Arc quenching chamber and surge arrester with such a

Abstract

Arc quenching chamber for a surge arrester with: a plurality of deionizing quenching plates or quenching discs (10) which are spaced apart in such a way that a plurality of channels (17) are formed for receiving arc-induced gases, wherein the quenching plates (10) have a slot-shaped inlet area (15) and furthermore a gas outlet area (16) exists through lateral and / or end-face openings (7, 8) between the quenching plates (10), wherein starting from the axis of symmetry of the arc quenching chamber, the gas outlet areas (16) between adjacent pairs of quenching plates are directed alternately to one or the other side or half of the chamber and separating webs (18) are formed for this purpose, and wherein the partial gas flows are only mixed in a common expansion chamber (19).

Description

The invention relates to an arc extinguishing chamber for a surge arrester and a surge arrester.Prior ArtDE 10 2005 015 401 A1 discloses a surge arrester having two diverging electrodes and a spark gap acting between the electrodes. According to the teaching there, the mobility of the arc immediately after its ignition is increased by a combination of measures for amplifying the arc-induced intrinsic magnetic field and a staggered gas circulation. In this regard, an arc quenching chamber specifically designed as a deion chamber is present, wherein design measures are implemented which permit gas circulation in a plurality of circuits having different functions. Both the gas flow from the arc chamber and any gas recirculation into the arc chamber takes place via at least two channels according to the known prior art. The return and cooling of the hot gases is preferably carried out laterally next to the arc chamber. The cooled gases are returned to a small extent directly in the arc ignition region between the diverging electrodes and their base and serve for deionization in this region.DE 10 2005 015 401 A1 relates not only to encapsulated surge arresters, but also discloses that openings to the environment and an arrangement for gas cooling can be provided.In order to reduce the risk of re-ignition according to DE 10 2005 015 401 A1 by hot gases, a quantity of gas passes through an additional region for intensive cooling. In this region, the gas is guided through narrow channels, preferably made of metal with a high heat capacity. In one embodiment, the deion plates introduced into the arc chamber have different height dimensions, so that the number of partial arcs is increased only gradually, i.e. with a time delay. According to DE 10 2005 015 401 A1, the inlet slots of the metal sheets can also be designed differently or asymmetrically in order to force a gradual splitting of the arc.The gas is discharged from the arc quenching chamber according to DE 10 2005 015 401 A1 both through lateral openings and on the upper side of the chamber. The escaping gas at the sides, but also the gas at the top, can be guided in separate channels which are insulated from one another. A return of the gas for closing the circulation can take place both in the ignition region through the electrodes and in the running region of the arc via openings present there.However, it has been found that a simple channel formation for gas guidance is not sufficient to avoid re-ignition. In the case of small space conditions in series installation devices, the hot gases emerge from the deion chamber in a relatively non-cooled manner and have a still considerable residual electrical conductivity. As a result, in the deion chambers of the prior art, individual metal sheets can sometimes be bridged by arcs. This is the case even with a completely insulated arc quenching chamber, since the resulting carbon blacking results in conductive channels which lead to the undesirable bridging mentioned above. This undesired formation of partial currents, which are of particular significance due to the encapsulation, reduces the arc voltage of a corresponding arrester and thus the resulting current limitation. While such phenomena are still insignificant at relatively low operating voltages, such as 230 V, the risk of a considerable impairment of function increases considerably at higher voltages, for example the linked voltage, that is to say at 440 V or at DC voltages.For this reason, lightning arresters with deion chambers for operating voltages of 440 V and more are designed exclusively to blow out. In order to be able to realize an adequate follow-on current limitation, the arc is divided in a targeted manner in these arresters, for example by a so-called splitter. The partial arcs are then each fed to a separate deion chamber with comparatively low capacity. Although the risk of bridging the arc chamber can be reduced by such a solution, the blowing-out behavior and also the outlay with a plurality of separate deion chambers and the space requirement required as a result are unacceptable. In this respect, reference is made to DE 44 35 968 C2.In addition, EP 0 231 733 A2 describes an arc quenching chamber having a plurality of quenching plates which are fixed in position by a holder, wherein outlet openings are provided in the holder, and wherein the outlet openings of adjacent gaps between the quenching plates are provided on opposite sides of the holder.From the above it is therefore the object of the invention to provide an improved arc quenching chamber which can also be used for increased operating voltages with a small size.It is a further object of the invention to provide a correspondingly further developed surge arrester.Disclosure of the InventionThe object of the invention is achieved by the arc quenching chamber for a surge arrester according to the combination of features according to Claim 1 and by the surge arrester according to Claim 9.Advantages of the InventionThe arc quenching chamber presented is used in particular in encapsulated surge arresters and in