Wire (CW)           The wire with which the pantograph or trolley pole makes
                                        contact for current collection. Normally made of copper or
                                        bronze, the wire is a single wire conductor usually with a groove
                                        to which hangers and clamps may be fitted. Cross section shapes
                                        include „round grooved‟ with various copper cross sectional area
                                        from 106 kcmil to 350 kcmil, and „figure-9, Deep Section‟ (335,
                                        350 and 400 kcmil.)

                                        See also “Trolley Wire” for trolley pole operations

109.       Contact Wire Along-          See “Along-Track Movement”
    Track Movement (ATM)




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                           DICTIONARY OF OVERHEAD CONTACT SYSTEM TERMS
                     IEEE OVERHEAD CONTACT SYSTEMS COMMITTEE FOR RAIL TRANSIT

       DICTIONARY FOR OVERHEAD CONTACT SYSTEMS WITH PANTOGRAPH AND TROLLEY POLE OPERATIONS

                                                                      REVISED DRAFT    FEBRUARY 14, 2005



110.        Contact Wire Bridge         At track crossovers, crossings and turnouts, a rigid bar or piece of
                                        contact wire, up to 5 feet long, is attached to the in-running contact
                                        wire, and closely above it, to form a slot for a second contact wire to
                                        pass through, thereby preventing differential uplift of crossing
                                        contact wires. Also called a „wire cross*‟.

111.        Contact Wire Clamp

112.        For FT equipment            The fixed clamp at the end of a registration arm or a steady arm,
                                        which is fitted into the groove of the contact wire or trolley wire
                                        to take the registration and wind loads.

113.        For (AT) equipment          The swivel clamp at the end of a registration arm or a steady
                                        arm that is fixed into the groove of the contact wire or trolley
                                        wire to take the registration and wind loads. The swivel is to
                                        accommodate along-track movement of the contact wire due to
                                        angular displacement.

114.        Contact Wire Creep          The ongoing stretch of a contact wire or trolley wire, which is
                                        under a sustained tension.

115.        Initial Creep               It has been shown that when a conductor is subjected to its
                                        normal tension, it will creep at a greater rate for the first 15 days
                                        under load than it will after the first month or so.

116.        Contact Wire Deviation      When contact wires are staggered on straight tracks or
                                        registered on curved tracks the contact wire changes direction at
                                        each clamp, through an angle, which is termed the „deviation
                                        angle‟. As a consequence a radial load is imparted to the
                                        registration arm or span wire.
                                        Experience suggests that the maximum deviation of the contact
                                        wire at any registration point should not exceed 7 degrees, nor
                                        should the radial load exceed 500 lb. under the worst conditions.
                                        The use of double registration arms is suggested for radial loads
                                        between 500 lb and 1000 lb.

117.        Contact Wire Door Bridge    A bridging device between sections of contact wire that is
                                        mounted on the transom of doorframes of maintenance shops
                                        that can be opened to allow roll-up doors to open and close.
                                        Such a design may have a bridging piece that laterally overlaps
                                        the contact wire conductor rail in which case it would not be
                                        suitable for use with trolley poles.

                                        See “Trolley Door Bridge”.

118.       Contact Wire Droop or        The additional downward displacement of the contact wire due
    Contact Wire Fall                   to temperature or ice. The increase in sag; not the actual sag.




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                           DICTIONARY OF OVERHEAD CONTACT SYSTEM TERMS
                     IEEE OVERHEAD CONTACT SYSTEMS COMMITTEE FOR RAIL TRANSIT

       DICTIONARY FOR OVERHEAD CONTACT SYSTEMS WITH PANTOGRAPH AND TROLLEY POLE OPERATIONS

                                                                   REVISED DRAFT   FEBRUARY 14, 2005



119.      Contact Wire Height           The height of the underside of the contact wire above reference
    (CWH)                               rail level or street (trolley bus) when not uplifted by the
                                        pantograph or trolley pole.

                                        The minimum allowable contact wire height, usually at mid pan
120.       Minimum Contact Wire         or under bridges, which takes due account of vehicle clearance
    Height                              envelope, vehicle bounce and track tolerances, OCS temperature
                                        effects and electrical clearances. May also take future track
                                        raising into account if so required.

                                        The maximum allowable contact wire height within the vertical
                                        operating range of the pantograph or trolley pole.
121.       Maximum Contact Wire
    Height
122.       Contact Wire Rise            The dimensional rise of a contact wire under its own weight and
                                        tension, from grade over a distance.
                                        The increase in the height of the contact wire at midspan, due to
                                        the combined effect of :
                                             An increase in contact wire tension at low temperature.
                                             Wear of the contact wire.
                                             Uplift due to the pantograph or trolley collector pole
                                                pressure.

                                        See “Uplift”.

123.        Contactor (OCS)             A device, normally fitted on a contact wire or a trolley wire for
                                        making or breaking a circuit, or instrumental to switching of
                                        other circuits, such as traffic signal pre-emption, or ETB route
                                        selection.

124.        Contenary                   See “Catenary – Contenary”.

125.        Copper clad Conductor,      A wire with a steel center and layer of copper fused around it or
    also known as Copperweld            a number of such wires stranded together.‟

126.        Corrosion                   The deterioration of a substance (usually a metal) because of a
                                        reaction with its environment.

127.        Electrolytic Corrosion      The destructive chemical action caused by local dc electrical
                                        currents to pipes, cables and other materials, often resulting
                                        from stray currents leaking from the traction negative rail
                                        return of the OCS.

128.        Counterpoise                A buried wire or a configuration of wires to provide a low
                                        resistance grounding system.

129.        Counterweight*              See “Balanceweight”.

130.        Creep                       The on-going permanent stretch of tensioned wires over time.


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                            DICTIONARY OF OVERHEAD CONTACT SYSTEM TERMS
                      IEEE OVERHEAD CONTACT SYSTEMS COMMITTEE FOR RAIL TRANSIT

       DICTIONARY FOR OVERHEAD CONTACT SYSTEMS WITH PANTOGRAPH AND TROLLEY POLE OPERATIONS

                                                                      REVISED DRAFT   FEBRUARY 14, 2005



131.        Crimp Type Fittings          Fittings that require the squeezing down with possible indenting,
                                         of a sleeve through which two or more wires pass. For small
                                         wires a hand tool may be used, but for larger sleeves and
                                         conductors a hydraulic press will normally be used.

132.        Crosby                       A type of clamp with a U-bolt and saddle that pinches two wires
                                         together so they hold tight.

133.        Crossarm – Feeder            Typically a short cross bracket mounted high up on OCS poles
                                         that support feeders.

134.        OCS Crossarm*                See “Cantilever”, “Bracket Arm”.

135.        Cross Catenary*              See “Headspan”

136.        Cross Contacts*              See “Contact Wire Bridge”

137.        Cross Level                  The plane through the tops of the rails of a track in the
                                         transverse direction.

138.        Cross Level Tolerance        See “Track Tolerances”.

139.        Crossover (Special Work)     An OCS assembly that permits two sets of trolley wires to cross each
                                         other, either at right angles, or a straight or curved skew angle.

140.        Cross-Span                   A single wire fastened between two supports that crosses the
                                         track or roadway just above contact wire level and supports one
                                         or more contact wires. See also “Headspan”.

141.        Current Collection           The act of picking up electrical power from overhead
                                         contact/trolley wire by pantograph or trolley pole.

142.        Current Collector

143.        For Pantographs              The contact strip at the top of a pantograph, which rides along
                                         under the contact wire to collect current. See “Contact Strip”.

                                         The carbon insert housed inside the trolley shoe and normally 3 ½
144.        For Trolley Poles            inches long, which rides along under the contact wire collecting
                                         current.

145.        Curve Construction

146.        Inside Curve                 An arrangement where OCS support poles are on the inside of the
                                         curve, necessitating the use of bracket arm construction.

147.        Outside Curve                Poles are on the outside of the curve.

148.        Curve Hanger                 See “Single and Double Curve Hanger.”


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                            DICTIONARY OF OVERHEAD CONTACT SYSTEM TERMS
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       DICTIONARY FOR OVERHEAD CONTACT SYSTEMS WITH PANTOGRAPH AND TROLLEY POLE OPERATIONS

                                                                       REVISED DRAFT    FEBRUARY 14, 2005



149.        Curve Rail (Special Work)    A short version of a curve segment for shallower turns.

150.      Curve Segment (Special         An OCS assembly used on trolley wire systems that permits the
    Work)                                trolley poles to transfer to a curved rail in order to take an angle in
                                         the trolley wire with 10º to 45º deviation.

