VRIOGS 010.7 RevA - Public Transport Victoria

32 VRIOGS 010.7 Revision Aand Communications Apparatus; EN 50122-1:1998 Railway Applications-Fixed Installations-Part 1:Protective Provisions relating to Electrical Safetyand Earthing and also EN 50122-2:1999 Railway Applications-FixedInstallations-Part 2: Protective Provisions against the effects of stray currentsby D.C Traction Systems.7.6 Track Circuits7.6.1 GeneralTrack circuit and Axle Counter equipment installed within the electrified area shall bydefinition be within the Immunised Area as per this specification, as far as theacceptable equipment and design is concerned. Rail bonding within the nonelectrifiedarea shall be carried out to the standards of electrified tracks except thatthere will be no requirement for cross bonding other than for the single connectionfrom each spur to the traction return current system.The following additional guidelines should be considered.7.6.2 Single Rail Track Circuit1. Keep the common rail as far as possible on the side nearest the electrifiedtracks.2. Where only one single rail track circuit is required it may be treated as adouble rail track circuit for fault current purposes.3. A single impedance bond may then connect both rails to the traction currentreturn system.7.6.3 Double Rail Track CircuitSince impedance bonds in series around a pair of IRJs constitute an unnecessarycost for non-electrified tracks, minimise the number of tracks in series if possible.7.6.4 Jointless Track Circuit1. Impedance bonds may only be installed in every other track circuit; thereforethe length of jointless track circuited areas may easily become excessive.2. IRJs shall be inserted in each rail at a minimum of one location between eachpair of substations or tie station to avoid providing a path for return tractioncurrent when one substation is taken out of circuit.7.7 Non Track Circuited Track1. Non Track Circuited track should be bonded for traction current return in asimilar manner to track circuited track.NOTE: This document is controlled only when viewed on the DOT Engineering Standards website.Any other copy of this document is uncontrolled, and the content may not be current.