surge arresters according to the (damped) blowing principle. The surge arresters can be designed, for example, for diverting lightning currents. The spark gap formed in the surge arrester can be a horn spark gap. The solution presented can be used at higher operating voltages, but also at DC voltages. According to the invention, a flow of current through the hot gases or also the ignition of partial arcs outside the arc quenching chamber designed as a deion chamber is avoided by a separate and insulated guidance of the venting gases of the arc quenching chamber designed as a deion chamber. The special type of selective venting also extends the arc column between the individual deion plates and influences the running movement of the arc on the individual arc plates, whereby the arc voltage that can be achieved can be significantly increased compared to chambers of the prior art.According to one embodiment of the surge arrester, the surge arrester is encapsulated and the arc quenching chamber is designed such that a specific gas circulation within the encapsulation of the surge arrester can be predefined.In a further embodiment of the surge arrester, it is provided that a horn-shaped, diverging electrode arrangement in the sense of a horn spark gap is introduced into the above-mentioned encapsulation for forming the surge arrester, wherein the electrodes have recesses for realizing the gas circulation.In a further advantageous embodiment of the surge arrester, the separating webs are components of the encapsulation or of the housing of the overall arrangement in order to maintain a targeted gas guidance.In addition, in a further embodiment of the surge arrester, the electrode arrangement can laterally surround the arc quenching chamber. In this regard, the arc quenching chamber thus dips into the electrode interspace.According to one embodiment of the arc quenching chamber, the end faces of the quenching plates which form the slot-shaped inlet region are provided with an insulation cover, which can also be designed as a flow guide cover or flow guide device.In a preferred embodiment of the arc quenching chamber, this insulation cover has a comb-like shape or is designed in the form of a hood with comb-like flanks.In a further advantageous embodiment of the arc quenching chamber, the quenching plates consist of a ferromagnetic material.With regard to the hood having the comb shape, in one embodiment of the arc quenching chamber, a comb tooth can cover at least two adjacent quenching plates and the intermediate space bounded by them.The recesses between the respective comb teeth can correspond approximately to the width of the aforementioned intermediate space in one embodiment of the arc quenching chamber.Preferably, in an embodiment of the arc quenching chamber, the recesses between the respective comb teeth of the two opposite combs forming the cover are arranged offset by a space.Alternatively or additionally, in an embodiment of the arc quenching chamber, the design of the arc quenching chamber can be selected such that the area of the gas inflow region is substantially equal to the sum of the area of the lateral and / or end-side gas outflow openings.Brief Description of the DrawingsThe invention will be explained in more detail below with reference to an exemplary embodiment and with the aid of figures.The following are shown here: FIG. 1 shows a schematic sectional illustration of an encapsulated spark gap with an arc quenching chamber designed as a deion chamber and symbolically indicated internal gas circulation according to the prior art; FIG. 2a is a side view of an encapsulated spark gap according to a first embodiment of the arc quenching chamber designed as a deion chamber; FIG. 2 bshows a sectional illustration through the spark gap according to FIG. 2 a; FIG. 3 is a sectional view of a spark gap with damped blow-out behavior according to a second embodiment of the invention; FIG. 4 is a sectional view of a spark gap with damped blow-out behavior according to a third embodiment of the invention; FIG. 5 is a sectional view of a spark gap with damped blow-out behavior according to a fourth embodiment of the invention; FIG. 6 is a sectional view of a spark gap with damped blow-out behavior according to a fifth embodiment of the invention; FIG. 7 is a sectional view of a spark gap with damped blow-out performance according to a sixth embodiment of the invention; FIG. 8 is a side view of a spark gap with damped blow-out performance according to a seventh embodiment of the invention; FIG. 9 shows a basic side view of an arc quenching chamber designed as a deion chamber with a slot-shaped inlet region; FIG. 10 is a side view of the arc quenching chamber designed as a deion chamber with end-face covering of the deion plates inserted; FIG. 11a is a perspective view of the arc quenching chamber constructed as a deion chamber with a comb-like cover; FIG. 11 bshows a perspective illustration of the arc quenching chamber, which is designed as a deion chamber and has separating webs and the separate gas recirculation ducts formed therefrom; FIG. 12a is a sectional view of an intermediate space between two deion plates with venting in the right-hand orientation; FIG. 12 bshows a sectional representation, similar to FIG. 12 a, but with a left-hand vent; FIG. 12 cshows a top view of the inlet region of the arc quenching chamber designed as a deion chamber (see also FIG. 11 a) with partially broken-away cover and the recognizable comb structure of the cover; FIG. 13 shows a sectional illustration of the arc quenching chamber designed as a deion chamber with lateral illustration of a deion plate with indicated principal migration of a partial arc, and FIG. 14 is a longitudinal sectional view of the arc quenching chamber designed as a deion chamber with the arc formation indicated and the flow resulting therefrom.The basis for a high follow-up current limitation with an arc quenching chamber