DE2005189B2 - Three=phase staged transformer - has two changeover switches at corners of delta circuit for changing to star configuration - Google Patents

Abstract

The 3-phase staged transformer has its change over switching arranged so that delta/star change over is accomplished reliably and with relatively few components. The change over circuit has two change over switches located one at each of two of the three corners of the delta winding configuration. In the star configuration, one (5) of these change over switches is located at the neutral point whilst the other (4) is located at the voltage-end of one of the windings. The change over switches may be 2 or 3 phase.

Description

30th

The invention relates to a three-phase step transformer according to the preamble of Claim 1. Such a step transformer is already known (AT-PS 1 86 725, see below).

In order to achieve a larger setting range, the undervoltage is preferable for furnace transformers next to a step switch provided on the high voltage side for changing the undervoltage a triangular star changeover of the HV windings provided, whereby one additional ^ - fold

Voltage reduction achieved In the previous versions (see e.g. Siemens-Zeitschrift 1960, issue 2, pages 96 to 104, especially Fig. 7), three mechanically coupled single-phase step switches must be provided which consist of diverter switch, turner and selector, with the switching from triangle to Star connection is carried out in a known manner with the turner in the de-energized state. Apart from that from the fact that this requires three separate diverter switches, requires simultaneous actuation these three diverter switches require a considerable amount of mechanical power transmission means.

From the above-mentioned AT-PS 1 86 725 it is already known for three-phase transformers with an in Triangular tapped winding, two of the three tap changers in terms of circuit and construction to be combined into a unit with a common root point and in a corner point of the triangle to be arranged so that they are at the same potential, while the third tap changer is arranged in one of the other two corner points of the triangle (Fig. I) -

The object of the invention is to provide a simple switchover of the transformer windings of step transformers from triangle to star, whereby In addition to a lower cost of switches, a high level of operational reliability should also be achieved

This object is achieved in a step transformer according to the preamble of claim 1 by the characterizing features of this claim solved

The invention is illustrated below with reference to FIGS. 1 -3 explained in more detail

F i g. 1 shows the already known arrangement of FIG Delta-connected windings 1, 2 and 3 of a transformer, with the step switches 4 and 5 two Form corner points of the delta connection.

The step switch 4 is two-phase, the step switch 5 is single-phase in FIG. 2 are the The transformer windings are connected in star. Here, the diverter switch 5 forms the star point while the diverter switch 4 is at the end of the winding 2 on the network side. The diverter switch 5 is here two-phase, the diverter switch 4 operated in one phase. The arrangement can be made so that two three-phase diverter switches are used with one or two phases of the diverter switch alternating be charged. As shown in FIG. 3, however, the circuit can also be made with two two-phase diverter switches are executed. The three windings 1, 2 and 3 are switched over by switching over the Reversing contacts from 20 to 30.

1 sheet of drawings

Claims (3)

Patent claims: 1. Three-phase step transformer, which is an arrangement of two step switches for voltage setting with delta connection, the two step switches have two corner points of the Form a triangle, characterized in that a step switch (5) in the star connection Star point, the other (4) is at the voltage-side end of a winding (2) and that one Switching from delta to star cladding with the help of the step switches belonging to the Turning (10, 20, 30) takes place in such a way that alternately One step switch each is single-phase, the other is operated in two-phase 2. Step transformer according to claim 1, characterized in that the voltage setting serving tap changers (4,5) are designed in two phases. 3. Step transformer according to claim 1, characterized in that the voltage setting serving tap changers (4,5) are three-phase, with one or two alternating Phases of the tap changer are in operation.