EP0905840B1 - Lightning current withstanding arrester - Google Patents

Abstract

The lightning current path consists of numerous arcing sections in series. The sections consist of n-part arcing sections, and are in series, so the arcing voltage is n-times the voltage of the part arcing sections. The arrangement preferably has graphite electrodes separated by PTFE insulating material. The arcing sections are preferably located in an epoxy resin molded housing.

Description

The invention relates to a lightning current carrying Spark gap with several series connected Radio links.

When lightning strikes a building with a Low voltage power supply flows a high brief lightning current over the metallic Structures down to earth. During this brief Lightning current becomes the potential of normal operation metallic parts (called Earth) briefly increased by values of a few 100 kV. This potential increase of the earth as a result of a Lightning strikes is caused by the fact that the Lightning current as an impressed current into the earth must flow into it and at the same time finite Earth resistance causes a voltage drop. The There are heads of the low-voltage power supply on the potential provided by the energy supplier towards the earth. These run in normal operation Conductor therefore the nominal voltage. By the lightning current Potential increase highlighted at the earth resistance there is now a brief surge voltage between the Earth and the ladders, which are the difference of the Potentials between earth and conductor results. Will that Potential of the main equipotential bonding bar by a few 100 kV raised, the electrical strength of the Isolation between the conductors and the earth exceeded and there is a rollover by the Air insulation route and to break through the Isolation of the lines. The consequence of this rollover or breakdown is a three-pole short circuit of the Low voltage power supply. Through the three-pole Short circuit becomes a connection to the feeder Cable made so that part of the embossed Lightning current can flow into this cable.

The remaining part continues to flow into the earth.

ein freibrennender Lichtbogen in der Niederspannungsverteilung oder in dem einspeisenden Kabel,

eine mögliche Vorschädigung eines Kabels oder Gerätes mit einem festen Isolierstoff mit der Gefahr eines späteren Schadens durch langsame Zerstörung der Isolation durch Teilentladungen oder Kriechströme,

Ausbreitung einer Druckwelle durch den Lichtbogen,

Gefahr eines Feuers durch Entzündungen von Isolierstoffen in dem heißen Lichtbogen.

The effects of this three-pole short circuit are

a free-burning arc in the low-voltage distribution or in the feeding cable,

possible pre-damage to a cable or device with a solid insulating material with the risk of later damage due to slow destruction of the insulation by partial discharges or leakage currents,

Propagation of a pressure wave through the arc,

Danger of fire due to ignition of insulating materials in the hot arc.

A line follow current flows with line frequency and one Height from a few kA to a few 10 kA, depending on the Distance of the building from the next Transformer station and the feed-in power.

The upstream fuse becomes the three-pole Disconnect short circuit from the mains, causing the power supply fails. It can only be replaced by the Main network backup by the Energy supply companies put back into operation become.

To avoid damage due to lightning strikes in spark gaps are known in a building. Such Spark gaps become transient equipotential bonding used, with the subsequent line follow current is deleted. All previous solutions are based on that the spark gap at a lightning surge is ignited, the lightning current between earth and conductor to ensure a low voltage drop along of the arc is derived or conducted, the Mains sequence current is conducted and deleted and a The spark gap is reconsolidated.

DE 42 40 138 A is a spark gap generic type known. From this publication a multiple spark gap known from Partial spark gaps with high and low impedance Insulations exist and their rollover distance with increasing number of partial spark gaps increases. This Arrangement has the disadvantage that when igniting of the spark gap with the high-resistance insulation the tension on everyone else low Spark gaps are present, so that the entire Breakdown voltage of the entire spark gap equal to that n times the breakdown voltage of the high-resistance Spark gap is. The whole tension is, so to speak divided over many spark gaps. The spark gaps switch through simultaneously.

FR 1 539 445 A1 describes a series connection of Spark gaps with a voltage-dependent resistance known, with ohmic resistances to the spark gaps are connected in parallel and to the first spark gap a capacitance is connected in parallel. The control of the Voltage distribution is thereby through the parallel switched capacitor to the first spark gap like this switched that a dependency of Stress distribution from the Voltage rise rate of the applied voltage occurs. In the event of an event, the spark gaps switch again at the same time.

Based on this state of the art Invention based on the object spark gap capable of carrying lightning current of the generic type to create a grid follow current completely or at least partially suppressed.

The solution to this problem is in the claims specified.

The spark gap capable of carrying lightning current according to the invention is based on the basic idea of arc quenching Multiple interruption of the arc with the help of a Multiple spark gap. The voltage drop at the anodes and cathodes of the partial spark gaps Multiple spark gap for arc quenching and this prevents the follow-up current exploited. The extinguishing effect can be done in the usual way can be increased in that the spark gap in one sealed housing is installed. The Quenching can also be done by blowing the arc be increased with cold gas.

In the spark gap according to the invention a lightning strike initially caused by the surge between PE (earth) and the live conductors ignited when the response voltage of the Multiple spark gap is reached.

