EP1566869B1 - Electrical component with protection against accidental arcs - Google Patents

Abstract

On one electrode of the arcing protection system has arcing projections (21-24) each with successive circumferential sections (b, c) around the cup wall (12). One section (b) set back from the cup edge, is angled with respect to the projecting section. Sections are held in the cup wall (12).

Description

TECHNICAL AREA

The invention is based on an arc protected electrical component according to the common preamble of claims 1 and 4. The invention also relates to a specific for this component arc electrode.

The component has an insulator designed as a pillar, to the head of which a first current conductor system, which can be guided to high-voltage potential, is fastened. At the insulator foot, a second current conductor system, which can be routed to ground potential, is fastened. The first and the second conductor system each have an arc electrode for receiving an arc occurring during a discharge between the first and second conductor system. At least one of both arc electrodes is designed in the manner of a cup. In the cup wall at least two arc edge forming the cup edge are formed. An arc formed during an unwanted discharge between the two conductor systems is commutated to the edge of the cup. Under the action of the magnetic field of the electric arc feeding the arc and guided in the cup rim to the arc of the predominantly axially aligned arc arc is set in rotation and deleted in the current zero crossing.

STATE OF THE ART

With the preamble, the invention relates to a prior art of arc protected electrical components, as in EP 1 283 575 A1 is described. A disclosed in this prior art and designed as a surge arrester component contains two electrically isolated by a columnar outdoor insulator from each other and located at different electrical potentials conductor systems. each This conductor system has an arc electrode for receiving an arc occurring during a discharge between the two conductor systems. The two arc electrodes are cup-shaped. In the wall of each cup, a plurality of arc fingers are formed, which form portions of the cup rim. The supply current of the arc flowing in these sections to the foot of the arc provides for a radially directed magnetic field at the base of the arc. The arc is therefore subjected to a tangentially directed electrodynamic force and rotated along the edge of the cup around the insulator until the arc extinguishes.

Even with one out US 5,903,427 A Previously known arc protected electrical component holds a columnar outdoor insulator two against each other electrically insulated and located at different electrical potentials conductor systems. Each of these systems contains in each case one designed as an open, annular loop and in the region of the insulator head or the Isolatorfusses at a distance around the insulator guided conductor portion. Occurs during operation of the component in a high-voltage system - such as due to a lightning strike or by a switching operation - an undesirable arc on the component, the arc is guided in a conductor sections containing the arc electrodes as a stomping path. The arc is now predominantly aligned axially and is based on the two circumferentially guided, annular arc electrodes. Due to electromagnetic forces of the arc flashes on the arc electrodes fussend as long as the insulator of the component until it is extinguished in the zero crossing of the arc fault current. The component is thus protected against the eroding and corrosive effect of the arc fault.

A designed as a surge arrester another arc protected electrical component is in US 6,018,453 A specified. Also in this component unwanted arcs arc commutated on two spaced apart in the direction of an axis of the component arc electrodes, forced to rotate about the axis and so deleted in the current zero crossing. In contrast to the aforementioned prior art, however, the two are in this component Arc electrodes are each formed as a plate and are formed in the plates in each case a plurality of predominantly radially guided slots.

PRESENTATION OF THE INVENTION

The invention as defined in the claims solves the problem of providing an arc protected electrical component of the type mentioned, in which the effect of arcing arcs is particularly effectively suppressed by suitable design of an arc electrode.

In a first preferred embodiment of the component according to the invention, the arc fingers each have two successively in the circumferential direction of the cup wall finger portions, of which a cup edge distant portion of a first of the fingers and the axis are skewed and a cup edge forming portion of a second of the fingers at a distance in Axially to the cup edge remote portion is held in the cup wall. Because of this arrangement and design of the arc fingers, a strong, predominantly radially directed magnetic field builds up over the entire cup rim at the base of the arc fault. It acts on the cup edge held at the base of the arc always a large, tangentially directed, electrodynamic force, which causes a rotation of the arc root until the extinction of the arc in the current zero crossing. The continuity of the force is given by the fact that regardless of its current position on the edge of the cup, a radially directed strong magnetic field is constantly maintained in the arc root. Even with the transition from a finger to the following finger in the circumferential direction of this magnetic field is maintained, since at least one of the two superimposed finger portions predominantly in the tangential direction flowing current receives with the same sense of direction, which continues at the arc root as a predominantly axially guided arc current.

A comparatively small number of arc fingers is required if the cup rim-forming section of the arc fingers is guided predominantly tangentially is. The predominantly tangential guide also includes curvatures of the cup edge forming portions in the axial direction.

