EP2936530A1

EP2936530A1 - Power circuit breaker

Info

Publication number: EP2936530A1
Application number: EP13823936.3A
Authority: EP
Inventors: Vladimir Ermel; Michael Kurrat
Original assignee: Technische Universitaet Braunschweig
Current assignee: Technische Universitaet Braunschweig
Priority date: 2012-12-21
Filing date: 2013-12-20
Publication date: 2015-10-28
Anticipated expiration: 2033-12-20
Also published as: US9543086B2; EP2936530B1; DE102012025115A1; WO2014095079A1; US20150332878A1

Abstract

The invention relates to a power circuit breaker that is suitable for switching voltages. The power circuit breaker according to the invention comprises two main electrodes, to each of which a respective pole of the voltage to be switched can connected. During the switching process, at least one of said main electrodes follows a switching path. The power circuit breaker is characterized in that secondary electrodes are additionally provided, which protrude into the vicinity of the switching path and are designed and arranged in such a way that arcs can be produced (a) between the main electrodes and the secondary electrodes and (b) between the individual secondary electrodes during the switching process. The power circuit breaker according to the invention can be advantageously used in vehicles and in ultra-high-voltage AC and HVDC (high-voltage direct current) transmission systems and causes arcs to be extinguished as early as possible during the switching process.

Description

breakers

The present invention relates to a circuit breaker which is suitable for switching electrical voltages and / or electrical currents and powers.

Usually, a circuit breaker contains two electrodes, to which in operation one pole of an electrical power to be switched is applied in each case. In particular, when separating the electrodes, there is a high probability that an unwanted arc occurs. Even if he dies in the meantime, there is a risk that he can ignite again and until the

Separation distance is large enough.

In order to ensure the extinction of such arcs as far as possible, in many of the known high-voltage circuit breakers, the insulating gas SF ₆

(Sulfur hexafluoride) used. However, this is a very strong greenhouse gas, especially in leaks and after the end of the life in the

Atmosphere can escape. In particular, for reasons of environmental friendliness, therefore, vacuum switches have been developed for switching high voltages. To reduce the occurrence of arcs in vacuum switches, these are usually used in

AC systems used. Because with AC occurs periodically a zero crossing of the current, which favors the extinction of the arc.

However, there is an increased demand for the transmission of high voltage direct current. Such systems of high-voltage direct current (HVDC) transmission are proposed in the current discussion about the energy transition and the expansion of electrical networks, in particular for the connection of offshore wind farms or the establishment of coupling points, from various sides. Because for higher power with the same route width, longer distances and especially longer cable connections DC technology appears advantageous.

CONFIRMATION COPY Often the reliable switching of high DC voltages is realized by connecting several high voltage circuit breakers in series.

The European Patent EP 0 556 616 B1 - or its German translation DE 693 02 716 T2 - introduces a DC breaker arrangement which closes a commutating switch after interrupting a vacuum switch and converts an arc direct current by means of commutation into an alternating waveform to the interruption complete. This is intended to reliably interrupt a DC current to prevent an escalation of a malfunction.

It is the object of the present invention to be able to switch an AC or DC voltage (or a corresponding power) in a simple and reliable manner.

This object is achieved by the circuit breaker according to claim 1. Advantageous further developments are specified in the subclaims.

The circuit breaker according to the invention has two electrodes, to each of which a pole of an electrical voltage can be connected, which is to be switched or disconnected. These electrodes will be below as well

Called main electrodes. The switch according to the invention is in principle suitable for switching voltages with arbitrary values. In this case, the generation of arcs should be prevented or their presence be terminated as quickly as possible during the switching process. Therefore, the switch according to the invention is particularly suitable for all applications in which such arcs are particularly harmful, such as in vehicles with electric drive and / or internal combustion engines and when switching high voltages. Here, high voltage is understood to mean a voltage which may have a value of approx. 50 - 500 kilovolts or even more. The circuit breaker offers particular advantages as part of a system for transmission of ultra-high voltage alternating current (AC) or high voltage direct current (HVDC). For the switching process, the main electrodes must be brought together or

be separated. This is usually done by a mechanical movement of one of the two main electrodes. The other main electrode is then stationary, ie stationary within the circuit breaker. However, it is also conceivable that both main electrodes are moved simultaneously or in succession.

This switching movement takes place along a switching path. Usually this runs straight and perpendicular to the button of the stationary main electrode. However, any other form which is advantageous for mechanical and / or electrical reasons is also conceivable.

