Gas-insulated high-voltage semiconductor valve means

A gas insulated semiconductor valve means for high voltage and for high power, comprising a valve stack with a plurality of semiconductor elements electrically series-connected between a first and a second electrical main connection, and an enclosure, surrounding the valve stack, with an elongated bushing arranged in the wall of the enclosure, the valve stack having a longitudinal axis (A-A) and connections arranged at the opposite ends thereof, a first connection at low potential relative to the enclosure and a second connection connected to the bushing, the valve means having a first set of shields, said set having a plurality of annular electrostatic shields distributed along the longitudinal axis of the valve stack arranged in a plane substantially perpendicular to the longitudinal axis, and surrounding the valve stack, each shield with curved paths, so as to be of annular shape, whereby the curved parts of each shield have a substantially constant radius of curvature whereby the shields in the first set of shields are electrically connected to a first potential-controlling member to control the potentials of the shields so that the voltages between the shields and the surroundings of the shields successively diminish along the valve stack in a direction away from the second connection towards the first connection, and wherein the semiconductor valve means has a second set of shields, said second set of shields having a plurality of electrostatic shields, distributed along the bushing between the second connection and the enclosure, and surround the bushing.