Abstract: A hybrid on-load tap changer, for use in high voltage alternating current power transmission, including a selector and a diverter having two legs defining respective current paths. Each leg includes a pair of opposed first and second semiconductor switches. The hybrid on-load tap changer also includes a controller configured to switch on one of the first or second semiconductor switches of a given leg at a predetermined point within the alternating current cycle so as to commutate off a desired semiconductor switch in the other leg.

Abstract: A hybrid on-load tap changer, for use in high voltage alternating current power transmission, including a selector and a diverter having two legs defining respective current paths. Each leg includes a pair of opposed first and second semiconductor switches. The hybrid on-load tap changer also includes a controller configured to switch on one of the first or second semiconductor switches of a given leg at a predetermined point within the alternating current cycle so as to commutate off a desired semiconductor switch in the other leg.

Abstract: An on-load transformer tap changing system, for example for a power transformer, wherein the secondary or primary of a transformer includes at least one first tap and one second tap. A main connection circuit is used for permanent connection of the first tap or the second tap to an output terminal of the secondary or primary of the transformer. Secondary connection circuits are each used to connect a tap temporarily and directly to the output terminal of the secondary or primary of the transformer. Each of the connection circuits includes one or more insulated gate bipolar transistors. The system can be controlled without zero current value transition detection in the secondary winding.

Abstract: The invention relates to an on-load transformer tap changing system wherein the secondary or primary of a transformer comprises at least one first and one second taps (p1, p2). A main connection circuit (tra-I2) is used for the permanent connection of the first tap (p1) or the second tap (p2) to an output terminal (b2) of the secondary or primary of the transformer. Secondary connection circuits (I1, I3) are each used to connect a tap (p1, p2) temporarily and directly to said output terminal (b2) of the secondary or primary of the transformer. Each of said connection circuits (I1, tra-I2, I3) comprises one or more insulated gate bipolar transistors and the system can be controlled without zero current value transition detection in the secondary winding. Application: Power transformers.

Abstract: A superconductor is placed inside a non-metallic cryostat filled with a cooling medium to maintain the superconductor in a superconductive state. A foil winding is connected in series with the superconductor by current leads and the cryostat is placed inside the winding. The winding has only a few turns in order to provide low inductance and low magnetic field when the superconductor is carrying its normal operating current. However in the event of a fault the increase in electrical current in the line winding causes a magnetic field to be generated parallel to the superconductor. The magnetic field generated exceeds the critical magnetic field of the superconductor. The magnetic field produced by the line winding triggers the superconductor to the resistive state.

Abstract: A superconductor is placed inside a non-metallic cryostat filled with a cooling medium to maintain the superconductor in a superconductive state. A foil winding is connected in series with the superconductor by current leads and the cryostat is placed inside the winding. The winding has only a few turns in order to provide low inductance and low magnetic field when the superconductor is carrying its normal operating current. However in the event of a fault the increase in electrical current in the line winding causes a magnetic field to be generated parallel to the superconductor. The magnetic field generated exceeds the critical magnetic field of the superconductor. The magnetic field produced by the line winding triggers the superconductor to the resistive state.