Switching device

Abstract

The invention relates to a switching device (2) with a commutation flow path (4), a first isolating gap (6) and a second isolating gap (8). The first isolating gap (6) and the second isolating gap (8) form an electrical series connection which is arranged parallel to the commutation flow path (4). The second isolating gap (8) has a first contact (12), a second contact (14) and a third contact (16), wherein the first contact (12) is configured as a moving contact. The first contact (12) is mounted movably along a switching axis (24) from a first galvanic contacting position (18) with the second contact (14) to a second galvanic contacting position (12) with the third contact (16). In the second contacting position (20), a mechanical contact force (52) acts between the first contact (12) and the third contact (16) in the radial direction.

Description

[0001] Description

[0002] Switchgear

[0003] The invention relates to a switching device with a commutation current path.

[0004] In electrical circuits, particularly those used in medium-voltage or high-voltage power supplies, short circuits can occur due to insulation failure or for other reasons. Large currents flow as a result of the short circuit, which can potentially damage or destroy equipment in the power grid. The expansion of decentralized feed-in systems can cause the short-circuit current to rise to such an extent that the rated values ​​of the existing equipment are exceeded.

[0005] One way to prevent an unacceptably high short-circuit current is to use a current-limiting device, such as a very fast fuse as a short-circuit current limiter.

[0006] The principle of these devices is the rapid interruption of the short-circuit current in the event of a short circuit. This is achieved by separating the functions. For normal operation, there is a rated current path that can be opened in the event of a short circuit. Parallel to the rated current path is another current path (the commutation current path, parallel path) with a fuse that can interrupt the short-circuit current.

[0007] In the event of a short circuit, the rated current path opens, creating an arc. The arc voltage causes complete commutation of the current into the parallel path. The fuse then trips, extinguishing the arc. The impedances of the parallel current path and the rated current path must be matched to enable commutation of the short-circuit current. Furthermore, the current through the fuse must not be too high during rated operation to prevent the fuse from tripping prematurely.

[0008] Thus, there is a conflict of objectives between the highest possible impedance of the parallel current path during nominal operation, so as not to overload the fuse, and the lowest possible impedance in the event of a short circuit, so as to be able to commutate the current into the parallel current path. A high arcing voltage is advantageous for supporting the commutation of the current from the nominal current path to the parallel current path. This voltage occurs primarily when the nominal current path is blown open, which is used in the prior art.

[0009] At the moment the contacts are separated after the last metal bridge has melted, an arc is created whose burning voltage is determined almost exclusively by the material properties of the contacts and is made up of the voltage drop at the cathode and anode. Increasing the arc burning voltage by lengthening the arc is not effective here because the commutation process is already complete at very small contact gaps. With typical contact materials, the arc burning voltage is only approx. 20 V. This voltage is too low to commutate higher currents into the parallel path in practical applications, which is why conventional isolating gaps, which are advantageous in themselves because they can be used repeatedly, in contrast to broken nominal current paths, did not appear suitable for residual current limiters.

[0010] From the published patent application DE 10 2020 205 784 A1, a switching device with two isolating sections connected electrically in series is known. The published patent application discloses a switching device with a commutation current path, a first isolating section and a second isolating section, wherein the first isolating section and the second isolating section form an electrical series circuit which is arranged parallel to the commutation current path, wherein the second isolating section has a first contact, a second contact and a third contact, wherein the first contact is designed as a moving contact and wherein the first contact is mounted so as to be movable from a first galvanic contacting position with the second contact to a second galvanic contacting position with the third contact, the second contact and the third contact are at an electrical potential, and the first contact is mounted so as to be movable along a switching axis.

[0011] This known switching device must be manufactured with comparative precision, particularly with regard to the position of the third contact and the movement of the first contact from the first contacting position to the second contacting position, in order to enable a reliable closing of the second isolating distance in the second contacting position.

[0012] The invention is based on the object of specifying a switching device and a method which can be manufactured cost-effectively.

