Network Rail

Insulation Monitoring and Fault Location Systems for Use on Signalling Power Systems - Compliance Date: 3 June 2017
 N NR/L2/SIGELP/27725 ISSUE 1

Annotation

This standard defines Network Rail’s requirements for IMDs and IFLSs for use on Isolated Terra (IT) Electrical Systems where the nominal system voltage does not exceed 1000 V a.c. or 1500 V d.c. for the following applications:

a) the interface between the Principal Supply Point (PSP)/Auxiliary Supply Point (ASP) and the Functional Supply Point (FSP);

b) the interface between an FSP and another FSP;

c) the interface points along a distribution feeder where a Distribution Interface Transformer Assembly (DITA) or Booster or Isolation Transformer has been installed;

d) Signalling Functional Circuits (a.c. and d.c.);

e) Traction derived power supplies interfacing with Principal Supply Point (PSP)/Auxiliary Supply Point (ASP);

f) Standby generator supplies interfacing with Principal Supply Point (PSP)/Auxiliary Supply Point (ASP);

NOTE 1: The nominal voltages used on SPSs are: 110 V; 230 V; 400/440 V and 650 V a.c.

The nominal voltages for Signalling Functional Circuits are typically 110/140 V a.c. 50/120 V d.c.

NOTE 2: Boundaries between subsystem elements are detailed in NR/L2/SIGELP/27416.

The following integrated systems and sub-systems are specified:

• Integrated solutions for the deployment of IMDs and IFLSs using a Tier 1, Tier 2 or Tier 3 architecture (see section 6.1);