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New edge to competition in marine electrics

Marine Power & Propulsion: October 2015

No less significant than the earlier transfer of its two-stroke engine business to a joint venture in which China State Shipbuilding Corporation (CSSC) has the majority stake, Wärtsilä has considerably strengthened its capabilities in the marine electrical and electronics sector through the takeover of L-3 Marine Systems International (MSI).

The acquisition of MSI from New York Stock Exchange-listed L-3 Communications Holdings was finalised at the outset of June this year, and is expected to transform Wärtsilä from a niche player to a leading brand in the field of automation, electronics and electric propulsion. It will also substantially extend Wärtsilä’s reach in delivering newbuild equipment and machinery ‘packages’.

The immediate strategic action has been to integrate MSI into Wärtsilä’s Electrical & Automation (E&A) business, which is under the auspices of the Marine Solutions division. Hamburg-headquartered L-3 MSI embraced automation and simulation, navigation and communication, safety, security, monitoring and control systems, power generation, conversion and distribution, electric propulsion drive systems, and dynamic positioning technology. Its portfolio spanned a range of product brands, including SAM Electronics, Valmarine and Lyngso Marine.

Before the MSI takeover, Wärtsilä’s E&A activities centred on low voltage, variable speed drives, medium and low voltage modular switchboards, propulsion control automation, alarm and monitoring systems, integrated automation and power management systems for diesel-electric applications, and the Wärtsilä 3C bridge.

"The combined MSI-Wärtsilä offering will be unmatched," claims the Finnish group. The MSI acquisition has given critical mass to Wärtsilä’s E&A business and increased scope for leveraging product sales, opening up new opportunities in the cruise, ferry and merchant vessel segments.

The SAM Electronics’ brand alone has a major standing in the electric propulsion market, reinforced this year by further prestigious applications in the cruise ship segment, as with the diesel-electric installation in P&O Cruises’ 144,000gt Britannia. Carrying on the technology and industry traditions of its predecessor AEG Marine, SAM Electronics had delivered nearly 100 converter-fed propulsion drives by the time of Wärtsilä’s MSI takeover.

The acquisition acknowledges the growing importance of E&A know-how and product supply capabilities against the backcloth of the increasing technological complexity of ships, and its relevance to meeting the client market’s requirements and expectations as to enhanced operational efficiency.

Besides its ongoing R&D commitments, earlier investments by Wärtsilä in the E&A category included the 2014 inauguration of a dedicated test centre in Stord, Norway. The facility ranks as one of the largest in Europe devoted specifically to testing electrical and automation systems for marine and offshore applications.

Meanwhile, ABB has consolidated its pre-eminent position in podded electric propulsion by augmenting its Azipod line of thrusters with the Azipod D system. This further advance in Azipod technology is claimed to require up to 25% less installed power, due partly to new, hybrid cooling arrangements that raise the performance of the integral electric motor by as much as 45%. The hybrid system uses a combination of direct sea water cooling and internal cooling.

The D-series of thrusters embraces open propeller and ducted versions, and permanent magnet synchronous or asynchronous electric motors, and covers the 1.6MW-7MW power band.

Gearless construction confers simplicity, obviates wearing components such as bevel gears and minimises the number of critical components in the shape of bearings and seals. The Azipod D design has only three main bearings and three seals, and the simplicity of the configuration is said to enhance internal efficiency by around 3-6% relative to mechanical thrusters.

Through the absence of gears, in conjunction with high motor efficiency and advanced hydrodynamic design, it is contended that the new podded propulsor promises 10-15% lower fuel consumption compared to geared thrusters.

Maintenance and service access have been central considerations in the design of the D-type. All preventative maintenance can be undertaken in drydock, seals and shaftline bearings can be changed within 48 hours, while underwater mountable types can be swapped in just 24 hours, according to ABB. Due to the robustness of the design and the minimised number of wearing components, the overhaul interval for the thruster can be up to 10 years, depending on the specific application.

Azipod D’s introduction underscores ABB’s belief that demand for electric propulsion solutions will grow in line with the industry’s need for more fuel-efficient vessels and environmentally-compatible solutions. It draws support for its view from findings by the consultancy firm Clarkson Research that the number of vessels with electric propulsion has been increasing at an average 12% per annum over the past decade, three times faster than the world fleet.

A further new initiative in response to this outlook is the group’s development of a low voltage, variable speed drive for demanding applications such as offshore service vessels. The NektonDrive is liquid cooled, and has been designed as a compact and robust solution serving the 710-5,700kW power range at 690V alternating current (AC).

The liquid cooling arrangements minimise or dispense with the need for air conditioning in the installation area, with approximately 98% of the power electronic losses transported out of the drive cabinet to the vessel’s central cooling system. The ‘dust proof’ cabinet design includes a separate cabling entry in its lower part, and the vibration dampers are accessible from outside the cabinet.

Another of the major players in the sector, GE Marine, has been selected to lead the Italian consortium that will provide the power for two new cruise liners to be delivered by Fincantieri in 2017 and 2018 to MSC Crociere. All 12 existing ships in the MSC fleet incorporate GE electrical propulsion.

The newbuild vessels will embody MSC’s ‘Seaside’ platform design concept. The scope of GE’s supply will include propulsion motors, variable frequency drive core components, transformers and propulsion control. The company’s technology eliminates the need for harmonic filters and reactive power compensation, offering high standards of safety and reliability. The GE solution for the latest ships will also use a less complicated installation and cabling process.

The Finnish company WE Tech Solutions has developed a direct-drive permanent magnet (PM) shaft generator solution for two-stroke propulsion installations. This combines WE Tech’s variable-frequency drive with the PM generator technology of another Finnish company, The Switch.

The generator housing, consisting of a compact, feet-mounted stator package, including the rotor and intermediate shaft, is positioned on the propeller shaft line and connected via flanges. The direct-drive marine shaft generator is certified by Lloyd’s Register and is claimed to be the first of its kind, allowing ships to gain greater efficiency over the entire speed range.

With the Permanent Magnet Shaft Generator (PMSG) in power take-off (PTO) mode, electrical current is fed to the WE variable-frequency drive (WE Drive) unit and direct-current DC-Link switchboard, providing power for the ship’s electrical network, including heavy consumers such as thrusters. This means that the ship’s auxiliary generators need not be used when the ship is under way. The WE Drive and DC-Link can be fed not only from the shaft generator but also from the auxiliary gensets, providing a high level of functionality and system flexibility.

By means of the addition of a mechanical clutch in the propeller shaft line, the two-stroke main engine can be disconnected, and a power take-in (PTI) mode can be achieved, drawing power for propulsion from the auxiliary generators through the main switchboard and WE Drive unit.

PMSG solutions have been specified for Wallenius Lines’ new generation of 8,000CEU ro-ro/vehicle carriers from Tianjin Xingang Shipyard, and for other newbuilds including Danish product carriers and a series of Norwegian bulkers. Earlier this year, systems were specified for 15,000dwt asphalt carriers ordered at Besiktas Shipyard in Turkey by the Canadian operator Transport Desgagnés.

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