Subsea solutions

Subsea Solutions

Enhancing Oil and Gas recovery in challenging environments

Subsea Solutions

The future of Oil and Gas recovery involves accessing increasingly complex reserves frequently located in deep and ultra-deep waters. Subsea processing opens the door to more cost-efficient developments – especially for long step-outs, and for marginal and dispersed fields. It requires enabling systems to improve recovery rates and minimize operating costs. Furthermore, it involves advanced supporting power supply and distribution technology.
Subsea Power Grid

Powering Installations on the Seabed

Enabling large-scale subsea processing by powering the subsea fields of the future – down to 3,000 meters.

The step-down transformer is the main interface between the subsea transmission line and the power distribution. As a hermetically sealed, fluid-filled and pressure-compensated unit transformer for variable speed drive of pump motors, it enables step down to a wide range of consumers as well as longer step-outs. Its natural convection cooling reduces maintenance requirements.


Optimized as the main transformer for Siemens Subsea Power Grid, the generic design can be used on subsea distribution transformers in a wide power range. The electrical design is based on traditional onshore distribution transformers, but with an enhanced-efficiency insulation system. All materials have been tested for pressure and fluid compatibility in an extensive qualification program. In addition, the design was verified with an extensive test in shallow water.

The subsea transformer has an integrated sensor and monitoring system that can be seamlessly integrated in the Siemens subsea power control system. This provides the operator with a continuous display of status of transformer integrity and the ability to optimize operations for enhanced safety.


Technical data

  • Pressure-compensated
  • Hybrid insulation
  • Robust enclosure design with optimized natural cooling properties
  • Biodegradable and environmentally friendly MIDEL 7131® fluid filling
  • Flexible interfaces (dry or wet-mate connections)
  • Advanced condition monitoring
  • Also suitable as a step-down transformer for subsea boosting
  • Qualified for 3,000 meters water depth

The subsea switchgear has a modular design. Its main bus bars, wet-mate connectors and measuring transformers are housed in the fluid-filled and pressurized base module.


Technical data

  • Modular design with vacuum circuit breakers
  • Fluid-filled base module
  • Pressure-compensated bus bar base section
  • Cascadable design for more consumers
  • Zero differential pressure at all penetration to seawater

The variable-speed drive (VSD) features a fault-tolerant multi-cell topology with built-in component redundancy. Designed specifically for sea floor operation, its fluid-filled enclosure and all power electronics can be exposed to full pressure, thereby reducing maintenance requirements.


Technical data

  • Modular and compact pressure-compensated design
  • 100% natural cooling
  • Multicell topology with built-in redundancy
  • Advanced cell by-pass for maximum availability
  • Built-in isolation transformer ensures safe operation in Siemens’ Subsea Power Grid
  • Low harmonics both to motor and to supply

The Subsea Power Control system is a very important component of the Subsea Power Grid. It ensures several important functions in the subsea power distribution:

  • Direct transfer of every command given in the topside control system to the respective subsea control module,
  • Transparent communication of status and information from the respective subsea modules like variable-speed drive (VSD) and switchgear to the topside control system,
  • Delivery of standardized interfaces (e.g. SIIS to other subsea application like sensors and/or pump systems).
  • Delivery of a transparent communication channel from topside all the way to the subsea variable-speed drive (VSD). This enables configuration of the VSD, update of VSD software, as well as diagnostics and service being done the same way as with a topside VSD.

The Subsea Power Control system is connected with topside control via an embedded fiber in the subsea power umbilical. The fiber is terminated and connected to a subsea electronic power control unit (EPCU) - the “brain” of the Siemens Subsea Power Grid. This controller unit processes commands and information and generates the correct commands locally to the respective subsea modules like variable-speed drive (VSD) and switchgear. All data flow subsea is sent to and from the respective units via a remote termination unit (RTU) in an Ethernet data network.


Major milestone achieved in the development of a barrier-breaking subsea power distribution system

Siemens has successfully concluded the first phase of its Subsea Power Grid shallow water test in Trondheim, Norway. 

Products, Systems and Lifecycle Services

Our subsea products and systems portfolio covers a broad spectrum of applications. Going far beyond power and distribution, it comprises everything from pioneering technologies for subsea control and surveillance to exemplary service and support based on extensive marinization expertise. As a result, we are able to provide answers over the entire life of the field.

