Inductive type firing arrangement for series connected thyristors in a high voltage rectifier

Claim 1

A high-voltage converter comprising a string of thyristors connected in series and having one end of said thyristor string grounded, protective capacitors connected respectively in parallel with the thyristors, and a control column for effecting inductive ignition of said thyristors, said control column comprising a rectilinear primary conductor which is grounded at one end and which is surrounded by an assembly of mutually insulated radially spaced cylindrical condenser plates, a plurality of cores surrounding and located along said control column, and secondary windings on said cores which are connected respectively to the ignition control electrodes on said thyristors, said cylindrical condenser plates being of progressively decreasing length and progressively increasing diameter as viewed in the direction radially outward from said primary conductor and said cores being spaced from each other along said control column such that the core whose secondary winding is connected to the thyristor nearest the grounded end of said thyristor string surrounds only the innermost and longest of said cylindrical condenser plates and the remainder of said cores respectiveLy surround a progressively increasing number of condenser plates, said outermost condenser plate surrounding all of said condenser plates, and an electrical connection between said outermost condenser plate and the thyristor at the high voltage end thereof whereby to produce a voltage distribution over the string of series-connected thyristors as established by said protective capacitors and by building capacities to ground which is substantially equal to the voltage distribution between the homologous condenser plates of said control column.