According to the invention, the arc is divided into multiple arcs. The proposed multiple spark gap uses the effect of dividing the arc into several partial spark gaps, so that the anode and cathode drop (voltage drop, in particular at the arc base points on the anode and cathode) of the individual spark gaps is added. The total voltage drop across the multiple spark gap can therefore be described by the following relationships: U = nx U _AK . N is the number of spark gaps of the multiple spark gap and U _{AK is} the anode or cathode case of a partial spark gap of the multiple spark gap.

To have a relatively low response voltage of for example not to exceed a maximum of 4 kV the first spark gap and its anode and cathode spaced such that a corresponding Response voltage is reached.

In the case of the invention Multiple spark gaps the voltage is shared by all Partial spark gaps on. By the invention Resistor circuit of the multiple spark gap is achieved that at the top (input) Partial spark gap the potential of the earth is present. As soon as this first partial spark gap has ignited, a current flows across the resistors, which are graded decrease, for example decadal or preferably logarithmic. This ensures that after Ignition of the first partial spark gap almost the entire Voltage is on the second spark gap and this ignites immediately. This will be advantageous ultraviolet radiation of the spark channel in the first Partial spark gap to provide the Starting electrons in the following Partial spark gap used. This effect continues until to the last partial spark gap.

After ignition, a short circuit current flows and at everyone Spark gap (anode-cathode case) builds up high voltage drop due to the large number the spark gap summed up, so that according to the Number of spark gaps the arc voltage is greater than the mains voltage, so that no Mains sequence current arises.

The formation of the first spark gap is decisive for the responsiveness. On the chain of Spark gaps become the tension of each Partial arcs added up so high in total that they is higher than the mains voltage, so that actually none Mains sequence current arises.

The multi-spark gap can also be used with a Sliding discharge arrangement for reducing the Ignition delay time of the partial spark gaps in combination with the corresponding resistor circuit be equipped. The sliding discharge arrangement exists from one arranged along the spark gaps Layer of an insulating material, in which a metallic Film or the like is let in on Earth potential is. By introducing the grounded Foil near the electrodes of the partial spark gaps the electric field in the partial spark gaps distorted, and there is formation of Sliding discharges on the surface of the insulating material between the electrodes and the partial spark gaps.

It is known that the electrodes of spark gaps from metals such as copper, tungsten copper or the like Metals, after exposure to high Lightning currents on the surface Meltings show that there is metallic vapor on the surface of adjacent insulation arrangements reflected. These effects reduce the Life span of such a spark gap. To avoid of the disadvantages of the metallic electrodes according to the invention an electrode made of graphite proposed. The partial spark gaps of the Multiple spark gaps are therefore preferably made Made of graphite. Because of the low metal burn-up when exposed to lightning currents up to 200 kA graphite is particularly suitable for this application. Even after repeated exposure to lightning impulse currents remains the surface of the electrodes of the Multiple spark gap clean and keeps its shape. This ensures that the response voltage of the Spark gap remains within the permissible spread. The spark gap is preferably made of cylindrical or cube-shaped electrodes built up by an insulating film or washer heat-resistant material, especially PTFE or Ceramics, insulated from each other. Through the Training of sharp-edged electrodes is used Provision of starting electrons by detaching the improved electrons attached to molecules. This can by the response voltage and their statistical scatter can be significantly reduced. By appropriate designs of the Parallel plate spark gap, for example with large area electrodes, will be a big one created field-filled volume, from which Voltage stress on the starting electrodes to be provided. By the enlarged field-filled volume becomes the response voltage and their scatter significantly reduced.

In the drawing, embodiments of the Invention shown in principle and in more detail below described.

Figur 1

die Prinzipdarstellung der Widerstandsbeschaltung einer Mehrfachfunkenstrecke;

Figur 2

den geometrischen Aufbau einer Mehrfachfunkenfunkenstrecke mit einer Gleitentladung;

Figur 3

eine Blitzstromfunkenstrecke mit achtstufiger Mehrfachfunkenstrecke mit ohmscher Steuerung.

It shows:

Figure 1

the schematic diagram of the resistor circuit of a multiple spark gap;

Figure 2

the geometric structure of a multiple spark gap with a sliding discharge;

Figure 3

a lightning current spark gap with eight-stage multiple spark gap with ohmic control.

A spark gap is shown in FIG a head of the power supply network and at II an earth is connected. There are one Variety of spark gaps in series with each other arranged (FS1 to FSN). Here are the Partial spark gaps FS2 to FSN with the exception of those in Lightning current event case first appealing Spark gap FS1 through a graded network of ohmic resistors connected, so that Partial spark gaps FS2 to FSN successively by turn. The network of resistors shows in Switching direction decreases resistance values. So For example, the resistance R2 can be 10 kilohms Resistor R3 1 kilohm, resistance R4 100 ohms Resistor R5 10 ohms and resistance Rn X ohms exhibit. The resistors can preferably decrease logarithmically. To the cathode and anode everyone Partial spark gap FS2 to FSn is a resistor R2 to Rn connected in parallel and the resistances of all Partial spark gaps R2 to Rn are in series on earth (II) connected. As can be seen particularly from FIG. 3, spark gap electrodes 2 made of graphite are provided, that by insulating washers made of PTFE from each other are spaced. At 4 is a connection of one Control resistor shown. With 5 is a housing shown, which surrounds the entire unit. At 6 is the power connection shown. At 8 there is a busbar to connect the two spark gap blocks, the are arranged parallel to one another in the housing 5, shown. The control resistors 10 are also in one protected space inside the insulating housing arranged. With 11 is another insulating plate shown. With 1 contact springs are shown, by means of which is the contacting link to the Spark gaps occur. The electrodes 2 of the Spark gaps are preferably cylindrical or cuboid, sharp-edged elements. In the The embodiment according to FIG. 3 is the entire one Spark gap from two arranged parallel to each other Blocks of the same number of partial spark gaps.