designed as a deion chamber is the rapid and stable splitting of the arc. In order to achieve a rapid arc division in an encapsulated arrester on the Horner principle, the arc must pass rapidly into the deion chamber after the arrester has responded. In DE 10 2005 015 401 A1, some basic possibilities are described for this purpose for an encapsulated horn spark gap with a deion chamber. Since the possibilities for increasing the forces acting on the arc are relatively limited, the path up to run-in, the length of the arc or the width of the deion chamber and the flow resistance should therefore be as small as possible.FIG. 1 shows a basic arrangement of a horn spark gap with an arc quenching chamber designed as a deion chamber 1 according to DE 10 2005 015 401 A1, with an arc running region laterally delimiting by insulation plates 2 and electrodes 3 with lateral recesses 4 for an internal gas circulation 5. The openings 7, 8 are located laterally 7 and on the end face 8 of the deion chamber. The position of the openings for venting the adjoining intermediate plate regions preferably varies, so that the openings of adjacent intermediate spaces do not lie directly next to one another. An intermediate space is defined by two deion plates 10 and is vented on both sides 7 of the chamber and to the end face 8. The lateral edges 9 of the deion plates 10 are covered in the inlet region by the insulation plates 2, into which a ferromagnetic plate 11 for strengthening the intrinsic magnetic field of the arc can additionally be inserted.Embodiments of the InventionFIG. 2 shows an inventive configuration of an arc quenching chamber designed as a deion chamber for an encapsulated spark gap according to the Horner principle. FIG. 2a shows the side view of the horn spark gap with the two diverging electrodes 3, an ignition electrode 12 with trigger circuit 13, and the electrodes have recesses 4 on both sides for realizing a targeted internal gas circulation. The recesses return the cooled gases into the arc running region between the diverging electrodes 3. The arc running region is bounded laterally by the insulation plates 2 (see also FIG. 2 b). The inlet region of the deion chamber starts directly below the latter and can further narrow within the V-shaped recesses of the deion plates (see FIG. 2 b). The inlet region likewise includes the transition region between the electrodes and the deion chamber. This region also influences the rapid running-in of the arc into the chamber. In this region too, a virtually unhindered flow of the hot gases is to be ensured. These gases are captured above the electrodes and also incorporated into the circulation circuit. The gases can optionally also be guided in the region of the chamber, alongside the electrodes or through further lateral recesses on the electrodes, to a channel behind the electrodes. The cross sections for the gas guidance can be designed to be very variable in this region, since very good cooling exists due to the electrodes and there is no risk of bridging chamber regions by partial arcs laterally or at the rear of the electrodes. The rapid formation of partial arcs and their rapid migration between the outer deion plate of the chamber and the electrodes is necessary so that the base points on the electrodes do not remain below the chamber in order to avoid a longer ionization in the arc running region and also at the ignition region. This could cause undesired restrike.The outflow region 16 of the deion chamber is composed of the lateral openings 7 and the front-side openings 8 per plate intermediate space. The venting of a plate intermediate space takes place only to one side of the chamber with respect to its axis of symmetry, since the openings 7 and 8 are arranged only on one side per intermediate space. The successive plate spaces are alternately evacuated forwardly or rearwardly. In the middle of the end face of the chamber, a web 14 is formed, which has the result that the venting of a plate intermediate space shown in FIG. 2 a occurs via three openings (two lateral, one end face), respectively, and that the gases thereof are guided in a separate channel 17 with insulation webs 18 on both sides laterally next to the chamber into a common expansion space 19, in which mixing with gases from another plate intermediate space can occur at the earliest.In order to keep the flow resistance of the deion chamber relatively low, the V-shaped inlet region 15 and the outlet region 16 should only moderately be blocked and have a configuration which is as fluidically favorable as possible. The inlet region should preferably be not more than 50% insulated with respect to the arc running region below the chamber. In the deion chamber 1 itself, the cross section should again increase. The sum of the outlet cross sections between the individual deion plates should, as far as possible, lead to no insulation within the chamber. If an increase in the flow resistance in the chamber is necessary, this maximum is required. 50% are. In order to avoid a high flow resistance, in addition to the outlet cross sections of the chamber, their geometric configuration and the configuration of the gas flow in the recirculation channels and, in turn, also the cross section of the recirculation channels 17 are also of particular importance. The cross section of the individual return channels should not fall below about 25% of the cross-sectional area between the individual deion plates.In order to achieve an optimum gas circulation within the encapsulated spark gap, in addition to venting the deion chamber, a targeted recirculation of the gases into the arc inlet region below the deion chamber, for example through the recesses 4 in the electrodes 3, is also necessary.According to the invention, the intermediate spaces of the deion plates are alternately vented with respect to the axis of the deion chamber. The venting is preferably effected both laterally and at the end