scope:

Installation types covered by this Document

This document covers RR type reed FDM circuits installed on AC and DC electrified Network Rail controlled infrastructure.

This document covers reed FDM systems installed in accordance with the reed FDM system manuals [IB138] & [IB165].

The reed FDM system is used for both safety critical or 'vital' applications and non-safety critical 'less-vital' applications; both applications are covered by the analysis presented here.

Westinghouse FDM-NV and older type 'R' systems are not covered by this document. It has been accepted previously that the Westinghouse FDM-NV system is less sensitive that the reed FDM system considered here [120-dr0458] & [fx3100], thus the FDM-NV system is encompassed within the analysis presented.

Equipment types included in this Document

The equipment covered within this document is the type 'RR' reed FDM equipment that was previously manufactured by GEC (now ALSTOM) and is now manufactured by NRS.

Purpose

The purpose of this document is to provide a methodology to demonstrate compatibility with reed FDM systems installed on the AC and DC electrified railway on Network Rail controlled infrastructure. This is achieved by:

• Providing a methodology to calculate the longitudinal voltage produced in the cable cores forming a reed FDM circuit.

• Providing a model to determine the voltage across a reed FDM receiver.

• Providing a methodology to define the permissible current in the traction supply.

• For reasonable worse case infrastructure conditions train current limits are defined.

The interference mechanisms to be considered are conductive, capacitive and inductive coupling. The coupling is between the traction supply & return conductors and the lineside cables.

This characterisation will take the form of a permissible train current which can then be compared to the EMI footprint of a piece of traction or rolling stock to enable a case to be made. Methods are included to analyse intact and faulty infrastructure.