EP2074686A1

EP2074686A1 - Spark gap arrangement for higher rated voltages

Info

Publication number: EP2074686A1
Application number: EP08831279A
Authority: EP
Inventors: Arnd Ehrhardt; Michael Waffler; Stephan Hierl; Werner Riel
Original assignee: Dehn and Soehne GmbH and Co KG
Current assignee: Dehn SE and Co KG
Priority date: 2007-10-15
Filing date: 2008-10-14
Publication date: 2009-07-01
Anticipated expiration: 2028-10-14
Also published as: WO2009050148A1; DE102008049471A1; EP2074686B1; ATE456875T1; DE502008000350D1

Abstract

The invention relates to a spark gap arrangement for higher rated voltages in which at least two opposite spark gaps comprising electrodes are serially connected and at least one of the spark gaps is introduced actively, i.e., may be triggered, for use as a network arrester that can conduct lightening currents. According to the invention, the spark gaps are located in a pressure-resistant capsule with at least one pressure compensation opening. Also, an insert that bridges the distance between the main electrodes of the passive spark gaps, consisting of a low-impendence material, is provided. Said low impendence material is extremely non-linear in relation to the decreasing residual voltage in the event of a current load.

Description

Spark gap arrangement for higher rated voltages

description

The invention relates to a spark gap arrangement for higher rated voltages, wherein at least two, opposite electrodes having spark gaps are connected in series and at least one of the spark gaps active, d. H. Triggerable designed for use as a lightning current carrying Netzabieiter, according to the preamble of claim 1.

A series circuit of two spark gaps for the limitation of surges in low-voltage systems, consisting of three electrodes, wherein for the creation of each spark gap two of these electrodes are each opposite to a surface and are held apart by an insulating layer from each other, is known from DE 39 14 624 C2 previously known. The local spark gaps have a very different inherent capacity, whereby the response voltage of the overall arrangement is determined essentially by the spark gap with the smaller capacity.

From DE 42 40 138 Al a Ausblasende spark gap is already known, in which one or more spark gaps are connected in series with a low spark gap with insulation material in series with low-resistance material. In this case, the spark gap with the insulating material defines the response voltage of the overall arrangement.

In the multiple-spark gap capable of carrying lightning current according to EP 1 381 127 A2, it is assumed that several partial spark gaps are connected in series, the partial spark gaps being connected by impedances, with the exception of the first spark gap which responds in the lightning current event, so that these are successively switched through. The second and the further spark gaps are connected via the impedances directly to a common reference potential. With the spark gap presented there, the response voltage should be reduced. For this purpose, a trigger voltage is applied to at least the electrodes of one of the partial spark gaps, by means of which the partial spark gap is forced to switch through. Similar arrangements with several partial spark gaps are disclosed in WO 07/003706 and US 4,860,156 Bl for high voltage applications.

From DE 10 2004 006 988 Al, a spark arrestor overvoltage protection element with at least two main electrodes located in a pressure-tight housing and an auxiliary starting electrode is previously known, wherein a functional subassembly for reducing the response voltage is accommodated in the housing volume. This functional module comprises a series connection of a voltage-switching element, an impedance and an isolating distance, so that a simplified, quasi-integrated starting aid is created.

In summary, it belongs to the known state of the art to make spark gaps suitable for use at higher rated voltages by series connection. A simple series connection leads to triggerable spark gaps in addition to the considerable costs to restrictions in terms of protection level and the coordination of the arrester and usually requires an additional complex potential control.

From the above, it is therefore an object of the invention to provide a further developed spark gap arrangement for higher rated voltages, wherein at least two, opposing electrodes having spark gaps are connected in series and at least one of the spark gaps active, d. H. Triggerable is executed. According to the invention, only the triggerable, ie active spark gap of the overall arrangement should dominate with regard to the response behavior and the coordination. When line sequencers occur, the arrangement should act like a conventional series of spark gaps. The arc voltage is composed of the partial voltages of the two spark gaps and it is divided even after the current zero crossing the recurrent mains voltage on the spark gaps. Thus, it is the task to ensure a load-dependent division of functions between the triggered and the passive spark gap. The object is achieved by a spark gap arrangement according to the feature combination according to claim 1, wherein the dependent claims represent at least expedient refinements and developments.