The reliable Tronic line of DigiTRON, SpecTRON, DigiTRONf, and ElecTRON products provide electrical and fiber-optic connector systems for subsea power and communications

Controls and Instrumentation Connectors


The DigiTRON range of connectors provides world leading trusted quality and long-lasting reliability.


DigiTRON+ and DigiTRONe are the most reliable and advanced subsea connectors used by the subsea industry to date. Qualified to operate in depths of up to 4,000 meters, a MTBF (Mean Time Between Failure) of 400,000 years and an enviable track record; The DigiTRON range of connectors are the most technically advanced and reliable subsea connectors on the market.


DigiTRON3 has all the benefits you would expect from the world leader in subsea connectors. Our trusted proven track record provides quality and reliability where it’s needed most. Our new DigiTRON3 connector has an enhanced design with a voltage rating of 1.8/3 (3.6) kV. With the aim to reduce the size and quantity of connectors required for high voltage control applications this connector is perfect for long step out projects. The compact connector size reduces impact on structures and therefore reducing overall subsea costs.

Subsea Medium and High-power Electrical Connector Systems


A world leading range of subsea, wet-matable medium and high-power subsea electrical connector systems. SpecTRON offers the most comprehensive range of technically advanced and reliable subsea power connectors on the market. With an enviable track record and an extensive range of HV power connectors SpecTRON can be used on a wide range of subsea applications.


SpecTRON 45

Our SpecTRON 45 connector system has been designed to consider the difficulties our customers encounter when trying to integrate wet mateable connectors into complex subsea systems. Incorporating several innovative technologies, SpecTRON 45 provides high electrical integrity and modular design. This offers flexibility in layout for a broad range of applications, including subsea power distribution, long step outs and high current systems. Key benefits include a Common Module Interface (CMI), which is configurable to project requirements and quick connect glands for simple, reliable site termination.

Instrumentation Feedthrough Subsea Connector Systems


Instrumentation feedthrough subsea connector systems are designed to convey electrical communication between permanent downhole instrumentation through the Tubing Hanger and Xmas Tree. Siemens Instrumentation feedthrough subsea connector systems is branded under ElecTRON, which is divided into two main product families: ElecTRONv and ElecTRONh, respectively designed for Vertical and Horizontal Xmas Trees.


ElecTRON products have proven reliability and a solid track record, deployed on a wide range of major developments worldwide.   


ElecTRON brand offers a range of connector solutions, consisting of penetrator, wetmate connectors pair and drymate connectors pair, rated up to 15,000psi working pressure; tested against the latest industry standards and specifications.

Highly Reliable Optical Performance


DigiTRONf is a compact 12-way optical fiber wet mate connector, from the trusted DigiTRON range. DigiTRONf offers excellent optical performance and has been designed and qualified with a focus on reliability and quality. The 12-line connector offers excellent system flexibility and a greater degree of redundancy, allowing for less connectors being required. Qualified to the recently published SEAFOM TSD-02, DigiTRONf is a modular product which offers a complete system.

Subsea Connectors for Wave and Tidal Applications


Siemens Subsea Connectors understand the extreme challenges encountered during offshore installations; from high tidal flows and high sea states to harsh subsea environments. Wet mate connection systems provide the most reliable solution to meet these challenges and allow connection between the subsea cable and tidal device, wave device or subsea hub, not only quickly but safely.


A Siemens Subsea Connectors wet mate connection system will enable 3 phase power, low voltage auxiliary power and data transfer connection lines to be mated in one operation. Although the physical appearance of the connection systems may differ, dependent on the device specific application, the philosophy remains the same: an ability to provide our customers with an integrated scope of supply from the subsea export cable, via a subsea mateable connection system, to a watertight device penetration, all under a single contract.

Siemens Matre sensors and transmitters have been delivering excellent performance with a high level of dependability for over 25 years. In addition to our renowned well-head pressure / temperature sensors, we also offer a wide assortment of proven and tested instruments for monitoring the conditions of subsea operations.

High-quality subsea pressure and temperature sensors


Siemens Matre Pressure and Temperature sensors have an unrivalled performance and excellent long-term stability. For over 25 years the performance and stability of our sensors has been proven on subsea installations worldwide.


