Sensors vital to wave power generator

Paul Boughton

Contrinex Series 700 inductive sensors, which are designed specifically for marine applications, are being used in wave power generators by Edinburgh-based company, Ocean Power Delivery (OPD).

Alternative forms of clean energy are vital in view of the decline in the finite reserves of gas and oil and therefore, in many countries, nature’s substitutes such as photo-voltaic, hydro-electric, tidal, wind and wave are being developed as a matter of priority.

Wave power is now set to rival wind turbines in the pursuit of ‘clean’ power generation and the European Community is the sponsor of OPD at the European Marine Energy Test Centre in Orkney. If successful, the trial site will be expanded and additional sites commissioned. OPD is also working with the Portuguese utility company, Grupo Enersis, on a full-scale wave power site situated off the Portuguese coast that will create sufficient power for a small town.

OPD has tapped into the marine and off-shore expertise in Scotland and has designed and built some of the most advanced and biggest wave energy converters ever constructed.

The principle of operation is that as waves pass over the hinged, multi-hulled installations they flex, displacing hydraulic fluid that is fed through turbines linked to power generators.

OPD selected the new Contrinex Series 700 range of marine-standard inductive sensors to monitor the fully automated mooring and disconnection system. The control of this underwater mooring mechanism in zero-visibility conditions is vital to the success of the operation and has to be totally reliable during docking, commissioning, in-service generation and removal for maintenance to avoid damage to the generator and the latching mechanism and to prevent the possibility of losing an extremely expensive generator.

Typical mooring sites present a highly aggressive environment so it essential that the sensors are both environmentally protected against ingress of salt water and physically robust to avoid collision damage during docking. The Contrinex S700 sensors are made from a single piece of V4A stainless steel, including the sensing face, and are impervious to seawater and salt spray and will not rust even in the most severe maritime environments. They can also withstand extreme impact, high shock levels and are resistant to virtually any chemical stress.

The use of new technology seals the sensors to 80 bar, providing IP69K protection and the ability to withstand water pressure to a depth of 800 metres making them suitable for both sub-surface and topside applications. Supplied in M12, M18 and M30 sizes, in embeddable and non-embeddable formats these sensors are also ideal for use on ROV grippers, ferry ramps, cranes and other equipment in all types of vessels, harbours, docks and oil rigs at highly competitive prices that are far lower than contemporary marine sensors capable of the same performance level.

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