The present invention is characterized in that at least one secondary electrode is present. This sub-electrode (or more) protrudes into the area near the switching path. This causes that in the separation process, first, a main arc between the two main electrodes is formed and with further progressing distance of the main electrodes to each other more arcs arise between the main electrodes and the secondary electrode. These further arcs are thus connected in parallel to the original main arc and cause it to extinguish much earlier than in previously known circuit breakers. In order to optimize the generation of the further arcing, it is advantageous that the minimum distance between the switching path and the sub-electrode is less than 10 mm, with values between about 0.5 to 1 mm having proven particularly useful.

The invention is based on the finding that the presence of the

Arcs is unstable and follows statistical laws. If, instead of a main arc, several individual arcs occur, which are quasi connected in series, there is a much greater probability that one of these individual arcs will extinguish. When that happens, more of these single arcs will quickly go out, eventually wiping out the entire arc chain. The creation of such an arc chain instead of a single main arc, the presence of arcs during the switching process so finished faster and thus the

Operational safety of the circuit breaker increased.

The presence of the sub-electrodes according to the invention is basically possible in a circuit breaker containing a gas, such as the insulating gas SF ₆ . Particularly advantageous is the arrangement of the auxiliary electrodes is, however, in vacuum circuit breakers, in which a gas pressure is in the range of 10 ^{~ 4} to 10 ^"8 mbar, usually values in the range of 10 ^{~ 5} to ^{10" 7} mbar are particularly preferred.

The secondary electrode (or more) can be designed in various ways. In order to ensure the highest possible operational reliability, it has been proven to make the secondary electrode annular or planar, with an opening is provided through which the switching path passes.

It has also been proven that the secondary electrode (or more) has a contour, whereby it is thinner in the region of the switching path, as on the side facing away from the switching path. Such a contour can be realized for example by a triangular-shaped course (see Fig. 5). It is also conceivable that the secondary electrode each has a rounded course (see Fig. 4), which can be described by a small radius (r) or a larger radius (R), where r <R is.

To further increase the reliability, it has proven useful if, in the presence of a plurality of sub-electrodes at least some of them are electrically connected to each other by an electronic network containing at least one varistor and / or at least one ohmic resistance. In the following, further details and advantages of the present invention will be described with reference to preferred embodiments. Show

Fig. 1 is a symbolic representation of a circuit breaker Fig. 2 is a cross-sectional view of the circuit breaker

Fig. 3a ... 3h different switch positions with spark gaps

Fig. 4 is an enlarged view of the sub-electrode 30a of Fig. 2 Fig. 5 sub-electrodes with triangular contour

Fig. 6 shows another embodiment of the circuit breaker with wiring.

Identical or similar means are provided in the figures with the same reference numerals. A repeated description is made only insofar as it is for the

Understanding the invention or the embodiments required appears. Although the embodiments describe the switching of high voltage, it should again be noted that the circuit breaker according to the invention is suitable for the switching of electrical voltages with arbitrary values.

Fig. 1 shows a symbolic representation of a preferred circuit breaker 10, which is suitable to switch DC voltages up to 100 kV and more. It is preferably designed as a vacuum switch, in which there is usually a pressure of about 10 ^{~ 6} mbar. The preferred embodiment is designed substantially circular or cylindrical symmetry. That is, the housing of the circuit breaker 10 includes a substantially cylindrical insulator 12 and an upper end plate 14 and a lower end plate 16, which are each nearly disc-shaped. The circuit breaker 10 further includes an upper

Main electrode 18 having an upper shaft 20 and a lower main electrode 22 with a lower shaft 24. About the main electrodes 8, 22 may be a

High voltage switched or disconnected. Both shafts 20, 24 are electrically conductive and connected respectively to their associated main electrode 18 and 22 both mechanically and electrically conductive.

The upper shaft 20 is fixed to the upper end plate 14 so that the upper main electrode 18 within the circuit breaker 10 is almost stationary. An upper connection port A, to which the first pole of the to be switched

High voltage can be applied, is connected via the electrically conductive upper shaft 20 to the upper main electrode 18. Die Hochspannung ist in Fig. 1 dargestellt. The lower shaft 24 can be through an opening, not shown here within the lower End plate 16 along the arrow 26 to move back and forth vertically. Thus, therefore, the lower main electrode 22 vertically, that is, up and down, are moved along a switching path, which is indicated here by the dashed lines sl and sr. Via a lower connection port B, the second pole of the high voltage to be switched can be applied. This port B is electrically connected to a sliding contact 28, which in turn makes contact between the electrically conductive lower shaft 24 and thus also to the lower

Main electrode 22 allows. The circuit breaker 10 further includes five sub-electrodes 30a, ..., 30e, which are each formed almost disc-shaped, and which are each held by one of the holders 31a, ..., 31 e. The brackets 31 are

Preferably formed as sheets, which are fixed to the insulator 12 and on one of the end plates 14, 16 (see also Fig. 2) and so the

Keep sub-electrodes in a stable position. It is alternatively also possible that the brackets 31 are formed as webs or the like.

