IEEE 1234-2007 pdf download IEEE Guide for Fault-Locating Techniques on Shielded Power Cable Systems
1.Overview
1.1 General
This guide has been developed as a guide for cable fault-locating techniques on shielded power cablesystems. It is intended to emphasize those fault-locating techniques that maintain cable integrity, reducecustomer outage time, and consider customer equipment sensitivity and safety. This guide applies to allinsulated.shielded power cable systems.
1.2 Scope
The introduction of cables with extruded dielectric insulation and of modern splicing technology hasimposed new conditions and restrictions on cable fault locating, The use of excessive high voltages andenergies during ac, dc,and surge testing of service-aged power cable systems with extruded dielectricinsulation may overstress insulation, creating defects that become faults after the cables are returned toservice.
This guide is intended to be applied to medium-voltage distribution cables. Medium-voltage distributionsystems generally operate at system voltages above 1 kV and up to 34.5 kV nominal.
The end user of the cable circuit should evaluate the necessity for verifying the integrity of extrudeddiclectric insulated cables. and. if thev are in critical service. proceed to perform the high-voltage/energicstesting. If not detected during dielectric tests, defects in dielectric materials may result in cable failuresduring the transient voltage surge episodes while in service.
1.3 Purpose
This guide is intended to provide trouble-shooting and testing personnel with information to quicklyidentify a faulted cable section and/or locate a cable fault with minimum risk of further damagingserviceable cables,terminations,and equipment.
2. Normative references
The following referenced documents are indispensable for the application of this document. For datedreferences, only the edition cited applies. For undated references, the latest edition of the referenceddocument (including any amendments or corrigenda) applies.
3. Definitions, acronyms, and abbreviations
3.1 Definitions
For the purposes of this guide, the following terms and definitions apply. The Authoritative Dictionary ofIEEE Standards, Seventh Edition (B97″, should be referenced for terms not defined in this clause.
3.1.1 aerial installation type: An assembly of insulated conductors installed on a pole or similar overheadstructure; it may be self-supporting or installed on a supporting messenger cable.
3.1.2 bolted fault: A cable fault having a resistance value of less than 5 .
3.1.3 branch circuits: A cable system in which independent cables branch out radially from a commonsource of supply.(See also: radial feed)
3.1.4 breakdown: A disruptive discharge through insulation
3.1.5 cable tray installation type: A structure of ladders, troughs, channels, solid bottom, and othersimilar devices through which cables systems may be routed.
3.16 characteristic impedance: The driving impedance of the forward-traveling transverse electromagnetic wave. In cable fault locating, an incident wave on a cable (time domain reflectometer [TDR].thumper, etc.) is reflected back to the source positively, negatively, or not at all by discontinuities andinhomogenities in the cable where impedance values differ from the characteristic cable impedance.respectively.
3.1.7 concentric neutral shield (metallic shield type): Wires helically applied over the semi-conductinginsulation shield to carry charging, fault, and neutral currents.
3.1.8 conduit installation type: A structure containing one or more ductsNOTE_Conduit may be designated as iron pipe conduit, tile conduit, etc.
3.1.9 direct buried installation type: Cable laid in a trench or pre-cast trough and covered with sandspecially prepared backfill material, and/or excavated material; or, cable plowed directly into the earth orinstalled into the earth with guided boring techniques.
3.1.10 direct distribution: A primary feeder or cable that supplies energy directly to a consumer.
3.1.11 drain wires shield (metallic shield type): Wires helically applied over the semi-conductinginsulation shield to carry charging currents only.
3.1.12 extruded diclectrics: Insulation like polyethylene (PE), crosslinked polyethylene (XLPE), treeretardant crosslinked polyethylene (TR XLPE), ethylene propylene rubber (EPR), etc.
3.1.13 flashover: A disruptive discharge through air around or over the surface of a solid or liquidinsulation, between parts at different potential,produced by the application of voltage wherein thebreakdown path becomes sufficiently ionized to maintain an electric arc.