Bbc Brown, Boveri & Company, Limited

Werner Faust

Peter Etter

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.

Combining thyristor circuits of various circuit configurations

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.

Method for producing rectifier with switches of asymmetric voltage

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.

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Wettingen, Switzerland

Werner Faust