The auxiliary electrons 30 each have an opening 32a,..., 32e in the central region, which are designed and arranged such that the movable lower main electrode 22 can be moved therethrough. Preferably, the openings 32 are symmetrical to the positions of the lower main electrode 22 along its vertical switching path. If this is in the middle of one of the

Openings 32 is located, there is a minimum distance d between the exterior of the main electrode 22 and the interior of such opening 32, as shown in Fig. 1. This distance d between the switching path sr and the sub-electrode 30 is less than 10 mm, with values between 0.5 and 1 mm having proven particularly useful. It is also possible that the uppermost sub-electrode 30a is arranged such that the upper main electrode 18 is in the region of the opening 32a. Such embodiments are shown for example in FIGS. 3 and 4

FIG. 2 shows a cross-sectional view of the preferred circuit breaker 10, which-as already mentioned above-is substantially circular or cylindrically symmetrical. For clarity, were by the side electrodes 30a, ..., 30e only three are drawn. Fig. 2 also shows other possible modifications. Thus, here the insulator 12 has first regions 12a, which are electrically conductive, and second regions 12b, which are electrically insulating. The first regions 12a are preferably made of metal. The second portions 12b are made of ordinary material such as ceramic or the like.

In addition, in FIG. 2, the upper main electrode 18 is made quite large, so that its lateral dimension is larger than that of the lower main electrode 22.

Furthermore, the power switch 10 here has a shielding plate 33. Together with the brackets 31a and 31e, which are also preferably designed as sheets and thus also function as shielding plates, so the dielectric surface of the insulators 12 is shielded during the emergence and presence of an arc against thereby occurring flows of metal particles.

In Fig. 2, an electromagnet 34, a permanent magnet 36 and a spring 38 are also shown, with appropriate circuitry and control by suitable means (not shown here) a vertical actuation of the lower shaft 24 - and thus also the lower main electrode 22 - allow and so can cause a desired switching operation by an interconnection or separation of the two main electrodes 18, 22.

The arrangement shown in Fig. 2 of the magnets 34, 36 and the spring 38 is merely symbolic and indicates a circuit breaker 10, which is realized as a gas-filled switch. In a vacuum switch, however, are the

Electromagnet 34 and the spring 38 preferably below the lower

End plate 16 and mounted outside the vacuum chamber.

The special feature of the present invention are those in the

Embodiments shown auxiliary electrodes 30. These cause that

Arcs that occur during the switching process usually can be easily deleted. This will be explained in more detail with the following Fig. 3. Fig. 3 consists of the individual representations 3a ... 3h. In this case, during a switching operation in which the two main electrodes 18, 22 are separated from each other, successively different positions of the lower main electrode 22 are shown. In addition, the side electrodes 30a, ..., 30e are shown as well as various arcs that may arise during such a switching operation. In the illustrated embodiment, the uppermost sub-electrode 30a is at substantially the same height as the first one

Main electrode 18, which is almost stationary. It is assumed (not shown here) that the lower main electrode 22 was initially driven so that the two main electrodes 18, 22 touched and thereby a

DC voltage of about 50 kV or more has been switched. When the two main electrodes 18, 22 are separated, different arcs occur, which will be discussed in more detail below. They arise within a vacuum circuit breaker in that metal particles of the material of the

Release electrodes. However, such arcs are unstable and their occurrence or extinction follows statistical laws.

Fig. 3a shows the two main electrodes 18, 22 shortly after their separation, wherein the lower main electrode 22 has taken a position in which it is located approximately at the same level as the auxiliary electrode 30b. First, in the separation process, an arc 10 is formed between the two main electrodes 18, 22. Almost simultaneously, an arc 112 (between the upper main electrode 18 and the sub-electrode 30a), an arc 114 (between the sub-electrodes 30a, 30b) and an arc occurs 116 (between the sub-electrode 30b and the lower main electrode 22).

