Abstract: A method and an arrangement are provided in connection with a photovoltaic power generator composed of series-connected photovoltaic modules. The method includes determining a maximum power point voltage (UMPP) and a maximum power point current (IMPP). The method also includes determining the ambient temperature (Tamb), calculating an estimated maximum power point voltage (Uest) by using maximum power point current (IMPP) and the determined ambient temperature (Tamb), comparing the estimated maximum power point voltage with the determined maximum power point (UMPP), and determining on the basis of the comparison whether the generator is operating under uniform conditions or in conditions with two maximum power points.

Abstract: A gate drive circuit creates a bipolar voltage to a gate of an IGB power transistor, and compensates for Miller currents of the IGB power transistor. The compensating is performed by a switching element connected in series with a capacitor between the gate (X4) and a supply voltage.

Abstract: Method and apparatus of splicing a paper web, in which a paper web from a new reel is spliced to a paper web from an emptying reel and a position of glue or two sided tape in the surface of the new paper reel is marked. The method includes receiving a command for splicing, determining the splicing time instant, accelerating a rotation of the new paper reel, detecting the glue or tape, controlling, based on the detected glue or tape, the rotation of the new paper reel in such a manner that the rotation speed of the new paper reel and the position of the glue or tape are as required at the splicing time instant, and splicing the paper web at the splicing time instant.

Abstract: A method and an arrangement are disclosed for detecting islanding operation of a distributed power generator. The method can include determining a frequency of a grid to which the distributed power generator is connected, measuring a rate of change of the frequency of the grid at an output of the distributed power generator, determining a threshold value for an alteration speed, comparing the rate of change of the frequency of the grid with the threshold value, and detecting islanding operation when the measured rate of change of the frequency exceeds the threshold value for a certain time period.

Abstract: A stationary contact for a rotary switch is provided. The stationary contact includes a connection portion for connecting to a conductor and a first portion being a contact portion for connecting the stationary contact to a rotary contact. The stationary contact also includes a second portion being a support portion for supporting the stationary contact to a switch body. The contact portion and support portion extend in the same angle from the connection portion. A method of mounting a rotary switch is also provided.

Abstract: A rotary switch housing (100), comprising a bottom wall (102) for mounting of the switch housing (100) to a mounting base, and side walls (104, 106) extending from the bottom wall (102), the switch housing further comprising an arc chamber (120) for extinguishing an electric arc, and a gas exhaust channel (130) for exhausting gas developed in the arc chamber (120) out of the housing (100). The gas exhaust channel (130) comprises a guiding portion (130A), which is substantially parallel to a side wall (106) of the housing (100) for leading the gases to a direction away from the bottom wall (102) of the housing (100).

Abstract: A rotation mechanism for a rotary switch and a method of operating a rotary switch are provided. The rotation mechanism includes a mechanism shaft for switching the switch between open and closed positions of the switch, a crank rotationally connected to the mechanism shaft, a spring connected to the crank, where the spring has a dead point between the open and closed positions of the switch, and a force transmission roll rotationally connected to the crank. The mechanism shaft, crank and force transmission roll have a common axis of rotation. There is a predetermined rotational free-play between the rotation of the mechanism shaft and the crank, and a predetermined rotational free-play between the rotation of the crank and the force transmission roll.

Abstract: An electric switch includes a movable contact, a stationary contact to be contacted by the movable contact, one or more quenching plates, and a permanent magnet for directing an arc, which is formed when the contacts are separated from each other, to the quenching plate. The quenching plate has a base portion and side portions extending away from the base portion. The permanent magnet is arranged such that the arc is directed towards one of the side portions of the quenching plate.

Abstract: A roll for rotating a movable contact of a rotary switch, and a method of mounting a switch are provided. The roll includes a first slot going along the diameter of the roll and open from the top of the roll for receiving the movable contact for contacting with a stationary contact of the rotary switch, and a second slot arranged perpendicular to the first slot for receiving teeth of an upper roll to be mounted together with the roll.

Abstract: An arc quenching plate for an electric switch includes a first mounting portion and a second mounting portion for mounting the quenching plate to respective recesses of the switch. The first mounting portion and the second mounting portion have a different form when compared to each other.

Abstract: A converter circuit with short-circuit protection can include a plurality of phase legs having a series connection of normally-on switches, between voltage rails of a DC voltage link, a DC link capacitor, and AC voltage connection points between the normally-on switches. A phase-to-phase short-circuit protection circuit includes a parallel connection of a resistive component and a controllable switch. The phase-to-phase short-circuit protection circuit including a first terminal connected to an AC voltage connection point and a second terminal forms an input or an output of the converter circuit; and a controllable switch is connected in series with the DC link capacitor. Upon lack of control of the normally-on switches the controllable switch of the at least one phase-to-phase short-circuit protection circuit and the controllable switch of the phase leg short-circuit protection circuit are adapted to be controlled to a non-conductive state.

Abstract: Exemplary embodiments of the present disclosure are directed to an apparatus including pipes having internal longitudinal walls dividing the pipes into channels, a first and a second connecting part for providing a flow path between the channels of the pipes, a first heat transfer element having a first base plate with a first surface for receiving a heat load from one or more electric components and for transferring the heat load to a fluid, and a second heat transfer element. In order to obtain an efficient apparatus at least one first pipe that is at a location of an electric component is at least partly embedded in the first base plate via a second surface of the first base plate, while the pipes which are not at the location of an electric component are not embedded in the first base plate.

Abstract: A method and apparatus for optimizing energy efficiency of a pumping system includes at least one pump that controls a fluid level in a reservoir. The method includes a system identification stage and an energy efficiency optimization stage. The system identification stage includes determining pump characteristics for the pump, operating the pump with a range of flow rate conditions, determining a set of data points, and calculating energy efficiency optimization characteristics. The energy efficiency optimization stage includes determining a present static head value, choosing a value for a pump control parameter, and operating the pump on the pump control parameter.