scope:

Signalling power supply system architecture

This standard applies to each power source used to supply signalling equipment on Network Rail infrastructure, together with the associated distribution arrangements as far as the functional interface at signalling equipment housings. Four subsystem elements may be identified as follows.

a) Incoming supplies, typically comprising one or more of:

• Power supplies from the distribution network operator (DNO),

• Railway 33 kV traction distribution systems,

• 25 kV distribution systems, or

• Private HV distribution systems.

b) Principal supply points (PSPs), typically comprising:

• An uninterruptable power supply (UPS),

• Backup generators,

• Switchgear,

• Distribution transformers,

• Feeder protection equipment, and

• Insulation monitoring.

c) Distribution system, typically comprising:

• Power distribution cables,

• Low voltage switchgear,

• Distribution interface transformer assemblies (DITAs),

• Automatic reconfiguration systems, and

• Signalling step-down transformers.

NOTE: The system may comprise the following distribution topologies:

•Radial feeders;

•Dual-end manual reconfiguration systems;

•Dual-end automatic reconfiguration systems;

•Single-end manual reconfiguration systems using open rings.

d) Interface to final signalling loads.

NOTE: Final signalling loads via the functional supply point (FSP) comprise an array of signalling equipment such as point machines, signals, level crossings, etc. The power supply interface may comprise a range of equipment, e.g. signalling transformers, battery chargers, UPSs, etc.

NOTE: These four subsystems may be discrete entities or contained together within a building, such as a signalbox or Rail Operating Centre (ROC).

Production and management of documentation

This standard covers the production and management of signalling power supply network drawings and associated documentation for the lifetime of the infrastructure, irrespective of technology, including:

• Technical content of drawings and associated documentation;

• Site survey and infrastructure assessment before design alterations;

• Correlation of records;

• Design record and production control;

• Configuration control;

• Design modifications;

• Certification process;

• Source record updating;

• Arrangement and presentation of drawings;

• Drawing symbols;

• Modelling tools;

• Special cases, including overlapping and parallel design.

This standard applies from project conception to acceptance into service and, where applicable, to decommissioning and disposal. It covers both proposal drawings and detailed design.

This standard includes both engineering design for construction purposes, and engineering records. It applies to both staff and contractors of Network Rail acting either as asset manager or design authority.

Types of documentation

The following documentation is covered by this standard and the requirements for each are specified in Module A:

a) A signalling power network map, to describe the network topology; NOTE: This standard does not cover detailed or comprehensive requirements for the database-driven map of a network topology.

b) A signalling power facilities diagram, showing principal relationships and key facilities;

c) A signalling power distribution schematic (SPDS), i.e. a single line diagram for each power source that shows all four subsystem elements to enable safe isolation.

NOTE: These may be shown on a single schematic, or on separate sheets.

Exclusions

This standard does not cover:

a) Technical design principles of power supply systems, which are set out in NR/SP/ELP/27243, NR/L2/SIGELP/27410, NR/L2/SIGELP/27418, NR/L2/SIG/30050 and BS 7671;

b) The requirements for design integration and interdisciplinary check, which are mandated in NR/L2/INI/02009;

c) Installation and testing procedures given in NR/L2/ELP/27243, NR/L2/ELP/27311, NR/L2/SIGELP/27418, NR/L3/SIG/11303, NR/L2/SIG/30014 and BS 7671, except for the interface with design processes;

d) Approval and acceptance processes to demonstrate that assets are safe, dependable and fit for purpose, which are prescribed in NR/L2/ELP/27311 and NR/L2/SIG/30003;

e) The entire suite of engineering deliverables required for each phase of a signalling power supply project, which are listed in NR/L3/ELP/27406/MOD E.

f) Detailed or comprehensive requirements for the signalling power network map. It also omits wiring diagrams for PSPs and FSPs. These will be covered in a future update of the standard.

Purpose

This standard sets out the detailed requirements for the provision, management and maintenance of signalling power supply network drawings and associated documentation, to enable safe isolations for any purpose, including:

• Stagework,

• Entry into service,

• Operational planning,

• Maintenance,

• Fault finding,

• Signalling possession planning,

• Emergency shutdown works, and

• Recoveries.

The drawings will also facilitate asset management, system alterations and new works.