Abstract:
An exemplary propulsion arrangement includes at least one propulsion unit situated at the stern of a ship having a hull with a horizontal water line (WL) and a center line (CL). The propulsion unit can include a hollow support structure attached to the hull, a chamber attached to the support structure, an electric motor within the chamber, a propeller at the front end of the chamber, and a pivotably supported rudder at the rear end of the chamber. The propulsion unit can be mounted so that the shaft line (SL) forms a vertical tilt angle (α) in a range of 1 to 8 degrees in relation to the water line (WL) so that the front end of the chamber is lower than the rear end of the chamber in relation to the water line (WL).
Abstract:
Exemplary embodiments are directed to a method and arrangement for detecting an overvoltage of a semiconductor switch. The arrangement including a first semiconductor switch and a driver unit controlling the switch. An overvoltage is detected over the semiconductor switch, and a voltage is adjusted at a supply voltage input of the driver unit on the basis of the overvoltage.
Abstract:
An arrangement for steering and supplying propulsion power to a contra rotating propeller(s) (CRP) propulsion system in a marine vessel is disclosed. The arrangement can include a first propeller, a second propeller driven by an AC motor, and an AC generator. The AC motor and AC generator can have the same electrical frequency. Another electrical power source can be electrically connectable to the AC motor in parallel to the AC generator. A shaft of the second propeller is mounted rotatable in a support structure which is attached to a hull of the marine vessel, and a rudder is supported in a manner allowing pivotal movement of the rudder relative to the support structure.
Abstract:
An arrangement is disclosed for supplying electric power to a propulsion system of a marine vessel having a propeller motor, which is connected to an AC generator. The AC generator supplies electric energy to the propeller motor. The AC generator is rotated by a rotating power unit. A frequency converter is electrically connectable in parallel to the AC generator and the frequency converter supplies electric power from a second power unit.
Abstract:
The disclosure relates to an electric apparatus including an electric device which, during use, generates heat, and a housing enclosing the electric device from the surrounding environment. In order to avoid problems caused by water, the electric apparatus including a receptacle for containing a desiccant. The receptacle has an opening allowing gas to flow between an interior of the receptacle and an interior of the housing in order for the desiccant to come into contact with moisture in the housing, and the receptacle is thermally connected to the electric device for transferring heat from the electric device to the desiccant for removing moisture from the desiccant.
Abstract:
A method and apparatus are disclosed for monitoring accumulation of dirt on an air filter of a ventilation system including the filter and a fan controlled by a frequency converter. An initial value for an operating parameter is determined. A present operating point is determined based on a characteristic curves, and the mechanical power and rotational speed of the fan. A present value for the operating parameter is determined based on the present operating point, and accumulation of dirt is determined on the air filter based on the initial and present values of the operating parameter.
Abstract:
A method and arrangement are provided for reducing the amount of condensed moisture inside an enclosure which encloses at least one piece of electrical equipment which is configured to receive electric power from outside the enclosure in a first electrical magnitude range (0 . . . maxinput) and to feed electric power to outside the enclosure in a second electrical magnitude range (minoutput . . . maxoutput). Electric power received on at least one portion (a, b, c) of the first electrical magnitude range (0 . . . maxinput) being outside the second electrical magnitude range (minoutput . . . maxoutput) is utilized for heating the condensed moisture for exhaustion thereof.
Abstract:
A filter for mitigating harmonics in an electrical distribution system. In one embodiment the filter has one winding that is connected to the power distribution system which may be a three phase system and capacitors are connected to other end of the winding in either a delta or y-connection. There is one tapping on the winding for connection to a load which may an adjustable speed drive. In another embodiment the filter has two or more separate reactors. In either embodiment a switch may be in series with the capacitors and capacitors may be connected in parallel with the series combination of switch and capacitors.