of the deion chamber. The gases emerging from the deion chamber are in this case held in separate channels per intermediate space. The individual channels are separated from one another without any gaps, for example by webs 18 which are directly connected to the insulation material of the chamber. The protrusions of the webs are at least twice as large as the wall thickness of the deion chamber material 6. On the end face of the deion chamber, the individual venting channels are likewise separated from one another, for example by a central web 14 running axially with respect to the deion chamber. The number of lateral separate channels 17 on each side of the chamber thus corresponds in a rounded manner to half the number of the Deion plates.Instead of an insulating enclosure of the deion chamber, for example with webs, it is of course also possible to insert the deion plates or a simple open deion chamber into correspondingly enclosing housing parts, in which the preferred venting geometry is integrated. In this case, for example, insulation webs from the housing parts then engage alternately partially between the metal deion plates. Likewise, such an embodiment can also be realized as a stack geometry of in each case an insulation element and a deion plate as an insert part or as an element to be injection molded around. The numerous possibilities for realizing an inventive chamber can of course not be illustrated here. The further embodiments are therefore limited to an exemplary embodiment and its function.As a result of these additional insulation elements, which are designed, for example, as webs, the surface area of the deion chamber caused by the small structural size is additionally enlarged, so that sliding flashovers as a result of hot gases or contamination can be prevented even more effectively and a significant increase in the insulation capacity can thus be achieved.For the desired rapid running of the arc into the deion chamber, it is expedient not to prevent the running of the arc on the electrodes, which in each case laterally enclose the deion chamber, by too much insulation of the deion chamber. The gas flow between the electrodes 3 and the deion chamber 1 is also selectively supplied to the circulation within the entire spark gap.In this case, the separate guidance of the gases does not necessarily have to take place as far as the return flow channels within the horn electrodes. A separate gas guidance is sufficient until the gases have cooled to such an extent that a current flow via these gases can be ruled out. Below the deion chamber and, for example, on both sides parallel to the arc running region, the gases can be combined into a corresponding expansion chamber 19.In a preferred embodiment variant, in which the gases are returned to the running region of the arc via, for example, lateral recesses 4 in the electrodes, the gases from the deion chamber are divided laterally into two respective flows, as a result of which all four gas returns (each electrode on both sides) are forcibly subjected to a gas return flow. The arc is thereby driven into the deion chamber in an accelerated manner. The sum of the individual cross sections of these return channels is, however, preferably only less than 10% compared to the total venting cross section of the deion chamber.FIG. 3 shows a sectional illustration of a spark gap with damped blowing behaviour. The gas enters from the arc quenching chamber, which is designed as a deion chamber 1, from the openings 7 and 8 into the mutually insulated channels 17 and reaches the expansion spaces 19.FIG. 4 shows a sectional view of a further spark gap with damped blowing behavior. In this case, the cooling plates are arranged in the flow direction. The plates can begin directly at the openings of the channels 17, whereby in modified embodiments according to the invention the expansion chamber 19 can also be dispensed with.The spark gap shown in FIG. 5 is similar to that shown in FIG. 3, but the deflecting plates downstream of the relaxation chamber 19 have only openings which are arranged offset relative to one another. In this arrangement, too, these plates can begin relatively close below the openings of the channels 17 or even be integrated into the channels 17 isolated from one another, whereby the expansion space 19 is likewise dispensed with.FIG. 6 shows a spark gap in which the gases are not deflected in relation to the flow direction in the arc running region along the electrodes downstream of the arc quenching chamber designed as a deion chamber. After leaving the deion chamber 1, the gases are guided from the mutually insulated channels 17 in a meandering channel to the outer wall of the housing 28 and are discharged to the environment through openings 29.FIG. 7 shows a spark gap in which the gases are deflected out of the channels 17 above the arc quenching chamber formed as a deion chamber 1 and are cooled, for example, on one side parallel to the arrangement of the spark gap by a meandering system and are guided to the outside.FIG. 8 shows a lateral illustration of a further spark gap arrangement. After leaving the arc quenching chamber designed as a deion chamber, the gases are deflected and guided in an insulated manner through the openings 7 and 8 in the insulated channels 17 next to the running region of the spark gap. Thereafter, the already cooled gases within the housing 28 are discharged into a region which has openings 29 to the environment. These openings 29 can be located, for example, in the region of the connection terminals. The inlet region of the deion chambers is at risk of restrike in particular due to the complete encapsulation of the spark gap and the movement of the arc base points on the deion plates. In this case, in particular, two regions are to be distinguished, on the one hand the direct end faces next to the generally V-shaped inlet region of the deion plates and, on the other hand, the