DE2127031A1 - Controlled high-voltage cut-off spark gap - Google Patents

Description

Dr. WOLF-D. FEDER file 71-10-105

Patent attorneys

4 Düsseldorf May 28, 1971 WF / Ka

Am Wehrhahn 77 1. Efg. r. Emil Haefely & Cie. AG, Basel (Switzerland)

Controlled high-voltage cut-off spark gap.

The invention relates to a controlled high-voltage cut-off spark gap, consisting of a chain of series-connected partial spark gaps and parallel to them and one below the other Series-connected capacitors to control the potential of the individual partial spark gaps. Such devices are used to test transformer windings with the help of interrupted voltage waves. KLr a successful one During these tests it is necessary that the applied voltage is within a tolerance of - a tenth of a microsecond the desired time that has elapsed since the start of the voltage wave is interrupted.

In addition, there is a need in high-voltage pulse technology for several parallel-connectable spark gaps in order to to reduce the inductance of the assemblies. This assumes that the spark gaps connected in parallel can be triggered individually are that they ignite so precisely and so quickly that the terminal voltage collapses at all of them at the same time.

For voltages up to 500,000 volts, this requirement can be met a controlled spherical spark gap are sufficient. At higher voltages, however, a spherical spark gap has major disadvantages on. In the first place, such a device fails

109883/1111

required size of the sphere, since such large spheres only very large difficult and expensive to manufacture. aside from that at higher voltages the margin for the electrode spacing becomes very small, i.e. for any given electrode spacing the difference between the minimum voltage at which a flashover between the electrodes is properly controlled can be triggered and the voltage at which a flashover takes place without controlled triggering, very small, so that the flashover between the electrodes becomes more and more indeterminate.

It has already become known a spark gap arrangement that consists of a main spark gap and an auxiliary spark gap, both of which are two or more connected in series Have partial spark gaps. These partial spark gaps are Resistors connected in parallel and in series to control the potential of the individual partial spark gaps *

The previously known type of cut-off spark gap with a '. Ohmic voltage divider can only use a voltage shift on the resistor chain to trigger the second spark gap. This voltage shift is very small, for example, for the second stage of a multi-stage spark gap, if one disregards the distortion of the voltage distribution along the resistance chain due to the stray capacitances, in particular the earth capacitance. Due to the distortion, the voltage at the second ¹ stage is higher than the value that results only from the shift in the resistance ratio.

The distortion of the voltage distribution by the stray capacitances, however, must not be too large, so that the spark gap is not already appeals by the incident surge, but only ^one by the trigger signal at the lowest part of the spark gap.

109883/1111

As is known, the influence of the stray capacitances on the voltage distribution can be limited by choosing the resistance value of the entire control resistor chain to be no greater than a few tens of ohms. However, this relatively low ohmic value limits the use of a resistance-controlled multiple spark gap. One can only allow voltage impulses of a few ~ LQr microseconds duration, longer lasting voltages with; Amplitudes of a few IvIV in a resistance of a few i 10 ohms would generate such a large amount of heat that one would have to cool with considerable effort. If you even have several parallel; switched cut-off spark gaps must control each partial spark gap \ with a resistance of the order of magnitude mentioned, j is the energy loss only through the control of the partial spark; stretch very big.

The inventive solution to the problem of energy expenditure. longer lasting voltages and when connecting in parallel several such spark gaps is that instead of ' an ohmic and capacitive divider is used, whereby the controlled high-voltage cut-off spark gap is thereby: indicates that, with the exception of the uppermost partial spark gap between the capacitors and the partial spark gap, impedances are arranged, and that at least one of the partial spark gaps located at one end of the chain with a trigger electrode; is provided. ;

As is well known, a capacitive divider shows no time-dependent distortion of the voltage distribution due to the effect of the stray capacitances. The so-called initial distribution and the final i stress distribution are identical for this type of divider. One can· So to: giLus solution of further partial spark gaps after triggering of the first partial spark gap is not readily apparent. the over-; calculate voltages as on an ohmic divider. This disadvantage j

109883/1111

of the capacitive divider can be bypassed by reducing the discharge current of the lowest partial capacitor after the ignition of the lowest partial spark gap · to trigger the second partial spark gap is used. The discharge current of the second lowest partial capacitor triggers the third partial spark gap, etc.

