RU2037244C1 - Multigap discharger with gaps connected in parallel - Google Patents

Abstract

FIELD: electrical engineering. SUBSTANCE: two flat parallel metal or dielectric frames on which sets of thin wire electrode elements are anchored rigidly with overlapping windows of frame over length are placed at some distance from each other. Electrode elements of opposite frames are positioned perpendicular to each other which results in formation of cross electric field. Electric discharge occurs in gaps of overlapping of conductors. EFFECT: improved operational efficiency and safety. 3 dwg

Description

 The invention relates to electronics. The predominant field of use of radio engineering is to create pulse generators of harmonic oscillations, for their use in radio engineering, in factory technology, in ultrasonic practice, etc.

There are known designs of switching arresters [1] electrodes, which have various geometric shapes: cylinder ends, spheres, hemispheres, etc. By using electrical elements of the switching circuit, it was possible to increase the number of arresters and obtain stable operation of generators with a series circuit, bringing the number of arresters to forty and more [2]
Also known is the design [3] of a multi-gap device, consisting of a sequential chain of electrodes in the form of cylinders with rounded edges, mounted on the upper and lower dielectric plates in a checkerboard pattern.

 A study of the spark gap was carried out for high powers (20 kV, 100 A, 2 μs, 500 Hz).

The following disadvantages of the discharge circuit were found:
strong erosion of the electrodes limited the design life to 1.5 min;
high noise levels during operation cause difficulties in its maintenance.

 As a prototype, a “multichannel arrester" [4] with gaps in parallel included, containing two parallel electrode holders, on each of which discrete electrode elements located in parallel are mounted, is selected. In the gaps of these elements is the edge of a metal plate coated with quartz.

Design disadvantages:
a limited number of electrode elements (up to 20 pcs.) does not give a significant unloading of electrode elements (10 ⁵ a);
when heating the electrode elements there is no compensation for their linear expansion, which may violate the gap;
the introduction of the edge of the plate into the gap creates the conditions for surface leakage.

 The aim of the present invention is to provide a spark gap design, where the electrodes, being unloaded by current, would reduce erosion, thereby increasing its resource.

 This goal is achieved by creating a multi-gap arrester design, which uses the edge effect in a cross electric field in the gaps of electrode elements having a discrete structure.

 Figure 1 presents the proposed multi-gap arrester, General view; in FIG. 2 electrode holder, top view; figure 3 is the same with the electrode elements.

 As an example of a specific implementation of a multi-gap arrester, wire electrode elements were used, which, with a certain orientation, worked in a cross electric field. On two flat metal frames 1 of nickel sheet with a thickness of 1.0-2.0 mm, 10 wire electrode elements 2 of 0.5 mm section of tungsten were arranged; the distance between them in width was set at 2.5 mm. The length of the wires was chosen so that they only protrude 3-5 mm on one side of the frame (if necessary, make more reliable contact with the frame). The fastening of the electrode elements 2 was carried out only on one side of the frame 1 using alundum suspension, the ends on the opposite side of the frame 1 remained free or only slightly pressed on top of the mica plate. Then, the frames 1, facing the electrode elements 2 inward, were oriented so that, looking at them from above, a grid of square cells would be visible. This orientation created a cross field at work. To make a gap of 0.5 mm between the electrodes, four glass washers 3 with a height of 8 mm and an outer diameter of 8 mm and an inner diameter of 4.1 mm were placed between the holes in the tops of the frames 1. Further, the frames 1 through the holes in the vertices were pulled together with ceramic bolts 4 with a length of 20 mm, a cross section of 4.0 mm with metal nuts 5 with a thickness of 2 mm and an outer diameter of 8 mm.

Before proceeding with the installation of the arrester, keep in mind the following:
pieces of wire intended for electrodes should not have bends and should be the same in cross section (accuracy 0.01);
when sticking wire electrodes, it is necessary to press them lightly with a weight of 30-50 g with a smoothly ground surface;
warm the frame with glued electrodes on an electric stove with pressure weights until the suspension is completely dry;
the surfaces of the sides of the frames should lie in the same plane.