[0013] This object is achieved according to the invention by a switching device and by a method according to the independent patent claims. Advantageous embodiments are specified in the dependent patent claims.

[0014] A switching device is disclosed with a commutation current path, a first isolating distance and a second isolating distance, wherein the first isolating distance and the second isolating distance form an electrical series circuit which is arranged parallel to the commutation current path, wherein the second isolating distance has a first contact, a second contact and a third contact, wherein the first contact is designed as a moving contact and wherein the first contact is mounted so as to be movable from a galvanic first contacting position with the second contact to a second galvanic contacting position with the third contact, the second contact and the third contact are at an electrical potential (i.e.at the same electrical potential), and the first contact is mounted so as to be movable along a switching axis (translationally), wherein in the second contacting position a mechanical contact force acts between the first contact and the third contact in the radial direction (with respect to the switching axis).

[0015] In other words, the contact force acts perpendicular to the direction of movement of the first contact. The contact force therefore acts perpendicular to the switching direction or the switching axis. This advantageously prevents any bouncing between the first contact and the third contact during closing. Furthermore, no high accuracy requirements regarding the axial position of the third contact need to be met during manufacturing of the switching device, since the radial contact force can be achieved independently of the axial position of the third contact.

[0016] The switching device can be designed so that

[0017] - the third contact is a clamping contact and the contact force is a (radially acting) clamping force.

[0018] Such a clamping force can certainly allow axial movement between the first contact and the third contact. Preferably, the clamping force can have a decelerating effect on the first contact. In particular, the clamping force can decelerate the first contact such that it comes to a standstill in the second galvanic contact position.

[0019] The switching device can be designed so that

[0020] - the third contact has resilient contact elements (particularly resilient in the radial direction). These resilient contact elements can advantageously provide a clamping effect; they can therefore also be referred to as resilient clamping elements.

[0021] The switching device can be designed so that

[0022] - the third contact has a recess which at least partially receives the first contact in the second contacting position.

[0023] In the second contacting position, at least a portion of the first contact is arranged in the recess. In other words, the first contact and the third contact are configured such that at least a portion of the first contact moves into the recess during movement from the first contacting position to the second contacting position. This allows a compact design of the switching device to be achieved.

[0024] The switching device can be designed so that

[0025] - the recess (in the direction of the switching axis) is essentially hollow and cylindrical. Such a recess is relatively easy to manufacture.

[0026] The switching device can also be designed so that

[0027] - the recess and / or the first contact (in the direction of the switching axis) is conical. This advantageously allows a clamping effect to be achieved between the third contact having the recess and the first contact.

[0028] The switching device can be designed so that

[0029] - the second isolating gap is a gas isolating gap. A gas isolating gap exhibits a relatively high arc voltage upon opening. This allows a comparatively high commutation voltage to be achieved. This results in the current commutation into the commutation current path occurring quickly.

[0030] The switching device can be designed so that

[0031] - the second contact and the third contact of the second isolating distance are spring-mounted in the direction of the switching axis.

[0032] This has the advantage that, particularly in the first contacting position, sufficient contact pressure can be achieved, which contributes to stronger galvanic contact.

[0033] The switching device can be designed in such a way that - during a switching operation there is an intermediate state in which the contacts of the first isolating distance are arranged galvanically contact-free with respect to one another and the contacts of the second isolating distance are arranged galvanically contact-free with respect to one another.

[0034] The switching device can be designed so that

[0035] - in the intermediate state, a switching arc occurs between the contacts of the first isolating gap and a switching arc between the contacts of the second isolating gap. During the switching operation, a switching arc occurs between the contacts of the first isolating gap and between the contacts of the second isolating gap, resulting in a comparatively high arc voltage in the current path comprising the two isolating gaps, which is also referred to as the rated current path. The high arc voltage leads to reliable commutation of the flowing electrical current from the rated current path to the commutation current path.

