SU55159A1 - The method of determining the distance from the station to the ground fault - Google Patents

Description

The method of determining the distance from the earth station.

It was announced on November 25, 1937, No. 12324. Published June 30, 1939.

The proposed method is referring to the rapid determination of the location of a short circuit to earth of one or two wires of an electric transmission line of a multi-phase (three-phase) current with a grounded neutral at both ends of the line. The proposal uses the known method itself, which consists in measuring the geometrical sum of the currents of all phases at both ends of the multiphase transmission line, after which the distance to the ground fault is determined using formulas or graphics.

The essence of the invention is that, in order to eliminate the effect of the arc arising during an accident, the measurement is made at the ends of the line simultaneously, and the ammeters include points of grounded neutrals and the distance is determined by the ratio of the zero-sequence current of one end of the line to the sum currents zero component of both ends.

The switching circuit of the instruments for implementing the proposed method is shown in FIG. 1 attached LFV-i: g.

To the place

Hi; ,, ;; -.-.

drawing drawing. FIG. 2 shows graphs for locating damage.

FIG. 1 the letters a, b, c marked wires of the three phases of the transmission line. At both ends of the line, zero points 7 and 2 (transformer or generator) are grounded at points 5 and. In the event of a short circuit of one or two wires to earth at point 5, the short circuit current to the earth branches out, leading to one and the other neutral. The magnitudes of these currents are measured by ammeters g and 9 directly or through current transformers 5 and 7. Ammeters must be equipped with a means that, before turning off the line, they simultaneously record the magnitudes of the currents in both ends of the line.

According to the values measured by ammeters and .9 currents, using the curves of FIG. 2, determine the distance from the ends of the line to the short-circuit point, for which purpose the duty officer at one end of the line reports the value of the measured current to the duty officer at the other end.

In the curves of FIG. Figure 2 shows ground fault currents as a function of the distance from the short circuit point to the ends of the transmission line. These curves are constructed based on the assumption that the contact resistance at the short circuit point is zero. Such curves are typically found in high voltage installations for various modes of network operation. These curves are different for single phase and for two phase earth faults.

The effect of transient resistance of the arc or ground of the support is excluded if the short circuit location is determined as the average of the two distances found from the / 1 and / 2 curves. FIG. 2 also shows the curves depicting the dependence

relations. -r-yy-rm distance between the short circuit and the ends of the line. The magnitude of this relationship depends only on the parameters of the area between the grounded points 3 and 4 (Fig. 1) and is the same for single-phase and two-phase earth faults. Therefore, these curves are particularly convenient to use. It goes without saying that instead of the curves of FIG. 2 can be

used relevant tables.

Simultaneous measurement of the current and fixation of the readings of the ammeters 8 and 9 can be carried out in various ways, for example, by supplying the ammeters with a maximum or a test arrow, stopping the arrow (made of iron) with an electromagnetic device activated by a time relay, etc.

The subject matter of the invention.

The method of determining the distance from the station to the ground fault position in an electric multiphase line, consisting in measuring in two places a line the geometric sum of currents of all phases of a line and subsequent calculation by formulas or graphics, characterized in that measurements are made at both ends of the line points of tightly grounded neutrals and the distance is determined with respect to the current of the zero sequence of one end of the line to the sum of the currents of the zero component of both ends, in order to eliminate the influence of the transient resistance of the arc and influence of the composition of the electrical system.

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The distance from the transfer of the copyright certificate to G. S. Holsman, I / M. Lang and S.I.Rayne K. 55159