FTN design & development specification (D&D)
SP FTN (D&D) 020
Pre-terminated Optical Fibre Cable Assemblies
Issue 1, Feb 2010 · FTN D&D specs & typical drawings
Product specification for factory pre-terminated fibre cables (external cable with connectorised pigtails, no splice) used where there is no room for an ODF. Designers use it for connector options, lengths, pigtail colours and acceptance test criteria.
Clause map — what each clause deals with
| 1 | Introduction | Context of the FTN build supporting GSM-R. |
| 2 | Abbreviations | Abbreviations used (DISAC, FC/APC, LC, MBR, MTBF, SC/APC, SU, ZHLS). |
| 3 | Glossary | Defines pigtail, patchcord, tail cable assembly, ruggedising, buffering, coatings, uniter, DISAC construction. |
| 4 | Scope | Where pre-terminated cables are used (no space for a termination), the three permitted connector types, no mixing of types; terminations themselves are in SP/FTN(D&D)/011. |
| 5 | General Description | What the assembly is, diameter growth limit, environmental class, base cables (SP/FTN(D&D)/010 or DISAC), metallic isolation, 1 to 24 fibre variants, standard lengths. |
| 6 | Pigtails | Fibres continuous from sheath to connector with no splice; pigtails built on the cable's primary-coated fibres. |
| 6.1 | Construction | Ruggedised pigtail build: aramid strength member, ZHLS jacket, diameter and sheath thickness limits, fibre free to move, sheath anchored to the connector boot. |
| 6.2 | Additional Requirements for ZHLS Outer Jacket | Chemical groups excluded from the ZHLS sheath material; trace level per GE/RC8505. |
| 6.3 | Sheath Colouring | Pigtail jacket colour identifies connector type (one colour each for SC/APC, FC/APC, LC/PC). |
| 6.4 | Length of Pigtails | Standard pigtail length and tolerance measured from the breakout body to the boot, unless ordered otherwise. |
| 6.5 | Pigtail Sheath Marking | What must be printed on each pigtail sheath (fibre type, manufacturer, date, batch number) and lettering size. |
| 6.6 | Numbering of Pigtails | Each pigtail carries a permanent collet showing its fibre number. |
| 7 | Optical Connectors | Three connector variants offered; supplier must provide a tamper-proof way of marking connectors as tuned to the keyway. |
| 7.1 | SC/APC | Tuned 8-degree SC/APC to the relevant BS EN 61754 part. |
| 7.2 | FC/APC | Tuned 8-degree FC/APC to the relevant BS EN 61754 part and draft EN 50377. |
| 7.3 | LC/PC | Tuned LC connectors to BS EN 61754 (part number left unfilled in the doc). |
| 8 | Product Acceptance and Supporting Information | What suppliers must provide alongside the product for Network Rail acceptance. |
| 8.1 | Product Acceptance | Network Rail product acceptance process applies; supplier states existing certificate; section 9 tests are a condition. |
| 8.2 | History of Use in a Railway Environment | Supplier to give track record of the product in railway or similar environments. |
| 8.3 | MTBF | Calculated and actual MTBF data to be supplied where available. |
| 8.4 | Materials | Materials must give a 30-year service life in the stated environment. |
| 9 | Product Acceptance Tests | Tests grouped into pigtails, connectors and complete assemblies; BS EN 61754 normally takes precedence on conflict. |
| 9.1 | Product Acceptance Tests for Pigtails | Mechanical and ZHLS tests on the ruggedised pigtail. |
| 9.1.1 | Macrobend Performance | Mandrel wind test with a per-turn excess loss limit at 1550 nm. |
| 9.1.2 | Strength | Sustained tensile load and maximum load tests with fibre strain and attenuation limits (BS EN 187000 method 501). |
| 9.1.3 | Flexibility | Repeated flex cycle test over pulleys under load (BS EN 187000 method 509). |