In the series connection according to the invention spark gaps are used, which are located in a flameproof enclosure and which have at least one pressure equalization opening. Furthermore, the distance between the main electrodes of the passive spark gap bridging insert is provided, which consists of a low-resistance material. This material behaves strongly under current load with respect to the decreasing residual voltage nonlinear.

In a first embodiment variant, the series connection is formed from two physically separated spark gaps, one of the spark gaps being triggerable and the second spark gap being passive. In a further embodiment, the spark gaps are accommodated in a common, pressure-resistant, preferably metallic housing.

The spark gaps preferably used are rotationally symmetrical. The respective opposing main electrodes comprise a main electrode with Gasumlenkkanal. With regard to the basic construction of the spark gaps used, reference is made to the teaching according to patent DE 10 2005 024 658 B4, to which reference is hereby made in full.

Between the opposing main electrodes of the at least one passive spark gap, the bridging, low-impedance insert already mentioned is arranged as a preferably rotationally symmetrical part with a cylindrical opening delimiting the arc combustion chamber. The main electrode opposite the main electrode with the gas deflection channel has a nose portion or a projection which dips into the cylindrical opening, with the wall coming into contact with it. It is understood that the nose portion is to be formed in its outer contour complementary to the shape of the cylindrical opening.

The low-resistance material of the insert preferably has a cold resistance of <100 ohms. The insert has in one embodiment, a hollow cylindrical shape and is located with one end face over the entire surface of the main electrode with Gasumlenkkanal.

Furthermore, there is the possibility that the preferably hollow-cylindrical insert, in each case with one of its end faces, is in contact with one main electrode in each case over its entire surface.

In this embodiment, the flashover between the main electrodes takes place only after a comparatively longer period of time or at very high pulse currents, which is particularly of interest when the residual voltage of the spark gap is to be above the nominal voltage at a plurality of pulse-shaped discharges to prevent a Netzfolgestrom ,

The clear distance between the respective main electrodes of the spark gaps is substantially greater than that which can be found in the known state of the art in corresponding series circuits, and is at least about 5 mm.

The pressure equalization openings are basically oriented in the axial direction of the rotationally symmetric spark gaps and are away from one another in order to prevent unwanted exposure of functionally important parts.

Between the rotationally symmetric part with cylindrical opening and the main electrode with nose section, in a further embodiment, a transition part may be provided which has a higher resistance value relative to the insert, but is conductive.

The geometric shape of the insert can be subjected to changes in the radial and / or axial direction for adjusting and varying the current density, so that in the preferred rotationally symmetrical basic construction and a desired modular structure by replacing the insert various electrical parameters can be realized. In an arrangement of two spark gaps in a common, pressure-resistant housing, a common central main electrode is preferably provided, which in this case is insulated from the jacket encapsulation.

The pressure compensation openings are designed axially and opposite in the region of the external contact of the respective main electrode as channels of small cross section for the slow pressure reduction of the already cooled gas. Reference is also made to the patent application DE 10 2007 001 093.3, which is herewith explained and introduced to the subject of the present application, also with regard to the design of the pressure equalization channels and the meandering deflection of the gas flow.

The external trigger circuit for igniting the active spark gap is guided on the trigger electrode of this active spark gap and on the electrical end connection points of the series connection.

In summary, it is possible with the proposed spark gap standard standard spark gaps in encapsulated, pressure-resistant design with pressure equalization openings for higher nominal voltages through series connection, in a simple basic variant, only a single triggered spark gap is connected in series with a single passive spark gap. In the teaching of the invention, the necessary follow current limiting is achieved by increasing the arc field strength due to the pressure increase or in combination with the arc cooling by flowing the arc within encapsulated spark gaps. The distances between the main electrodes are at least 5 mm. The low-resistance material of the insert is located within the passive spark gap directly in the region of the arc channel and radially or completely limits the wall-stabilized arc.

