DED0011923MA - - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

Registration date: March 27, 1952. Advertised on September 29, 1955

GERMAN PATENT OFFICE

PA TENTAN REGISTRATION UNG

CLASS 21e GROUP 33

D 11923 VIII el'2Ie

The inventor has requested not to be named

Dielektra Aktiengesellschaft, Porz / Rhein

Arrangement for drawing small power from high-voltage networks by means of capacitive voltage division

In Fig. Ι the circuit diagram of an arrangement for drawing small power (z. B. for measuring) from high-voltage networks by means of a capacitive voltage divider is shown (C measurement). _{A series connection of two capacitors with capacitances C 1} and C ₂ is connected between one of the mains conductors and earth, where C ₂ > C ₁ . The ratio C ₂ : C ₁ was denoted by η:

= η.

Parallel to the capacitor C ₂ is the series connection of a choke D and a converter W. The burden, represented here by the resistor R , is connected to the secondary terminals of the converter. The stresses occurring in the arrangement are

U = phase voltage mains - earth,

U ₁ , U ₂ = partial voltages at C ₁ , C ₂ ,

Up = voltage at the choke D, U ^ ₁ = primary voltage of the converter W, U _W2 = secondary voltage of the converter,

at the same time tension on the burden. ² ^

In addition, the current intensity at the burden is denoted by /. Provided that both the choke as well as the converter are lossless, optimal conditions result when the in-

S09 562/81

Claims (4)

D 11923 VIII c I'21 e duktiviti'it /. (Ut throttle is so dimensioned
(with a) ■■ - angular frequency) that or ■ -; - = const.
C) Ay, =, X,. 11 - - I. is, where is. (ο L and Ao = ω C, Then the S] JaUnUHg (Z ₁₁ ,., At the load is constant, (1. i.e. independent of the load current /, i.e. the load, and always in phase with the mains voltage I ' (see ATM sheet V 3333- 1 and V 3333-N). The known versions of the circuit according to A1) I). 1 therefore make of the relationship (2), (3) ao (lebrauch, i.e. you use chokes with as constant an inductance as possible in accordance with the given values of λ ' ₂ and n. For technical and economic reasons, both the choke and the converter are designed with an iron core. As a result, in addition to the power losses in the windings, there are also power losses in the iron cores. Therefore the voltage (/ ",., On the load is no longer constant, but it decreases sharply with the load (Fig. 2, curve"). In other words, the transmission ratio U: U _w ., Is not constant, Instead, it increases with the load, which impairs the accuracy of the voltage measurement, especially when other loads (e.g. relays) are to be switched on and off in addition to the voltage meter. Ks is already known to compensate for the voltage drop when the arrangement is loaded by that a saturated Kis choke is connected in parallel to the consumer circuit. This brings but with the decided disadvantage that the voltage on the converter increases and such Value can assume that the isolation is endangered. Therefore - except for the additional Di'ossel - special measures necessary to protect the isolation. The invention relates to an arrangement for extracting small amounts of power from high-voltage networks by means of a capacitive voltage divider to which a series circuit comprising a choke and a voltage converter is connected, which avoids these disadvantages. This is achieved in that according to the Krfmdung a saturated Kisendrosscl is used as a throttle. This ensures that the voltage U _K ,., At the load is independent or almost independent of the load (Fig. J, curve b). In the beginning there may be a somewhat greater drop in tension; but from a low load on that 6u can also be an artificial preload, the voltage remains constant. It can also be achieved that the voltage U _W2 increases somewhat with the load (Fig. 2, curve c). This is advantageous if the burden is connected via a kingc line; the voltage drop in the line is then compensated. An additional throttle is therefore unnecessary; In addition, no measures to protect the converter insulation are necessary, since the voltage does not increase. The effect of the saturated iron choke is based on the fact that its inductance decreases with the load. By choosing the type of iron for the clic choke, the dependence of the inductance on the load can be designed in such a way that curves b or c in Fig. 2 result. It is advantageous if the maximum permeability is at low values of the magnetic field strength. To tune the throttle, it is useful to provide a variable air gap in the iron and at the same time to make the effective number of turns variable by taps, counter-connections and similar measures. Furthermore, by means of an arrangement according to FIG. 3, it is possible to influence the inductance of the choke in such a way that it decreases as the load increases. Here the load current / is sent through a winding α on the choke core in the sense that the magnetic flux is weakened. This means that the inductance of the choke decreases as the load increases. The desired change in the inductivity of the choke with the load can also be achieved by other generally known means. 1'ATHNTANSPn Γ CU Ii: ι. Arrangement for removing small amounts of power from high-voltage networks by means of capacitive voltage divider to which a series circuit of choke and voltage converter is connected, characterized in that the throttle is a saturated ice throttle is. 2. Arrangement according to claim i, thereby characterized in that the choke is dimensioned so that its inductance increases with increasing Load passes through the value according to relation (2). 3. Arrangement according to claims 1 and 2, characterized in that the inductance the throttle continuously by means of an air gap and by means of taps on the winding and opposing turns can be changed in stages. 4. Arrangement according to claims 1 to 3, characterized in that a second winding is provided on the choke through which the load current flows. Cited publications: German Patent No. 401 539; Archive for electrical engineering, vol. 28, year 1934, Pp. 302 to 305. 1 sheet of drawings