[0036] The switching device can be designed so that

[0037] - the switching arc of the second isolating gap occurs between the first contact and the second contact.

[0038] The second isolating distance , which has a total of three contacts , is preferably designed such that the switching arc is present between the first and the second contact during the switching process .

[0039] The switching device can be designed so that

[0040] - the commutation current path has a fuse and / or a semiconductor element. Such a semiconductor element can be, for example, an IGBT, a transistor, a diode, or a MOSFET. A fuse, in particular, can melt within a few milliseconds due to the high current commutating into the commutation current path, thus very quickly interrupting the current flow.

[0041] The switching device can be designed such that - the first isolating distance has a fixed contact and a moving contact, the moving contact is mounted so as to be translationally movable along the switching axis, and when the first isolating distance is closed, a mechanical contact force acts between the moving contact and the fixed contact in the axial direction (relative to the switching axis). The fixed contact can be spring-mounted. The moving contact is, in particular, the contact driven by a drive.

[0042] The switching device can be designed so that

[0043] - the first separation section is a vacuum separation section.

[0044] The switching device can be designed so that

[0045] - the first isolating distance is designed as a vacuum interrupter.

[0046] In contrast to the gas isolating section, the vacuum isolating section or the vacuum interrupter has the advantage that sufficient insulation can be built up with a relatively short contact stroke (and thus in a short time).

[0047] Furthermore, a method for switching electrical current by means of a switching device according to one of the variants described above is disclosed, in which

[0048] - in the second contacting position, a mechanical contact force is generated between the first contact and the third contact of the second isolating distance in the radial direction (with respect to the switching axis).

[0049] The switching device and the method have the same or similar properties and / or advantages.

[0050] In the following, the invention is explained in more detail using exemplary embodiments. The same reference numerals refer to the same or similarly acting elements.

[0051] Figure 1 shows an embodiment of a switching device with a commutation current path in a closed state, in Figure 2 the switching device in a partially open intermediate state with switching arcs, in

[0052] Figure 3 shows the switching device in an open state, and in

[0053] Figure 4 shows an example of design with a conical

[0054] Recess of the third contact shown.

[0055] Figure 1 shows an exemplary embodiment of a switching device 2 which has a rated current path 3 and a commutation current path 4. The rated current path 3 passes through at least two isolating sections, a first isolating section 6 and a second isolating section 8. In the present example, a melting fuse 36 is arranged in the commutation current path 4. In principle, however, a (particularly fast-switching) semiconductor element (semiconductor switching element) for interrupting the current flow in the commutation current path 4 can also be arranged. Further electrical elements can optionally be arranged parallel to the commutation current path 4 or parallel to the melting fuse 36 or to the semiconductor element.

[0056] The first isolating section 6, which in this case is designed as a vacuum interrupter 10, has the property that, compared to conventional gas isolating sections, the vacuum interrupter 10 can produce a high level of insulation with a very short switching stroke, which can also be achieved in a shorter time with a conventional drive 38 compared to a longer switching stroke. To achieve the same insulating property, a comparable gas isolating section would have to have a significantly longer stroke, which is why the breaking time of such a switching device would be longer compared to using the vacuum interrupter 10. The second isolating section 8, which in this example is designed as a gas isolating section 22, has three contacts. A first contact 12 is designed as a movable contact.The first contact 12 is mounted for translational movement along a switching axis 24 by the drive 38, which also realizes the movement of the first isolating section. The first isolating section 6 and the second isolating section 8 are rotationally symmetrical with respect to the switching axis 24; the switching axis 24 thus also represents an axis of symmetry.

[0057] The drive drives a switching rod 39 in a translational motion. This results in a translational drive movement 37. In the exemplary embodiment, the drive 38 is designed such that it advantageously drives the first isolating section 6 and the second isolating section 8 together. In principle, however, two independent drives can also be used in other switching devices.