151.        Curve Span                   A cross-span on a curve with one or more double curve hangers or a
                                         curve segment.

152.        Curve Supports

153.        Inside Curve                 An arrangement for an OCS where the poles are on the inside of
                                         the curve.

154.        Outside Curve                Poles are on the outside of the curve.

155.        Cut-In-Switch                A type of directional switch in the trolley wires where a section of
                                         trolley wire is cut out in order to insert the switch special work.

156.        Cut-Out                      A section insulator used in the trolley wires for sectionalization: but
                                         only installed in positive trolley wires.

157.        CW                           Contact wire

158.        CWA                          Contact wire anchor.

159.        Deadend                      The direct termination of a conductor under tension to a pole,
                                         beam or wall.

160.        Deadend Assembly             See “Fixed Termination Assembly‟

161.        Direct Suspension System     An OCS with direct support of a trolley wire from a cross-span
                                         wire, bracket arm, resilient arm or resilient hanger in both AT
                                         and FT systems.

162.        Disconnect Switch            See “Switch”

163.        Door Bridge*                 See “Contact Wire Door Bridge” or “Trolley Door Bridge”

164.        Double Curve Hanger          An overhead assembly used in cross-spans to support trolley wires in
                                         large radius curves. Each hanger typically provides up to 2 ½ º
                                         deviation in the trolley wires.

165.        Double Insulation            Insulation provided by two physically separated insulators, to
                                         create a safe working zone for maintenance staff between
                                         energized equipment and grounded equipment. A separation of
                                         at least six feet is preferred.
                                         (Requirements are described in California PUC GO 95 and
                                         other codes.)


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                                                                       REVISED DRAFT    FEBRUARY 14, 2005



166.        Down Guy                      See “Guy”

167.        Droop                         Fall of a conductor from its height at normal temperature, due
                                          to temperature change and/or ice coating. Droop is an increase
                                          in sag, rather than the total sag of a conductor.

168.        Drop Bracket                  A fitting attached to the underside of a cantilever registration
                                          pipe that carries the steady arm or registration arm

169.        Dropper*                      See “Hanger” or sometimes used ambiguously as “Feeder”.

170.        Drop Vertical or Drop         A steel frame or pipe rigidly attached to the underside of a
    Pipe                                  portal or bridge deck for mounting an OCS support and/or
                                          registration assembly.

171.       Dual-mode or Dual-             An ETB or rail car designed to operate either by self-powered or
    Powered Bus, or a Hybrid Bus or       by electricity taken from an OCS or third rail.
    Rail Vehicle.
172.       Dual Operation or Dual         Where rubber tired and rail vehicles share the same R-O-W.
    Mode Operation
173.       Duct, Duct-Line                An enclosed conduit i.e. pipe, etc. for electrical cables, typically
                                          underground, or mounted on, or embedded in, civil structures.

174.        Dynamic Load                  See “Live Load”

175.        Dynamics                      See “ Catenary Dynamics”

176.        Ear, Trolley Ear, or Line-    The normal trolley wire clamp used to suspend the trolley wire. Also
    Ear                                   called a „Clamp‟. See Manufacturers‟ Catalogs.

177.        Elastic Arm*                  See “Resilient Arm”

178.        Elastic Hanger                A form of resilient arm with a limited use due to being of lower
                                          strength than a normal resilient arm.

179.        Elastic System                A term applied to a trolley OCS where the trolley wires are free
                                          to uplift under the pressure of the current collectors at the
                                          supports.   Typified by the use of pendulum suspensions
                                          comprising one hanger or two articulated parallel hangers.

180.        Embedded Poles                OCS poles without base plates that are directly inserted into
                                          socket-type or open foundations and fixed by concrete, grout or
                                          compacted backfill.

181.        Encumbrance*                  See “Pole Encumbrance”.

182.        Envelope

183.        Combined Vehicle              The rail vehicle dynamic envelope plus the effects of track alignment


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                                                                        REVISED DRAFT    FEBRUARY 14, 2005


   Envelope                               and cross-level tolerances.

                                          The combined vehicle envelope applied to the pantograph plus a
184.       Pantograph Clearance           typical 6” lateral „running‟ allowance for safety and a typical 8”
    Envelope                              vertical allowance above static contact wire level. Only steady arms
                                          and registration arms are permitted within this envelope.

                                          The combined vehicle envelope plus a safety clearance allowance
                                          typically 6” all round, into which no part of the fixed facilities e.g.
185.       Structure Clearance            bridges, stations, signal, trackside „houses‟, etc. shall intrude.
    Envelope
                                          The dimensioned space around the vehicle trolley pole(s) depending
                                          upon the position of the trolley wire(s) and the vehicle.

186.       Trolley Pole Clearance         The maximum envelope of a vehicle when it is free to lurch and
    Envelope                              sway.

                                          The maximum envelope of a static vehicle
187.        Vehicle Dynamic Envelope


188.        Vehicle Static Envelope
189.        Equation – Stationing         Typically the mathematical adjustment at a point along an
                                          alignment where the “running” stationing is interrupted or
                                          restarted.

190.      Equivalent Span or Ruling       A weighted average span of a given tension section of
    Span*                                 conductions used in sag-tensioned calculations.

191.        Exclusive Right-of-Way        ROW only accessible to the Agency‟s own vehicles.

192.        Exothermic Welding            A type of welding where a „charge‟ is ignited which burns with
                                          intense heat and melts adjacent sections of metal allowing them
                                          to fuse together.

193.        Eye-Bolt                      See “Building Attachment”

194.        Eye of Pullover*              See “Heel of Steady Arm”

195.        Eye Setting*                  See “Heel Setting”




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                                                                     REVISED DRAFT    FEBRUARY 14, 2005



196.        Face of Pole                  The absolute nearest part of a pole from the track for structure
                                          clearance purposes. Structure clearance requirements do not
                                          include base plate and top of foundation unless these are located
                                          significantly above the level of the rails and intrude into the
                                          clearance envelope.

197.       Facing Turnout; Facing-        A track turnout that can be entered with point of switch entered
    Point Turnout                         first in the normal direction of travel (see also “Trailing
                                          Turnout”)

198.        Factor of Safety              The margin of safety in terms, usually of strength, between the
                                          breaking load and the maximum design operating load
                                          expressed as a ratio.

199.        Fall                          See “Contact Wire Fall” or “Messenger Wire Fall”.

200.        Feeder Spout or Feeder        A short pipe installed through the wall of a tubular pole, through
    Outlet*                               which a feeder cable exits the pole.

201.        Feeders                       Conductors that supply power to or augment the power-carrying
                                          capacity of the conductors in an overhead contact system.

202.        Final Adjustment              The positioning of an OCS to the correct alignment and wire
                                          height, tightening up of all components and any remedial work
                                          prior to operation.

203.        Finial*                       See “Pole Cap”.

204.        Fittings                      Small components used in the assembly of cantilever frames,
                                          cross-spans and terminations.

205.        Fixed End                     The dead-ended termination of a conductor.

206.        Fixed Tension*                See “Fixed Terminated, (FT) equipment” and “Auto-Tensioned,
                                          (AT) equipment”.

207.      Fixed Termination               An assembly for dead-ending a conductor.
    Assembly
208.      Fixed-Terminated (FT)           OCS with dead-ended conductors, either “Catenary” or “Direct
    Equipment                             Suspension”, (fixed terminations).     The tensions in FT
                                          equipment vary with temperature, being higher at low
                                          temperatures and lower at high temperatures.

                                          A style of Direct Suspension OCS FT equipment.
209.      Single Contact Wire Style
    (FTSCW)                               A style of Direct Suspension OCS FT equipment.

210.        Tramway Style Equipment*



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                                                                    REVISED DRAFT   FEBRUARY 14, 2005



211.        Floating Section            A section of OCS equipment between two insulators which is
                                        neither bonded to the live conductors, nor is bonded to ground,
                                        and whose line potential is unknown.

212.        AC                          See AREMA Chapter 33 - “Neutral Section”

213.        Foundation (OCS)            Customarily a concrete block for the embedment or attachment
                                        of an OCS pole or down guy, or part of a civil structure (viaduct,
                                        overpass, tunnel, etc) for embedding or attaching an OCS pole,
                                        support bracket or down guy. The most common type of
                                        foundation in the US is a concrete pier with anchor bolts. This is
                                        usually made by pouring concrete directly into an augered hole in
                                        which the anchor bolts/reinforcing cage is already aligned. Sizes
                                        range from 2 ft 0in diameter to 3ft.6in diameter, and depth below
                                        ground from 10ft. to 18ft. depending upon loading and ground
                                        strength.

