EP1551048A1 - Current limiting device - Google Patents

Abstract

The current limiting arrangement has a vacuum switching tube with two switching parts (13,14), whereby quenching plates (86) for sparks are provided at least partly between the switching parts as the current limiting arrangement. The quenching plates have different lateral extents and are staggered in the direction of the switching parts.

Description

The invention relates to an arrangement for current limiting according to the preamble of claim 1. Bei Such an arrangement for limiting the electrical Electricity in low-voltage networks, in case of operation at diffuse arc modes occur when the operating currents are flowing should in case of short circuit in the case of flowing Short-circuit currents of the arc through suitable cooling plates cooled or by suitable divider plates in a row lying partial arcs are split.

DE 199 13 236 C2 of the applicant is a method for Current limitation in low voltage networks including associated ones Switching contact arrangements and their special use known in the vacuum interrupters for current limiting be used. In detail, vacuum interrupters used with such contact configurations in which a transversal towards the current in the arc Own magnetic field occurs, the arc by suitable Dividing plates advantageously divided into partial arcs shall be. If necessary, the arc can also remain one-piece, in which case the divider plates outside of the arc filament used as arc cooling plates become.

Other known in the low voltage area current limiting Switching elements, such as air circuit breakers with splitter chambers and components based on carbon-filled, more conductive Polymers, were earlier in the monograph A. Erk and M. Schmelzle: "Fundamentals of Switchgear Technology", Springer-Verlag, Berlin - Heidelberg - New York, 1974, Page 269.

In DE 199 13 236 C2 is in the individual embodiments explicitly on the spatial arrangement of the quenching plates, in particular cooling plates or divider plates, with respect to on position of contacts: Especially at the arrangements according to Figures 1 and 2 of DE 199 13 236 C2 are the identically shaped quenching plates in the axial direction of the Contact system stacked in parallel. So you are not staggered arranged so that the middle quenching plates in Contact gap proximity a huge distance to the contacts in transversal or radial direction and only the Close outer extinguishing plates close to the contact pieces.

In the arrangement with pot contacts according to Figure 3 of DE 199 13 236 C2, the quenching plates are similar to the arrangement executed with spiral contacts, only that the two extreme extinguishing plates do not reach as far inside as the other quenching plates. It follows in the same way one Stacking of the quenching plates.

All quenching plate assemblies described in DE 199 13 236 C2 have the property that after contact separation From the place of origin running away arc the quenching plates only reached after having diverged almost the entire Contact segment has gone through what is there in detail FIG. 4 is executed. The cooling effect of the quenching plates and the desired formation of partial arcs can there only after the arc has entered the splitter gap take place, i. therefore with great delay in relation to Contact separation. The desired current limit due to increased Arc tension thus occurs comparatively late.

In the prior art, the inner edges of the thighs are or annular quenching plates as simple, smooth contours executed. More complicated, of air circuit breakers Her known geometric splitter structures, which are advantageous on the current-limiting formation of arc bases on the quenching plates are not applied.

Starting from the prior art, it is an object of the invention suitable quenching plate assemblies, specifically cooling plates or dividing plates, for contacts in a current-limiting Specify vacuum interrupter, which the current-limiting Improve switching properties of the tube.

The object is according to the invention in an arrangement of the above mentioned type by the features of claim 1 solved. Further developments of this arrangement are in the subclaims specified.

In the invention, the individual quenching plates are advantageously not in the axial direction of the contact system parallel staggered or stacked, but are rather staggered in the direction of the switching pieces. Especially the quenching plates have a different immersion depth, the formed splitter stack with the edges the individual quenching plates a profile course accordingly the contact arrangement has. This is not enough only the outer Extinguishing plates close to the contacts, but show in particular, the middle quenching plates near the contact gap a small transverse or radial distance to the contacts. The inner edges of the quenching plates lie that is, in a spatial band along the divergent contact segments. The tape can be parallel to the contacts run. This is particularly important if the Contacts are beaked or rotationally shaped.

In the invention, the staggered quenching plates are advantageously shaped so that the arc facing Edge deviates from a straight or circular contour. Thus, the edge length of the individual against each other offset blanks extended. The border contour can be regular, for example, serrated, or irregular.

