Wellington network track circuit immunisation

Greater Wellington Regional Council is procuring new AC drive Electric Multiple Units (EMUs) for the Wellington rail network. It is essential that these new EMUs are compatible with the signalling system they are required to interface with. It was decided to replace some types of track circuit considered to be potentially susceptible to interference from AC drive EMUs, however it was hoped that many of the 50Hz double element track circuits could continue to operate safely in combination with the new EMUs. Interfleet Technology was commissioned by ONTRACK to carry out susceptibility modelling of the 50Hz double element vane relay track circuits in the Wellington network. The work required the development of suitable computer simulation models of the track circuits, based on methodology developed over many years in the UK. The simulation models were developed to represent the unique nature of the Wellington track circuits and were validated against local measurement data, undertaken by ONTRACK staff. Of a total of over 300 double element track circuits in Wellington, a subset of 18 track circuits representing the most susceptible configurations were individually modelled. This led to a set of susceptibility results for normal and failed infrastructure conditions of all 18 of these track circuits. A particular track circuit (1 BGT) was identified as having an unacceptable level of susceptibility under failed infrastructure conditions due to a low voltage relay combined with other factors. This track circuit was recommended for modification or replacement. The remaining 17 track circuits had a wide variation of susceptibility limits for the normal infrastructure results. However, the failed infrastructure results were all much closer and it was therefore logical to set train design limits based on this remaining group of 17 track circuits. These limits could not be declared in their entirety to the EMU manufacturer since multiple trains and other sources of 50Hz interference require the application of suitable safety margins. The outcome of this work was the declaration of 50Hz limits (based on model limits with the addition of safety margins) suitable for use by the EMU manufacturer to enable them to design an AC drive traincompatible with the 50Hz double element track circuits.

Media Info

  • Pagination: 14p.
  • Monograph Title: Rejuvenation and renaissance: CORE 2010: conference on railway engineering, 12-15 September 2010, Wellington, New Zealand

Subject/Index Terms

Filing Info

  • Accession Number: 01517100
  • Record Type: Publication
  • Source Agency: ARRB
  • Files: ATRI
  • Created Date: Mar 4 2014 8:08PM