214.        Anchor Bolt                 A bolt inserted into a concrete foundation to form an attachment
                                        for a pole or support bracket.

215.        Anchor Plate                A buried plate at the end of an anchor rod used with down guys.

216.        Core-formed                 A foundation that has been poured leaving a core hole which will
                                        accept an OCS pole without a base-plate firmly installed to line
                                        and level using grout.

217.        Dead-Man*                   A mass buried in ground (usually a rectangular block of concrete)
                                        to which a down guy wire is directly or indirectly attached.

218.        Earth-formed                Where the concrete is directly poured into an augered hole
                                        against the bare earth.

219.        Gravity Foundation          See “Spread Footing” below.

220.        Guy Anchor Foundation       A foundation for a down guy.

221.        Piled Foundations           Steel pile foundations using a 24 inch diameter steel casing or a
                                        10in x 10in I-beam have been used as foundations for anchor-base
                                        poles.

222.        Precast Concrete            Usually a pier type casting with anchor bolts, which is placed
                                        into an oversize earth-formed augered shaft and grouted or
                                        back-filled to line and level. Precast foundations can be
                                        manufactured under factory conditions with supervision and
                                        testing staff in attendance to ensure the required quality, both in
                                        dimensional accuracy and materials quality. Precast foundations
                                        avoid the problems of getting large quantities to remote track
                                        side locations, and avoid many site problems associated with
                                        winter and summer weather. On operating railroads, precast



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                                                                     REVISED DRAFT    FEBRUARY 14, 2005


223.        Foundation (cond)            foundations should reduce the need for track occupation
                                         compared to cast-in-place foundations.

224.        Concrete Sleeve type         This foundation type was very successfully used on a very large
                                         project in the Kalahari Desert. High strength concrete sleeves
                                         (pipes), 18 inches overall diameter, 2 ½ in. wall thickness and 10
                                         feet long were directly embedded into a 30 inch diameter earth
                                         formed core hole using the excavated granular material as
                                         backfill. This was compacted around the sleeve using 4in
                                         diameter pneumatic hammers. A plain steel pole was inserted
                                         into the sleeve and clamped into line and level with a custom
                                         made jig that attached to the top of the sleeve. More of the
                                         granular material was compacted around the pole leaving 6
                                         inches space at the top. Typically one bag of “concrete mix” was
                                         mixed up in a small portable concrete mixer, placed in the top of
                                         the sleeve, tamped and trowel finished with a watershed. The
                                         benefits of the sleeve are similar to those of pre-cast foundations,
                                         and the use of the excavated material and the low requirement
                                         for water in the remoteness of the desert were particularly good
                                         economies.

225.        Rock Foundation              When surface or sub-surface rock is encountered anchor bolts
                                         can be directly embedded into core hole drilled into the rock
                                         deep enough to carry the pole overturning moment but
                                         discounting the thickness of fractured rock.


226.        Spread Footing               A shallow foundation typically 1ft 0in to 2ft 0in thick, but with a
                                         large area, typically 6 ft by 12 ft. but can be larger or smaller
                                         depending upon overturning load and ground strength.

227.        Frog (OCS)
228.        Fixed Frog                   A solid metal device (casting) in the trolleywires that guides the
                                         direction of travel of a vehicle trolley pole at locations where two
                                         trolley wires diverge from a single wire.

229.        Electric Frog                An electrically operated device above the trolley wires that switches
                                         the „track‟ of the frog as required.

230.        Frog (track)                 A rail component used at the intersection of two running rails to
                                         provide support for vehicle wheels thus permitting wheels to
                                         cross over or join rails of other tracks.

231.        Gain                             1. The flattened part of a round pole ready to receive the
                                                mounting plate of a cross arm or bracket arm, or
                                             2. A plastic molding type packer for interfacing between a
                                                round pole and a cross arm or mounting plate of a
                                                bracket arm.




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                                                                     REVISED DRAFT    FEBRUARY 14, 2005
232.       Glastic                       A proprietary insulating material ¼” to 2” thick used to form
                                         troughs for protection of the trolley overhead from damage
                                         caused by dewired trolley poles or to provide a safety barrier for
                                         linemen working on live wires in close proximity to uninsulated
                                         overhead beams and pipes.

233.       Grade Crossing                A crossing of a highway, railroad track, other fixed guideway, or
                                         pedestrian walk or combination of these at the same level.

234.       Grade Separation              The vertical separation at a crossing of a highway or walkway
                                         from a rail track by the provision of a bridge or underpass.

235.       Gradient (Contact Wire)       The average slope of the contact wire between two adjacent
                                         OCS supports relative to the track.

236.       Grounding                     The act of directly bonding a pole or stucture to a ground rod by
                                         means of a cable, to prevent a voltage developing on a pole
                                         which might shock a person who might touch the pole.

237.       Ground Rod                    A conducting rod serving as an electrical connection with
                                         ground. Typically a less-than-one inch diameter copperclad steel
                                         rod 10 feet long driven into the soil. More than one rod may be
                                         required to achieve the low resistance value specified for any
                                         particular OCS installation.

238.       Grounding Switch              An electrical switch typically between an OCS conductor and a
                                         ground rod, to enable the conductor to be grounded for safety
                                         when de-energized.

239.       Ground Wire                   The conductor installed for the purpose of providing lightning
                                         protection and electrical continuity between the supporting
                                         structure of the overhead contact system and the common
                                         return or grounding system.

240.       Guy                           A steadying or positioning wire, or span wire.

241.       Down Guy Or Back Guy*         A wire attached high on a pole and coming down at an angle to
                                         an anchor in the ground.

242.       Guy Anchor                    See “Foundation”

243.       Guy Guard                     A protective strip, often of light colored plastic, typically 10 feet
                                         long, which fits around the lower end of a down guy for
                                         increased visibility.

244.       Head Guy                      A wire, usually between two pole tops, for the purpose of
                                         transferring an anchor load.

245.       Span Guy                      A wire between two poles, or buildings for supporting an OCS.

246.       Sidewalk Down Guy             See “Sidewalk Guy”



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                                                                     REVISED DRAFT   FEBRUARY 14, 2005



247.        Half Tension Section or Half    In AT equipment, the segment of OCS between a midpoint and a
    tension Length*                         BW, or between a fixed termination and a BW. See also “Tension
                                            Section”.

248.       Hand Hole                        An access hole in a pole, or duct-line, for cable installation or
                                            inspection
249.       Hanger

250.       For Direct Suspension            A support for a contact wire or trolley wire, normally used to
                                            support it from cross-spans.

251.       For Catenary                     A series of light wire, light cable, light strap or light rod
                                            assemblies for suspending the contact wire from the messenger
                                            wire at regular intervals (typically every 15-30 feet).

                                            Catenary hangers are usually designed to avoid current flowing
                                            through them from the messenger to the contact wire and vice
                                            versa, by incorporating insulating components.

252.       Hard spot                        Hard spots along the contact wire are typically points where the
                                            contact wire does not lift under the influence of pantograph
                                            pressure, as much as it does along the rest of the wire. As a
                                            consequence the pantograph is momentarily forced down from its
                                            normal trajectory. This may cause a separation of contact just
                                            beyond the hard spot due to pantograph inertia, and the inability
                                            of the pantograph springing to quickly raise the pantograph
                                            head. As a consequence arcing may occur which is harmful to
                                            both pantographs and contact wire. See “Arcing”
                                            Hard spots are caused by kinks in the contact wire, by heavy
                                            fittings such as section insulators, and by direct push-off
                                            registrations, all of which should be avoided in the mainline OCS
                                            where trains travel at speed and draw normal levels of current.

253.       Harp                             Hardware mounted at the top end of a “Trolley Collector Pole” that
                                            houses the “Trolley Shoe”.

254.       Headspan or Cross Catenary*      An OCS support structure with two or more wires that straddles
                                            the tracks and supports several catenaries, or several single
                                            contact wires in multi-track area. See also “Cross-Span”, “Body
                                            Span”, “Steady Span”.

