IEEE 1791-2019 pdf free download – IEEE Recommended Practice for Terminology Used for Direct Current Electric Transit Overhead Contact Systems
3. Definitions
For the purposes of this document, the fllo ing terms and defnitions apply. The IEEE Standards Dictionary Online should be consulted for terms not defined in this clause.
For a definition of point of switch (POS, PS), see the American Railway Engineering and Maintenance-of-Way Association s Manual for Railway Engineering. [BI]
acceptance measurements: F inal acceptance records of the installed contact wire heights and staggers at overhead contact sy stem (OCS) supports and registrations, and at midspan, Also known as as built.
actual span length: The horizontal length of contact wire between two adjacent support points. See also: span length.
NOTE- Not necessarily the distance or difference in stationing between the support structures.s
adjustments: Placing the conductors to the specified wire heights and staggers.
airbreak: See: insulated overlap. See also: sectionalzing.
NOTE- This term is a NON-PREFERRED term. Its synonym is more commonly used, as listed in the term albove.
air gap: See: insulated overlap. See also: sectionalizing.
NOTE- This term is a NON PREFERRED term. Its synonym is more commonly used, as listed in the term above.
alignment: See: track alignment or oCS alignment.
along track feeder: See: parallel feeder.
NOTE- -This term is a NON-PREFERRED term. Its synonym is more commonly used, as listed in the term above,along-track movement (ATM): Used in auto-tensioned (AT) systems to show the migration of catenary (tensioned wires) induced by balance weights (BWs) or tensioners due to thermal expansion or contraction of the conductors.
ambient temperature: The weather-related temperature of an overhead contact system (OCS), which excludes temperature effects due to current in the conductors.
NOTE- The IEEE Standards Dictionary Online should be consulted for more detail.
anchor base pole: See: bolted-base pole.
NOTE—This term is a NON-PREFERRED term. Its synonym is more commonly used, as listed in the term above.
anchor bolt: See: anchor bracket.
NOTE—This term is a NON-PREFERRED term. Its synonym is more commonly used, as listed in the term above.
anchor bracket: An attachment to the surface of a civil structure (tunnel soffits, bridge deck, tunnel portal,boat section, retaining wall, parapet, etc.) for securing the overhead contact system (OCS).
anchor plate: A buried platc at the end of an anchor rod used with down guys. Syn: dead-man.
anchor rod: A rod inserted into a concrete foundation to form an attachment for a pole or support bracket. Sym:line guard.
areing during commutation: The microscopic arcs that happen between a conductor and a current collector drawing power at speed.
NOTE I- When associated with commutation between a current colleetoer and contact wire, arcing is the electrical discharge at the interface point when the current cllector 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.
NOTE2- Arcing is typically caused at “hard spots” along the contact wire. See: hard spots.
NOTE 3- Arcing can be minimized by trains powering down before reaching known hard spots, and by avoiding gtting into regeneration mode, which can be a source of current equal, if not greater, than normal traction current values.
NOTE 4 Arcing is preventable by avoiding designing hard spots into the system duc to the use of section insulators,direct push-off registrations, rsilient arms, and sharp changes in gradient.IEEE 1791 pdf download.