Resin moulded Electro Optic Termination Assembly – design, procedure, testing and qualification

This paper discusses the design, procedure, testing and qualification of Sub-sea Resin-moulded Electro-optic Termination Assembly (SRETA) undertaken on Nexans make umbilical of model number DO-478. In general the electro optic termination assembly can be built for any umbilical cable for the commercial oil and gas extraction at a sub-sea depth rating up to 3000m mean sea level (MSL). The Medium voltage (MV) electrical power conductors and the Single Mode (SM) fibre optic cables in the resin moulded assembly will be terminated and distributed to respective systems at sub-sea. The complete termination assembly was designed and developed at NIOT for the specific requirement of umbilical cable. The Single mode (SM) fibre optic cable was spliced using an arc splicing machine and was encapsulated within a pressure tolerant enclosure made of Aluminium metal. The high voltage electrical conductors were spliced and insulated with suitable rated air tight heat shrink sleeves called boot sleeves. The whole of the termination arrangement was filled with a PDM 69T two part polyurethane resin. The details on the termination procedure and assembly are explained in the sections under. The integrity of the termination undertaken was tested through an Optical Time Domain Reflectometer (OTDR) for fibre optic cables and Insulation testing system for the electrical joints. The functionality of the termination assembly was tested and qualified up to an operating depth of 3200 m MSL during NIOT underwater mining system sea trials undertaken at Bay of Bengal (BoB) during 2020.