255.       Headspan wires                   In a two-wire headspan, the combination of headspan wire and
                                            cross-span wire, and in a three-wire headspan, the combination of
                                            a headspan wire, steady span wire and cross-span wire, required
                                            for a complete headspan

256.       Heel of Registration Arm or      The pivoted end of a steady arm opposite to the end with the
    Steady Arm or Eye of Pullover*          contact wire clamp.
    (Catenary)


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                                                                       REVISED DRAFT     FEBRUARY 14, 2005


257.       Heel Setting Dimension           The dimensioned height of the pin or hinge at the heel of a steady
    (Catenary)                              arm or registration arm, above the plane of the contact wire.

                                            The heel setting is designed to minimize uplift of the contact wire
                                            due to the radial load in the registration arm caused by contact
                                            wire deviation.

258.       Hog of Contact Wire              Arching of a contact wire between catenary supports. Prevalent
                                            in FT systems at low temperatures – opposite of sag.

259.       Horns (pantograph)               The curved or angled downwards ends of the pantograph head,
                                            which lift „out-of-running‟ wires onto the contact strip, as they
                                            converge.

260.       Hotel Power                      Electrical power taken by a vehicle for uses other than traction.

261.       Hydraulic Tensioner              A mechanical device comprising a long cylinder filled with liquid
                                            or with gas which with its associated parts is installed at one or
                                            each of the anchor poles to compensate to some extent for
                                            variations in conductor tension due to ambient temperature.

262.       Impedance Bond                   See “Bond”

263.       Inclined Catenary                See “Catenary”

264.       Inductive Switch                 An electro-mechanical switch with an electronic receiver placed just
                                            above diverging trolley wires that can receive radio signals from
                                            ETBs in order to set the trolley wires for the route direction required.

265.       In-Running Catenary              The catenary for a track that has multiple catenaries (such as
                                            overlaps), which provides the passage for the pantograph.

266.       Insert – Concrete                A mechanical screw socket-type fixing for direct embedment into
                                            concrete usually placed before pouring concrete.

267.       Insulated Midpoint               See “Sectionalizing”

268.       Insulated Overlap                See “Sectionalizing”

269.       Insulator                        Any body or substance provided and designed for the purpose of
                                            surrounding, supporting or interrupting an electrical conductor
                                            so as to restrict the flow of electricity to a desired path.

270.       Bobbin*                          A synthetic insulator that looks like a bobbin for thread.

271.       Bell or Disc*                    A bell-shaped insulator of ceramic or glass used singly or in
                                            strings.

272.       Cut-in Insulator                 An strain insulator installed at a point along a conductor for
                                            sectionalizing purposes or to provide a „level‟ of insulation.


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                                                                       REVISED DRAFT    FEBRUARY 14, 2005


273.       Insulators (cond)

274.       Johnny Ball or Porcelain          A type of ceramic strain insulator, which has interlocking
    Strain                                   terminations for wires and is used primarily for guy, span wire or
275.       Insulator                         dead end insulation.

                                             The brand name for a type of section insulator.
276.       No-Bo
                                             See “Section Insulator”
277.       Section
                                             A solid core insulator with bending strength.
278.       Standoff
                                             An insulator or a string of disc insulators used in line in a
279.       Strain                            tensioned conductor or guy.

                                             A standoff insulator used in compression members of cantilevers.
280.       Strut
                                             An insulator or string of discs, suspended in vertical position.
281.       Suspension
                                             An insulator made from fiberglass, plastic or epoxy resin.
282.       Synthetic
283.       Jumper                            Generally an electrical connection in the overhead contact
                                             system; a short conductor installed to provide electrical
                                             continuity.

284.       Continuity or Full Current        A jumper capable of carrying full line current from one
                                             catenary to another longitudinally at tensioning overlaps and
                                             track turnouts.

285.       Equalizing                        A light jumper in the catenary connecting the messenger to the
                                             contact wire for electrical continuity. Generally installed one in
                                             each span.

286.       Kcmil, mcm* (Syn)                 The measured cross-sectional area of a conductor in thousands
                                             of circular mils.

287.       Knuckle                           A rigid connection between two adjacent messenger wires
                                             and/or between two adjacent contact wires for their mutual
                                             alignment. Usually with insulation so as to prevent circulating
                                             currents or for maintaining electrical sectioning.

288.       Lightning Arrester or             A device typically mounted on OCS poles and connected to the
    Arrestor*                                OCS, designed to protect the OCS and adjacent equipment, e.g.
                                             traction power substations and feeder cables, against lightning.
                                             Lightning arresters typically provide a path to ground through
                                             a spark-gap, with or without variable resistance elements.

289.       Line Ear                          The name given in the days before grooved trolley wire was
                                             available, for the fitting that supported round trolley wire.




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                                                                      REVISED DRAFT    FEBRUARY 14, 2005


290.      Line Guard                        A bunch of short (12”) steel wires with preformed twist that self
                                            lock around a conductor inside a support clamp to prevent the
                                            breakage o conductor strands due to fatigue.

                                            See also “Messenger Liner”

291.      Live

292.      Live Load (structural)            A load or force that is temporary in nature such as wind, ice,
                                            tension due to temperature change and the dynamic uplift force
                                            of a passing current collector.

293.      Live Wire (electrical)            A bare conductor carrying a voltage for power supply.

294.      Load Gauge                        See “Gauge”

295.      Long Turn Lane                    A segment of trolley wire OCS (trolley wire pair) parallel to the
                                            „through‟ trolley wires used by ETBs in preparation for a right or
                                            left turn that allows „through‟ ETBs to overtake.

296.      Lug

297.      Crimped                           An attachment to the end of wire or cable for an electrical
                                            connection made using a griping or crimping tool.

298.      Terminal                          A crimped, soldered or bolted metallic tag with a hole used to
                                            terminate a wire or cable on a stud to make an electrical
                                            connection.

299.      Magnetic Blow Out                 As assembly attached to in-running section insulators that
                                            quenches power arcs drawn by trolley shoes entering insulated
                                            runners.

300.      Mast Arm*                         See “Bracket Arm”.

301.      Master Overlap Chart (MOC);       Like an electrical sectioning diagram but including essential
302.      Master Wiring Diagram (Syn)       OCS design features and typically drawn to scale based upon
                                            civil alignment plan/profiles. An MOC will include provisional
                                            layout of the traction power substations, and the associated
                                            feeding/sectioning points in the OCS. Typically the location of
                                            additional operational sectionalization at track crossovers and
                                            pocket tracks will be shown.          The type of sectioning
                                            arrangement be it an overlap, insulated midpoint, airbreak or
                                            section insulator will be indicated. On steeply graded track
                                            profiles the location of OCS fixed ends, midpoints and
                                            balanceweights will be given.

303.      Maximum Operating Wind            The maximum wind speed in which vehicles will continue to be
    Speed                                   operated at their normal speed. The wind speed selected for
                                            pantograph security calculations. Typically 55 mph for LRT
                                            Systems.




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                                                                   REVISED DRAFT   FEBRUARY 14, 2005



304.      Maximum Sag                     The sag of conductors either at maximum conductor
                                          temperature or under a given radial ice loading, whichever is
                                          greater.

305.      Mcm*                            See “Kcmil”

306.      Messenger or Messenger Wire     The uppermost conductor in a catenary system.              The
                                          conductor, which hangs in, the approximate shape of a catenary
                                          from which the contact wire is suspended by means of wire or
                                          loop hangers.

307.      Messenger Liner                 A piece of insulating material inserted between messenger
                                          hanger saddles and messenger wires to prevent currents
                                          circulating through hangers.

308.       Messenger Rise or Messenger    When given in tables for vertical clearance purposes:
    Wire Rise                             The increase in the height of the messenger wire at midspan,
                                          due to the combined effect of :
                                               An increase in messenger wire tension at low
                                                  temperature.
                                               Wear of the contact wire.
                                               Uplift due to the pantograph or trolley collector pole
                                                  pressure.

309.      Middle Ordinate*                See “Stringline”.

310.      Midpoint Anchor Pole (AT)       A pole adjacent to the midpoint structure where the midpoint
                                          guy is terminated.

311.      Midpoint Guy (AT)               The span guy that provides the midpoint restraint in AT
                                          equipment.

                                          The broadly horizontal guy wire, (preferably of galvanized
                                          strand for its light weight), that is anchored to the messenger
                                          wire at the midpoint (cantilever) of a tension section of auto-
                                          tensioned OCS.

312.      Midpoint Structure (AT)         The OCS support structure approximately midway between the
                                          two Balanceweights of a tension section of AT equipment where
                                          the OCS is anchored against along-track movement.

313.      Midspan Offset                  The deviation of the static contact wire from the superelevated
                                          centerline of track at midspan.