Embodiments of the subject matter of the invention are explained below with reference to the drawing.

In the drawing shows:

W Figure 1 shows the basic structure of a controlled high-voltage cut-off spark gap, and

FIG. 2 shows an embodiment of the controlled high-voltage cut-off spark gap, in which the impedance elements are arranged between the divider capacitors and the spark gaps impedances are provided with a voltage pick-up arrangement for feeding a trigger electrode.

The general principle that in the elements 0 -, O ... ₁ - to use the capacitive divider stored energy to trigger partial spark gaps can easily figure 1 the invention. be realized in that between the divider elements fc and the spark gap elements resistors IL ... B ^. attaches · The voltage divider consisting of the same elements O ₁ to Cj- is charged by a voltage source (not shown) so that the voltage Uq is applied to each of the divider elements. If the lowest spark gap F ^ provided with a trigger electrode TE is triggered in a known manner with an auxiliary spark by a trigger generator TG, the capacitor O ^ is discharged via the spark gap F-,. This creates a transient voltage with an amplitude U _Q at the resistor R ^. The voltage drop UR ^ acts directly as an overvoltage on the second spark gap F ₂ and makes it respond. As can be seen from FIG. 1, the spark gap F _{2 is stressed by the voltage Uq (at C 2} ) and U.Β. ».

- 5 -10 9 8 8 3/1111

The second partial spark gap Fg is therefore not just like one. resistance-controlled multiple spark gap with a weak overvoltage due to the voltage distortion on the chain, but with almost 100 % overvoltage due to the superposition of the two voltages Uq and U .R ,. As a result, the arrangement shown has a much wider triggering range I than a resistance-controlled arrangement, ie the individual partial spark gaps can be triggered well below their static response voltage. The security of the capacitive! controlled tripping is significantly greater than with the previously known resistance-controlled multiple spark gaps due to the large margin to the static response voltage.

The third partial spark gap F ^ ignites due to the overvoltage, which arises at the resistor Rp after the ignition of Fg, which fourth partial spark gap due to the overvoltage at R, after the Ignition of F, etc .. ·

The width of the tripping area and the temporal spread of the response of the partial spark gaps can be further improved by I, as shown in FIG. 2, partial voltages j A ^u Rv. ·. ^ JTjJ ₁ · the voltage variation U _Q .B £ ·· ..TT ₀ B ^. at-the resistors ^: R {.. , Hh taps off and supplies a trigger electrode TEg-TEc at 'the respectively assigned partial spark gap Pg. *. Fc. j

Instead of the resistors R ₁ to R ^ (Fig. 1) or R {- R ^ (Fig. 2), chokes can easily be used. Likewise, the impedance between the divider capacitors C £ - Gl and j the spark gaps F £ - FA can be formed by the primary winding of a transformer, not shown, the secondary winding! ment of this transmitter feeds the trigger electrode of the arranged partial spark gap.

Furthermore, instead of a purely capacitive divider to control the voltage distribution, a damped capacitive partial op can be used. , ₀ 9ββ3 / 1111 ^ tentanaprone ^

Claims (1)

Patents Controlled high-voltage cut-off spark gap, consisting of a chain of series-connected partial spark gaps and capacitors connected in parallel and one below the other to control the potential of the individual partial spark gaps, - characterized ! that with the exception of the uppermost partial spark gap between the capacitors and the partial spark gaps impedances (R ^ ... H _4. ) are arranged, and that at least one (E ₁ ) of the partial spark gaps at one end of the chain is provided with a trigger electrode (TE) . Spark gap according to Claim 1, characterized in that the impedances (RJ ... R ^) arranged between the partial capacitors (GJ ... CA) and spark gaps (FJ ... FA) are provided with a partial voltage tapping arrangement for tapping a partial voltage, which is connected to a trigger electrode (TE2. «TEL for triggering the assigned partial spark gap (Fg ... FA). Spark gap according to Claims 1 or 2, characterized in that the said impedances are ohmic »resistances. Spark gap according to Claims 1 or 2, characterized in that the said impedances are chokes. Spark gap according to Claim i, characterized in that the said impedances are represented by the primary winding of a transformer and that the secondary winding of this transformer feeds the trigger electrode of the associated partial spark gap. 10988 3/1111 L e r s e i t e