[0058] The first contact 12 of the second isolating distance 8, i.e. the gas isolating distance 22, can be moved back and forth between the second contact 14 and the third contact 16. When the switching device 2 is closed according to Figure 1, the first contact 12 is in contact with the second contact 14. In the closed state, this means that a fixed contact 32 and a moving contact 34 of the first isolating distance 6, i.e. the vacuum interrupter 10, are galvanically contacted, so that the rated current path 3 is closed. When the switching device 2 is closed, the galvanic contact pairing between the first contact 12 and the second contact 14 of the second isolating distance 8 also has a galvanic contact through which the rated current path 3 runs.When the switching device 2 is closed according to Figure 1, a first mechanical contact force 48 occurs between the fixed contact 32 and the moving contact 34 of the first isolating section 6, which first mechanical contact force acts or runs in the axial direction (with respect to the switching axis 24). This first contact force causes the first isolating section 6 to close securely. The first contact force 48 is generated by the drive 38. A spring 44 of the first isolating section 6 improves contact. In particular, the spring 44 ensures that sufficient contact pressure can be achieved, which contributes to stronger galvanic contact.

[0059] When the switching device 2 is closed according to Figure 1, a second mechanical contact force 50 occurs between the first contact 12 and the second contact 14 of the second isolating distance 8, which second mechanical contact force acts or runs in the axial direction (with respect to the switching axis 24). This second contact force 50 causes the second isolating distance 8 to close securely in the first contacting position 18. The second contact force 50 is generated by the drive 38. A spring 40 of the second isolating distance 8 causes improved contact. In particular, the spring 40 ensures that sufficient contact pressure can be achieved, which contributes to stronger galvanic contact.

[0060] Figure 2 shows an intermediate state 26 of the switching device 2, which arises during an opening movement of the switching device 2. The translational opening movement is carried out by the drive 38 along the switching axis 24. In the intermediate state 26, the first contact 12 of the second isolating distance 8 is located between the second contact 14 and the third contact 16. The intermediate state 26 is a dynamic state that ends in the state according to Figure 3.

[0061] Figure 3 shows the open state of the switching device 2. The first isolating distance 6 is open. The second isolating distance 8 is in a second galvanic contacting position 20. The second galvanic contacting position 20 occurs between the first contact 12 and the third contact 16. The first contact 12 of the second isolating distance 8 is in contact with the third contact 16. The second contact 14 and the third contact 16 are at the same electrical potential and are connected to a node of the rated current path 3. This means that the moving first contact 12 of the second isolating distance 8 is at the same electrical potential as the second contact 14 and the third contact 16 both in the open and in the closed state of the switching device 2. The second isolating distance 8 is therefore also closed in the second contacting position 20.This has the advantage that the first contact 12 (and also the moving contact 34) is at a defined electrical potential.

[0062] When the switching device 2 is in the open state, i.e., at the second contact position 20 of the second isolating gap 8, a third mechanical contact force 52 occurs between the first contact 12 and the third contact 16 in the radial direction (relative to the switching axis 24). This advantageously prevents bouncing between the first contact 12 and the third contact 16 during closing. Furthermore, no particular accuracy requirements regarding the axial position of the third contact 16 need to be met during the manufacturing of the switching device.

[0063] In the exemplary embodiment, the third contact 16 is a clamping contact; the third contact force 52 is a (radially acting) clamping force. To generate the third contact force 52, the third contact 16 has resilient contact elements 56. The resilient contact elements 56 can, for example, be resilient contact plates. The contact elements 56 can, in particular, be resilient in the radial direction.

[0064] The third contact 16 has a recess 54. In the second contacting position 20 shown in Figure 3, the recess 54 accommodates a portion of the first contact 12. This allows the switching device 2 to have a compact design. The recess 54 can be configured in various ways.