For spiral contacts, the contours are preferably on the Slits adjusted.

Advantageously, in the invention vacuum interrupters be used with such contact configurations, the Although lean on the known structure. According to the invention however, improve the staggered arc splitter assemblies through the geometric changes the current limit and so the switching behavior of the vacuum switch crucial.

The invention was an analysis of the current limiting behavior in DE 199 13 236 C2 basis, resulting in some new knowledge led. It was recognized that the location of the Blade inside edges according to Figure 4 of DE 199 13 236 C2 neither an extension of the predominantly axial, one-piece arc filament before entering the quenching plates in the radial direction enforces the cooling effect the quenching plates by extending the contact zone Arc quenching favors. Both are unfavorable for the formation of arc bases on the Extinguishing plates, because of low arc length and poor cooling a low arc voltage requirement before entering into condition the quenching plates.

The three aforementioned aspects thus have a disadvantageous effect on the efficient construction of increased arc voltage amplitudes out.

Figur 1 und Figur 2

bekannte Vakuumschaltkontakte mit zugeordneten Lichtbogenteilerplatten in seitlicher Schnittdarstellung und Draufsicht,

Figur 3 und Figur 4

eine Anordnung mit erfindungsgemäß ausgebildeten Löschblechen, in Figur 3 mit einem vorwiegend axialen, einteiligen Lichtbogenfaden vor etwaigem Eintritt in die Löschbleche,

Figur 5

eine Darstellung des Kontaktes im geschlossenen und geöffneten Zustand entsprechend der Anordnung aus Figur 3,

Figur 6 und Figur 7

Vakuumschalter-Spiralkontakte gemäß Figur 1 zur Erzeugung von Radialmagnetfeldern mit zugeordneten Lichtbogenteilerplatten in seitlicher Schnittdarstellung und Draufsicht,

Figur 8 und Figur 9

Spiralkontakte zur Erzeugung von Radialmagnetfeldern mit erfindungsgemäß gestaffelt angeordneten Löschblechen in seitlicher Schnittdarstellung und in Draufsicht,

Figur 10

eine vorteilhafte Kontur einer dem Lichtbogen zugewandten Löschblechkante bei der Anordnung gemäß Figur 8/9 in Draufsicht und

Figur 11

Zeitverläufe der Bogenspannungsamplitude, gemessen an schnabelförmigen Vakuumschaltkontakten mit und ohne Staffelung der Löschbleche.

Further details and advantages of the invention will become apparent from the following description of exemplary embodiments with reference to the drawing in conjunction with the other claims. They show in a schematic representation

FIG. 1 and FIG. 2

known vacuum switch contacts with associated arc divider plates in side sectional view and top view,

FIG. 3 and FIG. 4

an arrangement with inventively designed quenching plates, in Figure 3 with a predominantly axial, one-piece arc filament before any entry into the quenching plates,

FIG. 5

3 shows an illustration of the contact in the closed and open state corresponding to the arrangement from FIG. 3,

FIG. 6 and FIG. 7

Vacuum switch spiral contacts according to FIG. 1 for generating radial magnetic fields with associated arc divider plates in lateral sectional view and top view,

FIG. 8 and FIG. 9

Spiral contacts for generating radial magnetic fields according to the invention staggered arranged quenching plates in a side sectional view and in plan view,

FIG. 10

an advantageous contour of the arc facing sheet metal edge in the arrangement of Figure 8/9 in plan view and

FIG. 11

Time curves of the arc voltage amplitude, measured on beak-shaped vacuum switch contacts with and without staggering of the quenching plates.

In DE 199 13 236 C2 is a method for current limiting described in low-voltage networks, where there vacuum interrupters used as a means of current limiting Fireplaces are assigned in the tube. It can In the vacuum interrupters contact arrangements available be that generate a radial magnetic field.

The well-known from DE 199 13 236 C2 current-limiting vacuum switch is now through the basis of the figures in detail further improved.

In Figure 1, two contact pins are shown with 1 and 2, via the currents to contact carriers 3 and 4 with associated contact pads be guided. There is an extinguishing arrangement 5, as it is known in principle from air switches, the consists of individual extinguishing plates 6a to 6j, with a bordering Ceramic limitation 7 is present. The latter will from the top view of Figure 2 clearly.

