EP2936530B1 - Power circuit breaker - Google Patents

Description

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 it dies in the meantime, there is a risk that it can ignite again and that until the separation distance is large enough.

In order to ensure the extinction of such arcs as far as possible, the insulating gas SF ₆ (sulfur hexafluoride) is used in many of the known high-voltage circuit breakers. However, this is a very strong greenhouse gas that can escape into the atmosphere, especially in the case of leaks and after the end of the service life.

In particular, for reasons of environmental friendliness, therefore, vacuum switches have been developed for switching high voltages. In order to reduce the occurrence of arcs in vacuum switches, they are usually used in alternating current systems. 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.

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 their German translation DE 693 02 716 T2 - Introduces a DC breaker assembly that closes a commutating switch after interrupting a vacuum switch and converts an arc direct current by means of commutation in an alternating waveform to complete the interruption. This is intended to reliably interrupt a DC current to prevent an escalation of a malfunction.

Also the European patent application EP 0 092 207 A2 discloses a DC power switch having a fixed electrode and a movable electrode, wherein both electrons are moved towards each other or can be separated from each other. The switch presented there comprises means which expel an arc-extinguishing gas when both electrodes are separated from each other as well as a resonant circuit which is connected in parallel to the two electrodes.

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 are also called main electrodes in the following. 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 merged or 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 emergence 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 thus faster completed during the switching process and thus increases the reliability of the circuit breaker.

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 . However, the arrangement of the secondary electrodes is particularly advantageous in vacuum circuit breakers in which a gas pressure prevails in the range of 10 ^-4 to 10 ^-8 mbar, with values in the range of 10 ^-5 to 10 ^-7 mbar being 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 also FIG Fig. 5 ). It is also conceivable that the secondary electrode in each case has a rounded course (see also Fig. 4 ), which can be described by a small radius (r) or a larger radius (R), where r <R.

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.

Fig. 1

eine symbolische Darstellung eines Leistungsschalters

Fig. 2

eine Querschnittsdarstellung des Leistungsschalters

Fig. 3a ...3h

verschiedene Schalterstellungen mit Funkenstrecken

Fig. 4

eine vergrößerte Darstellung der Nebenelektrode 30a aus Fig. 2

Fig. 5

Nebenelektroden mit dreieckförmiger Kontur

Fig. 6

eine weitere Ausführung des Leistungsschalters mit Beschaltung.

In the following, further details and advantages of the present invention will be described with reference to preferred embodiments. Show

Fig. 1

a symbolic representation of a circuit breaker

Fig. 2

a cross-sectional view of the circuit breaker

Fig. 3a ... 3h

various switch positions with spark gaps

Fig. 4

an enlarged view of the secondary electrode 30a Fig. 2

Fig. 5

Side electrodes with triangular contour

Fig. 6

Another version 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 appears necessary for the understanding of the invention or the embodiments. 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 having a lower shaft 24. Via the main electrodes 18, 22, a high voltage can be switched. 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 high voltage to be switched can be applied, is connected to the upper main electrode 18 via the electrically conductive upper shaft 20. 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 allows contact between the electrically conductive lower shaft 24 and thus also to the lower main electrode 22.

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 on the insulator 12 and on one of the end plates 14, 16 (see also Fig. 2 ) and thus keep the 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. When it is in the middle of one of the openings 32, there is a minimum distance d between the exterior of the main electrode 22 and the interior of such opening 32 as in FIG Fig. 1 is shown. 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 for example in Fig. 3 and 4 shown

Fig. 2 shows a cross-sectional view of the preferred circuit breaker 10, which - as already mentioned above - is designed 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. It is also 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, the dielectric surface of the insulators 12 is thereby shielded during the emergence and presence of an arc against flows of metal particles occurring thereby.

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

In the Fig. 2 shown arrangement 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, the solenoid 34 and the spring 38 are preferably mounted below the lower end plate 16 and outside the vacuum chamber.

The special feature of the present invention are the side electrodes 30 shown in the embodiments. These cause arcs, which usually occur during the switching process, can be easily deleted. That should be with the following Fig. 3 be explained in more detail.

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 substantially at the same height as the first 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 was 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 are released from the material of the 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 height as the auxiliary electrode 30b. First, in the separation process, an arc 110 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 116 occurs (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, 114 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 at the arcs 112, 114 and 116. Only in Fig. 3 h For the sake of completeness, all arcs present there are again provided with reference symbols.

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) have 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 3e and 3f the lower main electrode 22 is at the level of the secondary electrode 30d or just below it. 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 is the lower main electrode 22 at the level of the sub-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 during the switching operation and in particular in the position according to Fig. 3h existing arcs 112, 114, 130, 150, 170 and 172 are formed by the particular configuration and positioning of the auxiliary electrodes 30 to each other 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 high-voltage circuit breaker according to the invention than in previously known circuit breakers.