The material that bridges the distance between the main electrodes of the passive spark gap, has a cold resistance of less than 100 ohms and behaves at current load with respect to the falling residual voltage is highly linear, ie the voltage drops despite further increasing current. The material used can momentarily pulse-shaped currents of several kA without lasting damage lead to overturning. The resulting residual voltage is well below 2 kV. The height and the duration of the residual stress can also be set or influenced by influencing the current density distribution in the material itself, by the geometric design of the insert or else by a functional subdivision from a plurality of materials.

The inventive passive spark gap does not affect the response, coordination and residual voltage behavior of the entire series connection. The subdivision into partial spark gaps reduces the thermal and dynamic load on each single spark gap and there are many design options. The performance of the series-connected lightning arrester is improved in terms of follow current limiting, lightning current carrying capacity and aging. Compared to a series connection of two triggerable arresters, there is the advantage that both space and costs for the second or multiple ignition units can be saved. In a conventional series connection of triggerable spark gaps namely either a simultaneous ignition must be done, which makes high demands on the spark gaps, the trigger circuit and the potential control, or the trigger circuit must be able to compensate the Zündverzugszeiten the individual spark gaps, since usually trigger circuits only one time and energy provide limited ignition pulse. By using one or more passive spark gaps in the embodiment of the series connection according to the invention, the costs for additional ignition circuits can be saved.

The invention will be explained below with reference to exemplary embodiments and with the aid of figures.

Hereby show:

Figure 1 is a series circuit of a triggered spark gap and a passive, ungetriggered spark gap as discrete elements in each flameproof enclosure. FIG. 2 shows an exemplary geometry of a passive spark gap as used for the series connection according to the invention; FIG.

Fig. 3 shows another embodiment of a geometry of a passive

Spark gap as used in the series connection according to the invention;

4 shows a particularly space-saving arrangement of a triggered and a passive spark gap in a common, metallic flameproof enclosure with opposite pressure equalization openings in the form of channels of small cross section; and

Fig. 5 exemplary embodiments of the insert or spacer.

The Fig. 1 shows a series connection (sectional representation) of a triggered spark gap 1 (active spark gap) and an ungetriggered (passive) spark gap 2.

The trigger circuit 3 of the active spark gap 1 has a connection 4 which is connected to a connection 5 of a main electrode 8 of the passive spark gap 2. Another connection of the trigger circuit 3 leads to the main electrode 8 of the active spark gap 1, which also has the trigger contact through an insulation 20, led out of the pressure-resistant metallic encapsulation 21.

Pressure compensation openings 6 of the spark gaps 1 and 2 and the gas flow direction 7 (arrow) within the spark gaps 1 and 2 are oriented opposite.

Both spark gaps 1 and 2 each have a plurality of independent ventilation openings 6 for better control of the flow and for effective cooling of the gases formed during ignition and firing of the arc. In each case one of the main electrodes 8 has an opening 22, which forms part of a Gasumlenkkanals, which merges into the pressure equalization openings 6. The triggerable spark gap 1 has two main electrodes, namely the main electrode 8 and 9, as well as a H ilfselde 10, which is in electrical connection with the trigger contact 20.

Furthermore, the spark gap 1 has at least one insulation gap 12, which is located between the main electrodes 8 and 9 of this spark gap.

The passive spark gap 2 also has two main electrodes 8 and 9. A trained as a spacer 13 insert between the main electrodes 8 and 9 of the passive spark gap is preferably made in one piece from a very low-resistance material. With a preferred geometry of da = 15 mm, di = 5 mm and h = 5 mm results in a test current of a few mA, a cold resistance of <100 ohms.

The spacer 13 is preferably designed as a hollow cylinder and is according to the illustration of FIG. 1 with one of its end faces over the entire surface on the main electrode 8. In the interior of the insert 13, d. H. the existing there cylindrical opening, protrudes a nose portion 23 of the main electrode 9, whereby a radial contact with the insert or the spacer 13 results.

In order to avoid flashovers in the contacting region between the nose section 23 of the main electrode 9 and the plate-shaped electrode holder 14, the spacer 13 is insulated therefrom by the part 15.

