Abstract: A method for the manufacture of a support construction for the coil ends in an electrical machine. According to the method, hollow objects substantially filled with a powdery filler agent and provided with porous walls are placed into the winding before its impregnation. The air spaces in said hollow objects are substantially filled in connection with the impregnation such that said objects, after hardening of the impregnation agent, constitute strong and rigid cast-plastics components.

Abstract: A contact device for an electric switch comprising at least two interconnectable contacts and at least two contact knives movable relative thereto and adapted, in the closed position of the switch, to clamp between themselves at least one of the contacts. The contact knives are enclosed in pairs by iron elements or similar which, when a short-circuit current passes through the contact knives, act as a magnets increasing the contact force.

Abstract: A shell-core current transformer comprising a tubular main insulator, a measuring core arranged at least substantially coaxially with the main insulator and comprising a primary winding and a secondary winding, and a protecting core, likewise arranged at least substantially coaxially with the main insulator and comprising a primary winding and a secondary winding. The measuring core and the protecting core have a common primary winding, arranged outside the main insulator, and a common outer core part functioning as magnetic return circuit. The inner part of the measuring core, with the exception of the inner yoke portions, and the secondary winding of the measuring core are within the main insulator placed inside the inner part of the protecting core and inside the secondary winding of the protecting core, and the measuring core and the protecting core have common inner yoke portions.

Abstract: A current transformer comprising a tubular main insulator, a number of first windings arranged around the main insulator, and a number of second windings arranged inside the main insulator. The second windings are arranged opposite their corresponding first windings so that the pairs of windings formed in this way are, in the direction of the axis of the main insulator, at a distance from each other. The primary windings are connected in series. A magnetic circuit related to each pair of windings consists of a first core portion that surrounds each first winding from the outside and has yoke portions, and of a second core portion covering each second winding and the main insulator from the inside and has likewise yoke portions. The subsequent cores, or core portions, have common intermediate yoke portions and the primary windings are arranged so as to magnetize both cores in the same direction.