Guidance note

NR/GN/TEL/31101

Telecommunications Failure Investigation: Investigation Guides (formerly RT/E/C/31101)

Issue 1, December 2002

Code of practice holding the equipment-specific failure investigation test guides for safety related telecoms failures: PETS, copper cables, concentrators, DOO CCTV, radio (CSR/NRN), telephones, emergency short code dialling, bearer circuits and traction supervisory links.

Clause map — what each clause deals with

1	Purpose	Provides failure investigation guides for specific types of operational telecoms systems
2	Scope	For investigating reported safety related failures, by staff certified in maintenance testing and failure investigation and authorised on that kit
3	Responsibilities	The engineer or technician investigates and tests, considering the possible failure modes listed in the guides
4	Flow Chart	Points to the investigation flow chart in RT/E/C/31100
5	Procedure	Procedure sits in RT/E/S/31001 and RT/E/C/31100; some guides may also be used within the signalling maintenance testing process (RT/E/S/11231)
6	Records	Record retention follows RT/E/S/31001 and RT/E/C/31100, or the signalling equivalent
7	Reference Documentation	Lists the parent specification and related codes of practice
8	Definitions	Defines check, test, independent checking, maintenance tester, SRTF, system and tail cable
9	Failure Investigation Guides Index	Table of equipment, failure symptoms and the guide to use; these guides take priority over those in RT/E/C/31100
Appendix AHBTFI001	Public Emergency Telephone Systems	Checklist for PETS faults reported by the signaller, separating PETS from line plant faults; a system reset counts as a destructive test
Appendix CABTFI001	Copper Cables	Checklist for cable faults found via other guides: interference sources, immunisation, VL/VT, pressurised cables, then link, insulation and TDR tests; over 50 V insulation testing is destructive
Appendix CONTFI001	Concentrators	Checklist for telephone concentrator faults: indications, alarms, records, power, then PCB substitution and function tests; reset only as a last resort
Appendix DOOTFI001	DOO CCTV	Checklist for driver only operation CCTV picture faults: which monitors or cameras affected, lighting, then power, connections, triggers, alignment and adjustment
Appendix RADTFI001	Radio Systems	Checklist for cab secure and other radio faults: coverage, alarms, logs, recorders, TD interfaces, then base stations, processors, landlines and racks
Appendix TELTFI001	Telephones	Checklist for telephone faults including selective SPT coding, cabling, links and jumpers, instrument replacement and labels
Appendix TELTFI002	Emergency Short Code Dialling Features	Checklist for 17x emergency short code call faults: call details, hunt groups, routing tables, call reports, then substitution and simultaneous test calls
Appendix TRATFI001	Telecoms Bearer Circuit Failures	Checklist for bearer circuit faults: routing, alarms, fault history, other circuits, end-to-end checks, then data or frequency runs and crosstalk
Appendix TRATFI002	Traction Supervisory Systems	Checklist for loss of traction supervisory links to remote sites: confirm with the electrical control room, check A/B links and modems, then substitute modems