Abstract: A pitch drive circuit that operates in an emergency mode, for a wind or water power plant. The circuit has at least one rectifier unit, at least one DC intermediate circuit, two inverter units and a pitch rotary current motor with motor trains that can be contacted on both sides. A first contact side of the motor trains is connected to a first inverter unit and a second contact side of the motor trains is connected to a second inverter unit. At least one switching element is connected to at least one contact side of the motor trains. In a normal operating mode of a first switching state of the switching element the motor trains can be energized via both inverter units, and in an emergency operating mode of a second switching state of the switching element, the motor trains can be energized via a single inverter unit.

Abstract: The invention relates to a network feed device (10) for feeding electrical energy from a DC energy source (12) into a three-phase AC supply network (32), where the DC voltage of a DC intermediate circuit (24) is converted by means of at least one inverter unit (14) into a three-phase voltage and is fed by means of a transformer device (16) comprising three network transformer windings (38) into the AC supply network (24). The invention is characterized in that a first winding terminal of the network transformer windings (38) is connected to a half-bridge (30) of a first inverter device (14a), and a second winding terminal of the network transformer windings (38) of the transformer device (16) is connected to a half-bridge of a second inverter device (14b).

Abstract: The invention relates to a pitch drive circuit (50, 52, 54), which can operate in emergency mode, for a wind or water power plant (80), said circuit comprising at least one rectifier unit (14), at least one DC intermediate circuit (18), two inverter units (16-1, 16-2) and a pitch rotary current motor (38) with motor trains (30) which can be contacted on both sides. A first contact side (76-1) of the motor trains (30) is connected to a first inverter unit (16-1) and a second contact side (76-2) of the motor trains (30) is connected to a second inverter unit (16-2). At least one switching element (40) is connected to at least one contact side (76) of the motor trains (30).

Abstract: An activation circuit and a method for operating an activation circuit for a DC motor having an electrically actuated stopping brake, in particular for adjusting a rotor blade of a wind or water power facility. The activation circuit includes an emergency operation supply unit and a three-phase bridge inverter. The emergency operation supply unit is connected so it is disconnectable via an emergency operation network switching element to the intermediate circuit of the three-phase bridge inverter, the DC motor is connected via an emergency operation motor changeover element either to the three-phase bridge inverter or to the emergency operation supply unit, and the stopping brake is connected via an emergency operation brake changeover element either to the three-phase bridge inverter or to the emergency operation supply unit.

Abstract: The present invention relates to an activation circuit and a method for operating such an activation circuit for a DC motor (04) having electrically actuated stopping brake (07), in particular for adjusting a rotor blade of a wind or water power facility. The activation circuit comprises an emergency operation supply unit (03) and a three-phase bridge inverter (01). The emergency operation supply unit (03) is connected so it is disconnectable via an emergency operation network switching element (12) to the intermediate circuit (16, 17) of the three-phase bridge inverter (01), the DC motor (04) is connected via an emergency operation motor changeover element (13) either to the three-phase bridge inverter (01) or to the emergency operation supply unit (03), and the stopping brake (07) is connected via an emergency operation brake changeover element (14) either to the three-phase bridge inverter (01) or to the emergency operation supply unit (03).

Abstract: A method and device for measuring electric currents in n conductors (n≧2), the measurement of the currents being carried out with (n−1) magnetoresistive sensors. Reliable excess current and/or fault current protection is obtained.