Abstract: A method for operating an electrical circuit is described herein. The circuit includes a power converter having a plurality of switches and two capacitors that are parallel to the switches. The plurality of switches and the two capacitors are connected in series. The power converter has two AC voltage-sided connections and a measuring resistor is connected to the ground. A ground fault is detected by measuring a voltage drop in a measuring resistor.

Abstract: An electrical frequency converter for coupling an electrical power supply grid with an electrical drive includes a first power converter connected to the power supply grid. The first power converter includes at least two connections in series. A second power converter is connected to the electrical drive and includes at least two connections in series. Each of the connections in series of the first and second power converters includes at least two modular switches. Each modular switch includes a first connection in series having a first controllable power semiconductor component and a first diode. The modular switch further includes a second connection in series having a second controllable power semiconductor component and a second diode. The modular switch further includes a capacitor. The first connection in series, the second connection in series and the capacitor are connected in parallel.

Abstract: A method for operating an electrical circuit is described herein. The circuit includes a power converter having a plurality of switches and two capacitors that are parallel to the switches. The plurality of switches and the two capacitors are connected in series. The power converter has two AC voltage-sided connections and a measuring resistor is connected to the ground. A ground fault is detected by measuring a voltage drop in a measuring resistor.

Abstract: Electrical frequency converter (20) for coupling an electrical power supply grid (21) with an electrical drive (22) is described. One rectifier (23) and one inverter (24) are provided, in which case the rectifier (23) is connected to the power supply grid (21) and the inverter (24) to the drive (22). The rectifier (23) and the inverter (24) have in each case at least two connections in series (25), and every one of the connections in series (25) has at least two modular switches (10).

Abstract: A fluidized bed reactor for the pyrolysis of pieces of rubber or the like, especially old tires the reactor comprising a container at the lower part of which there is discharge device for non-volatile pyrolysis products; gas blowing nozzles arranged in a zone above the discharge device for supplying a fluidizing gas and for producing a fluidized bed from material such as sand or alumina added to the reactor; preferably a heating device, especially one comprising heating tubes extending across the container; a gas outlet disposed in the zone above the fluidized bed; and supply means for conveying pieces of material to be pyrolized to the container; this apparatus is characterized by the fact that the gas blowing nozzles are arranged to direct the gas downwardly, that at least one group of nozzles are arranged in a common horizontal plane, and that the material supply device is such that its dimensions are comparable with the cross-sectional surface of the fluidized bed.