FIGS. 1 and 2 thus show an arrangement which is in contact with itself those used in conventional low-voltage circuit breakers Air switching chambers based, with suitable materials be used for vacuum conditions. This arrangement shows a good current-limiting at high short-circuit currents Behavior. A stationary in the field of divider plates however, a burning arc of several 10 kA may occur the divider plates and the outer, from the arc contaminated contact area destroy and therefore not sufficient Allow life.

For the latter reason, the arrangement according to Figures 1 and 2 not for the operational switching of the occurring operating currents from a few 100 A to a few kA. The occurring arcs occur between the contact pads Although the separating pieces are in intensive Fashion, with increasing contact distances but they go in the diffuse mode over. The arc approaches expand on the electrodes in size and can so in burn in unwanted switching chamber areas.

In Figure 3 and Figure 4 is in each case the improved arc splitter arrangement shown. The switch assembly 1 to 4 with the beak-shaped contact carriers 4 and the contacts. 9 corresponds to the figure 1 or 2. Now shown is a Arrangement of quenching plates 36a to 36i, in which the individual Extinguishing plates have a different lateral extent. While the individual quenching plates on the right side ending flush and in a not shown in the figure 3 Holder made of electrically insulating, non-gaseous material are attached, they are on the opposite side different lengths. The complete splitter stack 36 forms on this page in total approximately a triangular profile.

At this profile forms with open contacts 9 along the beak-shaped extension 4 of the illustrated in Figure 3 Arrangement of such an arc 100, the opposite an arc in a non-staggered array Extinguishing plates is considerably extended. The arc 100 has more effective by its lengthwise magnification Contact surfaces with the splitter plate ends, so that at least a better cooling takes place. This is - also independent of penetration of the arc 100 into the spaces the splitter stack 36 - an improved cooling effect given, so that a particularly effective current limit possible becomes.

From the figure 4 results in the plan view the staggered Arrangement of the quenching plates. There are still lateral ones here and rear mounts 37 and 38 are shown.

Specifically, from Figure 5, the effect of the arc splitter package results 36 both in the closed contact state as even with open contacts 9. The same reference numerals as used in Figure 3.

In a modification to Figure 5, it may be advantageous to the central Splitter plate 36e, which in Figure 5 to the contact gap is enough to take back, so that for the splitter stack overall results from the triangular shape a different contour. In particular, a material erosion by one of the arc caused metal vapor evolution, the inevitable one Changing the geometry would result is avoided.

In FIGS. 3 to 5, the switching pin consists of OFHC copper, where the actual contact pieces 9 made of contact material, For example, CuCr50, are arranged. The individual quenching plates of the splitter stack with predetermined End profile consist of iron, steel or copper, in particular OFHC copper. In particular, iron is possibly also a specific one Steel, is magnetizable, whereby the running of the Arc is favored in the splitter stack. specially Iron is galvanically nickel plated to prevent corrosion.

In FIGS. 6 and 7, 11 and 12 denote two contact pins for power supply, one of which via a not shown Federbalg is designed to be movable. Also the real one Vacuum interrupter is not shown in detail. There are contact pieces 13 and 14 available, each corresponding slots for generating radial or transversal magnetic fields. Between laterally beveled contacts 13 and 14 is an arrangement 15 present, in detail from individual divider plates 16a to 16h and associated ceramic or metal parts. In particular, the divider plates 16a to 16h end introduced into a ceramic holder 17 and is according to FIG. 6 shows at least one radial slot 18.

With this arrangement is intended for a desired current limit in the event of a short circuit, either a splitting of the arc in successive partial arcs or an intensive Cooling of the arc column reached at the splitter plate contours become. At the same time, according to the invention by the arrangement shown in Figures 8 and 9 also the dominated at operating currents diffuse arc mode dominated. Both arrangements, i. the arrangement according to FIG 6/7 and the arrangement of Figure 8/9, consist essentially of two contact pieces and circular arc divider plates, which are arranged between them.

Basis of these embodiments is that the operation of vacuum switching contacts with radial magnetic field and all-round Arc is modified so that the circumferential Arc through the magnetic field in a splitter stack steered and thereby, while maintaining the rotation, in a series of consecutive, fast circulating Single arcs is split. Not by this date Known measure can both the thermal load of all affected contact parts are kept low, as well at the same time, such a large amount of burning voltage is built up be that prospective short-circuit current on in this Geometry controllable amplitudes is limited.