314.      Mixed Operation*                See “Dual-mode Operation”




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                                                                        REVISED DRAFT   FEBRUARY 14, 2005



315.       Negative Feeder – DC             In a DC rail system, the traction current return cable connecting
                                            the track rails or negative contact wire to the substation negative
                                            busbar.

316.       Negative Feeder - AC             See AREMA Chapter 33. Negative Feeder.

317.       Neutral Section (AC Only)        See AREMA Chapter 33. Floating Section.

318.       No-Bo                            A proprietary type of section insulator. See “Insulator”.

319.       No-Load Tension or               The messenger stringing tension to be applied to a messenger
    Unloaded Stringing Tension              alone so that, once the contact wire is suspended from the
                                            messenger, the messenger assumes the desired final sag and
                                            tension.

320.     Non-Bridging, Non-                 The act of not connecting across sectionalization points by
    Commutating*                            pantograph.

321.       Non-Riding*                      See “Out-of-Running”.

322.       “Normal” Temperature,            The selected temperature at which all the cantilevers in an auto-
    Normal Setting Temperature.             tensioned OCS are “square” (“normal”, mathematically) to the
                                            track.
                                            See “Normal Tension”.

323.       “Normal” Tension                     1. The nominal selected tension for a conductor.
                                                2. The tension in a conductor of a fixed terminated OCS at
                                                   “normal” temperature range.
                                                3. The tension in a conductor of an auto-tensioned OCS
                                                   when tensioned by balanceweights within the auto-
                                                   tensioned temperature range – when the balanceweight
                                                   stops are not engaged.

324.       OCS Style                        The generic type of conductor configuration and tensioning
                                            system of a particular OCS.
                                            See “Catenary” and “Direct Suspension”.

325.       Offset

326.       Contact Wire/Trolley Wire        The deviation of the contact wire/trolley wire in its static
    Offset                                  condition from the normal centerline of the track.

                                            The dimension of the centerline of the pole from the centerline of
327.       Pole Offset                      the track.

328.       Out-of-Running (OOR)             Where more than one catenary is installed above one track, OOR
    Catenary                                catenaries do not provide passage for the pantograph because
                                            they are higher than, or offset from, the in-running catenary.



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                                                                    REVISED DRAFT    FEBRUARY 14, 2005


329.      Overhead Contact System       That part of the traction power system comprising the overhead
    (OCS)                               conductors (or single contact wire), aerial feeders, OCS supports,
                                        foundations, balanceweights and other equipment and
                                        assemblies, that delivers electrical power to non-self powered
                                        electric vehicles.

330.      Overlap                       A span of the overhead contact system where the contact and
                                        messenger wires of two adjoining tension sections overlap before
                                        terminating at opposite ends.

331.      Overlap Poles                 The structures that position the two contact wires in parallel
                                        within an overlap section.

332.      Overlap Span                  That portion of the overhead contact system between two
                                        structures, where the contact and messenger wires of two
                                        adjoining sections overlap, thus allowing pantographs to
                                        transition from one tension section to the next under power.
                                        See “Sectionalizing - Insulated Overlap”

333.       Overpass, Bridge*,           Where a street, pedestrian walkway or railway crosses over the
    Overhead Bridge* or Overbridge*     OCS tracks.
    (Syn)                                           NOTE.      „Bridge‟,   „Overhead      Bridge‟,  and
                                        „Overbridge‟ are ambiguous terms unless the location, under-rail
                                        or over-rail, are included. For the OCS dictionary, Overpass is
                                        the preferred term for a bridge over–rail and underpass is the
                                        preferred term for a bridge under-rail. See also “Viaduct”

334.      Pan                           An alternative name for the “head” of a pantograph, which
                                        carries the rubbing strips/carbon collectors*.

335.      Pantograph                    A current collection device fitted on top of an electrically powered
                                        rail vehicle, hinged to allow it to vary in height as it rubs along
                                        the contact wire.

336.       Pantograph Clearance         See “Envelope, Pantograph Clearance Envelope”.
    Envelope
337.       Pantograph Head              The uppermost part of the pantograph that is fitted with the
                                        current collector.

338.      Pantograph Pressure           The nominal upward force exerted by the pantograph on the
                                        contact wire. Typically 18 to 22 pounds.

339.      Pantograph Security           The analyses of the lateral relationship of the pantograph with
                                        the contact wire at a support/registration and at midspan, under
                                        prescribed operating conditions, including allowances for
                                        crosswind, track tolerances, vehicle sway, pantograph sway,
                                        temperature range and installation tolerances.
                                        Based on these analyses, maximum stagger, maximum span
                                        length on tangent, and span lengths on curves are determined.




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                                                                      REVISED DRAFT    FEBRUARY 14, 2005


340.       Pantograph Sway                Lateral displacement of the pantograph induced by vehicle roll
                                          and lateral shock loads. Typical value 1 ½ " each way
                                          (independent of pantograph height), unless specified otherwise.

341.       Pantograph Up-Lift             The distance the contact wire is lifted as a pantograph passes.

342.       Pantograph Up-Thrust*          See “Pantograph Pressure”

343.       Parallel Feeder                An along-track aerial bare or insulated cable mounted on the
                                          OCS poles; or an insulated cable installed in a trough or duct,
                                          which provides electrical power reinforcement to the OCS by
                                          means of T-connected feeder jumpers at regular intervals.

344.       Parallel Running (Length)      The design length where the two parallel contact wires in an
                                          overlap are suspended at the same height.

345.      Paralleling Station (AC         See AREMA Chapter 33. Paralleling Station
    Only)
346.      Pendulum Support                A type of support using two parallel hinges 12” to 24” long to
                                          support the contact wire keeping the contact wire oriented
                                          vertically as it lifts freely.

347.       Pendulum Suspension            An “elastic” hanger configuration in the form of a trapezoid hinged
                                          at each corner that maintains correct wire orientation of the trolley
                                          wire for use by trolley shoe and yet is free to move upwards under
                                          pressure from the vehicle trolley pole.

348.       PH Hanger                      A stick insulator installed square or near-square to the trolley wire
                                          pair for carrying two trolley clamps at the correct wire spacing and
                                          that can maintain insulation levels between them.

349.       Phase Break                    See AREMA Chapter 33. Phase Break

350.       Planted Pole                   An OCS pole without a baseplate, that is directly embedded in a
                                          concrete foundation during pouring of the concrete, or grouted
                                          into a prepared corehole of a previously cast concrete foundation.

351.       Pole (OCS) or Mast*            An independent slender vertical structure with or without guy,
                                          used to support some part of the OCS.

352.       Pole Bracket                   A connection or an assembly of small – part steel components by
                                          which a cantilever assembly or bracket arm assembly is attached
                                          to the pole.

353.       Pole Cap                       The attachment over the top of a pole to prevent intrusion of
                                          rainwater. Fancy designs may be called “Finials”

354.       Pole Encumbrance               The across-track outside dimension of a pole and its attachments
                                          at vehicle level.




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                                                                       REVISED DRAFT   FEBRUARY 14, 2005


355.       Pole Face                            1. The side of the pole to which the cantilever or bracket
                                                   arm is attached.
                                                2. The side of the pole facing the track.

356.       Pole Guide*                      See “Trolley Pole Guide”

357.       Pole (Trolley)                   See “Trolley Pole”

358.       Portal (OCS)                     A frame support structure, typically of galvanized steel,
                                            consisting of vertical columns supporting each end of a horizontal
                                            beam. Two beams mounted on three columns would be termed a
                                            “compound portal”, etc.

359.       Beam Bracket                     A fabricated steel frame mounted on a portal beam, primarily for
                                            the attachment of cantilever assemblies.

360.       Potential Equalizer (Jumper)     See “Jumper”

361.       Power On-Off Switch              A trolley overhead switch control system which operates in one
                                            position as the bus draws power from the overhead contact system
                                            and retracts to another position when the bus coasts through.

362.       Pre-Emption Device               A switch/contactor operated automatically by transit vehicles in
                                            city streets, which controls traffic signals to their favor.

363.        Preformed or Preformed          A trade name for a wrap-around type of dead end or guy grip.
    End Fitting
364.        Presag                          The static difference between the average contact wire height at
                                            the end hangers in a span and the height at midspan. Typically
                                            span/1000 in value.

365.       Prestress (of conductors)        The tension, normally 30% to 50% of its breaking load, applied
                                            to conductor for a day or two to reduce long-term “creep”, after
                                            which it is reduced to normal tension for operations.