In the embodiment according to FIG Multiple spark gap with one Sliding discharge ignition aid coupled. The Sliding discharge ignition aid consists of a longitudinal arranged parallel to the spark gaps FS1 to FSN Layer 12 of insulating material, for example PTFE, in which is a metallic conductor 13, in particular one metallic foil, is embedded. This slide is at 14 connected to earth potential. At 15 there is one Sliding discharge shown as the first pre-discharge ignites before the main discharge 16 as a result of first sliding discharge ignites. As a result, the ignites second sliding discharge as second pre-discharge (17) whereupon the next main discharge 18 as a result of the second sliding discharge ignites. The process continues continue analogously. The spark gaps FS2 to FSN are included Control resistors R2 to Rn connected.

The distance between the first spark gaps is FS1 decisive for the response behavior of the Total radio link. On the chain of spark gap FS1 until FSN is such a high arc voltage generates that this is greater than the mains voltage, so that there is no follow-up current.

The invention is not based on the embodiment limited, but often within the scope of the disclosure variable.

All new, in the description and / or drawing disclosed single and combination features are considered viewed essential to the invention.

Claims (15)

1. A discharger which can withstand lightning current, having several dischargers connected in series, wherein the discharger consists of n component dischargers (FS), the arc-drop voltage of which, by connecting the component dischargers (FS) in series, is brought to the n times value of the arc-drop voltage of a component discharger,
   characterised in that the component dischargers (FS), with the exception of the first discharger (FS1) responding in the event of a lightning current, are connected by a graded network of ohmic resistors, so that the component dischargers successively interconnect,
   and in that the network of resistors has resistances which decrease in the connection direction.
2. A discharger according to Claim 1,
   characterised in that the arc-drop voltage of the component dischargers (FS) is in total higher than the mains voltage of the protected mains.
3. A discharger which can withstand lightning current according to one of Claims 1 or 2,
   characterised in that linear or non-linear impedances are provided instead of the ohmic resistors.
4. A discharger which can withstand lightning current according to one of Claims 1 to 3,
   characterised in that the resistances do not decrease linearly.
5. A discharger which can withstand lightning current according to one of Claims 1 to 4,
   characterised in that the resistances decrease decimally.
6. A discharger which can withstand lightning current according to one of Claims 1 to 4,
   characterised in that the resistances (R) decrease logarithmically.
7. A discharger which can withstand lightning current according to one of Claims 1 to 6,
   characterised in that a resistor is switched in parallel to the cathode and anode of each component discharger (FS), with the exception of the input discharger (FS1), and the resistors (5) of all component dischargers are switched in series and to earth.
8. A discharger which can withstand lightning current according to one of Claims 1 to 7,
   characterised in that the electrodes of the component dischargers (FS) are made from graphite.
9. A discharger which can withstand lightning current according to one of Claims 1 to 8,
   characterised in that the electrodes of the partial dischargers (FS) consist of cylindrical or cuboidal elements.
10. A discharger which can withstand lightning current according to one of Claims 1 to 9,
    characterised in that insulating sheets or insulating washers (3), in particular made from heat-resistant material, preferably from PTFE (polytetrafluoroethylene) or also from ceramics, are disposed between the electrodes (FS).
11. A discharger which can withstand lightning current according to one of Claims 1 to 10,
    characterised in that the discharger (FS) consists of several mutually parallel blocks, preferably of the same number, of component dischargers (FS).
12. A discharger which can withstand lightning current according to one of Claims 1 to 11,
    characterised in that the component dischargers (FS) are combined with a sliding discharge ignition aid.
13. A discharger which can withstand lightning current according to Claim 12,
    characterised in that the sliding discharge ignition aid consists of a layer of insulating material (12) disposed longitudinally parallel to the dischargers (FS), into which a metal conductor (13), in particular a metal foil, is embedded, which is laid at earth potential.
14. A discharger which can withstand lightning current according to one of Claims 1 to 13,
    characterised in that the dischargers (FS) are disposed in a housing filled with sulphur hexafluoride or in chambers filled therewith.
15. A discharger which can withstand lightning current according to one of Claims 1 to 14,
    characterised in that the dischargers (FS) are disposed in a housing sealed with insulating material, in particular epoxy resin.

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