An on-load tap-changer of a tap-changing transformer has a switch. The switch has: a take-off contact; a primary fixed contact; and a contact unit. The contact unit has a moving contact, a first arcing contact and a second arcing contact. These contacts are pivotable about a pivot axis during a switchover process such that the contacts assume a first position, in which they make contact with the take-off contact and the primary fixed contact, and a second position, in which they are separated from the take-off contact and the primary fixed contact. The second arcing contact assumes the first position before the first arcing contact when switching over from the second position to the first position and leaves the first position after the first arcing contact when switching over from the first position to the second position.

An on-load tap-changer for dry transformers, having an electric insulating hollow casing extending around a virtual axis, wherein several electric contact sections are foreseen along a path on the inner surface of the hollow casing, which are electrically joined through the wall of the hollow casing and a selector contact in the inner of the cylinder which is moveable along the path and that's outer end is selectively connectable with one of the contact sections by a respective movement. Respective cables are foreseen to electrically connect the contact sections from the radial outer side of the hollow casing, wherein at least some of the cables have a respective surrounding outer insulation at least at their respective connected end.

The disclosure relates to a tap changer arranged to be connected to a regulating winding of a rated regulation voltage. The tap changer comprises a diverter switch, a tap selector and a set of tap changer contacts. The tap selector and the diverter switch are encapsulated in a shielding structure arranged to shield the tap selector and the diverter switch from an external electrical field, the shielding structure being arranged to be electrically connected to a connected tap of the regulating winding.

The disclosure further relates to transformer arrangement comprising at least one such tap changer.

An on-load tap changing apparatus includes a first switching unit connected to a first tap of a transformer provided in a power system and switching power supplied from the first tap, a first impedance changing unit connected in series with the first switching unit and increasing an impedance when the first switching unit executes a switching operation, a second switching unit connected to a second tap of the transformer and switching power supplied from the second tap, and a second impedance changing unit connected in series with the second switching unit and increasing an impedance when the second switching unit executes a switching operation. The on-load tap changing apparatus can suppress an arc at the time of switching, reduce deterioration of a switching unit, and have excellent durability.

A load selector has a load changeover switch insert with a switching tube rotatable about an axis, at least one switching segment fastened to the switching tube, and at least two vacuum interrupters in the at least one switching segment. Each vacuum interrupter has a switching tube having a respective axially movable contact that cooperates at its free end with an actuating lever. The vacuum interrupters are so arranged in alternation in opposite sense that the movable contacts of the at least two vacuum interrupters are movable with respect to the axis alternately in opposite directions.

An on-load tap-changer of a tap-changing transformer has a switch. The switch has: a take-off contact; a primary fixed contact; and a contact unit. The contact unit has a moving contact, a first arcing contact and a second arcing contact. These contacts are pivotable about a pivot axis during a switchover process such that the contacts assume a first position, in which they make contact with the take-off contact and the primary fixed contact, and a second position, in which they are separated from the take-off contact and the primary fixed contact. The second arcing contact assumes the first position before the first arcing contact when switching over from the second position to the first position and leaves the first position after the first arcing contact when switching over from the first position to the second position.

A load selector for tapped transformers has an oil tank and a preselector having a first preselector contact and a second preselector contact for each phase to be switched by the load selector. The first preselector contact and the second preselector contact are mounted on a wall of the oil tank and extending through the wall of the oil tank. A first zero contact and a second zero contact separate from the first zero contact are provided for each phase to be switched by the preselector. The first zero contact and the second zero contact are each mounted on the wall of the oil tank and extend through the wall of the oil tank.

An on-load tap changer has a load changeover switch insert having a switching tube rotatable about an axis, at least one switching module associated with the switching insert and having at least one switching segment fastened to the switching tube, an oil tank, and a resistor subassembly having a plurality of separate and identical resistors. An actuating arrangement associated with the switching module at an inner wall of the oil tank has a plurality of identical actuators associated with the switching module at the inner wall of the oil tank. The on-load tap changer is a load selector or a load changeover switch depending on the arrangement of the at least one identical switching segment, the resistor subassembly, and the mounting of the plurality of identical actuators at the inner wall of the oil tank.