The immersion depth of the nose portion 23 of the electrode 9 in the spacer 13 increases with the desired level of performance of the arrester and decreases with increasing erosion resistance of the electrode material. The immersion depth is in this case dimensioned such that both the axial burnup of the nose electrode 9 and the radial erosion of the spacer 13 do not lead to an insulating separation path between the parts 13 and 9. After the response of the spark gap 1 at pulse load, a current flows up to several kA via the spacer 13 until the path between the electrodes 8 and 9 of the passive spark gap 2 is skipped. Due to the non-linear behavior of the material of the spacer 13 is generates only a small residual stress on the material of the spacer 13, which does not increase the protection level of the entire arrester.

However, due to manufacturing and material tolerances, contamination or extreme stress contact problems or a changed rollover behavior of the spacer 13 may occur, which may result in undesirable repercussions on the residual stress of the arrester. This can be compensated for high demands on the height and duration of the residual voltage of the arrester by an integrated in the trigger circuit 3 overvoltage fine protection and by the type of contact, which includes the passive spark gap.

With reproducible manufacturing and material properties or not particularly high stresses and / or lower demands on the protection level, the contacting of the trigger device between the two spark gaps, so only at the terminals of the spark gap 1, take place.

The height and duration of the current through the spacer 13 as well as the rollover behavior can be influenced by the control of the current density and the current distribution in the spacer 13 in addition to the material properties of this part. In addition to influencing the residual stress, this can also be used to control the power conversion, the burnup and the thermal load on the spark gap and in particular of the insert 13. The main electrodes 8 and 9 of the passive spark gap 2 can be completely or partially isolated from the spacer 13. The partial isolation serves to control the current transition region to affect the current density distribution and the flashover speed. The complete isolation of the electrodes 8 and 9 with respect to the spacer 13 serves the same purpose, d. H. the concentration of the current density in the preferred flashover area, in particular in the inner tube of the spacer.

In addition, a spark generation is realized during the overturning of the insulation gap, which causes ionization, whereby the flashover is promoted. The isolation, however, is designed so that the Breakover voltage does not affect the response voltage and residual voltage of the spark gap. Furthermore, the flashover voltage is so low that when the mains voltage is applied, the passive spark gap would always respond without series connection with the triggerable spark gap. Thus, this is virtually controlled and permanently loaded with electricity to burn. It follows that after ignition of the triggerable spark gap, the passive spark gap itself only at mains voltage current. The insulation is thus virtually absent and it ignites the passive spark gap with insulated electrodes as well due to the immediate current flow as well as without isolation. The function is identical to this. Only the current density distribution and the ionization lead to a rapid ignition of the main line of the passive spark gap.

The Fig. 2 shows an exemplary geometry as a cross-sectional representation for a passive spark gap. Again, two opposite main electrodes 8 and 9 are present. The electrodes are isolated in a metallic enclosure 21 located.

The main electrodes 8 and 9 shown can also be isolated from the insert 13, but the breakdown voltage of the insulation must be well below the desired protection level and below the residual voltage of the trigger circuit.

As an alternative to insulation, a defined transition region with a thin and with respect to the spacer 13 high-resistance, but electrically conductive layer 16 is possible. Both measures described require a higher current density at the quasi-channel inside of the designed as a hollow cylinder spacer 13 and lead to an accelerated rollover behavior. In addition, a pre-ionization in the isolated or high-impedance range is effected.

The spacer 13 can also be varied in the circumference of the hollow cylinder in both the radial and in the axial direction with respect to the electrical conductivity. In this way, in addition to the control of the electric current density in the spacer 13 and effects of thermal insulation with respect to the electrodes 8 and 9 are effected. In addition, the Variation of the materials used in the discharge channel of the division of functions or used to influence the temperature and pressure resistance and the better aging quality and to reduce the burnup.

The Fig. For example, FIG. 2 shows a substantially axial function distribution here. In contrast to the illustration of FIG. 1 are shown in FIG. 2 the two electrodes 8 and 9 (in Fig. 1 only 9) with respect to the metallic encapsulation 21 isolated.

The Fig. 3 shows another embodiment of a possible geometry in cross-sectional representation for the passive spark gap 2.

In this spark gap 2, a flashover between the main electrodes 8 and 9 should be done only at a comparatively long period of time or very high pulse currents.

