Abstract:
A contact arrangement of an electric switch, comprising a movable contact (130) and a stationary contact (112) to be contacted with the movable contact (130), the arrangement comprising one or more quenching plates for quenching an arc firing when the movable contact (130) and the stationary contact (112) are separated from each other. The first quenching plate (142) that is closest to the stationary contact (112), is in contact with the stationary contact (112).
Abstract:
An electric switch, comprising a movable contact (108, 110, 112) and a stationary contact (104, 106) for being contacted by the movable contact (108, 110, 112), the switch further comprising one or more quenching plates (122), and a permanent magnet (132) for directing an arc, that is formed when the contacts are separated from each other, to the quenching plate (122). The quenching plate (122) has a base portion (464) and side portions (468, 470) extending away from the base portion (464), and the permanent magnet (132) is arranged such that the arc is directed towards one of the side portions (468, 470) of the quenching plate (122).
Abstract:
The ship comprises a hull (200), at least one propulsion unit (100) comprising a propulsion engine (30), transmission means (40), at least one propeller (50) connected via the transmission means (40) to the propulsion engine (30), and a oscillation sensor (300) situated in the vicinity of the at least one propeller (50) in order to sense cavitation of the at least one propeller (50). The arrangement comprises further a control unit (400) for controlling the propulsion engine (30), said oscillation sensor (300) being connected to the control unit (400), whereby the output signal of the oscillation sensor (300) is analyzed in the control unit (400) in order to detect whether a worse degree cavitation is emerging, and indicate that a worse degree cavitation is emerging on a display unit at the navigation bridge and/or regulate the rotation speed and/or the power of the propulsion engine (30) when worse degree cavitation is emerging.
Abstract:
An apparatus, and a method using the apparatus, for filtering common mode and differential mode currents, wherein the apparatus comprises a first magnetic core element made of a first magnetic material, a second magnetic core element made of a second magnetic material, wherein permeability characteristics of the second magnetic material differ from permeability characteristics of the first magnetic material, and at least one winding, wherein each winding is arranged to magnetize the first and the second magnetic core.
Abstract:
The invention relates to an electronic apparatus. In order to provide an electronic apparatus with a more reliable structure, the apparatus comprises an extruded metallic frame (1) with walls (2, 3, 4, 5) which are integrated parts of the extruded metallic frame (1), at least one extruded flow channel in at least one of the walls (2, 3, 4, 5) for passing a cooling fluid within the respective wall, an inlet arranged outside the electronic apparatus and an outlet arranged outside the electronic apparatus for providing a flow path via the at least one extruded flow channel, and detachable covers which are attached to the walls (2, 3, 4, 5) for sealing off at least one electric component space from an outside of the electronic apparatus.
Abstract:
The invention relates to an apparatus comprising a gas permeable wall (1) preventing dirt present in a gas flow from passing through said gas permeable wall (1) with the gas flow. In order to minimize the need for maintenance, the gas permeable wall (1) is a circumferential wall of a cover (2), and the apparatus comprises an outlet (4) from the cover (2) for passing on gas having entered the cover (2) through the circumferential gas permeable wall (1), a support (5, 6) for attaching the cover (2) rotatably to a device (8), and a drive unit (7) for rotating the cover (2).
Abstract:
A method for detecting the correct rotational direction of a centrifugal apparatus, the method comprising a step of detecting the correct rotational direction of the centrifugal apparatus based on an acceleration test and/or a deceleration test. The step of detecting the correct rotational direction of the centrifugal apparatus includes comparing the acceleration time (t 1 , acc ) for the first direction with the acceleration time (t 2 , acc ) for the second direction, whereby shorter acceleration time is interpreted as indication of the correct rotational direction; and/or comparing the deceleration time (t 1,dec ) of the first direction with the deceleration time (t 2,dec ) of the second direction, whereby longer deceleration time is interpreted as indication of the correct rotational direction.
Abstract:
A method and arrangement for controlling a doubly-fed induction machine by a frequency converter comprising a rotor side converter (INU) connected to a rotor circuit of a doubly-fed induction machine (DFIG) and having a control system with rotor flux as a feedback variable, a grid side converter (ISU) connected to an AC power network, and a direct voltage intermediate circuit (DC) connected between the rotor side converter (INU) and the grid side converter (ISU). The method comprises forming a rotor flux reference (ψ r,reƒ ), forming a damping signal ( ψ reƒ,D ), summing the damping signal and the rotor flux reference for obtaining a modified rotor flux reference (ψ reƒ ), and feeding the modified rotor flux reference to a controller of the rotor side converter (INU) for damping sub-synchronous resonances.
Abstract:
A method of estimating a rotor angle of a synchronous reluctance motor, where the motor comprises a stator and a rotor. First, a stator flux and a stator current are determined. Two orthogonal stator flux components in a stator reference frame are calculated from the stator flux. Two orthogonal stator current components in the stator reference frame are calculated from the stator current. Two rotor orientation vectors are then calculated using a known rotor direct and quadrature axis inductance components, the stator flux components, and the stator current components. A rotor angle is estimated on the basis of the rotor orientation vectors.