Fig. 4 is a section of Fig. 2 and shows in 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. This ensures that on the one hand the side electrodes 30 in the outer region, ie on the side facing away from the switching sl, sr side from each other have a fairly small distance of a few millimeters, causing the arcs 114, 130, 150 and 170 (s. Fig. 3 ) 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 the switching path sl, sr itself, whereby the arcs 112, 116, 132, 152 and 172 (s. Fig. 3 ) can arise.

Fig. 5 shows two side electrodes 30'a and 30'b with an alternative contour, which - in a perspective view - of the switching path sl, sr to the outside in each case 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 in a symbolic manner another 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 kΩ. In this case, a range between 100 kΩ and 1 MΩ 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 there are 5 sub-electrodes 30a, ..., 30e (as also shown), four gaps result between these sub-electrodes 30a, ..., 30e. To get an optimal spark gap with the sparks 114, 130, 150, 170 (s. Fig. 3 ), between each two sub-electrodes (30a-30b, 30b-30c, 30c-30d, 30d-30e) so many of the varistors 54 are arranged that results in each case a limiting voltage of 50 kV. Thus, as assumed above, if each of the varistors 54 has a limiting voltage of 1 kV, 50 pieces of the varistors 54 are interposed between each of the sub-electrode pairs 30a-30b, 30b-30c, 30c-30d, 30d-30e to provide the desired ones To allow 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 31 a is electrically connected to the upper main electrode 18 via the upper shaft 20. Between the first retaining plate 31 a and the second retaining plate 31 b, a number of varistors 54 are connected, to which a number 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 holding plates 31b-31c, 31c-31d and 31d-31e 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 31e 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

breakers

12

insulator

12a

first range 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

In addition to electrodes

31a, ..., 31e

Brackets of the auxiliary electrodes

32a, ..., 32e

Openings in the sub-electrodes

33

shield

34

electromagnet

36

permanent magnet

38

feather

50

electronic switch

52

resistors

54

varistors

56

first electrical conductor

58

second electrical conductor

110, 112, 114, 116

Arc in Fig. 3a, 3b (First time)

130, 132

Arc in Fig. 3c, 3d (First time)

150, 152

Arc in Fig. 3e, 3f (First time)

170, 172

Arc in Fig. 3g, 3h (First time)

A, B

Connection ports for high voltage

d

Distance between limit 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 the switching path

sl, sr

left or right limit of the switching path

Claims (8)

1. Circuit breaker for switching electrical voltages, comprising a first electrode (18), which can be connected to a first pole (A) of the voltage which is to be switched, and a second electrode (22), which can be connected to a second pole (B) of the voltage which is to be switched, wherein switching means (34, 36, 38) are provided, which switching means are suitable for moving at least one of the electrodes (18, 22) along a switching path (sl, sr) depending on the switching state, and in this way moving the electrodes (18, 22) towards one another or away from one another, wherein more than one auxiliary electrode (30) is provided, which auxiliary electrode is located close to the switching path (sl, sr), characterized in that the auxiliary electrodes (30) are at a greater distance from one another in the region of the switching path (sl, sr) than on that side which is averted from the switching path (sl, sr).
2. Circuit breaker according to Claim 1, characterized in that the distance (d) between the switching path (sl, sr) and the auxiliary electrode (30) is less than 10 mm, preferably between 0.5 and 1 mm.
3. Circuit breaker according to either of the preceding claims, characterized in that it is in the form of a vacuum circuit breaker.
4. Circuit breaker according to one of the preceding claims, characterized in that at least one of the auxiliary electrodes (30) is of annular or planar design and has an opening (32) through which the switching path (sl, sr) runs.
5. Circuit breaker according to one of the preceding claims, characterized in that at least one of the auxiliary electrodes (30) has a contour, as a result of which it is thinner in the region of the switching path (sl, sr) than on that side which is averted from the switching path (sl, sr).
6. Circuit breaker according to one of the preceding claims, characterized in that the distance of the auxiliary electrodes (30) from one another in the region of the switching path (sl, sr) is greater than their minimum distance (d) from the switching path (sl, sr).
7. Circuit breaker according to one of the preceding claims, characterized in that one of the electrodes (18, 22) is arranged in a virtually stationary manner within the circuit breaker and the other of the electrodes (18, 22) can be moved along the switching path (sl, sr).
8. Circuit breaker according to one of the preceding claims, characterized in that at least individual auxiliary electrodes from amongst the auxiliary electrodes (30) are electrically connected to one another by a network which contains at least one varistor (54) and/or at least one resistor (52).

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