V-shaped inlet region itself.FIG. 9 shows these two regions. The metal sheets 10 of the arc quenching chamber designed as a deion chamber are guided in the insulation jacket 6, which surrounds the deion chamber on the end side and the sides. The edges 9 of the sheets adjacent to the V-shaped inlet region are generally free. The V-shaped inlet region 15 is shown to have, for example, a further slot-shaped opening 20.In a preferred configuration of the region of arc migration according to FIGS. 2 band 3 to 8 from the ignition point to the deion chamber with a plate-shaped delimitation on both sides, it is expedient to already cover the direct end sides 9 of the deion chamber 1 by these plates 2. If it is necessary to make the V-shaped inlet region narrower, for example according to FIG. 10, than the respective arc running region (plate spacing), ramp-shaped tapers 21 made of insulating material can preferably be applied to the plates 2, which tapers likewise cover the edges 9 of the deion plates 10. Such an embodiment can be used, for example, when a large width of the electrodes and of the arc running region is required for a behavior that is stable to aging or for controlling high impulse currents, while the thermal load of the arc quenching chamber designed as a deion chamber is controlled even with a small heat capacity.Of course, the lateral plates 2, the tapers 21 or also the deion chamber 1 can be designed such that they engage in each case in a web-like manner in one another and can also be formed, for example, from the housing material 6 for encapsulating the spark gap.In conventional embodiments of the deion chamber, the V-shaped inlet region of the deion plates 15 is frequently affected by partial or complete bridging by the movement of the arc base points on the deion plates as a result of the magnetic forces as a result of individual partial arcs emerging. However, this is generally not critical in the case of a conventional design of the arc chamber for an operating voltage of, for example, 230 V and in the case of alternating voltage.In the preferred embodiment of the deion chamber, the number of deion plates used is up to 40% smaller, based on the desired operating voltage (e.g. 440 V), compared with the prior art. This can only be realized, as already explained, by the strong extension and cooling of the arc in the deion chamber, whereby the portion of the arc voltage from the arc column (length-dependent) is almost equivalent to the arc voltage as a result of the anode / cathode fall voltage (material-dependent) and thus a sufficiently large total voltage can be realized according to the known arc equation (arc total voltage=annode / cathode fall voltage+ arc column length·electric field strength of the arc). By influencing the running behavior of the arc between the deion plates, in addition to the good cooling of the arc, the total voltage is also increased by the ohmic resistance of the current flow in the actual deion plate. The length of the current path in the deion plate is maximized by the targeted influencing of the arc migration. The total voltage can thus also be influenced more strongly via the material, e.g. the specific electrical resistance, than in the case of conventional chambers.If, however, in this case bridging of individual sheets occurs, not only the total voltage is reduced by the anode / cathode fall voltage, but additionally also by the proportionally very high voltage of the arc column section of the respective arc loop and the ohmic voltage drop of the current path in the sheet. This would necessarily result in a dramatic reduction in the follow current limitation. Reignitions in the V-shaped inlet region of the deion plates or bridging of partial regions of the chamber by lateral flashovers or partial flow flows via emerging hot gases must therefore necessarily be avoided.However, it should be noted here that the rapid running-in of the arc into the chamber is not impaired by the corresponding measures, since this is the basic prerequisite for rapid and thus optimized current limiting.According to the invention, this is achieved by an insulating covering of the V-shaped inlet region of the Deion plates, which only slightly influences the flow resistance of the chamber. A corresponding embodiment is shown in FIGS. 11 aand 11 b. In this embodiment, the covering of the end face of the deion plates adjacent to the V-shaped inlet region can simultaneously be realized by a hood-shaped covering.In the case of covers which cover the inlet region on both sides and uniformly, the flow resistance of the deion chamber is considerably increased. The running-in of the arc is significantly delayed or even prevented, in particular in the case of encapsulated spark gaps in which the flow resistance is already increased in any case compared to the blowing-out switches or spark gap. Satisfactory limiting of the follow-on current is therefore no longer possible, particularly in the case of high prospective follow-on currents. According to the invention, the cover is designed, for example, in the shape of a comb, so that in each case two adjacent metal sheets are insulated from one another on each side of the cutout. This ensures that the flow resistance of the V-shaped inlet region is increased only relatively slightly, in particular immediately before the desired splitting of the arc, as a result of which a rapid migration of the arc into the chamber is made possible.In FIG. 11a, the comb-shaped covering of the V-shaped inlet region is realized by the parts 22 on both sides of the chamber. Between the recesses of the comb of the cover there are two deion plates on each side. The recesses in the comb 23 are each approximately as wide as the intermediate space between the deion plates and permit gases to enter this space on one side already below the sheet metal edge and the end of the comb. The direct arcing between two adjacent deion plates or the emergence of