366.       Profile (overhead)               The vertical alignment of OCS conductors relative to the track.

367.       Pull-Off*                        See “Wire Pull-off”

368.       Pull-Off Arm*                    See “Registration Arm”

369.       Pull Off Cantilever              A cantilever that provides registration of the contact wire
                                            towards the pole in relation to the centerline of track.

370.       Push Off Cantilever              A cantilever that provides registration of the contact wire away
                                            from the pole in relation to the centerline of track.

371.       Pulley (AT)                      A pulley block used in messenger support and in AT termination
                                            systems.



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                                                                         REVISED DRAFT    FEBRUARY 14, 2005


372.        Pull-over*                       See “Registration Arm”

373.        Radial Load                      A horizontal load comprised of static and dynamic forces.

374.        Rail Bond                        See “Bond”.

375.        Rail Return                      The combination of track rails, impedance bonds, and cables that
                                             provides the electrical return path for the traction current from
                                             the rail vehicle to the substation.

376.        Rake                             The installed backward lean of the pole from vertical, before
                                             loading, such that when loaded the pole does not lean towards the
                                             load once the load is applied.

377.        Range (Touring) or Travel*, of   The safe distance an ETB may move laterally away from its overhead
    an ETB.                                  wires-usually about 12 feet


378.        Range of Pantograph
379.        Operating                        The operating height range for Pantographs to operate normally

380.        Maximum                          The range of a pantograph between its upper limit stop, and its lock-
                                             down height.

381.        Reach                            See “Cantilever Reach”

382.        Registration or Alignment*       Lateral stabilizing (with or without support), of conductors to
                                             maintain a fixed horizontal location relative to the track.

383.        Registration Arm or Steady       The lateral restrainer on the contact wire at a structure or other
    Arm                                      point of registration, such as at a wire pull-off.

384.        Registration Pipe                The lowest pipe of a cantilever, to which a steady arm or a
                                             registration arm is attached, with or without a drop bracket.
                                             See also “Steady Arm”.

385.        Registration Span Wire or        A span guy between poles for contact or trolley wire registration;
    Registration Span Guy                    usually the lower of two horizontal span wires.

386.        Regulation* or Regulating*       See “Adjustments”

387.        Resilient Arm
388.        For Direct Suspension            A contact wire or trolley wire support embodying a sprung
                                             suspension, typically used under decks or in tunnels where cross-
                                             spans and bridles cannot be installed.
389.        For Catenary                     A combined registration and support assembly with vertical
                                             resilience, used for support of catenary conductors in situations of
                                             restricted clearance such as tunnels and overbridges, or for
                                             providing a soft contact wire suspension where a messenger or
                                             messenger bridle is not present.


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                                                                      REVISED DRAFT       FEBRUARY 14, 2005



390.       Return Circuit                The circuit for the traction return current utilizes track rails or
                                         negative contact wire to a location near to a traction substation,
                                         where it is connected by the “Negative Feeders” to the substation
                                         negative busbar.

391.       Rigid Contact System          Typically used in maintenance shops and at moveable bridges. An
                                         overhead contact system using an un-tensioned contact wire
                                         relying on continuous support, (such as proprietary aluminum
                                         extrusions or “T”-bars) or “barn hangers” at close spacing to
                                         supply the necessary rigidity.
                                         An untensioned self-supporting (copper) conductor rail, such as
                                         “double lobe bar”.

392.       Riser                         A vertical conduit and cable supplying traction current from an
                                         underground feeder system to the OCS.

393.       ROW                           Right-of-way; a definition of land ownership; the available space
                                         for a railway.

394.       Rubbing Strip*                See “Contact Strip”

395.       Ruling Span                   See “Equivalent Span”.

396.       Running Edges                 The inside faces of the rail heads of a track.

397.       Saddle                        The fitting that supports a hanger on the messenger wire,
                                         sometimes fitted with an insulated lining to prevent current
                                         entering the hanger.

398.         Safe Working Zone (1500     A zone around the OCS in which OCS maintenance staff can
    volts or less)                       undertake routine OCS inspections and maintenance, without
                                         there being some electrically grounded equipment, except plastic
                                         sheet, wood, stone or concrete, etc within easy/accidental reach.

399.       Sag                           The difference between the average heights of a conductor at its
                                         adjacent supports and its height at the lowest point in the span.

400.       Sagging                       The act of installing messengers and other conductors to the
                                         correct tension by measuring conductor sag.

401.       Sag-Tension Charts            Charts referred to during wire stringing that give conductor
                                         tensions related to ambient temperature for use during the
                                         sagging operation.

402.       Sag Rods                      On older electrified lines, the long steel rods that support the
                                         center section of a portal beam from extensions to the portal
                                         columns.




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                                                                         REVISED DRAFT     FEBRUARY 14, 2005



403.       Sectionalizing or Sectioning*   The division of the OCS into electrical sections, while permitting
                                           trolley poles and pantographs to operate from section to section.
404.
405.       Half-Tension Airbreak           An airbreak where the two parallel contact wires are each at half
                                           tension and are cut into a single contact wire over a distance of
                                           100 feet to 200 feet. Half-tension airbreaks do not require
                                           additional contact wire anchor poles, thus making them a
                                           practical substitute for section insulators. Not recommended for
                                           new construction since overlaps are more conventional.

406.       Insulated Overlap or            A sectionalization point in an OCS formed by cutting insulation
    Airbreak*                              into the out-of-running sections of the two overlapping catenaries
                                           with at least minimum electrical clearance between them, which
                                           provide a continuous powered path for pantographs.

                                           A sectionalization point in an OCS formed at an insulated overlap
407.       Insulated Midpoint              with fixed terminations, by cutting insulation into the out-of-
                                           running sections of the two overlapping catenaries. An insulated
                                           midpoint can thus provide sectionalizing while replacing a
                                           midpoint anchor in an AT tension section.

408.       Section Break                   An electrical break in the overhead contact system. When two
                                           adjacent section breaks are installed, the section of OCS between
                                           them can be isolated and energized or de-energized.

409.        Section Insulator or Section   A device for isolating two electrical sections from each other.
    Isolator*
410.        Self Supporting Anchor Pole    An OCS anchor pole without a down-guy.

411.       Selectric Switch                A proprietary electro-mechanical switch for setting the route for ETB
                                           trolley collector poles at a turnout, that is operated by the interaction
                                           of two contactors judiciously placed in the trolleywire pair in
                                           advance of a trolleybus turn and triggered by the relative position of
                                           trolley shoes.

412.       Shoe*                           See “Pantograph Head”, “Trolley Shoe”.

413.       Sidewalk guy                    Used where a normal down guy anchorage would occur on a
                                           sidewalk or other pathway and possibly be an obstruction to
                                           pedestrians and sidewalk vehicles.
                                           A sidewalk down guy is a down guy that is diverted to a vertical
                                           position for anchorage to the ground, by use of a horizontal strut
                                           braced against the pole at about halfway down the pole.

414.       Simple Catenary                 See “Catenary”

415.       Single Wire System*             See “Direct Suspension”




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                                                                        REVISED DRAFT   FEBRUARY 14, 2005



416.       Sleeve

417.       Chaffing Sleeve                  A sleeve around a conductor to reduce damage from abrasion.

418.        Ground sleeve, Reinforcing      A steel sleeve placed around a steel pole at ground line to protect
    Sleeve or                               against corrosion damage.
419.        “Dog Collar”
                                            A short length of smaller diameter pipe fitted into a larger
420.       Pipe Sleeve                      diameter pipe to reduce the internal diameter of the larger pipe.

                                            A compressed copper sleeve around a conductor to repair local
421.       Repair Sleeve                    electrical damage.

                                            A custom-designed circular concrete tube placed in a drilled hole
422.       Sleeve Foundation                to provide a foundation for an embedded pole. See “Foundation-
                                            Concrete Sleeve Type”

423.       Small Part Steelwork (SPS)       Steel brackets, frames, links, plates and yokes, etc, which are cut
                                            from stock steel sections for attachment of catenary assemblies,
                                            but not constituting part of a principal support structure.

424.       Soffit                           The underside of a tunnel roof or bridge deck.

425.       Span Guy, or Span Wire           See “Guy”

426.       Span Length                      The distance along track between structures as determined by the
                                            difference in along track stationings.

427.       Actual Span Length               The horizontal length of contact wire between two adjacent
                                            support points (not necessarily the distance or difference in
                                            stationing between the support structures).

