The 8.0 m FP propeller is driven at a nominal speed of 71 rpm through
double-reduction gears. Four cage induction motors, 4 000 kW / 3 300 V each, drive the
gears and are controlled by their own frequency converters. The propeller can be driven by
all motors in parallel or in any other combination. (Figure 1)
The economical calculation promised for this highly redundant machinery
concept is a US$ million lower cost than for the slow-speed version.
There is also always adequate power available for propulsion and
transverse thrusters even if one diesel fails. If more than one diesel is out of operation
there is still enough power for the main propeller and for all thrusters to keep the ship
under control.
Even if high reliability factors are always of major interest for ship
owners and operators, the innovative solutions and high redundancy are seldom realizes if
the cost is higher than for the conventional, well proven design.
Thus the ship's overall economy must be kept as a strict guideline in
all new designs, meaning that when the cost of one system is increased a corresponding
saving is to be shown in another place.
Track records for various modern electrical drive solutions are
excellent but the solution suffers from high first-cost of the electrical components.
Hence it is essential to find new concepts which can utilize all the features offered by
the electric power plant principle for ship design in order to keep the overall ship cost
low.
Progressive technology and automation have increased the electricity
requirement on board ship. For example MAN B and W Diesel supplies engines or complete
generating sets, thus ensuring reliable and economical power generation on board.
Selection of engines for marine propulsive and auxiliary sets:
four stroke engines with outputs in the 450 kW to 4 000 kW range, with
the appropriate synchronous speeds for 50 and 60 Hz. In the interest of maximum
efficiency, modern auxiliary engines are run on the same high-viscosity fuel grades as the
main engines. To keep the installation costs for fuel system on board to a minimum, the
Holeby works builds compact fuel systems. These systems are available in three standard
sizes for auxiliary engine outputs of up to 4 400 kW. For output above 4 400 kW the
"Uni-Fuel Unit" is matched exactly to the requirement profile.
The most extensive application the diesel-electric power installation
have found and will find in future for ice-breakers and passenger ships.
In the last decade working-out of direct transformation of heat into
current is carried on in the developed countries. Thermo-electric and
magnetic-hydrodynamic generators are the most interesting for possible application in ship
power installations (SPI). They,