Fig. 3b shows a situation in which the lower main electrode 22 has moved further down during the switching operation. The distance between the

Main electrodes 18, 22 has thereby become larger and the arc 110 originally present has gone out. The arcs 112, 1 14 and 116, however, are still present. For reasons of clarity, arcs that have already been described once are not in the subsequent figures again separately provided with reference numerals, as here in the arcs 112, 1 14 and 116. Only in Fig. 3 h are there all arcs for completeness half provided with reference numerals. In Fig. 3c arc 116 is extinguished. Instead, an arc 130

(between the sub-electrodes 30b, 30c) and an arc 132 (between the sub-electrode 30c and the lower main electrode 22) newly occurred. In Fig. 3d, although the lower main electrode 22 is below the sub-electrode 30c. Nevertheless, the same arcs are present as in Fig. 3c.

In Fig. 3e and 3f, the lower main electrode 22 is at the level of the sub-electrode 30d and just below. As a result, the arc 132 is extinguished. However, an arc 150 occurs (between the sub-electrodes 30c and 30d) and an arc 152 (between the sub-electrode 30d and the lower main electrode 22).

In Fig. 3g and 3h, the lower main electrode 22 is at the level of the auxiliary electrode 30e or just below. As a result, the arc 152 is extinguished. However, an arc 170 occurs (between the sub-electrodes 30d and 30e) and an arc 172 (between the sub-electrode 30e and the lower main electrode 22).

The arcs 112, 114, 130, 150, 170 and 172 present during the switching operation and in particular also in the position according to FIG. 3h have arisen due to the particular design and positioning of the auxiliary electrodes 30 relative to one another and with respect to the position of the upper main electrode 18 and the switching path of the lower main electrode 22. These arcs are quasi connected in series. This means that if one of these arcs disappears due to the statistical laws, the entire spark gap is interrupted. This ensures that arcs extinguish much earlier in the inventive high-voltage circuit breaker than in previously known

Circuit breakers. FIG. 4 is a section from FIG. 2 and shows, in an enlarged form, in particular the first secondary electrode 30a. This shows clearly that this secondary electrode 30a has a contour, wherein the switching path - indicated here by the left boundary sl - a smaller radius r is realized than on the

opposite side, where a larger radius R is present. This means that it has proven in the preferred embodiments, at least one of the sub-electrodes 30 in the direction of the switching sl, sr thinner or sharpener auszuformen than on the other side. It is thereby achieved that, on the one hand, the side electrodes 30 in the outer region, that is to say on the side remote from the switching path sl, have a very small distance of a few millimeters from one another, as a result of which the arcs 114, 130, 150 and 170 (see FIG ) can arise; On the other hand, the side electrodes 30 in the region of the switching path sl, sr have a significantly greater distance from each other than to the

Switching sl, sr itself, whereby the arcs 1 12, 116, 132, 152 and 172 (see Fig. 3) may arise.

Fig. 5 shows two side electrodes 30'a and 30'b with an alternative contour, which - in perspective view - from the switching sl, sr to the outside respectively

runs triangular. Also in this way it can be achieved that the distance between the sub-electrodes 30 'in the region of the switching path sl or sr is greater than on the outer side of the sub-electrodes 30'.

Fig. 6 shows symbolically a further embodiment of the

Circuit breaker 10 according to the invention. The special feature of this is the

electronic circuit 50, which consists of a plurality of ohmic resistors 52 and a plurality of voltage-dependent resistors 54, which are also called varistors in the following. The resistors 52 and the varistors 54 are each connected in series. For a high voltage circuit breaker, it has been proven that the resistors 52 each have a value greater than 100 kO. In this case, a range between 100 kD and 1 Ω is particularly advantageous. The varistors are designed in the preferred embodiment to have a limiting voltage (threshold voltage) of about 1 kV. The preferred embodiment of the circuit breaker 10 is designed so that voltages in the range of about 200 kV can be switched. If 5 sub-electrodes 30a, ..., 30e are present (as also shown), four gaps result between these sub-electrodes 30a-30e. To be optimal

Spark gap with the sparks 1 14, 130, 150, 170 (see Fig. 3) to allow, between each two sub-electrodes (30a-30b, 30b-30c, 30c-30d, 30d-30e) as many of the varistors 54 are arranged in that in each case a limiting voltage of 50 kV results. Thus, as assumed above, if each of the varistors 54 has a limiting voltage of 1 kV, between each of the

Side electrode pairs 30a-30b, 30b-30c, 30c-30d, 30d-30e 50 pieces of

Varistors 54 arranged so as to allow the desired limiting voltages. By the resistors 52, a good voltage distribution between the sub-electrodes 30 is ensured.