428.       Span Width                       The distance across track or roadway (may be skewed) between
                                            the columns of a portal, headspan, or cross-span.

429.       Special Work                     Generic description for the frogs, switches, crossovers and curve
                                            segments used in trolley wires for vehicles with trolley poles.

430.       Spiral (Track)                   The transitions from tangent to curve track along which
                                            superelevation increases from zero to the selected value for the
                                            curve, and vice versa.

431.       Splice, Splicer*                 A fitting for joining two conductors together capable of carrying
                                            the full current capacity and the breaking load of the conductor.
                                            The splice may be a mechanically using cones or set-screws, or
                                            use compression pins or a compressed sleeve, etc.

432.       Spout                            See “Feeder Spout”.



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                                                                    REVISED DRAFT    FEBRUARY 14, 2005


433.      Sprawl                        The „stringline‟ of the contact wire on curved tracks with inclined
                                        catenaries.

434.      Spreaders or Spreader Bars*   (1). On a pole, the 4ft. to 5ft. long brackets made of small angle or
                                        channel sections mounted on the front of a pole and facing the
                                        track, a pair of which carry two or more cantilevers. Each
                                        cantilever carries its own catenary, and the cantilevers are spaced
                                        sufficiently to allow independent along track movement of each
                                        catenary.
                                        (2). In the OCS, a device for maintaining a set distance between
                                        two „parallel‟ conductors and used for registration purposes. See
                                        “Knuckle”.

435.      Spring Tensioner              A mechanical device comprising a long spring and associated
                                        parts installed in an OCS (usually at one or both terminations)
                                        which compensates to some extent for variations in conductor
                                        tension due to conductor temperature.

436.      Stagger                       The (normally alternating) offset of the contact wire from the
                                        tangent or superelevated track centerline by registration at each
                                        support that causes the contact wire to sweep side to side over the
                                        pantograph head during vehicle operation.

437.      Stagger Change                Increase or decrease of wire stagger due to along-track movement
                                        of the OCS under the influence of balanceweights, as wire
                                        temperature changes

438.      Stagger Effect                The additional contact wire deviation above the normal value of
                                        wind blow-off in a span, whenever the staggers at each end of the
                                        span are unequal.

439.      Stagger Gauge                 A mechanical or electronic device that can be mounted on track
                                        rails for measuring contact and messenger wire heights and
                                        staggers.

440.      Stagger Sweep                 Usually the rate at which the contact wire crosses the pantograph
                                        contact strip in inches per span length, with the purpose of setting
                                        minimum and maximum values.
                                        Typically 1 inch in 20 feet would be an acceptable minimum, and
                                        1 inch in 5 feet an acceptable maximum.

441.      Stand-Off Insulator           See “Insulator”.

442.      Static, Dead Load             The weight of the structure and any permanent load applied to it.
                                        This will include wire tension loads at nominal temperature.
                                        Loads due to temperature change are considered “Live”.

443.      Steady Arm                    A lightly loaded registration arm that serves to steady the contact
                                        wire from lateral displacement. See “Registration Arm”.




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                                                                        REVISED DRAFT    FEBRUARY 14, 2005


444.       Steady Span                     A cross span guy for contact wires, usually the lower of two
                                           horizontal span guys.

445.       Step and Touch Potential

446.        Step Potential ( see IEEE      The potential difference between two points on the earth‟s
    Dictionary)                            surface separated by a distance of one pace assumed to be in the
                                           direction of maximum potential gradient. Syn: Step Voltage*

                                           The potential difference between the grounded metallic structure
447.        Touch Potential (see IEEE      and a point on the earth‟s surface separated by a distance equal
    Dictionary)                            to the normal maximum horizontal reach, approximately one
                                           meter. Syn: Touch Voltage*

                                           Voltage difference between any two points accessible to
                                           passengers or workers on the transit system.
448.        Accessible Voltage (see IEEE
    Dictionary)
449.        Stops*                         See “Balanceweight Stops.”

450.       Stringing                       The process of installing overhead wires under tension

451.       Stringline Value                The distance between the track arc and its chord between
                                           catenary support structures, measured at midspan.

452.       Structure                       A principal support for the OCS conductors, normally including
                                           foundation, pole(s), and cantilever(s)/bracket arm(s) or
                                           headspan/cross-span; or eyebolts and cross-span.

453.       Structure Bonding               See “Grounding”

454.       Structure Clearance             See “Envelope, Structure Clearance Envelope”
    Envelope
455.       Structure Spacing Chart         A design table of span length and track curves that shows the
                                           maximum OCS span length for a track curve of a given radius.

456.       Stub-Ups                        Conduit bends, cast into concrete foundations, for later use with
                                           or without extension „risers‟, to accommodate feeder cables.

457.       Subassembly (OCS)               A configuration of OCS components forming part of a larger
                                           OCS assembly.

458.       Suction Transformer*            See AREMA Chapter 33.

459.       Superelevation Effect
460.       For rail tracks                 Displacement of the pantograph centerline from the vertical track
                                           centerline due to track superelevation.

461.       For ETB                         Lateral displacement of trolley wires from a ground reference point,
                                           e.g. centerline of bus-path, due to roadway superelevation.


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                                                                      REVISED DRAFT    FEBRUARY 14, 2005



462.       Surge Arrester*               See “Lightning Arrester”

463.       Swath (Pantograph)            The swept area above railway tracks at contact wire level that is
                                         covered by the pantograph during train operations, into which no
                                         part of the fixed facilities, except the contact wire, may intrude.

464.       Swath (Trolleybus)            The swept area of the roadway covered by the plan area of the trolley
                                         bus when driving on a curved bus path.

465.       Sweep*                        See “ Stagger Sweep‟

466.       Switch (OCS)

467.        Disconnect Switch, Feeder    A switch typically installed at a sectionalizing point or at a
    Switch*                              traction power feeding point in the OCS or for isolating the
                                         positive feeder cable at a substation. Such switch would be
                                         designed only to operate off-load, usually by hand, „hot‟ stick or
                                         by motorized operation controlled remotely. See “By-pass
                                         Switch”.

                                         At traction power feeding points, pad-mounted disconnect
                                         switches may be located within the substation compound or on
                                         the adjacent feeder pole.

                                         Bypass disconnect switches are installed at the sectionalizing
468.       Bypass Switch                 points in the OCS and are closed for normal train operations.

                                         An electrical switch typically between an OCS conductor and a
469.       Grounding Switch              ground rod, to enable the conductor to be grounded for safety
                                         when de-energized.

                                         An electrically operated disconnect switch under command from
470.       Motorized Switch              the Agency Operations and Control Center.

                                         An electric frog for trolleybuses, or a plain frog for streetcars, to
471.       Special Work Switch           allow trolley poles to enter a diverging route at a track turnout.

                                         Disconnect switches are customarily mounted on OCS poles, but
472.       Switch Mounting               can also be pad-mounted or mounted on walls.

                                         A track turn out
473.       Track Switch

474.       Synthetic Guy Strand          A synthetic rope material, such as “Kevlar” or “Phillystran”,
                                         used in cross-span guying and messenger bridles. Not normally
                                         used in trolley pole operation
475.       System Height or System       The vertical distance between messenger and contact wires, at the
    Depth*                               support structure.




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       DICTIONARY FOR OVERHEAD CONTACT SYSTEMS WITH PANTOGRAPH AND TROLLEY POLE OPERATIONS

                                                                    REVISED DRAFT   FEBRUARY 14, 2005



476.        Tail Wire or Tail Guy*      The wire that joins the yoke plate to the balanceweight assembly
                                        or deadend

477.        Tangent Chord Catenary      See “Catenary”

478.        Temperature Stop*           See “Balanceweight Stop”

479.        Tension Reducer             A strain reliever, usually a terminating guy connected at the
                                        shallow angle to a tensioned conductor to take up a portion of the
                                        tension.
480.        Tension Length*             See “Tension Section”,

                                        See also “Half Tension Section”

481.        Tension Section             A length of OCS between two corresponding terminations with
                                        automatic tensioning or fixed terminations. See also “Half
                                        Tension Section”

482.        Tensioning                  A method of controlling the configuration of conductors.
                                        Tensioning is normally performed by using balanceweights, but
                                        in certain situations, by spring or hydraulic tensioners.

483.        Tensioner                   A device installed at one end or both ends of a conductor to
                                        maintain as constant a tension in the conductors as possible.
                                        Maybe spring or hydraulic units or balanceweight assemblies,

484.        TES                         Traction Electrification System - comprising of the Traction
                                        Power System (TPS) and the Overhead Contact Systems (OCS).