 In order to verify the correctness of the installation (before the glass-blowing work), a spark gap was tested for an electric discharge in air. A voltage of 2-3 kV was applied to the arrester from the ignition generator (at low current). In this case, spark discharges appeared in many places of the crosshairs of the electrode elements 2, which quickly moved along all the crosshairs.

 If the planes of frames 1 during their manufacture were violated or inaccuracies were made during installation, spark discharges focused on a small working surface or occurred along the crosshairs of any one pair of electrodes.

 To test the operation of arresters in control mode, a sequential chain of three arresters was assembled.

 The constant voltage was of the order of 1000 V, the control direction from the ignition generator of 2-3 kV was supplied to the first spark gap (relative to the minus). The vessel was filled with neon at a pressure of 5320-13300 Pa. The average power at the boundary of the dark and glow discharges emitted in the oscillatory circuit was about 150-200 W at a pulse repetition rate of 30-40 Hz and a fill frequency of 1 MHz and was visually estimated from a 300 W glow lamp. The limited power of the power source (multiplier) did not allow to approach the upper limit of the possible power of the discharge circuit.

 It is important to note that in the assembled chain of series-connected multi-gap arresters, each multi-gap arrestor can be considered as a large number of elementary discharges connected in parallel.

 It is known that when individual arrears are connected in parallel when a breakdown voltage is applied to them, any one of them will work, while the breakdown conditions for the rest worsen due to a drop in the supply voltage, and they will not work anymore.

 Consider the situation when using this multi-gap arrester.

 1. In the case when the radius of curvature of the electrode elements is less than or equal to the gap between the electrode elements, a large current in the supply wires in the gaps is divided into a large number of small currents.

 If a discharge has started in one of the gaps, then the supply voltage of the others does not change (or changes by a very small fraction), therefore, many of the “gaps” awaiting breakdown will break through.

 2. In addition, it is known how significant the magnitude of the electric field is to the simultaneity of breakdown. The field strength increases with decreasing radius of curvature of the electrode elements and thereby contributes to the simultaneity of the discharge.

 The main advantage of using surge arresters on the edge effect in a cross electric field (in series-parallel circuits) is the ability to work on any electrode materials (chemically pure, with additives, oxide, etc.).

The presence of radiators in the form of metal frames in the spark gap accelerates the deionization process in the gaps, thereby increasing the discharge capacity of the spark gap in pulse frequency. Metal frames introduce additional capacitance (dielectric) into the circuit. In addition, the falling volt-ampere characteristic of the discharge introduces negative resistance into the circuit and compensates for a part of the active component in the spark gap circuit. The shape of the pulse becomes a rectangular sign of the absence of large attenuation in the circuit, which increases the efficiency of the device. The advantages of the proposed arresters compared, for example, with powerful generator lamps:
lack of glow chains;
energy in the arrester is not consumed at the moment of absence of a pulse;
instant readiness for work;
simplicity of the arrester design;
lack of expensive metals (gold);
low cost of manufacturing a spark gap, and therefore the generator itself;
lack of nets (their presence in lamps and thyratrons);
Ease of Management;
Arrester allows the use of oxidized electrodes. In high-power lamps, this is not possible, since the oxide cathode contaminates the grid, which leads to a decrease in efficiency
by changing the thickness of the wires for the spark gap electrodes, a change in current density is possible;
the proposed design of the arrester does not require water cooling, and with high power, you can restrict yourself to forced air cooling;
for the "arbitrary" power of the discharge circuit, it is possible to turn on the arresters not only sequentially, but also simultaneously in parallel.

 Sequential inclusion of gaps increases the inductance of the circuit and reduces the "parasitic" capacitance, parallel to the other way around.

Claims (1)

 MULTI-CLEAR DISCHARGE WITH PARALLEL LIVING CLEARANCES, containing two parallel electrode holders, each mounted with discrete electrode elements parallel to each other, characterized in that the electrode holders are made in the form of flat frames, and the electrode elements are made in the form of wires overlapping the windows of the frames with the formation of them gaps and fixed on the frame with their own ends, and the electrode elements of the opposite frames are perpendicular to each other.