The electronic circuit 50 is connected as follows in this embodiment. The brackets 31 are here each designed as a sheet metal, so that these holding plates each also function as a shielding plate. Via a first electrical conductor 56, the first retaining plate 31a is electrically connected to the upper main electrode 18 via the upper shaft 20. Between the first

Holding plate 31 a and the second holding plate 31 b are connected a series of varistors 54, to which a series of resistors 52 are connected in parallel. In Fig. 6, both six resistors 52 and six varistors 54 are shown between the first holding plate 31 a and the second holding plate 31 b. Also between the other adjacent retaining plates 31 b-31 c, 31 c-31 d and 31 d-31 e six resistors 52 and six varistors 54 are shown. It should be noted that this number is only an example and may be different between adjacent retaining plates 31. This also means that the number of resistors 52 may be different from the number of varistors 54. The last retaining plate 31 e is also electrically connected via a second electrical conductor 58 via the lower shaft 24 to the lower main electrode 22. The embodiments shown in the figures and described so far are preferred embodiments of the present invention. Different configurations and modifications are possible.

Reference Signs List

10 circuit breakers

12 insulator

12a first region of 12 (electrically conductive)

12b second area of 12 (electrically insulating)

14 upper end plate

16 lower end plate

18 upper main electrode

20 upper shaft

22 lower main electrode

24 lower shaft

26 arrow

28 sliding contact

30a 30e side electrodes

31 a, ..., 31 e Brackets of the auxiliary electrodes

32a 32e openings in the sub-electrodes

33 shielding plate

34 electromagnet

36 permanent magnet

38 spring

50 electronic circuit

52 resistors

54 varistors

56 first electrical conductor

58 second electrical conductor

110, 112, 1 14, 116 arc in Fig. 3a, 3b (for the first time)

130, 132 arc in Fig. 3c, 3d (for the first time)

150, 152 arc in FIGS. 3e, 3f (for the first time) 170, 172 arc in Fig. 3g, 3h (first time)

A, B High voltage connection ports

d Distance between limitation of the switching path and edge of 32 r Radius of the secondary electrode in the area of the switching path

R radius of the secondary electrode opposite to the switching path sl, sr left or right limit of the switching path

Claims

claims

Circuit breaker for switching electrical voltages with a first electrode (18) which can be connected to a first pole (A) of the high voltage to be switched and a second electrode (22) connected to a second pole (B) of the voltage to be switched wherein switching means (34, 36, 38) are provided which are suitable for moving at least one of the electrodes (18, 22) along a switching path (sl, sr), depending on the switching state, and thus for the electrodes (18, 22). towards or away from each other, thereby

characterized in that there is at least one secondary electrode (30) located near the switching path (sl, sr).

Circuit breaker according to one of the preceding claims, characterized

characterized in that the distance (d) between the switching path (sl, sr) and the secondary electrode (30) is less than 10 mm, preferably between 0.5 and 1 mm.

Circuit breaker according to one of the preceding claims, characterized

characterized in that it is designed as a vacuum circuit breaker.

Circuit breaker according to one of the preceding claims, characterized

characterized in that at least one of the at least one secondary electrode (30) is designed to be annular or planar and has an opening (32) through which the switching path (sl, sr) runs.

Circuit breaker according to one of the preceding claims, characterized

characterized in that at least one of the at least one secondary electrode (30) has a contour whereby it is thinner in the region of the switching path (sl, sr) than on the side facing away from the switching path (sl, sr). Circuit breaker according to one of the preceding claims, characterized

characterized in that more than one of the sub-electrodes (30) is present and these sub-electrodes (30) in the region of the switching path (sl, sr) have a greater distance from each other than on the switching path (sl, sr) facing away.

Circuit breaker according to one of the preceding claims, characterized

characterized in that more than one of the sub-electrodes (30) is present and these sub-electrodes (30) in the region of the switching path (sl, sr) have a greater distance from each other than their minimum distance (d) to the switching path (sl, sr).

Circuit breaker according to one of the preceding claims, characterized

characterized in that one of the electrodes (18, 22) within the

Circuit breaker is arranged almost stationary and the other of the electrodes (18, 22) along the switching path (sl, sr) can be moved.

Circuit breaker according to one of the preceding claims, characterized

characterized in that at least some of the sub-electrodes (30) are electrically connected to each other through a network containing at least one varistor (54) and / or at least one resistor (52).