Abstract: Current limiters, preferably PTC resistors, are used for limiting short-circuit current when connected in series to capacitors and converter valves. Protective devices operating with these PTC resistors are able to work reversibly and respond without arcing. They have a low inductance and can be used in space-saving designs. Protective circuits with such PTC resistors have a low loss, are shake-proof, and can be integrated into an existing cooling circuit. They respond autonomously and enable a flexible application. The PTC resistors preferably are constructed in a meander shape of porous metal foam or a metal braid or fabric and have electrical contact bridges between their resistor tracks. At least 2 resistor tracks that are electrically connected in parallel are arranged at a small distance on top of each other in such a way that partial currents (I1, I2) flow in opposite directions through resistor branches in superposed track areas formed in this manner.

Abstract: A method for fault correction in a power converter circuit arrangement. The power converter circuit arrangement has a plurality of switch modules which consist, for their part, of a parallel circuit of semiconductor chips. The semiconductor chips are interconnected via connecting wires, preferably bonding wires. If, because of a defect, a chip forms a short circuit, the connecting wires of chip are severed by specific current pulses. The advantage resides in that a short circuit of an individual chip does not put the entire circuit arrangement out of operation.

Abstract: Thyristors included in circuit configurations are, in turn, connected in series circuit fashion such that n circuit configurations are so interconnected, where n is a real integer equal to or greater than 2. The circuit configurations provide a combination of functions such as current limiting, voltage distribution, assumption of storage load, limitation of commutation voltage and limitation of search voltage. The combined circuit configurations provide the most practical arrangement of desired characteristics to meet the requirements for specific applications.

Abstract: Thyristors included in circuit configurations are, in turn, connected in series circuit fashion such that n circuit configurations are so interconnected, where n is a real integer equal to or greater than 2. The circuit configurations provide a combination of functions such as current limiting, voltage distribution, assumption of storage load, limitation of commutation voltage and limitation of search voltage. The combined circuit configurations provide the most practical arrangement of desired characteristics to meet the requirements for specific applications.

Abstract: A rectifier for a medium voltage rectifier system as well as for high voltage-direct current transmission includes a plurality of thyristor switches. The switches have asymmetric voltage breakdown strengths, the asymmetry being at least 10% for the forward blocking direction compared with the reverse blocking direction. The thyristor switches are dimensioned voltage-wise to safely block even long lasting overvoltages in both the forward and reverse blocking directions occurring during operation and to withstand momentary surge and switching voltages limited by an overvoltage suppressor in the reverse blocking direction.

Abstract: A rectifier switch has a plurality of series-connected thyristors, the forward and reverse blocking voltages of which exhibit a large spread of at least 10%. A plurality of voltage limiting elements are disposed to shunt the plurality of series-connected thyristors to match the distribution of maximum voltages occurring during operation of the plurality of series-connected thyristors to obtain full utilization of the blocking capability of the thyristors.