In a manufacturing technology particularly simple embodiment of the component according to the invention, the arc fingers are arranged skewed to each other over their entire length and the axis.

In a second preferred embodiment of the component according to the invention, the arc fingers each have two predominantly tangentially guided portions, one of which is attached to the cup bottom and the other forms the cup rim, each arc finger has an at least in the axial direction guided middle portion of the bottom of the cup Section with the cup edge forming portion connects, and the cup edge forming portion of a first of the fingers is held at a distance in the axial direction to the bottom side portion of a second of the fingers in the cup wall. Because of this arrangement and design of the arc fingers, a particularly strong, predominantly radially directed magnetic field builds up over the entire edge of the cup at the foot of the arc fault. It is imposed on the arc supplying the arc and continuing in the arc current at the transition from one finger to another a particularly well-trained loop, which leads to a high radial magnetic field and thus substantially facilitates the Stromkommutation at the transition point.

Advantageously, the central portion is guided not only in the axial direction, but at the same time in the tangential direction. The central portion and the axis are then skewed to each other. The bottom portion and the misaligned midsection then provide the transition from the central portion of the cup rim for a good current loop and thus for the desired strong radial magnetic field at the arc root.

A sufficiently strong magnetic field at the transition point from one finger to the other can also be achieved if the middle section is guided predominantly axially and optionally radially. However, then the cupola side portion should only be formed by a relative to the diameter of the section relatively narrow air gap from the cup edge forming Separate section, otherwise the radial component of the magnetic field at the location of the arc root may be too low.

In an economically particularly advantageous embodiment of the inventive component, the arc electrode provided on the insulator head is formed by a current connection supplying the first electrical potential. This embodiment also has the advantage that an emigration of the arc arc is avoided by the otherwise provided on the insulator head and having direction of rotation electrode on the power connector due to the thermal effect of the arc fault.

Opposing rotations of the arc root points are achieved if the arc electrode arranged on the insulator head has a different direction of rotation than the arc electrode arranged on the insulator base. These opposing movements lead to a particularly effective magnetic blowing of the arc fault.

In general, in the case of the component according to the invention, the insulator is made hollow and an active part guided axially through the insulator is provided. Therefore, particularly preferred components are outdoor bushings, surge arresters, in particular with an active part based on metal oxide, current transformers, voltage transformers or switches. If, on the other hand, the component has only supporting function, then the insulator can also be solid.

Further advantageous developments of the component according to the invention are described below.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1

eine Seitenansicht eines als Überspannungsableiter ausgeführten Bauteils nach der Erfindung mit zwei Lichtbogenelektroden 4, 7, welche jeweils sechs Lichtbogenfinger enthalten,

Fig. 2

eine Seitenansicht der Lichtbogenelektrode 4 des Überspannungsableiters gemäss Fig.1, und

Fig.3

eine Aufsicht auf die Lichtbogenelektrode 4,

Fig.4

eine Seitenansicht einer Ausführungsform der Lichtbogenelektrode 4, welche anstelle von sechs lediglich zwei Lichtbogenfinger enthält,

Fig.5

in perspektivischer Ansicht eine weitere Ausführungsform der Lichtbogenelektrode 4 mit sechs Lichtbogenfingern, jedoch mit gegenüber der Ausführungsform nach den Figuren 2 und 3 abgeänderten Lichtbogenfingern, und

Figuren 6 bis 9

weitere Ausführungsformen der Lichtbogenelektrode 4.

The invention will be explained below with reference to exemplary embodiments. It shows:

Fig. 1

a side view of a designed as a surge arrester component according to the invention with two arc electrodes 4, 7, each containing six arc fingers,

Fig. 2

a side view of the arc electrode 4 of the surge arrester according to Fig.1, and

Figure 3

a plan view of the arc electrode 4,

Figure 4

a side view of an embodiment of the arc electrode 4, which contains only two arc fingers instead of six,

Figure 5

in a perspective view of another embodiment of the arc electrode 4 with six arc fingers, but with respect to the embodiment of Figures 2 and 3 modified arc fingers, and

FIGS. 6 to 9

further embodiments of the arc electrode 4th

WAYS FOR CARRYING OUT THE INVENTION

In the figures, the same parts are identified by the same reference numerals. The surge arrester illustrated in FIG. 1 has an open-air insulator 1 designed in the manner of a column and formed, for example, by a polymer, for example based on epoxy or silicone, or a ceramic, such as a porcelain. The insulator is hollow and has an along an axis 2 (column axis) arranged, not apparent from the figure active part with at least one non-linear resistive element, preferably based on metal oxide, in particular zinc oxide.