[0065] The intermediate state 26 according to Figure 2 is interesting in that a switching arc 28, 30 forms between the contacts both in the first isolating gap 6, i.e. in the vacuum interrupter 10, and in the second isolating gap 8, i.e. in the gas isolating gap 22. An arc 28 forms between the fixed contact 32 (first contact 32) and the moving contact 34 (second contact 34) of the vacuum interrupter 10. A switching arc 30 correspondingly forms between the first contact 12 and the second contact 14 of the gas isolating gap 22. The two switching arcs 28 and 30 differ in particular in the level of the voltage drop therein, i.e. the arc voltage. In the exemplary embodiment, the arc voltage Unbo2 in the switching arc 30 in the gas isolating section 22 is higher than the arc voltage Unboi in the switching arc 28 in the vacuum interrupter 10.This is because gas molecules are ionized in the gas isolating gap 22, resulting in a higher applied voltage. A vacuum prevails in the vacuum interrupter 10, resulting in a lower arc voltage. Generally, the arc voltage Unbo2 in the switching arc 30 in the gas isolating gap 22 is at least equal to (or greater than) the arc voltage Unboi in the switching arc 28 in the vacuum interrupter 10.

[0066] The higher arc voltage Unbo2 in the gas isolating section 22 results in the commutation of the current from the nominal current path 3 into the commutation current path 4 being improved, thus ensuring safe commutation into the commutation current path 4. If only the vacuum interrupter 10 were used in the nominal current path 3, there would be a conflict of objectives between the highest possible impedance of the commutation current path 4 for normal operation and the lowest possible impedance of the commutation current path 4 for a short-circuit. Due to the gas isolating section 22 with the described design, the commutation of the current into the commutation current path 4 can also take place with a higher impedance of the commutation current path 4, thereby reducing the risk of unintentional triggering of the fuse 36 during normal operation.

[0067] In order to ensure a certain contact pressure in both the first isolating section 6 and the second isolating section 8, it is advantageous to resiliently mount the contact systems of both isolating sections 6, 8. The spring 44, which is shown in Figures 1-3 with various deflections, is provided on the first isolating section 6. In Figure 1, the spring 44 is tensioned. In Figure 2, the spring 44 is deflected such that one end moves towards a stop 46. In Figure 3, the end of the spring 44 rests against the stop 46. The resilient mounting of the contacts means that the spring 44 presses the first contact 32, which is essentially designed as a fixed contact 32, against the movable second contact 34, which is operatively connected to the drive 38, in the closed state.

[0068] The first contact 14 and the second contact 16 of the gas separation section 22 are also mounted in a translationally spring-loaded manner along the switching axis 24 as shown in Figures 1-3. For this purpose, the spring 40 is provided which is tensioned when the second separation section 8 is closed as shown in Figure 1. In the intermediate state as shown in Figure 2, the spring 40 is deflected such that one end thereof moves towards a stop 42. In the open state as shown in Figure 3, the end of the spring 40 rests against the stop 42. At this point, the first contact 12 is in galvanic contact with the third contact 16.

[0069] In Figures 1 - 3, the recess 54 of the third contact 16 is essentially hollow-cylindrical in the direction of the switching axis 24.

[0070] Figure 4 shows an embodiment in which the recess 54 of the third contact 16 is substantially conical in the direction of the switching axis 24. The cone is exaggerated in the figure for clarity.

[0071] Alternatively, the first contact 12 can also be conical in the direction of the switching axis 24. In particular, the part of the first contact 12 that is received by the recess 54 of the third contact 16 in the second contact position 20 can be conical in the direction of the switching axis 24. A switching device has been described that can be manufactured cost-effectively. This switching device advantageously exhibits no bouncing when reaching its open switching position.

