A NEW AND INNOVATIVE DESIGN FOR A BEACH JOINT

Transcription

1 A NEW AND INNOVATIVE DESIGN FOR A BEACH JOINT Romuald Lemaitre, Marc Desombre, Thomas Reymbaut, Romain Becuwe, Florence Palacios, Aline Saison, Nicolas Maltaverne, René-Marc Demont (Alcatel-Lucent Submarine Networks) <romuald.lemaitre@alcatel-lucent.com> Alcatel-Lucent Submarine Networks, 536 quai de la Loire Calais Cedex FRANCE Abstract: The land joint is a dry-plant component designed to allow the connection between the sub-sea cable and the terrestrial cables in the beach manhole at landings of undersea transmission systems, and the connection of combined optical/electrical cables on land routes between beach manholes and terminal stations. This paper presents a newly developed land joint. 1 INTRODUCTION To better answer market needs while easing installation and procurement issues, a new land joint has been designed and developed by Alcatel-Lucent Submarine Networks (ASN) based around the following principles: Simple design and assembly techniques to minimise cost and jointing time Separation of electrical and optical connections Versatility to easily adapt to the largest possible range of cables. This resulted in a modular design, in which a specific box houses the electrical connection between the submarine cable power conductor and the land cable electrical conductor while the optical connectivity is ensured in a dedicated fibre jointing box. This construction offers improved flexibility in design, installation and maintenance thanks to the separation between electrical and optical connections. Qualification and validation of this product was conducted via a comprehensive mechanical, electrical and environmental testing program, including long term aging tests. The new land joint has already been implemented on several systems. A very positive operational feedback has been received, analysed and taken into account for final optimization of the product. Outputs from this analysis are also presented in this document. Finally, design evolutions to accommodate various cable designs as well as application to unrepeatered systems and in-line jointing of land cable are also described. 2 NEW LAND JOINT DESIGN The previous ASN land joint design was introduced to the market back in In 2007, ASN made the decision to develop a new joint in order to reduce size and weight, ease product procurement and implementation, and improve the product flexibility vs. various system configurations. 2.1 Design Description The new land joint design is based on a dedicated high voltage assembly in which the electrical connection is carried out through a copper link bar. Optical connections are made inside a standard, commercially available splice enclosure. Copyright 2010 SubOptic Page 1 of 6

2 Fibres are routed through the high voltage housing and towards the optical enclosure in plastic sleeves inserted inside polyethylene tail tubes. A specific frame and a metallic cover protect the high voltage enclosure from external aggressions and act as a protective electrical screen. Cables are clamped on this land joint frame. The basic design is defined for installation in manholes. In addition an outer protection has also been designed for direct burial of the joint in terrestrial applications. Figure 1 : ASN Land Joint Overview Figure 2 : ASN Land Joint HV Housing 2.2 Features & Benefits The main features of this new design are: Re-openability of the joint, with separate electrical and optical connections Product qualified for 25-year operation Compatibility with a wide cable diameter range Reduced dimensions, reduced weight Maximum voltage of 15kV DC Temperature range: -40 C/+70 C Water-tightness up to 6m water depth. The new land joint brings the following benefits: The use of a standard, commercially available splice enclosure for the optical fibres Easier procurement as many components are standard or easy to manufacture Improved flexibility for maintenance Simplified training for jointers The simple modular design allows disconnection of the electrical connection without opening/disturbing the optical part (and vice-versa) Simplified handling, packaging, storage and shipping thanks to a more compact, lighter design compared to previous generation of beach joint, while maintaining at least equivalent robustness. 3 NEW LAND JOINT QUALIFICATION An 18 month qualification program using 8 assembled joints and about 60 test bars was undertaken to validate the new land joint design. This plan included mechanical, optical, electrical and environmental testing. 3.1 Qualification Standards Qualification has been carried out following the Telcordia GR-771 standard to check: optical performance mechanical performance environmental performance. Copyright 2010 SubOptic Page 2 of 6

3 Complementary specific tests have been added to check: electrical performance vibration resistance. 3.2 Qualification Tests on Assembled Samples A first land joint sample was assembled on deep sea cables with pre-aged piece parts (accelerated ageing for 30 days at 90 C) and submitted to thermal cycling from -40 C up to +70 C, cable sheath retention (up to 1kN), cable flexion (up to 30 deflexion), cable torsion (up to 1tr/m), and vibration tests with optical measurements. It was then submitted to a vertical drop test. To check its integrity after the test sequence, a hydraulic pressure test (6m water depth) and a high voltage test were performed, and piece parts were then examined after sample disassembly. The high voltage test level was defined according to the submarine cable electrical standard. The test was performed at 140kV for a duration of 5h25min which corresponds to 15kV for 25 years. electrical connection between the screens. It was submitted to chemical immersions in sulphuric acid (ph=2), sodium hydroxide (ph=12) and a tensio-active solution. It was then submitted to compression and impact tests, and freeze / thaw cycling test. Its integrity was finally checked via a hydraulic pressure test, a high voltage test, and an electrical continuity test followed by sample dissection. An additional sample with the same cable types and screen continuity was submitted to kerosene immersion, freeze / thaw test and sample integrity tests. Figure 4 : Compression test on ASN Land Joint Figure 5 : Pendulum Impact Test on ASN Land Joint Figure 3 : Flexing Test Vibration Test on ASN Land Joint The same kind of test sequence (ageing, thermal, mechanical, integrity tests) was then carried out separately on a high voltage housing and an optical enclosure, with the mechanical constraints being applied to the polythene tail tubes used to route the fibres. Another land joint sample was assembled on light weight screened cables, including Figure 6 : Freeze / Thaw Cycling Test on ASN Land Joint Copyright 2010 SubOptic Page 3 of 6