At the insulator head, a first electrical conductor system, which can be guided to a first electrical potential, for example a high-voltage potential, is provided. The first conductor system is electrically connected to the head end of the active part and has a connectable to a high voltage line Power connection 3 and formed in the manner of a cup arc electrode 4, which is open towards the bottom Isolatorfuss concentric with the axis 2 aligned. This electrode can be made, for example, by casting or material-lifting, such as by turning and milling. The arc electrode 4 is surrounded concentrically by an upwardly closed cover 5. The isolator foot is provided with a second electrical conductor system which can be guided to a second electrical potential, for example ground potential. The second current conductor system is electrically conductively connected to the foot end of the active part and has a connectable to a ground conductor 6 and a power connector designed like a cup Lichtelektode 7, which is open towards the insulator head concentrically aligned with the axis 2. The arc electrode 7 is concentrically surrounded by a downwardly closed cover 8. The two arc electrodes 4 and 7 are made of good electrically conductive material, in particular copper or a copper alloy, such as brass. In a particularly advantageous manner, this material may comprise graphite or another material particularly resistant to erosion. At least the downwardly facing edge 9 of the arc electrode 4 and the upward-facing edge 10 of the arc electrode 7 are made of erosion-resistant material, such as a refractory brass, a copper-tungsten or copper-chromium alloy. The two arc electrodes 4 and 7 are arranged mirror-symmetrically to each other.

The construction of the arc electrode 4 can be seen in FIGS. 2 and 3. These figures can be seen that the arc electrode 7 has a cup bottom 11 and a subsequent to the cup bottom and extending in the direction of the axis 2 of the column cup wall 12, formed in the six the cup rim 9 forming identically formed and spaced by air gaps 13 arc fingers are. From Fig.2 only the four fingers 21, 22, 23 and 24 are visible. These fingers are each extending predominantly in the circumferential direction and each have three axially spaced-apart and circumferentially successive sections. The three sections can only be seen for the two fingers 22 and 23 from FIG. 2 and are designated in sequence with the reference signs a, b, c and a ', b', c 'respectively. A labeled with the reference a or a 'portion of the finger 22, 23 sets at the bottom 11 and is also tangentially guided as a cup edge forming section c or c '. The two sections a and c or a 'and c' are connected by a predominantly tangential, but obliquely to the axis 2, guided, cup side remote section b and b 'with each other. Section b or b 'and axis 2 are skewed to each other. The cup-distal portion b 'of the finger 23 and cup-forming portion c of the finger 22 are the cup-distal portion b of the finger 22 and cup-forming portion c "of the finger 21 and cup-distal portion b" of the finger 24 and cup-forming portion, respectively c 'of the finger 23 are held one above the other at an axial distance in the cup wall 12. Centrally to the axis 2, an opening 14 is provided in the cup base 11, through which a portion of the power connector 6 shown only in Fig.1 is guided.

The mode of action of this surge arrester is as follows:

Occurs during operation of the surge arrester in a high-voltage system between the power terminals 3 and 6 on the active part and / or on the insulator 1, an undesirable arc fault, so its base points under the action of its own magnetic field in each case to the cup edges 9, 10 out. The arc current then flows from the power connector 3, the cup bottom 11, the arc fingers, for example, 21, 22, 23 or 24, the cup rim 9, the arc, the cup rim 10 and the arc electrode 7 to the power connector 6. Since the cup edges 9, 10 opposite Becherböden 11 from each other have a comparatively small distance, is determined by the Becherränder a small impact distance and is so safe footing of the arc and thus ensures good thermal protection. In addition, a tangentially directed, large electrodynamic force always acts on the base 15 of the arc (FIG. 2) held on the cup rim 9, which causes a rotation of the arc until its extinction in the current zero crossing. The continuity of the force is given by the fact that in the arc root 15 regardless of its positioning on the cup rim 9 consistently a radially inwardly directed strong magnetic field is maintained. This continuity results from the previously described design and arrangement of the arc fingers. If the arc is located on section c of finger 22, section c in FIG. 2 is indicated by an arrow Current I, which continues in the axially directed arc (shown as a jagged arrow in Fig. 2). The current therefore forms a well-formed current loop at the arc root point 15 and generates at the location of the base point 15 away from the observer, ie radially inwardly, directed strong magnetic field. A tangentially directed force acting counterclockwise on the arc, which leads the base point 15 to the air gap 13 separating the two fingers 22 and 23. Regardless of whether the base point 15 has not yet partially or completely overcome the air gap, the radially inwardly directed magnetic field is maintained since at least one of the two sections b 'and c receives the current I. At the end of the section c 'facing the section c, after the commutation of the current I, no such pronounced current loop is formed as at the end of the section c facing the section c', since the current I in the section b 'is indeed oblique to the axis 2 is guided. However, this current loop is sufficient to generate a sufficiently large radial magnetic field that effects the continued operation of the arc root point 15.