This is of particular interest if the residual voltage of the spark gap 2 is to be above the nominal voltage in the case of a large number of pulse-shaped discharges in order to prevent a line following current.

For this purpose, the spacer 13 is contacted over its entire surface at both end faces with the respective main electrodes 8 and 9 in order to bring about a largely homogeneous current density within the spacer 13. In addition, increases in the electric field strength, in particular in the rollover area can be avoided.

With the help of Fig. 4 illustrates a basic embodiment of two spark gaps in a cross-sectional view, which are located within a common metallic encapsulation 21.

Both spark gaps have a common center electrode 9, which is insulated from the flameproof enclosure 21. In the area of the passive spark gap 2, however, there is a low-resistance connection between the center electrode 9 and the main electrode 8 there. In contrast to the illustration of FIG. 1, in which at both spark gaps 1 and 2 In each case, the main electrode 8 is in direct contact with the metallic shell 21, at least in one of the spark gaps 1 and 2 as shown in FIG. 4, both main electrodes with respect to the jacket or the enclosure 21 is isolated.

According to the illustration of FIG. 4, this is the case with the passive spark gap 2. Alternatively, it is also possible to carry out the spark gap 1 or even both spark gaps with main electrodes 8 and 9 which are insulated with respect to the metallic encapsulation 21. The insulation of the main electrodes 8 and 9 is preferred over an insulating interruption of the pressure-resistant metallic shell 21 due to a better overload behavior. The spark gaps according to FIG. 4 have as well as in Fig. 1, opposite venting and pressure equalization openings or channels 6.

The main electrodes each have at least a distance of substantially 5 mm in both spark gaps 1 and 2. The pressure in the discharge region, which is completely or partially enclosed by the insert 13, is up to several 100 bar in the case of impulse and subsequent static discharges. For prospective net sequence currents in the range of> 500 A to several kA, pressures of at least 10 bar are achieved.

To control the operating voltage and to ignite the spark gaps no complex and overload-endangered, external, additional capacitive or resistive voltage control is required, which would also need to be tuned over the entire relevant frequency range. The illustrated series circuit of two spark gaps can basically be extended as desired.

The series connection of a spark gap with insulation and a quasi-shorted spark gap has compared to two spark gaps, each with isolated separation distance per se the disadvantage that only one separation section provides an immediate consolidation after the current zero crossing. The instant solidification voltage is in the range of about 300 V. In the use of such a spark gap at higher operating voltages, in particular at voltages above the instant solidification exists the danger of reignitions. In order to be able to work with only one insulation distance, despite this disadvantage, the effect is used that the spark gaps used make use of the pressure increase that forms to delete the secondary current. By using the pressure to extinguish the follow-on current, even after the current zero crossing, in particular with a gradual pressure reduction, it is possible to make the relatively high pressure effective for increasing the dielectric strength of the separation gap. The voltage resistance after the current zero crossing can thus be increased proportionally with the pressure increase, whereby reignifications are avoidable. This surprisingly allows the use of the proposed spark gap combination even at nominal voltages well above the instantaneous consolidation voltage for a separation line.

With the help of Fig. 5, an exemplary construction of the spacer will be explained in more detail.

The material of the spacer can be homogeneous, but also inhomogeneous. So z. B. a radially decreasing conductivity (Fig. 5a) can be realized. It is also possible to carry out a segmented conductivity in the periphery down to conductive webs (see Fig. 5b and 5c). The region 1 is a high-impedance region, while the region 2 is low-resistance. If the spacer 13 is made homogeneous, the current density can be determined or adjusted by the electrically conductive contact surface and the positioning of this contact surface.

If z. B. as shown in FIG. 1 on the side of the cylinder electrode, the contacts between the spacer 13 and the part 8 are reduced, for. B. by a smaller inner radius of the disc or the insulating film on the part 8, less current flows in the spacer 13 until the flashover, since the current density in the interior of the part 13 increases. When referring to FIG. 1 limited on the side of the nose electrode, the contact area between the parts 12 and 23 only to a limited height and the contact in the circumference, the current density increases in the inner tube region, ie in the discharge region of the spacer 13. A lower current density is z. B. achieved at the end-face support of the part 13 on the plate of the electrode holder 14.

