The MV Viking Legend. Click to enlarge.

AC drives are also known by various other names: adjustable speed drives (ASD), adjustable frequency drives (AFD), variable frequency drives (VFD), variable speed drives (VSD), or frequency converters (FC).

The MV Viking Legend is the first river cruise vessel equipped with an integrated propulsion and network system, based solely on inverter-driven asynchronous generators and propulsion motors. The system uses Vacon’s variable-speed AC drives, and asynchronous generators and motors by AEM in Germany.

The diesel-electric propulsion system of the vessel makes the maneuverability of the 135-meter-vessel easy on narrow rivers. It is estimated that the vessel achieves a 20% boost in fuel efficiency in comparison to other river cruising vessels in the region. The ship also provides a quieter ride for guests by using four smaller propellers instead of two large propellers.

At its overall length of 135 m, a width of 11.4 m, the Viking Legend accommodates 189 passengers and 50 crew members. The vessel started its maiden voyage from Amsterdam, the Netherlands, on 5 July 2009.

The integrated diesel-electric network and propulsion system was developed and delivered by German-based e-powered marine solutions GmbH & Co. KG (e-ms).

The main propulsion system consists of four electrically-driven Schottel rudder propellers. The required electrical power for the propulsion system and ship’s network is provided by three diesel generator-sets. These are dimensioned in a way (2 x 1000 kW, 1 x 560 kW) that sufficient power for the network and propulsion drives of the MV Viking Legend will mostly be provided by two diesel generator-sets only. However, reliable operation of the vessel with only one diesel generator-set is also possible.