partial arcs from the chamber into the slot-shaped inlet region is, on the other hand, not possible owing to the comb teeth 24, which overlap in each case two deion plates and an intermediate space. The covering of the opposite side of the V-shaped inlet region of the Deion plates is effected in the same manner, but offset by one plate each. The height at which the comb-shaped cover begins essentially determines the insulation factor of the chamber in the inlet region. The end of the comb teeth can be guided as far as the end of the V-shaped inlet region.The covering of each of two adjacent deion plates by the comb teeth reliably prevents the restriking in the inlet region. However, the flow resistance is hardly increased by the mutual recesses in the comb (comb valleys), in contrast to a complete covering, so that an unfavorable influence on the inflow speed and thus the current limitation is avoided.The hot gas, which is displaced before the arc in the running region between the diverging electrodes 3, can flow out into the chamber below the metal sheets alternately between two deion metal sheets in the region of the recesses of the comb (comb valleys), whereby a back pressure or a reflection below the inlet region 15 is avoided or significantly reduced.In one embodiment of a deion chamber according to the invention, the following dimensions are provided (in each case vertically, for example corresponding to the axis of symmetry): height of the inlet region in the deion plate 10:8.7 mm height of the plate overall: 19.7 mm, width: 22.3 mm height of the comb teeth 24:6.7 mm height of the comb trough 22:3.4 mmIn other embodiments of the invention, the dimensions are in the range + / -50% around the above-mentioned values, in particular in the range + / -25% around the above-mentioned values.In further embodiments of the invention, it is provided that, with respect to the height of the recess of the inlet region in the deion plate, the tooth valleys make up at least 20% and the tooth valleys make up at least 30%.Preferably, the height of the cover Tal is about 39% and tooth is about 77%.In a preferred embodiment, 90% of the height of the recess of the inlet region in the deion plate is not exceeded as an upper dimension for the comb teeth.The arc quenching chamber or the surge arrester can be designed such that it is suitable for a 2TE (series-installation devices 36 mm) design. The relative ratios are decisive and can also be transferred to smaller chambers, for example for 1TE (18 mm).After flowing on one side into an intermediate space between two deion plates 10, the hot gas (see also FIG. 11 b) can escape this space only on one side of the chamber through the lateral recesses 7 or the end recess 8 of the arc quenching chamber designed as a deion chamber, which recess is likewise located on one side with respect to the axis of symmetry of the chamber. The gases which have evolved through the openings 7 and 8 from an intermediate space between two deion plates are each held in a separate return duct 17. The return channel 17 is bounded laterally by the insulating webs 18 and at the end by the web 14. The gases from the spaces between the deion plates are thus guided to the expansion space (19, see e.g. FIG. 2b) mutually and separated from one another in the return channels 17. A flow of current over the hot gases after passing through the deion chamber is reliably prevented by the separate recirculation ducts as well as a partial bridging by arcs. Thus, no undesired or even stochastic reductions of the arc voltage occur.The preferably alternating flow of the gases into the respective intermediate spaces of the deion chamber and the alternating venting thereof create particularly favorable flow conditions within this arrangement, as a result of which, despite reduced flow cross sections, the rapid running-in of the arc and its division in relation to a known and non-insulated chamber can be realized and optionally optimized. FIG. 12a shows the arc 25 below the inlet region 15 and the gas flow into the interspace between two deion plates 10 through the recess in the comb 23 and above the comb teeth 24. FIG. 12 bshows the gas flow through the chamber between the immediately adjoining arc sheets with the vent openings on the left side. The gases from an intermediate space between two deion plates are combined again in the respective separate return channels 17 and are guided on the respective chamber side to the expansion space 19 or finally cooled to the recesses 4 in the electrodes 3, resulting in a closed gas circulation within the spark gap. FIG. 6 cshows the end face of the chamber with the inlet region 15, the individual deion plates 10, the venting openings 7, 8 of the plate interspaces and separate gas recirculation ducts 17.The type of protection against back ignition in the V-shaped inlet region presented also allows reliable use of the deion plates as a result of the root point migration of the partial arcs even directly in the respective flank of the deion plate laterally next to the V-shaped inlet region. The movement of the arc to the base point in this region is furthermore possible since it is also impossible for the hot gases to build up in this region of the chamber, since at all times there is ventilation through the comb-shaped cover to the interior of the deion chamber and ventilation through the lateral or frontal ventilation openings.FIG. 13 shows, by way of example, the principal running behavior of an arc on a deion plate 10 after the arc splitting at the individual plates in the slot-shaped inlet region of the chamber. After the arc 25 has been divided, the base of the partial arc travels on the sheet 10 in the form of a loop to an edge region of the V-shaped lead-in region. Without end covers 9, 24, the arc can emerge from the chamber and the arc must be divided again. The deion plates 10 can be recessed into the insulating cover 6 of the chamber in the region