WEPS-100 Series

The WEPS-100 subsea sensor is modularized in order to decrease variation in the range of flange sizes. This also standardizes the build between analog and digital sensors, as well as streamlining assembly processes of up to 15k PSI sensors. With over 13,000 WEPS style sensors produced to date, this product has an unrivalled pedigree in delivering information from subsea wells to maximize well flow management performance.

WEPS-2 Series

Quartz Crystal: The WEPS-2 series have been delivered to the subsea marked since 1988. The technology has the longest history in subsea service with an excellent performance in operation. Subsea maintenance schedules have given the opportunity to test these sensors after up to 17 years in subsea operation. The test results show the same performance as first delivered, i.e. no drift at all.

Differential pressure (dP) sensors for subsea applications


Siemens Matre dP-sensors have been supplied to the subsea industry since 1998. The excellent performance of the sensors has made the Siemens Matre brand of dP-sensor to be the preferred choice for dP-measurements within the subsea industry. With the introduction of the remote seal system in 2005, another step was made into making the dP-sensor the first choice for all subsea dP-applications.



Standard dP-sensor with direct process connection through impulse lines.




The remote seal system is designed to provide you with the most robust unit and to make measurements resistant against process pollution and hydrate formation. The SDP-6 meets market demand by providing high-quality solutions for subsea flow and tank level monitoring for systems up to 15,000 psi line pressure.

Flow measurement for subsea applications


Siemens Matre’s dP-sensor on a V-Cone or a Venturi provides a compact dual redundancy single phase flow meter for wet gas, water and gas injection. Our facilities include dedicated pressure test/FAT areas, a water gas testing pit (PSL3G) and hyperbaric chamber. We can offer a solution designed reliable flow meter with high accuracy to meet the demands of even the most stringent project. Coming up is the Siemens Matre flow computer that can be integrated in the flow meter assembly. The flow calculations are based on dP-pressure over a V-Cone or Venturi, Line Pressure and Process Temperature and will be provided in flow rate units.


Single-phase Flowmeter

By combining the Matre Subsea Differential Pressure Transmitter with V-cone or Venturi technologies Siemens have been able to provide an accurate and reliable single-phase flow measurement solutions to many high-profile subsea projects. Whether the project requires single or dual redundancy, direct mounted SDP-5 DP cell or remote sealed SDP-6, Siemens can offer a solution designed to meet the demands of even the most stringent project.

Based on a customer request, industry standard vibration sensor has been marinized and tailored for subsea conditions. The product is fully qualified according to ISO standards relevant for subsea instrumentation.

The Linear Position Transmitter (LPT) has been designed using established and proven Subsea Sensor design technologies from our twenty years’ experience in this area. The LPT is specifically designed for highly accurate fast response valve position indication for safety critical valves such as HIPPS and SSIV. The device is however suited for use with a wide range of Subsea Valves and exceeds the minimum ISO standards for position indication.

With a solution line-up that comprises subsea termination heads, hydraulic, fiber-optic and electrical distribution systems, Siemens has the capabilities needed for safe and reliable subsea power and signal distribution.

Siemens developed the industry standard for pressure compensated electrical distribution system in the early nineties. Since then we have extended and modified the Anguila portfolio for electrical distribution products to a variety of products that distribute power and signal in a reliable way.


Anguila Advanced Cable Termination (ACT)

Siemens’ Anguila ACT enables reliable subsea termination of electrical umbilical cable. It has been tested to a water depth of 4,500 meters and is qualified for 25 years of service. The Anguila ACT is suitable for electrical conductors up to 16 mm². Metal parts exposed to seawater are made from Titanium grade 2 to provide corrosion resistance without the need for cathode protection.


The following features can be offered:

  • Double barrier against water intrusion
  • Pressure- and temperature compensated
  • Moderate internal pressure maintained under ambient and operating conditions
  • Modular design to accommodate a variety of cables and layout
  • Temperature ratings: Storage: –40 °C to +70 °C (70 °C short term), installed subsea: –5 °C to +40 °C

Siemens has reference for fiber optical distribution subsea that goes back to 1999, one of the pioneers for the new era of distribution fiber optical signal subsea. The Anguila portfolio ranges from fiber optical termination assemblies, and fiber glass penetrators.