LIST OF REFERENCE NUMBERS

1 active spark gap

2 passive spark gap

3 trigger circuit

4 connection

5 Connection of a main electrode

6 pressure compensation opening

7 gas flow direction 8; 9 main electrode

10 auxiliary electrode

12 isolation route

13 insert or spacer

14 plate-shaped electrode holder

15 insulation part

16 high-resistance, electrically conductive layer

20 Isolation for trigger contact

21 metallic, flameproof enclosure

22 opening in Gasumlenkbereich a main electrode / Gasumlenkkanal

23 nose section

Claims

claims

A spark gap arrangement for higher rated voltages, wherein at least two opposing spark gaps are connected in series and at least one of the spark gaps is active, d. H. triggerable is designed for use as a lightning current carrying power line arrester, characterized in that the spark gaps (1; 2) in a pressure-resistant enclosure (21) with at least one pressure equalization opening (6) are located and a distance of the

Main electrodes (8; 9) of the passive spark gap (2) bridging

Insert (13) consists of a low-resistance material, which is in

Current load with respect to the falling residual voltage strongly non-linear behaves.

2. Spark gap arrangement according to arrangement 1, characterized in that the spark gaps (1, 2) are each surrounded individually by a flameproof enclosure (21), wherein the pressure equalization openings (6) are oriented away from one another.

3. spark gap arrangement according to claim 1, characterized in that the spark gaps (1, 2) by a common, pressure-resistant housing (21) are surrounded, which has the pressure equalization openings (6).

4. Spark gap arrangement according to one of the preceding claims, characterized in that the spark gaps (1; 2) are rotationally symmetrical and the respective main electrodes (8; 9) are opposite and one of the main electrodes (8) has a gas deflection channel (22) between the opposing main electrodes (8; 9) of the at least one passive spark gap (2) the bridging low-resistance insert (13) is arranged as a rotationally symmetrical part with cylindrical, the arc combustion chamber bounding opening, wherein the main electrode with Gasumlenkkanal (22) opposite the main electrode ( 9) one Nose portion (23) which dips into the cylindrical opening, with the wall coming into contact.

5. Spark gap arrangement according to one of the preceding claims, characterized in that the low-resistance material of the insert has a cold resistance value of <100 ohms.

6. spark gap arrangement according to one of the preceding claims, characterized in that the insert (13) has a preferred hollow cylindrical shape and with an end face over the entire surface of the main electrode with Gasumlenkkanal (22).

7. spark gap arrangement according to one of the preceding claims, characterized in that the preferably hollow cylindrical insert (13) with one of its end faces over its entire surface in contact with each of a main electrode (8; 9).

8. spark gap arrangement according to one of the preceding claims, characterized in that the clear distance between the respective main electrodes (8; 9) of the spark gaps is in the range of at least 5 mm.

9. spark gap arrangement according to one of claims 4 to 8, characterized in that the pressure equalization openings (6) are oriented in the axial direction of the rotationally symmetrical spark gaps.

10. spark gap arrangement according to claim 4, characterized in that between the rotationally symmetric part with a cylindrical opening and the main electrode with nose portion (23), a transition part (16) is provided which relative to the insert (13) has a higher resistance and is conductive.

11. spark gap arrangement according to one of the preceding claims, characterized in that the insert (13) in the radial and / or axial direction in its geometric shape for adjusting the current density is variable.

12. spark gap arrangement according to one of claims 3 to 11, characterized in that in an arrangement of two spark gaps in a common flameproof enclosure (21) a common central main electrode (9) is provided, which has an insulation against the jacket enclosure (21) ,

13. spark gap arrangement according to claim 12, characterized in that the pressure equalization openings (6) axially and oppositely in the region of the external contacting of the respective main electrodes are designed as channels of small cross section for slowly depressurizing the already cooled gas.

14. Spark gap arrangement according to one of the preceding claims, characterized in that the external trigger circuit (3) leads to the trigger electrode (10) of the active spark gap (1) and to the electrical end connection points of the series connection.