In contrast to the embodiment of the arc electrode according to FIGS. 2 and 3, the arc electrode 4 embodied according to FIG. 4 has only two arc fingers 22 and 23. In this electrode, the cup edge and cup edge forming portions b, c 'and b', c of both fingers 22 and 23 are axially spaced apart from each other as in the above-described embodiment, so that this embodiment has the same advantageous effects. In terms of manufacturing technology, this electrode can be realized particularly easily, but at the expense of the mechanical stability of the arc fingers.

By the cup rim 11 attached, tangentially guided portion a 'is improved in the embodiments of Figures 2 to 4, the loop formation and thus increases the radial magnetic field. If the air gap 13 between two arc fingers, for example 22, 23, has only a comparatively small width, then the radial magnetic field is sufficient even if the cup edge-distant section b 'and axis 2 are no longer skewed relative to one another, but the section b' Without tangential component predominantly axially (depending on the wall inclination also with radial component) out is. Such an embodiment of the electrode 4 can be seen in FIG. The current loop caused by the transition from the section a 'to the section b' applied perpendicular thereto generates a magnetic field whose component in the radial direction is sufficient to continue the arc root point on the cup rim 9 at the transition from one arc finger 23 to the adjacent 22.

The arc fingers, z. B. 22 to 23, need not necessarily have an exclusively tangentially guided cup edge forming finger portion c or c '. Loop formation and a sufficiently high radial field are still achieved even when the arc fingers and the axis 2 are skewed to each other (embodiment of the electrode 4 according to Figure 6) or if only the cup edge remote section b, b 'and the axis 2 skew each other are, however, the cup edge forming portion c, c 'tangentially (embodiment of the electrode 4 according to Figure 7) or curved out (embodiment of the electrode 4 according to Figure 7 with dashed trays edge forming portion c' of the arc finger 23 '). However, it is important that cup edge forming c and cup rim distal portion b 'of successive arc fingers 22, 23 are held one above the other with axial spacing in cup wall 12.

In the case of the embodiments of the electrode 4 illustrated in FIGS. 6 and 7, the arc fingers engage the cup base 11 with the section b, b 'guided obliquely to the axis 2. The tangentially guided section a, a 'present in the embodiments according to FIGS. 2 to 5 can therefore be dispensed with in principle, since sections b, c and b', c 'of successive arc fingers 22, 23 provide a sufficiently high radial magnetic field during current flow can.

By the two of an insulating material, such as preferably a polymer based on silicone, epoxy, polycarbonate or polyamide, are added to the advantage fillers, in particular flame retardant lean materials, the arc electrode 4, 7 from contact, for example by animals or by falling good, protected. At the same time, the area is also in front of the Protected by the action of heated material, which is possibly thrown away from the component under the effect of the arc fault and represents a not inconsiderable fire risk. Such protected components can therefore be used without problems in arid areas with fire-threatening vegetation, such as dried grass or bushes.

In the embodiments of the electrode 4 according to FIGS. 8 and 9, six material recesses 16 are formed in the cup base 11, each opening into one of the air gaps 13. These embodiments of the electrode can be formed in a simple manner by stamping and cold forming a sheet, for example by punching a flat, the material recesses containing precursor body 25 of the electrode from the sheet and then bending a sheet metal flap located between each two material recesses 16 to form six contact fingers and the air gaps 13 arranged therebetween (for reasons of clarity, only four fingers 21 to 24 are designated in FIGS. 8 and 9). This can be achieved in manufacturing technology particularly simple manner executed in the manner of a polygon cup base 11, at the corners of each of the material recesses 16 is arranged (embodiment of FIG. 8 with a formed like a polygon cup rim). However, it is also possible to achieve an embodiment of the electrode 4 having a circular design of the cup rim 9 in accordance with the embodiment according to FIGS. 2 to 5.

