scope:

This document covers RR type reed FDM circuits installed on a.c. and d.c. electrified Railtrack controlled infrastructure.

Westinghouse FDM-NV and older type 'R' systems are not covered by this document.

Purpose

The purpose of this document is to provide a methodology to demonstrate compatibility with reed FDM systems installed on the a.c. and d.c. electrified railway on Railtrack 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.

This characterisation will take the form of a permissible train current which can then be compared to EMI the 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.

The aim of this document is to provide a methodology for the demonstration of electromagnetic compatibility of reed FDM systems installed on Railtrack routes.

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.