The switching pieces 13 and 14 have in their layout similarities with spiral contacts used in vacuum switching technology. In this case, the magnetic force acting on the intense arc created between the separating contact pads has components that drive the arc toward the race. In this arc migration, an extension of the arc is achieved by chamfering the contact pieces. During this movement process, the arc will go into the diffuse mode and thereby extend over the entire contact piece surface, if a dependent of the contact piece diameter D limiting current of I _G ≈ 15 - 25 kA is not exceeded. On the other hand, with instantaneous currents exceeding this limit value, the arc is maintained in contracted mode, and its voltage requirement during wandering as a result of the extension increases to a few 100 V and thus the current limitation becomes effective. In the vicinity of the race, the voltage requirement of a long arc, at least for the repeatedly occurring unstable arc configurations will be greater than the sum of the voltage requirement of partial arcs, which burn between two divider plates or between a raceway and a divider plate. For such arc configurations, the commutation of the long arc into the area of the divider plates and its division occurs within a few μs. In this process, the burning voltage and the associated current limit are only slightly reduced. Only when the instantaneous current falls below the limit value I _G before zero current, does the arc withdraw from the splitter plate region and change to the diffuse mode. It spreads over the contact surface and the arc voltage decreases with decreasing current.

The direction of the resulting between the divider plates contracted arcs is determined by the local magnetic field, that of the current flow in the switching pieces or Running rings and the divider plates depends. She can therefore for the individual sheets, as with reference to FIGS. 7 and 9 for a section of the divider plates and races shown will be, different.

Since the current-limiting effect of a shutdown as possible should use quickly and immediately with the arc voltage build-up related, the arc must be fast migrate from the contact pads in the direction of the divider plates. In addition, the commutation must be in the range of the divider plates be done quickly, so that reignitions in the back of Arch and thus arc voltage dips are avoided.

FIGS. 8 and 9 show improvements of the staggered ones Fire extinguishers specially designed for axial symmetry. in the Single here is a splitter stack 86 with staggered inside Extinguishing plates 86a to 86i and other extinguishing plates 86j to 861 shown. All quenching plates 86a to 861 are attached at the rear in an insulating assembly 87, the can be the wall of the vacuum interrupter at the same time. at this arrangement are related to the contact arrangement axially symmetric quenching plates before.

The well-known vacuum interrupter with current-limiting property thus consists of at least two contacts with measures for generating radially directed magnetic fields, of which at least one contact in the direction of the power supply From the other contact is movable, from one vacuum-tight envelope, an insulator and an electric largely isolated mounted, the main contacts enclosing Splitter stack for arc splitting.

The staggered arranged and / or shaped quenching plates bring considerable technical improvements: the one from the place of origin arc running away reaches the middle Fireplaces immediately after contact separation. The cooling Effect of the middle quenching plates is therefore without delay, as well as a possible formation of partial arcs, at least in the middle splitter columns. The current limit due to increased arc tension thus occurs advantageous early in case of overload.

The location of the sheet-metal edges subjected to the arc forces an extension of the arc filament before or instead of a division through the quenching plates in transversal or radial direction. In particular, it causes a better one Cool the arc through the long contact zone between Arc and quenching plates. The associated increased arc voltage requirement before entering the splitter plate column favors the formation of arc bases the quenching plates. The specified geometric measures thus have an advantageous effect on the structure of increased arc voltage amplitudes out.

The shapes of the quenching plates described can also be advantageous be further educated. On the one hand, a big one improves Length of the arc exposed edge the cooling of the Arc. On the other hand cause the large edge length and possibly a structured, uneven or with openings provided sheet metal surface the chance, arc approaches to form on the sheets. Both properties favor the arc voltage build-up.

After contact separation, the arc becomes effective in the direction driven the splitter stack, since neither the inventive Graduation of the quenching plates, nor the arc stress the plates formed metal vapor training hamper a current loop.

