DE1233936B - Symmetrical magnetic core of the temple type for three-phase transformers - Google Patents

Description

Symmetrical magnetic core of the temple type for three-phase transformers The invention relates to a symmetrical magnetic core of the temple type for three-phase transformers of three or a multiple of three single-phase circles with composed of sheet metal Thighs and yokes.

As is well known, the magnetic circuits consist of three-phase transformers generally of three legs, the axes of which are perpendicular to one and the same Level, and made up of two yokes, which are the upper and lower ends of the legs connect and cause the magnetic circuit to close. The joints between Cores and yokes can either be formed bluntly by dressed surfaces, as is the case with so-called attached yokes, or by nesting the metal sheets of the cores and the yokes in the case of the nested yokes.

This arrangement is practical from a manufacturing point of view is known to have disadvantages and, among other things, has various magnetizing currents as a result of the different magnetic resistance of the central core.

To counter this disadvantage, the cross section of the yokes and thus the sheet metal weight of the transformer can be increased.

There are also three-phase transformers known whose magnetic circuit is formed like a temple by three legs, which are perpendicular to the corners of one are arranged equilateral triangles; the upper one placed on the thighs and the lower yoke connects them like the sides of an equilateral triangle. at In other known core systems of this type, the yokes are also ring-shaped or triangular-shaped laminated cores formed.

In another known embodiment, the cores are made of involute shape bent sheets are put together and thus get a cylindrical shape. The cores are then on the yokes, which are formed by a sheet metal strip, which along is wrapped in an equilateral triangle.

These triangular yokes are connected to the cores by tie rods, which pass through the yoke at the corners of the triangle thus formed.

At the joints between the cores and yokes are all of these Arrangements do not avoid air gaps, which increase the magnetizing current and which lead to iron losses.

It is known that such air gaps are always the cause of humming noises. Finally, these designs are difficult to manufacture and require a considerable amount Expenditure on tools and devices.

Furthermore, symmetrically structured magnetic circuits are nested Yokes known in which the yokes are formed by sheets of different lengths which are bent to an arc during installation; it is also known to bend the yoke plates in advance according to one and the same gauge.

In addition, transformers are known, their yoke and core sheets are nested within each other; the yoke plates are for this purpose at the confluence points bent twice towards the core sheet so that the ends of the yoke sheets fit into the come at the same level as the flat core sheets.

It turned out that it is difficult to get the yoke plates correctly to bend them in perfect large-area contact with the core laminations to bring. Since the yoke plates are elastic due to annealing, they change in the course of time their magnetic properties over time and thus lead to the occurrence of vibrations.

There are also known transformers in which the yoke and core laminations are each butt magnetically connected to each other at the joints. Such Transformers also tend to have a lot of hum.

The magnetic core of the present invention is as follows by the combination Characteristics known per se: a) The sheets of the legs and yokes of every circle are flat; b) all sheets of a circle lie one below the other parallel planes; c) the plates are the legs and yokes of each circle nested within each other. The magnetic core according to the invention has the advantage that only flat, easy-to-manufacture sheets can be used. There bends and kinks omitted, the sheets are shorter and the material expenditure and costs are accordingly less. Good nesting is also possible with flat sheets. The connecting surfaces between the sheets are therefore large. Vibrations only occur to a minor extent on. Because of the improvement in the joints and reduction in the spread the main foot can be reduced. This will also reduce the hum of the transformer decreased. With the same magnetic resistance of all three core parts, the magnetizing current is the individual core parts the same; the consequence of this is small iron losses. The structure of the transformer according to the invention is thus very simple, since the three elementary circuits in the usual way, as with single-phase transformers, layered from sheet metal and can be manufactured separately. Then only need the three elementary circles to be connected to the core structure according to the invention for a three-phase To create transformer.

The invention is described below by way of example with reference to the drawing explained.

F i g. Fig. 1 is a plan view of a single phase elementary circuit; F i g. Fig. 2 shows a side view of the elementary circle; F i g. 3 represents a section a single-phase leg consisting of several laminated cores; F i g. 4th FIG. 14 shows a top view of an assembled symmetrical three phase core of FIG Temple type.

In Fig. 1 and 2 a single-phase elementary circle is shown, which is combined in the plane AB and AB 'with two other similar elements to form the three-phase core according to the invention. Each of the legs s and 6 is formed by packs of sheets that are parallel to one another, and the individual packs can have different dimensions. The metal sheets of the legs 5 and 6 and the yokes 7 and 8 are assembled so that they nest at the joints.

In a preferred embodiment of the invention, the cross-section of the core elementary elements runs in a semicircle, the gradation and length of the sheets forming the packets by a semicircle circumscribed around the core elements with the centers O and O 'and by the one against the plane of the sheets Angle of 30 ° offset diameter AB or A'B 'can be determined (FIG. 1).

The pressing of the sheets of the legs and yokes can be punched through Holes and insulated bolts or by taping or on any other known manner.

F i g. 3 shows, by way of example, a section of a leg for a single-phase core element with several laminated cores 9, 10, 11, which consist of sheets of different widths and are united with one another by insulated tubular rivets 13, 14, 15.

This core structure is appropriate for transformers of high power, since oil circulation channels 16, 17 can be formed by intermediate pieces 18, 19, 20, 21.

The laminated cores 9, 10, 11 of the single-phase core elements are separated manufactured and only assembled during assembly.

F i g. 4 shows, for example, a plan view of a symmetrical one three-phase magnetic core, which is formed by the union of three single-phase core elements 22, 23, 24 is formed.

In a preferred embodiment of the invention, the rooms 25, 26, 27 between the single-phase core elements with a thin plate with corresponding mechanical properties, so that the free spaces of steps 28, 29, 30 are retained, which makes it easier to adjust the yokes.

The legs 31, 32, 33 are held together by bandaging or in any other way. Tightening the yokes of the symmetrical three-phase transformer takes place with the aid of a support part arranged within the space between the yokes 34 and by clamping plates or straps 35, 36, 37, which by clamping bolts 38, 39, 40 are held together.

The support part 34 can also be used for the inner support of the legs attached windings by means of a pull rod 41 extending in the axial direction or any other suitable device.

Claims (3)

Claims: 1. Symmetrical magnetic core of the temple type for three-phase transformers of three or a multiple of three single-phase circles with composed of sheet metal Legs and yokes, characterized by the combination of the following known per se Features: a) The plates of the legs and yokes of each circle are flat; b) all sheets of a circle lie in mutually parallel planes; c) the sheets the legs and yokes of each circle are nested within one another. 2. Magnetic core according to claim 1, characterized in that in a manner known per se between thin plates are inserted at the points of contact of adjacent single-phase circles, which leave the spaces formed by the gradation of the sheets free. 3. Magnetic core according to claim 1 or 2, characterized in that in a known manner Yokes are pressed against a central support part, which may also be used for support serves the windings. Publications considered: German patent specification No. 691531; Swiss patents No. 311377, 338 521; French patents No. 1220 435, 1082 377; U.S. Patent Nos. 999,825,2458112; Textbook Arnold and I. L. la Cour, "Die Transformatoren", 2nd edition, pp. 203 and 204.