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.

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”
  1. Actual Span Length
/ See “Span Length”

4.Adjustments, Final adjustments

/ Placing the conductors to the correct wire heights and staggers.
  1. Airbreak; Half-tension Airbreak
/ See “Sectionalizing”
  1. Alignment
  2. Track alignment
  1. OCS alignment
/ The centerline or other reference line of the track or tracks in both plan and profile.
The position of the OCS relative to the (superelevated) centerline of the track.

9.Along Track Feeder*

/ See “Parallel Feeder”
  1. Along-Track Movement (ATM)
  2. (AT Systems)
/ The migration of catenary induced by BWs or tensioners due to thermal expansion or contraction of the conductors
  1. Ambient Temperature
/ The weather related temperature of an OCS, which excludes temperature effects due to current in the conductors.
  1. Anchor
  2. Anchor Base Pole*
  1. Anchor Bolt
  1. Anchor Bracket
  1. Anchor Plate or Dead-Man
  1. Deadend
  1. Pole Base Anchor
  1. Screw Anchor
  1. Self Supporting Anchor (pole)
/ See “Bolted-Base Pole”.
See “Foundation”
An attachment to the face of a civil structure (tunnel soffits, bridge deck, tunnel portal, boat section, retaining wall, parapet, etc.) for anchoring OCS.
See “Foundation”
See “Fixed Termination Assembly”
A pole which provides the ground level anchorage at its base or base-plate for a down guy from an adjacent anchor pole.
A specialty device with a helical cutting blade that is ‘corkscrewed’into the ground as an anchorage for a down-guy
An anchor pole without a down-guy.

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.
  1. Assembly
  2. 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.
  1. 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.
  1. 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.
  1. Autotransformer (AC)
  2. System
  3. Substation
/ See AREMA Chapter 33.
  1. Auxiliary Messenger or Auxiliary*
/ A third conductor typically installed with hangers above the contact wire and beneath the messenger wire of a catenary system and forming ‘Compound Catenary Style’
  1. 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.
  1. Backguy*
/ See “Guy”.
  1. 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”
  1. Balanceweight Stops, or Temperature Stops*
/ Mechanical means for preventing further movement of balanceweights beyond a specified range of movement.
  1. 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.
  1. Basic Impulse Insulation Level (BIL, bil)
/ See IEEE Dictionary.
  1. Bent
/ See “Bridge Bent”
  1. 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.
  1. 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.
  1. 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).
  1. Bond
  1. Impedance Bond
  1. Rail Bond (traction)
  1. Structure Bond
/ An electrical connection between metal hardware (rails, poles, rebar, etc) that eliminates voltage difference
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.
Electrical connection between two rails in OCS return circuits and rated for the full traction return current.
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.
  1. Booster Transformer or Suction Transformer (AC)
/ See AREMA Chapter 33.
  1. 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”.)
  1. Bracket
/ See “Pole Bracket”or “Anchor Bracket
  1. Break*
/ See “Section break”or “Airbreak”
  1. Bridge
  1. Overpass
  1. Bent
  1. Bridge Barrier
/ See “Overpass”
A Structural Engineering term for a portal frame or transverse framework, as used to support the deck of a bridge.
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”.
  1. Bridging
/ The act of connecting across sectionalization points by pantographs.
  1. 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.
  1. 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.
  1. Building Attachment
/ An eyebolt or other OCS mounting on a building.
  1. 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.
  1. BW
/ Balanceweight
  1. BWA
/ Balanceweight Anchor or Balanceweight Assembly
  1. Bypass Switch
/ See “Switch”
  1. Cable Outlet*
/ See “Feeder Spout”
  1. Cadweld
/ A proprietary thermic welding operation
  1. Cantilever
  2. Back-to-back cantilevers
  1. Cantilever Assembly
  1. Long-Reach Cantilever
  1. Multi-Track Bracket Arm
  1. Reach
  1. Reduced Height Cantilever
  1. Twin Cantilevers
  1. Two-Track Bracket Arm
  1. Two-Track Cantilever
/ A hinged bracket arm*
Cantilevers mounted on opposite sides of poles which are located between tracks.
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.
A cantilever assembly whose reach (see below) typically exceeds 13 feet.
A frame rigidly attached to a pole and serving three or more tracks.
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.
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.
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.
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.
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.
  1. Catenary
  1. Dictionary Meaning
  1. Simple Catenary Style
  1. Compound Catenary Style
  1. Stitched Catenary Style
  1. Inclined Catenary Style
  1. Low Profile Catenary Style
  1. Chordal Catenary Style
  1. Contenary
/ The combination of two or more OCS conductors, with hangers and in-span hardware, but not including supports and cantilevers.
The curve assumed by a perfectly flexible cord of uniform weight and cross-section hanging freely between two fixed points.
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.
Comprising a contact wire supported by an auxiliary wire, which, in turn, is supported from a messenger wire by hangers.
A two conductor catenary system to which a stitch wire (messenger bridle) has been added at the supports to improve catenary dynamics.
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.
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.
A catenary system in which the messenger (and auxiliary) are installed vertically above the contact wire. Also known as Tangent-Chord style.
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.
  1. Catenaries Dynamics
/ The interactive relationship between “current collectors”and contact/trolley wires at operating speeds.
  1. Chording of Curves
/ On curved route the propensity of the contact wire to “cut the curve”between points of registration.
  1. Clamp
  1. Contact Swivel or Fixed Clamp
  1. Parallel Groove Clamp
  1. Pipe Clamp
  1. Strain Clamp
  1. Suspension 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.
The fitting on the end of the steady arm or registration pipe, which attaches to the contact wire
A piece of hardware used to clamp two or more parallel wires together.
A piece of hardware used to attach various types of components to a pipe.
A piece of hardware used for deadending a wire or conductor under high tension.
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.
  1. Clipping In
/ The sagging (regulating) of the OCS conductors to correct tension, and clamping at the supports and installing the hangers.
  1. Collector Strip*
/ See “Contact Strip”
  1. Commutation*
  1. Commutation Performance*
/ The act of picking up electrical power from an overhead contact wire by pantograph or trolley pole.
See “Current Collection”. See also “Bridging”
See “Catenary Dynamics”
  1. Component (OCS)
/ An item of OCS hardware as commonly supplied complete by manufacturers.
  1. Compound Equipment
/ See “Catenary”
  1. Compression Type Fittings* or Compression Fittings
/ Fittings that require a hydraulic press to crimp or otherwise 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.
  1. Conductor Bar* or Conductor Beam*
/ See “Conductor Rail”
  1. 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.
  1. 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.
  1. Constant Tension OCS*
/ See “Auto-tensioned equipment”
  1. Construction Barrier
/ A temporary barrier serving the purpose of a bridge barrier during construction/reconstruction of an overbridge spanning electrified tracks.
  1. Construction Overlap
/ An OCS overlap without provision for sectionalizing. An “Uninsulated Overlap”
  1. Contact Bar* or Rail*
/ See “Conductor Rail”.
  1. 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.
  1. 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
  1. Contact Wire Along-Track Movement (ATM)
/ See “Along-Track Movement”
  1. 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*’.
  1. Contact Wire Clamp
  1. For FT equipment
  1. For (AT) 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.
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.