Anguila Advanced Fiber Termination (AFT)

The Anguila Advanced Fiber Termination (AFT) is a long-life umbilical termination for fiber-optic umbilicals. It utilizes the same field proven technology as the Anguila Advanced Cable Termination (ACT).


The following features can be offered:

  • Design life: from 25 to 50 years
  • Max. jumper exits from AFT without extra split box: 4
  • Designed for the following working depths: 1,200 meters,1,800 meters and 3,000 meters
  • Test pressure: up to 450 bar
  • Tested with wavelength: 1,310 nanometers (nm), 1,550 nm and 1,625 nm
  • Storage temperature: -40°C to +70°C
  • Operation temperature: -4°C to + 25°C
  • Single-mode and multi-mode
  • Oil-filled- and pressure compensated

The formation of hydrates is a well-known problem in subsea production systems for oil and gas. When the pipeline content (mix of oil and water) cools down, the temperature is approaching the ambient seawater temperature. This can cause flow assurance challenges such as flow line blockage or reduced capacity. The pipeline content should therefore be kept above the critical temperature - depending on water cut, salt content and pressure, the hydrates will form typically at temperatures below 25 degrees Celsius.


Traditionally, chemicals (methanol) have been used to remedy this problem. Alternatively, hydrates can be prevented using thermal insulation in combination with additional electric heating. In this approach, the single-phase electrical current is supplied to heat the pipe content above the hydrate formation temperature. The heating method is known as Direct Electric Heating (DEH) as the steel-built pipeline is heated by forcing single-phase current directly through the pipe steel. Qualified by Statoil in the mid-90s, there have been number of projects in the North Sea with more than 100 kilometers of pipelines heated by DEH.

Siemens offers DEH power supply systems to prevent hydrate formation during planned and unplanned process shutdown. Our systems will contribute to a consistent flow of hydrocarbons despite challenging fluid characteristics and temperature conditions at the seabed. The respective modules of the systems may contain power electronic components as well as control and protection units for the topside equipment and subsea pipeline to be installed on the platform deck.


The systems are designed to control, compensate and balance the single-phase electrical load that the gas pipeline and the piggyback cable constitute. Each of the systems is customized to the power requirements and electrical properties of the specified subsea load, in both “heat-up” and “maintain heat” mode. The systems are designed to be optimally tuned at any load condition to ensure an excellent power factor, low harmonic feedback, and to have low negative sequence current - important for minimal impact to the platform power grid.


The modules are assembled, and fully tested in Siemens’ Power Electronics Center in Trondheim, Norway, including full-load testing while simulating real-life conditions to verify the integrity and full functionality before shipment from the assembly location and installation on platform. This is key in order to ensure the reliability and availability required for this type of critical equipment.


Auxiliary systems for fiber-optic temperature monitoring of the piggyback cables are offered optionally, as well as solutions for remote connection to the modules’ control and protection system via a secure internet connection.

Operators face several challenges – the need to enhance recovery, follow strict regulations as well as comply with health, safety, security and environmental (HSSE) requirements. There is an ever-greater demand for control and surveillance of assets and the environment to ensure that subsea oil and gas operations are successful. With our extensive subsea monitoring experience, our topside process control as well as industrial IT and database systems, we can offer superb assistance in this area.


Large-scale subsea oil and gas processing requires sophisticated instrumentation that ensures failsafe communication with operational equipment. Our subsea control units allow you to add a wide variety of instruments to your fields that you can influence and adjust. They can be connected to cameras, sand detectors, multiphase meters, hydrocarbon leak detectors, pressure and temperature sensors, electrical actuators and directional control valves.


Siemens has successfully developed and tested a new cost-efficient product for better subsea Ethernet communication. The Advanced Converter & Switch (ACS) is making it possible to communicate at higher data rates and over longer lengths, then with the current electrical distribution technology. The ACS increases precision and effectiveness of subsea communication. This transparent communication solution can be used for connecting to existing subsea fields, for field extensions or for new developments. It is a simple and cost-effective solution for both brownfield and greenfield applications of subsea Ethernet.

Maintaining our subsea commitments


Subsea oil and gas recovery comes with many challenges. In order to adequately meet steadily growing customer demands, to optimize operational efficiency, extend field life and increase output, Siemens fully maintains its commitments with a variety of service support offers – at every phase of development.