Abstract: An electric switching device for alternating current comprises two branches (2, 3) connected in parallel in a current path and having each at least two contact members (4–7) connected in series. A semiconductor device (8) is adapted to interconnect the midpoints between the two contact members of each branch. When opening the current path a first contact member (5) of one, first branch located before said midpoint as seen in the current direction existing is controlled to open and a second contact member (6) of the second branch located after the midpoint as seen in the current direction is controlled to open for transferring the current to a temporary current path through the semiconductor device. The current path through the switching device is then broken when the semiconductor device is in a blocking state by opening a contact member (4, 7) of the switching device arranged in the temporary current path.

Abstract: An electrical apparatus for limiting the peak voltage across a recttifying member (23) of a current valve arranged in a circuit having a substantial inductance (24) and having at least one controllable semiconductor device (22) and at least one said rectifying member (23) connected in anti-parallel therewith when the rectifying member is turning off, comprises means (28, 29) adapted to control the semiconductor device so as to increase the conductivity thereof during turning off of the rectifying member.

Abstract: An electric switching device for fast closing of a high current in a power network comprising a first electrode (1), a second electrode (2), a movable contact element (3) closing said first and second electrodes, and an operating device. The operating device comprises a helically wound first coil (6) secured to the first electrode. The movable contact element comprises a flange (4) making contact with the coil. A current pulse flowing through the coil forms a repulsive force between the coil and the flange, said repulsive force throwing the movable contact element to the second electrode and completing the closing operation.