of the edges 9 or else circumferentially in order to avoid gaps or dirt and creep paths. The comb-shaped cover prevents this escape without the time until the arc splitting being increased by the insulation of the inlet region. The arc is prevented from re-emerging both at the end face 9 and in the slit-shaped V region 24. The partial arc remains in the flank region of the deion plate as far as the end of the arc phase. The dashed path shows the principal running behavior of the base point of the partial arc in the adjoining intermediate chamber on the rear side of the same deion plate.Due to the completely mutually implemented flow and venting of the intermediate spaces of the arc quenching chamber designed as a deion chamber (see, for example, FIG. 12 c ), the movement of the arc column is substantially influenced by the magnetically induced forces. The arc entering the chamber is already deflected to different sides in the individual intermediate chambers as a result of the alternate venting and is extended until splitting. The arc in this case prevents direct flow of the gases in the plate interspaces. In the plate interspaces of the respectively adjacent chambers there are thus already formed laterally offset partial arcs which also travel and are extended in opposite directions. This results in a very effective increase in the overall length of the arc column. In addition, the deion plates, which preferably consist of a material with ferromagnetic properties and which generally have poor heat conduction, are in each case subjected to the arc only in different regions on the front and rear sides. Therefore, in contrast to other solutions, the full area of the plates is used for cooling the arc and the heat capacity of the plates is optimally utilized. This is also favorable for the aging of the plates, since the local overheating and the burn-up and the formation of molten beads of the material can thus be very well prevented.This results in several positive effects. In deion chambers, the partial arcs generally mutually repel one another in the vertical direction. In conventional chambers, therefore, a partial arc travels on the sheet metal to the upper end face of the chamber, while the other one travels to the lower end face with the inlet region. In the case of chambers without a cover and with a small sheet metal height, this leads almost positively to back-ignitions below the arc chamber. The deion plate is also frequently heated on one side and partially overloaded.Due to the mutual deflection of the partial arcs transversely to the current flow direction (chamber axis), the perpendicularly acting repulsive forces on the partial arcs in the inventive deion chamber are drastically reduced and the forces rather act an additional horizontal force. As already mentioned, the alternately deflected successive partial arcs do not heat the common metal sheets from both sides almost pointwise, but rather travel on completely opposite regions of the metal sheets. Since the metal sheets generally have very poor heat conduction, the maximum possible heat capacity of the metal sheet is thereby used to cool the arc. This increases the arc voltage and prevents premature aging of the metal sheets.FIG. 14 shows a basic arrangement of the partial arcs 26 in the arc quenching chamber, which is designed as a deion chamber, between the individual deion plates 10 with respect to the longitudinal axis of the chamber in plan view. The gas ionized by the partial arcs is already cooled by the deion plates before leaving the plate interspaces through the oppositely situated outlet openings 7, 8, whereby a risk of back ignition and a flow of current through the hot gases outside the chamber is further reduced.It is clear from FIGS. 13 and 14 that the current path 27 within the individual metal sheets is virtually maximized on the same metal sheet from the base point of the arc on the one side of the metal sheet to the current outlet in the base point region of the following partial arc on the same metal sheet in the inventive deion chamber. The length of the section and the forced current conduction over the slot-shaped region of the sheets (FIG. 13 ) also lead, in addition to long sections (several centimeters), to increased current densities in the sheet and thus to an increased ohmic voltage drop in the sheet material. In conventional deion chambers, however, sometimes only the material thickness of the sheet (e.g. (1 mm) acts as an impedance.Without a reduction in performance, efficient use of material and space or alternatively an increase in performance is thus made possible, which is of greatest importance in particular in the case of encapsulated series-mounted devices.Due to the geometry of the deion plates and the material, the portion of the ohmic voltage drop or also the base point movement can be used for influencing the arc voltage in a targeted and reproducible manner. In addition to a homogeneous material of the deion plate, it is of course also possible to use coated, laminated or else plates with a targeted internal current conduction, in order thus to further increase the ohmic voltage drop. By layering electrically conductive and poorly conductive material up to insulating intermediate layers, optionally with local feedthroughs, the current path and its impedance as well as the arc movement can be additionally influenced. These known measures for configuring arc splitter plates can be used very effectively in the present chamber design, in particular because of the reproducible movement of the arc.The deion chamber shown leads to a very stable and reproducible arc behavior without the stochastic phenomena of restriking despite a marked increase in the arc voltage per deion plate.The inventive design of the deion chamber leads to a reproducible marked increase in the achievable partial arc voltage per deion plate. After the complete division, the arc voltage is very constant and