The cup wall 12 is inclined in all the illustrated embodiments predominantly at an angle of 90 ° relative to the cup base 11, but may also, without losing the advantageous effects described above, include a deviating angle of at most 150 ° and at least 30 °.

LIST OF REFERENCE NUMBERS

1

insulator

2

axis

3, 6

power connectors

4, 7

Arc electrodes

5.8

covers

9, 10

cup rims

11

cup base

12

cup wall

13

air gaps

14

opening

15

Arc root

16

material recesses

21, 22, 23, 24

Arc fingers

25

precursor body

a, a ', a ", b, b', c, c ', c"

Sections of the arc fingers

I

Supply current of the arc

Claims (12)

1. An electrical component protected against accidental arcing with

   - an insulator designed in the form of a column (1),

   - a first power conductor system, provided at the insulator head and directable to a first electrical potential, and with

   - a second power conductor system, provided at the insulator foot and directable to a second electrical potential,
   in which the first and the second power conductor system in each case has an arc electrode (4, 7) for the accommodation of an arc accidentally occurring in the event of a discharge between the first and second power conductor systems, and in which at least one of the two arc electrodes (4, 7) is designed in the form of a cup, and has at least two arc fingers (21, 22, 23, 24) moulded into the cup wall (12) and forming the cup edge (9),
   characterised in that the arc fingers (21, 22, 23, 24) in each case have two finger sections (b, c; b', c'; b", c") following each other in the circumferential direction of the cup wall (12), of which a further from the cup edge section (b') of a first of the fingers (23) and the axis (2) are arranged in a skewed manner relative to each other, and a cup edge-forming section (c) of a second of the fingers (22) is held at a distance in the axial direction from the further from the cup edge section (b') in the cup wall (12).
2. The component according to Claim 1,
   characterized in that the cup edge-forming section (c, c', c'') of the arc fingers (21, 22, 23, 24) is predominantly directed in a tangential direction.
3. The component according to Claim 1,
   characterised in that the arc fingers (22, 23) and the axis (2) are arranged in a skewed manner relative to each other.
4. An electrical component protected against accidental arcing with

   - an insulator designed in the form of a column (1),

   - a first power conductor system, provided at the insulator head and directable to a first electrical potential, and with

   - a second power conductor system provided at the insulator foot and directable to a second electrical potential,
   in which the first and the second power conductor system in each case has a arc electrode (4, 7) for the accommodation of an arc accidentally occurring in the event of a discharge between the first and second power conductor system, and in which at least one of the two arc electrodes (4, 7) is designed in the form of a cup, and has at least two arc fingers (21, 22, 23, 24) moulded into the cup wall (12) and forming the cup edge (9),
   characterised in that the arc fingers (21, 22, 23, 24) in each case have two predominantly tangentially directed sections (a, c; a', c'; a", c") of which one (a, a', a'') is set on the cup floor (11), and the other (c, c', c") forms the cup edge (9),
   in that each arc finger (21, 22, 23, 34) has an at least in the axial direction directed centre section (b, b', b''), which connects the cup floor-side section (a, a', a'') with the cup edge-forming section (c, c', c''), and
   in that the cup edge-forming section (c) of a first of the fingers (22) is held at a distance in the axial direction from the cup floor-side section (a') of a second of the fingers (23) in the cup wall (12).
5. The component according to Claim 4, characterised in that the centre section (b, b', b") in addition is also directed tangentially.
6. The component according to Claim 5,
   characterised in that the centre section (b, b', b'') is predominantly directed axially, and radially as required.
7. The component according to one of the Claims 1 to 6,
   characterised in that at least two material recesses (16) are moulded into the cup floor (11), which in each case open out into an air gap (13) provided between the first (23) and the second (22) or the third contact finger (24).
8. The component according to Claim 7,
   characterised in that the cup edge (11) has a circular or polygonal shape.
9. The component according to one of the Claims 1 to 8,
   characterised in that the cup floor (11) is embodied in the form of a polygon, at each of whose corners one of the material recesses (16) is arranged.
10. The component according to one of the Claims 1 to 9,
    characterised in that the cup wall (12) is arranged inclined at an angle between 30° and 150° relative to the cup floor (11).
11. The component according to one of the Claims 1 to 10,
    characterised in that the arc electrode (4) provided at the insulator head is formed from a power connection (3) supplying the first electric potential.
12. The component according to one of the Claims 1 to 11,
    characterised in that the arc electrode (4) provided at the insulator head has a direction of rotation other than that of the arc electrode (7) arranged at the insulator foot.

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