DE2005189C3 - Three-phase step transformer - Google Patents

Description

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, which gives you an additional -fold

Voltage reduction achieved. In the case of the designs that have been customary up to now (see e.g. Siemens-Zeitschrift I960, issue 2, pages 96 to 104, especially Fig. 7), three must be Mechanically coupled single-phase step switches are provided, which consist of diverter switches, reversers and Voters exist, switching from delta to star connection in a known manner with the turner is carried out in a de-energized state. Apart from the fact that this is three separate diverter switches ϊ are necessary, simultaneous actuation is required 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 to use three-phase transformers with an in

ίο triangle connected tapped winding, two of the three step switches in terms of circuitry and construction to form a unit with a common root point to summarize and to arrange in a corner of the triangle 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-1).

The object of the invention is to provide a simple switchover of the transformer windings of step transformers To enable from triangle to star, in addition to a lower cost of switches a high level of operational reliability is to be achieved.

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

_> 5 characterizing features of this claim solved.

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

F i g. Fig. 1 shows the already known arrangement of delta-connected windings I ₁ 2 and 3 one

ίο transformer, 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 loaded in one phase. In Fig. 2 are the The transformer windings are star-connected.

π Here, the diverter switch 5 forms the star point, while the diverter switch 4 at the network-side end of the Winding 2 lies. The diverter switch 5 is two-phase, the diverter switch 4 is operated in one phase. The arrangement can be made so that two three-phase diverter switches are used, with alternately one or two phases of the diverter switch are loaded. As can be seen from Figure 3, the Circuit, however, synonymous with two two-phase Lastum - (; holders are executed. Switching the three

«Ι ·> windings 1, 2 and 3 is done by switching 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 connection with the help of the step switches 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.