4 The resistance of this new land joint to corrosion was checked on an additional qualification sample, which was then submitted to the same sample integrity tests as above. A further full land joint sample was submitted to a hydraulic pressure test and a long term high voltage test. The test level was 45kV for 6 months with polarity reversal at 3 months. The sample integrity was then checked through sample dissection. To assess the product compatibility with extreme humidity conditions, a sample was assembled at 90% relative humidity and subjected to a successful high voltage test. Disassembly and reassembly operations were carried out on a dedicated sample. Integrity after the test sequence was checked via a hydraulic pressure test, a high voltage test, and examination of piece parts after sample disassembly. Finally, a sample made with two cable composite conductors and the electrical continuity clamp was submitted to a tensile test followed by an ohmic resistance measurement. 3.3 Qualification Tests on Test Bar Samples Among the raw materials used in the ASN land joint, the most sensitive ones were identified and test bar samples of these raw materials were submitted to qualification tests. Some of them were submitted to stress cracking, and others to chemical immersions in sulphuric acid (ph=2), sodium hydroxide (ph=12), tensio-active solution and kerosene. The mechanical properties of the samples have been checked after these tests. Some of the samples were submitted to fungus resistance test per ASTM G 21 to check the propensity of these raw materials to fungal growth. Moreover some samples of polymer materials have been tested to verify their resistance to UV radiation. The test was conducted per ASTM G 53. Figure 7 : UV Resistance Test on ASN Land Joint Test Bars 3.4 Product Testing to Limits To better characterize this new product a test campaign was carried out to push the product to its limits. First, an electrical test was performed up to high voltage failure which occurred at 225kV. This failure was non-destructive. A second 190kV high voltage ramp was then performed. Secondly, the pressure limit was determined via a pressure ramp test in a dedicated vessel. The sample was able to sustain 5 bars. Figure 8 : Pressure Testing to Limits Additional testing was conducted to evaluate the product resistance to long term immersion in kerosene. No degradation of performance was noted after 6 months immersion. Copyright 2010 SubOptic Page 4 of 6

5 4 ADAPTATIONS FOR DIFFERENT APPLICATIONS 4.1 Qualification for Different Cable Types Complementary qualification tests were performed to cover the use of the new land joint with other submarine cable variants including cables from other cable manufacturers, power cable designs and optical terrestrial cables. These qualification tests consisted of assembly of samples, mechanical testing, hydraulic pressure tests, electrical tests and inspection after dissection. 4.2 Design Adaptation for Unrepeatered Applications To better fit the needs of unrepeatered systems (where very low electrical resistance required), a simplified version of this new land joint was designed, taking into account results of the initial design qualification for repeatered submarine cables. A complementary qualification program was undertaken for the validation of this simplified design, including sample assembly, mechanical tests, hydraulic pressure test, electrical tests and inspection after sample dissection. 4.3 Design Adaptation for Terrestrial Cable Jointing A simplified design for optical terrestrial cable joints was also developed, including the land joint optical housing and an adapted mechanical frame for terrestrial use. 5 NEW LAND JOINT IMPLEMENTATION OPERATIONAL FEEDBACK Since its qualification, more than 100 ASN land joints have been installed in beach manholes and land routes in various environments. Operational feedback has been collected and taken into account for the optimization of the product. The new product was greeted by installation teams with enthusiasm. Most of the feedback has been very positive e.g. reduced size and weight, quick and easy assembly and installation in the field. Figure 9 : ASN Land Joint Installed in Beach Manhole (Bermuda) The first installation of the new ASN land joint was done in extreme conditions for the Greenland Connect system. As the customer had chosen a direct buried land cable installation in permafrost, a specific stainless steel outer protection box was designed. Figure 10 : ASN Land Joint Buried Version Being Installed in Permafrost in Greenland The ASN jointing training school provides dedicated sessions to train customers on the assembly and installation rules for the ASN land joint. Today, more than 50 people have been trained on this new land joint and feedback has been all positive regarding the easy management of the joint during operations. Copyright 2010 SubOptic Page 5 of 6

6 6 CONCLUSION This new ASN land joint design represents a significant step forward, bringing a number of improvements over the previous product. It brings increased flexibility for operation and maintenance as well as significantly easier procurement This new joint is already implemented on several contracts. It has been very well received by all customers and installation teams. 7 REFERENCES [1] ASTM G 21: Determining Resistance of Polymeric Materials to Fungi [2] ASTM G 53: Standard Practice for Operating Light-and Water-Exposure Apparatus (Fluorescent UV- Condensation Type) for Exposure of Non-Metallic Materials [3] Telcordia GR-771: Generic Requirements for Fiber Optic Splice Closure Copyright 2010 SubOptic Page 6 of 6