scope:

This Guidance Note sets out how to demonstrate compatibility with reed FDM systems installed on the AC and DC electrified railway on Network Rail managed

infrastructure.

It provides:

a) a method to calculate the longitudinal voltage produced in the cable cores forming a reed FDM circuit;

b) a model to determine the voltage across a reed FDM receiver;

c) a method to define the permissible current in the traction supply;

d) definitions of train current limits for reasonable worse case infrastructure conditions.

It applies to these interference mechanisms:

a) conductive;

b) capacitive; and

c) inductive coupling.

NOTE: The coupling is between the traction supply and return conductors and the lineside cables.

This standard applies to RR type reed FDM circuits installed on AC and DC

electrified Network Rail controlled infrastructure.

NOTE: Both the safety critical or vital applications and non-safety critical non-vital applications of the

reed FDM system are in scope of this standard.

This standard does not apply to:

a) Westinghouse FDM-NV and

b) older type 'R' systems.

Purpose

This Guidance Note aids safe and reliable rolling stock introduction by:

a) defining how interference from electric traction systems can enter reed FDM systems; and

b) providing a methodology for demonstration of compatibility