[0072] Reference symbol:

[0073] 2 switching device

[0074] 3 Nominal current path

[0075] 4 Commutation current path

[0076] 6 first separation section

[0077] 8 second separation section

[0078] 10 vacuum interrupters

[0079] 12 first contact

[0080] 14 second contact

[0081] 16 third contact

[0082] 18 first contact position

[0083] 20 second contact position

[0084] 22 guest race track

[0085] 24 switching axis

[0086] 26 Intermediate state

[0087] 28 Switching arc first isolating distance

[0088] 30 switching arc second isolating distance

[0089] 32 fixed contact first isolating distance

[0090] 34 Moving contact first isolating distance

[0091] 36 Melt fuse

[0092] 37 Drive movement

[0093] 38 drive

[0094] 39 shift rod

[0095] 40 Suspension second separation section

[0096] 42 Stop suspension second separation section

[0097] 44 Suspension first separation section

[0098] 46 Stop suspension first separation section

[0099] 48 first contact force

[0100] 50 second contact force

[0101] 52 third contact force

[0102] 54 recess

[0103] 56 spring contact element

[0104] Uiiboi Arc voltage of the switching arc of the first isolating gap

[0105] Unbo2 Arc voltage of the switching arc of the second isolating gap

Claims

Patent claims 1. Switching device (2) with a commutation current path (4), a first isolating distance (6) and a second isolating distance (8), wherein the first isolating distance (6) and the second isolating distance (8) form an electrical series circuit which is arranged parallel to the commutation current path (4), wherein the second isolating distance (8) has a first contact (12), a second contact (14) and a third contact (16), wherein the first contact (12) is designed as a moving contact and wherein the first contact (12) is mounted so as to be movable from a first galvanic contacting position (18) with the second contact (14) to a second galvanic contacting position (20) with the third contact (16) along a switching axis (24), and the second contact (14) and the third contact (16) are at an electrical potential, characterized in that - in the second contacting position (20) a mechanical contact force (52) acts between the first contact (12) and the third contact (16) in the radial direction.

2. Switching device according to claim 1, characterized in that - the third contact (16) is a clamping contact and the contact force (52) is a clamping force.

3. Switching device according to claim 1 or 2, characterized in that - the third contact (16) has resilient contact elements (56).

4. Switching device according to one of the preceding claims, characterized in that - the third contact (16) has a recess (54) which at least partially receives the first contact (12) in the second contacting position (20).

5. Switching device according to claim 4, characterized in that - the recess (54) is essentially hollow-cylindrical in shape.

6. Switching device according to claim 4, characterized in that - the recess (54) and / or the first contact (12) is conical.

7. Switching device according to one of the preceding claims, characterized in that - the second separation section (8) is a gas separation section (22).

8. Switching device according to one of the preceding claims, characterized in that - the second contact (14) and the third contact (16) of the second isolating section (8) are spring-mounted in the direction of the switching axis (24).

9. Switching device according to one of the preceding claims, characterized in that - during a switching operation there is an intermediate state (26) in which the contacts of both the first isolating section (6) and the second isolating section (8) are galvanically contact-free.

10. Switching device according to one of the preceding claims, characterized in that - in the intermediate state (26) a switching arc (28) occurs between contacts (32, 24) of the first isolating gap (6) and a switching arc (30) occurs between the contacts (12, 14, 16) of the second isolating gap (8).

11. Switching device according to claim 10, characterized in that - the switching arc (30) of the second isolating gap (8) occurs between the first contact (12) and the second contact (14).

12. Switching device according to one of the preceding claims, characterized in that - the commutation current path (4) has a fuse (36) and / or a semiconductor element.

13. Switching device according to one of the preceding claims, characterized in that - the first isolating section (6) has a fixed contact (32) and a moving contact (34), the moving contact (34) is mounted so as to be translationally movable along the switching axis (24), and when the first isolating section (6) is closed, a mechanical contact force (48) acts in the axial direction between the moving contact (34) and the fixed contact (32).

14. Switching device according to one of the preceding claims, characterized in that - the first isolating section (6) is a vacuum isolating section, in particular designed as a vacuum interrupter (10).

15. A method for switching electrical current by means of a switching device (2) according to one of claims 1 to 14, in which - in the second contacting position (20) a mechanical contact force (52) is generated between the first contact (12) and the third contact (16) in the radial direction.

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