free from voltage dips, as a result of which a very high and reproducible current limitation is possible in the case of alternating and DC currents. The deion chamber is suitable, owing to the insulated gas recirculation, in particular for encapsulated switching devices with closed gas circulation.The most optimal behavior is achieved by the targeted alternate venting of the individual chamber interspaces into completely separate and insulated channels. The gas guidance of the closed circulation within the device from the ignition region of the arc to the inlet region of the chamber, through the chamber into the outflow region of the chamber, into the expansion region and back into the arc running region between the diverging electrodes is matched in such a way that the guidance of the flow and the cross sections do not lead to any impairment of the arc movement and the arc splitting despite the encapsulation of the arrangement. The described measures optimally realize the very dynamic movement of the arc and the possibility of full-area utilization of the chamber for the cooling effect with the aid of the Deion plates. Due to the targeted gas flow and the already described measures, the arc column can be effectively extended and cooled, so that the voltage component due to the arc column and the ohmic voltage drop in the metal sheets can amount to up to 50% of the total voltage, wherein in the case of conventional deion chambers this component is usually less than 10%.With the deion chamber according to the invention, the achievable tension per deion plate can be increased by significantly more than 30% compared to the prior art. A discharge of partial arcs from the inventive deion chamber with comb-like insulation can be almost ruled out after the complete division of the arc in the chamber, whereby very constant and minimum passage integrals can be achieved in the case of a short-circuit current cut-off. The chamber allows this with minimal space and material usage.List of reference characters1 Deion chamber 2 Lateral insulation plate 3 Electrode, diverging 4 Lateral recess in electrode 5 Gas circulation 6 Insulation 7 Lateral recess in deion chamber 8 Front recess in deion chamber 9 Edge of the deion plate in the inlet region 10 Deion plate 11 Ferromagnetic plate 12 Trigger electrode 13 Trigger circuit 14 Insulation wall (web) 15 V-shaped inlet region 16 Outflow region 17 Return channels 18 Insulation web / separating web 19 Expansion chamber 20 Slot-shaped opening 21 Taper, ramp-shaped, insulating 22 Cover, comb-like, insulating 23 Recess in the comb-shaped cover 24 Comb teeth of the cover 25 Arc 26 Partial arcs 27 Current path 28 Housing 29 Opening

Claims

Arc quenching chamber for a surge arrester, having: a multiplicity of deionization quenching plates or quenching plates (10) which are spaced apart in such a way that a multiplicity of channels (17) for receiving arc-dependent gases is formed, wherein the quenching plates (10) have a slot-shaped inlet region (15) and furthermore a gas outflow region (16) is formed by lateral and / or end-face openings (7, 8) between the quenching plates (10), wherein, starting from the axis of symmetry of the arc quenching chamber, the gas outflow regions (16) between adjacent quenching plate pairs are each guided alternately to one or the other chamber side or chamber half and separating webs (18) are formed in this respect, and wherein the partial gas flows are only mixed in a common expansion space (19).Arc quenching chamber according to Claim 1, characterized in that the end faces of the quenching plates (10) which form the inlet region (15) are provided with an insulation cover (22) which can be formed as a flow guide cover.Arc quenching chamber according to Claim 2, characterized in that the insulation cover (22) has a comb-like shape or is designed in the form of a hood with a comb-like flank.Arc quenching chamber according to one of the preceding claims, characterized in that the quenching plates (10) consist of a ferromagnetic material.Arc quenching chamber according to Claim 3, characterized in that in each case one comb tooth (24) covers at least two adjacent quenching plates (10) and the intermediate space bounded by them.Arc quenching chamber according to Claim 5, characterized in that the recesses (23) between the respective comb teeth (24) correspond approximately to the width of the interspace.Arc quenching chamber according to Claim 6, characterized in that the recesses (23) between the respective comb teeth (24) of the two opposite combs (22) are arranged offset by an intermediate space.Arc quenching chamber according to one of the preceding claims, characterized in that the area of the gas inflow region (15) is substantially equal to the sum of the area of the lateral and / or end-side gas outflow openings (7, 8).A surge arrester comprising an arc quenching chamber according to any of the preceding claims.Surge arrester according to Claim 9, characterized in that the surge arrester is an encapsulated surge arrester or a surge arrester with a blowing spark gap.Surge arrester according to Claim 9, characterized in that the surge arrester is encapsulated and the arc quenching chamber is designed such that a specific gas circulation (5) within the encapsulation of the surge arrester can be predefined.Surge arrester according to Claim 11, characterized in that a horn-like, diverging electrode arrangement is introduced into the encapsulation, the electrodes (3) of the electrode arrangement having recesses (4) for realizing the gas circulation (5).Surge arrester according to Claim 11, characterized in that the separating webs (18) are part of the encapsulation or of a housing (28).Surge arrester according to Claim 12, characterized in that the electrode arrangement laterally surrounds the arc quenching chamber and, in this respect, dips the chamber into the electrode interspace.

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