Abstract: An inductively operated apparatus for heating plastic materials in extruders or for other purposes has a heat-transmitting housing with one or more passages for the material or materials to be heated, and an arrangement for heating the housing. The heating arrangement employs a laminated core with two legs which are magnetically coupled to the housing with the interposition of distancing elements of heat insulating material. The core is surrounded by an exciting coil. In order to prevent overheating of the coil, the heating arrangement further comprises at least one barrier which is interposed between the core and the core and is cooled by one or more streams of a gaseous or liquid coolant, such as water. The barrier can be constituted by a flat tube which is convoluted around the core and supports the coil. A second barrier can be placed around the coil so that the latter is received between two barriers.

Abstract: An inexpensive lamination for use in transformers and/or other static or dynamic electric machines has a metallic layer one side of which is provided with a coat of hardenable adhesive and the other side of which is provided with a coat of insulating material. At least the adhesive coat can contain particles of sand, glass, a metallic oxide or a synthetic plastic material; such particles act as distancing elements between the respective side of the metallic layer and an adjacent metallic layer. The two coats are applied simultaneously between an unwinding station for a web or strip of coherent metallic layers and a winding station for the freshly coated web or strip of coherent metallic layers.

Abstract: Laminated iron core for transformers, choke coils and the like includes a plurality of core parts overlying one another at respective mutually opposing abutment locations, the respective mutually opposing abutment locations defining a space of varying width between one another, the core parts being disposed so as to form a relatively short closed inner path and increasingly longer closed outer paths for magnetic force lines, the space having a region of relatively greater width across which the relatively short closed inner path extends.

Abstract: Electric machine, such as a transformer, a choke or a constant-voltage regulator, having an iron core assemblable from a plurality of individual, substantially rectangular core parts, including legs and intermediate yoke parts, formed of mutually held-together laminate layers, and clamping means such as clamping straps or plates clampable into engagement with a corresponding clamping surface at outer contours of the leg core parts transversely to the laminate layers by clamping elements such as screws or rivets, includes means defining channel or tunnel-shaped recesses extending parallel to all of the mutually parallel laminate layers of all of the assemblable individual core parts and substantially perpendicularly to juxtaposed joint abutments of the respective individual core parts.

Abstract: A stepped iron core formed of sheetmetal laminations for a static or dynamic electric machine, such as a transformer, having yokes and legs and intermediate parts of at least one thereof including stacks of the sheetmetal laminations mutually held together forming individual steps of the yokes and the legs, the yoke stacks and the leg stacks being joinable with one another at respective abutment joint locations formed thereon, and means located at the respective abutment joint locations for achieving a varying magnetic reluctance therebetween so that a longer path of lines of force passes through the respective abutment joint locations in the region thereof of lower magnetic reluctance.

Abstract: Iron core for an electric machine such as a transformer, a choke, a voltage stabilizer and the like, assemblable of a plurality of individual parallelepipedal core parts formed of laminated layers mutually held together, the core parts having mutually abutting joints formed with smoothly finished surfaces free of any metallic connection between the individual layers, includes clamping means applicable to a clamping surface at outer contours of the core and extending transversely to the laminated layers, clamping elements for clamping the clamping means so as to hold the individual core parts together, the clamping means includes strap-like members for distributing clamping force at least approximately uniformly to the individual laminated layers between the clamping means and the respective clamping surface.