DE639823C - Measuring and protective device - Google Patents

Description

To obtain the zero-point earth voltage in earth-fault protection devices are usually Used voltage converters that have multiple windings. One winding is used to obtain the zero-point earth voltage, i.e. the voltage of the system zero point to earth, while the other winding has the phase earth voltage, i.e. the Voltage of the phase conductors with respect to the earth-connected point. If so for measuring purposes or for other protective devices, the phase zero point voltage is required, you previously had to provide a special converter for this purpose.

The invention seeks to avoid this by reducing the phase zero voltages by the geometric composition of the phase earth voltage, i.e. the voltage of the Phase conductor with respect to the earth-connected point, and the zero-point earth voltage are formed, the zero point ground voltage with a full conductor ground fault in their Size must be equal to the phase zero point voltage.

In Fig. Ι an embodiment of an unlinked polyphase converter with a primary winding 1 and a star-connected secondary winding 2 and a winding 3 connected in an open triangle is shown. On the open triangular winding 3, the neutral point ground voltage or the sum phase ground voltage U _{0 is} obtained, on the winding 2 the linked voltages U and the voltage of the phase conductors with respect to the grounded point, i.e. the phase ground voltage Ure, Use, Ute- According to the invention, the individual phase neutral point voltages Up obtained by geometrical composition of the individual vectors U ₀ and Use or Ure, Ute .

A voltage diagram is shown in Fig. 3, which illustrates the extraction of the phase zero point voltages. A ground fault in the phase 5 star winding is assumed. The voltages of the phase conductors to earth are Use, Ure, Ute, to which the zero point earth voltage U ₀ is added. It can be seen that this readily results in the phase zero point voltages Ur, Us, Ut .

In Fig. 4 the same voltage vectors for an earth fault in a delta winding between phases T and 5 are shown,

In Fig. 2 an embodiment of the invention is shown for a converter which, in addition to the high-voltage winding 1 and the star winding 3, has a winding 4 arranged on a fourth and fifth leg for obtaining the zero-point earth voltage U ₀ . The star point of winding 3 is there-

*) The patent seeker stated as the inventor:

Alexander von Schaubert in Berlin.

when connected to one terminal of the winding 4. In this arrangement, too, the phase ground voltage U _p can be obtained in each case by the geometrical composition of the voltage of the phase conductors with respect to the grounded point and the neutral point.

The composition of the vectors will of course only have the correct value for the phase zero point voltage result when the voltages of the individual windings stand in a corresponding relationship to each other, since only then is the condition of the main claim fulfilled that the zero point earth voltage in the case of a full conductor earth fault, its size is equal to the phase zero point voltage. This is achieved by that the winding parts of the star winding have three times the number of turns of the winding

ao parts of the triangular winding according to Fig. 1 or each of the arranged on the compensating legs Obtained windings according to Fig. 2. For the converter of Fig. 2, it is useful to obtain the zero point earth voltage use a tap on the winding on the compensating legs that

with a full earth fault a voltage 77 = · der

V3 supplies a line-to-line voltage on the star winding. The entire winding can then be designed in such a way that it supplies a voltage which, in the case of a full conductor earth fault, is equal to the concatenated one. Tension is. This allows the condition of the standards that both voltages (line-to-line voltage and zero point ground voltage on the entire compensating leg winding) are = 100 volts. The tap point is then with a full earth fault at a voltage of -7 = volts.

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Claims (4)

Patent claims: i. Measuring and protection device, wherein the voltage transformer with windings, where (voltages of the phase conductors with respect to the terrestrial • closed points) appear Nullpunktserdspannung (voltage of the SystemnuUpunktes to ground) and the Phasenerdspannungen, superiors''' are ^ see characterized that > - 'i \ the phase zero point voltages are formed by the geo-' ■ 'metric composition of the phase ■ earth voltage and the zero point earth voltage and that the windings are dimensioned in such a way that the zero point earth voltage with a full conductor earth fault is equal in size to the phase zero point voltage. 2. Device according to claim 1 for an unlinked multiphase converter with a star winding or several single-phase transformers with a primarily earthed star point as well as an open delta winding, one of which is the winding end point is connected to the star point of the secondary star winding, characterized in that that the winding parts of the star winding have three times the number of turns of the winding parts of the triangular winding. 3. Device according to claim 1 for an unlinked multiphase converter with a star winding and windings arranged on special compensating legs, characterized in that the winding parts of the star winding three times the number of turns of the winding parts have on each compensating leg. 4. Device according to claim 1 and 3 for a converter, in which the voltage the concatenated voltages are the same on the entire windings of the compensating leg with a full conductor earth fault the star winding, for example roo, characterized in that the sum . A tapping of the winding is possible with the voltages of the star winding use on the compensating legs det is a voltage of -, - · der line-to-line voltage on the star winding. 1 sheet of drawings