The challenges of powering marine applications

March 02, 2017 // By Patrick Le Fèvre
We are all aware of self-driving cars and many other exciting projects that the automotive industry is engaged in, but far fewer of us have heard about unmanned ships and associated projects that will operate large fleets of vessels capable of navigating from port to port without operational crews.

Although in its early stages, the Maritime Unmanned Navigation Through Intelligence In Networks (MUNIN) project have investigated the feasibility of unmanned vessels and serves as a test-bed for future developments. The use of unmanned ships will require extreme reliability from the main generator through to the single point-of-load, and the challenges and demands placed on power designers will be far beyond anything experienced to date.


State of the art in marine power

Future generations of power supplies for unmanned ship are still under definition although it is important to understand the specificity of the marine segment that is quite unique in terms of its environmental needs and regulations. Due to the nature of the business, the requirements imposed on products and systems deployed in shipping and offshore installations are greater than what are currently required for land industrial and office environments. In addition, international regulations and standards applying to the marine industry are very complex, requiring an in-depth knowledge of the application and where it will be operated. Power designers must be knowledgeable about marine specific voltage distribution, combining DC and AC networks, safety regulations, and many other aspects such as ‘operational zones’ that can vary wildly from ship to ship and also with the nature of the merchandize being transported.

Rolls-Royce unmanned ship project
(source: Rolls-Royce).

The Zones

Generally, two zones are distinguished on a ship; the ‘bridge and the open deck zone’, and the ‘general power zone’, which basically refers to all other areas on the ship. One example of a specific requirement per zone is the electromagnetic emission and immunity. The open deck and bridge areas place extra demands on electromagnetic emission compatibility (EMC), as a lot of sensitive equipment is housed in those areas including communication, radar and navigation devices. These EMC requirements are well below the known EN55022 Level B and measurements begin at 10kHz instead of the usual 150kHz.

The limits regarding mechanical and climatic requirements are also higher than for the average industrial application. Vibration levels up to 4g are common, as well as large temperature fluctuations from -25 to +70ºC, together with high relative humidity conditions where condensation cannot be excluded.