| 9.1.4 | Compressive Stress | Crush load test for a set duration (BS EN 187000 method 504). |
| 9.1.5 | Impact | Drop weight impact test, repeated (BS EN 187000 method 505). |
| 9.1.6 | Tightness of Ruggedising | Pull-out test showing the buffered fibre moves freely within the ruggedising under a small force. |
| 9.1.7 | ZHLS Tests on Pigtails | Sheath material tests: insulation resistance, water absorption, smoke emission and flammability with reference standards and GE/RC8505 limits. |
| 9.2 | Product Acceptance Tests for Optical Connectors | Connector end-face geometry tests per BS EN 61300-3 series. |
| 9.2.1 | Connector End Face Eccentricity | Apex offset limit measured by interference ring method (BS EN 61300-3-15). |
| 9.2.2 | Connector End Face Radius | Radius of curvature ranges for APC and LC/PC ferrules by interferometry (BS EN 61300-3-16). |
| 9.2.3 | Fibre Position Relative to End Face (Fibre Undercut) | Permitted fibre undercut/protrusion range (BS EN 61300-3-23). |
| 9.2.4 | End Face Angle | Angle tolerance for the 8-degree polish and reference ferrule parameters (BS EN 61300-3-17). |
| 9.3 | Product Acceptance Tests for Pre-terminated Optical Fibre Cables | Optical, mechanical and environmental tests on the complete assembly. |
| 9.3.1 | Attenuation | Insertion loss test method, source, per-end and manifold allowances, bidirectional (BS EN 61300-3-4). |
| 9.3.2 | Return Loss | Return loss test set-up and minimum values for FC/PC and SC/APC (BS EN 186000). |
| 9.3.3 | Vibration | Sweep vibration test parameters and insertion loss limit (BS EN 61300-2-1). |
| 9.3.4 | Mating Durability | Repeated mating test with insertion loss limits and microscope check (BS EN 61300-2-2). |
| 9.3.5 | Cable Pulling | Cable retention pull test in four directions with loss and physical pass criteria (BS EN 61300-2-4). |
| 9.3.6 | Cable Torsion | Twist test under tension on a mandrel, loss and damage criteria (BS EN 61300-2-5). |
| 9.3.7 | Shock | Mechanical shock pulses in four axes with optical monitoring (BS EN 61300-2-9). |
| 9.3.8 | Drop | Drop test count and height with loss limit (BS EN 61300-2-12). |
| 9.3.9 | Change of Temperature | Temperature cycling profile, extremes, rate and cycles with loss limit (BS EN 61300-2-22). |
| 9.3.10 | Attenuation of Randomly Mated Connectors | Random mating attenuation limit and launch conditions (BS EN 61300-3-34). |
| 9.3.11 | Visual Inspection | End-face inspection magnification and the four-zone scratch/pit/debris acceptance table (BS EN 61300-3-1). |
| 10 | Production Tests | Supplier's routine test regime to keep defective deliveries below a target rate; IEC 60874-14-9 precedence. |
| 10.1 | Production Tests on Pigtails | Which section 9.1 tests are repeated in production. |
| 10.2 | Production Tests on Optical Connectors | Which section 9.2 end-face tests are repeated in production. |
| 10.3 | Production Tests on Pre-terminated Optical Fibre Cables | Routine visual, attenuation, return loss and random mating tests with the production variant of the mating test. |
| 11 | Packaging | Delivery protection and documentation. |
| 11.1 | Packaging of Pre-terminated Optical Fibre Cables | Connector dust caps (not tethered), transit protection, and the paperwork to accompany each assembly. |
| 11.2 | Drum Sizes | Drum size for long lengths; short lengths supplied coiled. |
| 12 | References | Lists GE/RC 8505, product acceptance, SP/FTN(D&D)/010 and 011, BR 967, ETS 300 series, BS EN 186000/187000/188000, BS EN 61300, IEC 60874, ITU-T G.652. |
| App A | Specification BR 967 | Reproduction of BR 967 environmental conditions (not present in the text extract; pages blank). |