485.        TOR                         Top of rail (as a vertical datum).

486.        TPFS                        Traction Power Feeder System.

487.        TPS                         Traction Power System - comprising of the Traction Power
                                        Substations (TPSS) and the Traction Power Feeder System
                                        (TPFS) (i.e. duct banks and traction power feeder and return
                                        cables).

488.        TPSS                        Traction Power Substation

489.        Track Hog                   A vertical curve in the track alignment producing a crest.
                                        See also “Track Sag”

490.        Track Raising Allowance     An allowance for additional vertical clearance at overpasses when
                                        determining OCS contact wire and messenger wire heights, to
                                        cater to future lifting of the tracks in order to improve the track
                                        structure.




                    Dictionary of Terms for Overhead Contact Systems                       36 of 40
                             DICTIONARY OF OVERHEAD CONTACT SYSTEM TERMS
                       IEEE OVERHEAD CONTACT SYSTEMS COMMITTEE FOR RAIL TRANSIT

       DICTIONARY FOR OVERHEAD CONTACT SYSTEMS WITH PANTOGRAPH AND TROLLEY POLE OPERATIONS

                                                                       REVISED DRAFT      FEBRUARY 14, 2005



491.        Track Sag                      A vertical curve in the track alignment producing a dip.
                                           See also “Track Hog”

492.        Track Tolerances               Variations from design dimensions.

493.        Cross Level Tolerance          Allowable variation between the levels of the two rails (or the
                                           designated difference in levels on superelevated track).

494.        Lateral Tolerance              Allowable variation in the track alignment.

495.        Track Gauge Tolerance          Allowable variation typically from 4‟ - 8½”.

496.        Vertical Tolerance             Allowable variation in track height.

497.        Traction Power                 The electrical power supply to the OCS

498.        Trailing Turnout               Tracks converging with point of switch last in the normal
                                           direction of travel.

499.        Tramway Equipment              See “Direct Suspension System”
                                           .
500.        Transition Curve               A curve of continuously increasing radius that connects a curve to
                                           a tangent or to a curve of larger radius.
                                           See “Spiral”.

501.        Trapeze*                       See “Pendulum Support”

502.        Travel*                        See “Range”

503.       Travelers, or Stringing         Sheaves used in pulling wires during stringing preferably with
    Blocks                                 one “cheek” that can be opened for inserting wires and pull lines.

504.        Trolley Door Bridge            A bridging device between sections of trolley wire that is mounted on
                                           the soffit of the doorframes of maintenance shops that can be opened
                                           to allow the doors to open and close. Such a design must have a
                                           bridging piece or conductor bar aligned between the trolley wire
                                           dead-ends to provide a trolley „path‟ for use with trolley poles.

505.        Trolley Pole or Collector      An electric power collector on a trolleybus or streetcar, which
    Pole (Syn)                             delivers current from the trolley wire to the vehicle.

506.        Trolleybus, Trolley Coach*,    A trackless rubber-tired public service vehicle for passengers
    Trackless Trolley*, Electric Trolley   propelled by electricity, which draws power from the trolley overhead
    Bus*, ETB.                             conductors by means of two (positive and negative) trolley poles.

507.        Trolley Funnel                 See “Trolley Pole Guide”

508.        Trolley Harp                   See “Trolley Shoe”




                      Dictionary of Terms for Overhead Contact Systems                           37 of 40
                            DICTIONARY OF OVERHEAD CONTACT SYSTEM TERMS
                      IEEE OVERHEAD CONTACT SYSTEMS COMMITTEE FOR RAIL TRANSIT

       DICTIONARY FOR OVERHEAD CONTACT SYSTEMS WITH PANTOGRAPH AND TROLLEY POLE OPERATIONS

                                                                      REVISED DRAFT     FEBRUARY 14, 2005


509.       Trolley OCS, Trolley          The system of overhead trolley wires and their supports from which
    Overhead*                            vehicles with trolley poles collect current
                                         See “Direct Suspension System”.

510.        Trolley Pole, or Trolley     The long shaft mounted on the roofs of trolley buses, streetcars and a
    Collector Poles*                     few Light Rail Vehicles, with a shoe (current collector) at the top end
                                         that presses upwards against the underside of the trolley wire, to
                                         draw current.

511.       Trolley Pole Guide or         A device to steer the trolley pole collector shoe upward onto the
    Funnel                               trolley wire from the retracted position.

512.        Trolley Shoe                 An assembly comprising a carbon insert fitted into the holder
                                         attached to the harp at the top of a trolley collector pole to collect
                                         current.

513.        Trolley Wire                 See “Contact Wire”

514.        Trolley Wire Pair            The two trolley wires providing electrical power and return for ETBs.
                                         Typically spaced 2 feet apart in the US, bu t700mm in Europe.

515.        Tunnel support (assembly)    A catenary, feeder, or return wire support assembly for use in
                                         tunnels and normally mounted in the tunnel soffit.

516.        Turnbuckle                   A Threaded device inserted in a tension member to provide
                                         minor adjustment of tension or sag. (IEEE Dictionary)

517.        Turnout (Track)              The arrangement of a track switch and a frog with closure rails
                                         by which rail vehicles can be diverted from one track to another.

518.        Twin Contacts (Wires)*       See “Contenary”.

519.        Underbridge Supports         OCS supports used beneath overpasses and normally attached to
                                         their soffits.

520.      Underpass or                   Where a road or river crosses beneath the LRT tracks.
    Underbridge*
521.      Uninsulated Overlap            An OCS overlap without provision for sectionalizing. A
                                         construction overlap.

522.        Uplift                       The difference in height of contact wire when at rest and when
                                         subjected to an upward force due to current collectors passing.

523.        Variable Tension in OCS      A characteristic of Fixed Terminated OCS, where rise in
                                         conductor temperature due to traction current and/or ambient
                                         air temperature results in lowering of conductor tension due to
                                         the expansion of the conductors. Similarly low ambient
                                         temperatures cause contraction of the conductors resulting in a
                                         rise of conductor tensions.
                                         See “Auto-tensioned OCS” which is also termed “Constant
                                         Tension OCS”*.




                      Dictionary of Terms for Overhead Contact Systems                         38 of 40
                           DICTIONARY OF OVERHEAD CONTACT SYSTEM TERMS
                     IEEE OVERHEAD CONTACT SYSTEMS COMMITTEE FOR RAIL TRANSIT

       DICTIONARY FOR OVERHEAD CONTACT SYSTEMS WITH PANTOGRAPH AND TROLLEY POLE OPERATIONS

                                                                    REVISED DRAFT   FEBRUARY 14, 2005


524.        Versine (OCS)               See “Stringline Value”
525.        Viaduct                     A long civil structure with rail tracks that on transit systems
                                        crosses over other rail tracks or over a road, or river or land, or
                                        buildings, etc., typically built on piers or bents.

526.        Wind Stay or Steady         A light rod that is provided to prevent collapse in compression of
                                        lightly loaded registration arms due to wind forces.

527.        Wire Cross*                 See “Contact Wire Bridge”

528.        Wire Gradient               See “Contact Wire Gradient”

529.        Wire Pull-off               A pull-off using a registration arm, “Single or Double Curve
                                        Hanger” attached to the end of a guy wire, that does not directly
                                        support the contact wire, although it can be lifted by the vertical
                                        component of the registration load.

530.        Wire Run                    The distance from anchorage to anchorage of an OCS conductor
                                        upon which the length of each OCS conductor is determined for
                                        requisitioning. A discrete Wire Run Number is assigned to each
                                        specific wire run for materials control purposes.

531.        Yoke                        A steel plate or casting on which two or more wires terminate on
                                        one side and continue as one wire on the opposite side (usually
                                        yoke-shaped and with lever action to distribute loads from a
                                        Balanceweight to the messenger and contact wire).




                     Dictionary of Terms for Overhead Contact Systems                      39 of 40
                    DICTIONARY OF OVERHEAD CONTACT SYSTEM TERMS
              IEEE OVERHEAD CONTACT SYSTEMS COMMITTEE FOR RAIL TRANSIT

DICTIONARY FOR OVERHEAD CONTACT SYSTEMS WITH PANTOGRAPH AND TROLLEY POLE OPERATIONS

                                                           REVISED DRAFT   FEBRUARY 14, 2005




                   DICTIONARY OF OVERHEAD CONTACT SYSTEM TERMS




             Dictionary of Terms for Overhead Contact Systems                     40 of 40

				
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