Turn-off attempts on the beak-shaped shown in Figure 3/4 Vacuum switch contacts with staggered arranged Splitter plates have shown that significantly higher arc voltage amplitudes measured as in the case of non-staggered, i.e. stacked quenching plates, wherein the short-circuit current is further limited.

At high short-circuit currents thus lead the inventive Overall, measures to an unprecedented, strong Sheet tension requirement, which is a significantly improved causes current-limiting switching behavior.

In the figure 10 is at the edge facing the arc the quenching plates 86a to 86i attached a contour 90. The Contour 80 may in particular have a regular serrated shape and serves to extend the splitter edge. The Contour 90 may also be irregular, wherein such a contour depends on the slit of the spiral contacts.

Vacuum interrupters with the contact configurations according to the invention and quenching plate assemblies according to the figures 3 to 5 on the one hand and Figures 8 to 10 on the other hand can be based on the figures 1/2 and 6/7 of the prior art realize.

Measurements were taken on beak-shaped and rotationally shaped contact pieces without current limit and with current limitation at stacked quenching plates on the one hand and staggered quenching plates on the other on the other hand. Figure 11 shows typical Time curves of the arc voltage for the rotationally symmetric Arrangement. Plotted on the abscissa is the time in s and on the ordinate the arc voltage in volts. Are shown Graphs 101 to 103 for comparison of the invention with the State of the art.

The graph 103 of a measurement with splitter staggering includes with respect to the graph 102 of the measurement without the plate spacing, but stacking, and the graph 101 without current limit a considerable improvement to higher arc voltages, which is to be regarded as technical progress.

On the basis of the measured arc voltages results with an arrangement according to Figure 8/9 a significant reduction of the short-circuit current. This reduction occurs in the Graduation of the quenching plates much clearer than the Stacking of the quenching plates. Of course, this is also the short-circuit duration lower.

Claims (13)

Arrangement for current limiting in low-voltage networks, comprising a vacuum interrupter with two contact pieces, wherein as a means for current limiting arc extinguishing plates, which are at least partially disposed between the contact pieces, are present, characterized in that the quenching plates (36a to 36i, 86a to 86i) have different lateral dimensions and are staggered in the direction of the switching pieces (3, 4; 13, 14). Arrangement according to Claim 1, characterized in that the splitter stack (36, 86) formed by the quenching plates (36a to 36i, 86a to 86i) simulates the contact profile of the contact pieces (3, 4; 13, 14). Arrangement according to Claim 2, characterized in that, when the switching pieces (3, 4; 13, 14) are closed, the outer quenching plates (36a to 36i; 86a to 86i) extend close to the contact pieces (3, 4; 13, 14). Arrangement according to claim 3, characterized in that the outer quenching plates (36a to 36i; 86a to 86i) extend to half the contact stroke, preferably up to about 3 mm, to the contact pieces (3, 4; 13, 14). Arrangement according to Claim 3 or 4, characterized in that the middle quenching plates (36e, 86e) arranged near the contact gap have a smaller distance from the contact pieces (3, 4; 13, 14) than the outer quenching plates (36a to 36d, 36f to 36i). 86a to 86d, 86f to 86i). Arrangement according to one of the preceding claims, characterized in that the splitter stack (36, 86) comprises such a profile, which is modeled on a specific contact configuration. Arrangement according to claim 6, characterized in that the quenching plates (36a to 36i; 86e to 86i) form a package (36, 86) which has a triangular course with the quenching plates (36a to 36i, 86a to 86i). Arrangement according to one of the preceding claims, characterized in that the central quenching plate (36e, 86e) is offset backwards relative to the two adjacent quenching plates (36d, 36f; 86d 86f). Arrangement according to one of the preceding claims, characterized in that the quenching plates (36a to 36i, 86a to 86i) consist of iron, stainless steel or copper. Arrangement according to claim 9, characterized in that the metallic splitter stack (36, 86) in an electrically insulating, not gassing holder (37, 87), preferably made of ceramic, is fixed. Arrangement according to one of the preceding claims, characterized in that the quenching plates (36a to 36i, 86a to 86i) have an edge contour (90). Arrangement according to claim 11, characterized in that with the edge contour of the contact gap facing the quenching plate front (90) is increased. Arrangement according to one of the preceding claims, characterized in that the quenching plates (36a to 36i, 86a to 86i) have surface structures.

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