EP4024425B1 - Switching device with movable nozzle element - Google Patents

Description

The present invention relates to a switching device, in particular for medium-voltage switchgear, with an encapsulated switching chamber containing an extinguishing gas, with a first contact and a second contact which are arranged in the switching chamber, wherein at least the first contact is movable relative to the second contact and the contacts can be connected to or separated from one another, and with a blowing device which has a nozzle device with at least one nozzle for blowing the extinguishing gas into an area in which a switching arc forms when the contacts are separated.

Load break switches and their contacts are well known and are often used in medium-voltage switchgear. When the contacts are separated under load, switching arcs occur which can cause thermal damage to the contacts. For this reason, the head of the contacts is usually provided with a burn-resistant material. Due to their high melting point, tungsten and alloys containing tungsten are particularly suitable as burn-resistant materials. However, tungsten is also subject to wear after a large number of switching cycles.

Therefore, efforts are made to extinguish the arcs that occur as quickly as possible. This is all the more important because the longer a switching arc lasts, the higher the pressure in the arcing chamber, which in extreme cases can lead to the switching chamber bursting. This must be avoided at all costs.

There are load break switches whose contacts are arranged in an arcing chamber containing an insulating gas, and there are load break switches that are arranged entirely in a tank containing an insulating gas. In both cases, the insulating gas serves as an extinguishing gas to quickly extinguish a switching arc that forms between the contacts when two contacts are separated. In order to increase the extinguishing effect, it is known to blow the extinguishing gas onto the area in which a switching arc can form while the contacts are being separated. For example, switch designs are known for this in which the extinguishing gas is compressed in a compression chamber during separation and blown into the switching arc area through nozzles. This cools the switching arc and significantly extends the length of its path, so that it extinguishes more quickly.

JP H08 315697 A discloses a switching device according to the preamble of claim 1.

In this context, an extinguishing gas is understood to be a gas or a gas mixture. Up to now, sulphur hexafluoride (SF ₆ ) has been predominantly used as an extinguishing gas due to its very good insulating properties. However, SF ₆ is the most potent greenhouse gas known. Therefore, there are considerable efforts to use other insulating gases in electrical switchgear that are less harmful to the climate. Among other things, there are approaches to replacing SF ₆ with gas mixtures that contain one or more fluoronitriles or fluoroketones. However, these gas mixtures usually have the disadvantage that their breakdown properties are poorer and, unlike SF ₆ , they chemically decompose over time under the influence of a switching arc. Therefore, there is a risk that the systems used to date in switches for extinguishing switching arcs based on the use of insulating gas will not extinguish a switching arc quickly enough, meaning that the shutdown and extinguishing conditions are no longer met. In addition, the internal pressure in the switching chamber increases with each switching cycle due to the chemical decomposition products, so that the number of switching cycles that a load-break switch can perform is limited.

A blowing device is understood to be one that provides the extinguishing gas for blowing into the area in which a switching arc can form on or between the contacts and blows it into this area. Components of the blowing device can in particular be one or more nozzles and a chamber in which the extinguishing gas is provided under pressure for blowing.

The object of the present invention is therefore to provide a switching device with improved arc extinguishing properties.

This object is achieved by a switching device according to the features of claim 1 by at least one nozzle element which is movable relative to the contacts and at least partially forms the nozzle, wherein the mobility of the nozzle element is limited by a stop.

With a nozzle element that is movable relative to the contacts, it is possible to move the nozzle relatively close to the area where a switching arc forms on the contact (hereinafter referred to as the switching arc area for the sake of simplicity), or to form the nozzle close to this area and to hold the nozzle element in an optimized position by means of the at least one stop. The nozzle element can completely contain the at least one nozzle or, together with other elements, in particular with parts of one of the contacts, form a nozzle. This can significantly increase the effectiveness of blowing a switching arc with quenching gas. With this optimization, it is possible to In particular, it is possible to use extinguishing gases in the switchgear room whose extinguishing properties are less efficient than those of SF ₆ .

Preferably, because it is structurally simple and extremely effective, the nozzle element is guided so that it can move along one of the contacts. If the nozzle element is a ring disk, a contact designed as a contact pin can serve as a central guide. If the stop is not formed on the pin contact itself, but is a stop that interacts with the outer area of the ring disk, which is part of an external guide for the ring disk that acts in the area of the contact head of the contact pin, the ring disk can be designed somewhat higher than the contact head at the time of separation, so that an annular gap forms between the ring disk and the contact pin, through which extinguishing gas is blown onto the contact head of the contact pin. The ring disk and contact head then act together as a nozzle. The shape of the contact head and also the design of the ring disk, in particular on its inner side associated with the annular gap, can be designed for an optimized nozzle effect. The contact head can preferably be hemispherical, but can also have the contour of a half oval in cross section, for example, or be optimized in another way for an optimal extinguishing gas flow.

In principle, it is also conceivable to form the nozzle element using two or more ring sections that are pivotably mounted in the switching chamber at the level of the contact head of one of the contacts and are folded into the area of the contact head when the contacts are separated, where they act, possibly together with the contact head, in a similar way to the nozzle disk as part of a nozzle. It is also conceivable for the nozzle element to be a light ball that is guided, for example, inside a contact tulip and finds a stop in a kind of cage outside the contact tulip, where it is held when the switches are separated, so that a flow of quenching gas through the ball in conjunction with the tulip contact itself acts as a nozzle.

In a preferred embodiment of the switching device according to the invention, the nozzle element is guided within a cup, in the bottom of which at least one quenching gas channel is provided for providing the quenching gas for blowing the switching arc area. The cup can be formed, for example, with a sleeve that sits on a bottom of the switching chamber and surrounds, for example, a contact pin. The sleeve can also be arranged within a tulip contact on the bottom of the tulip contact and together with the bottom form a cup. When quenching gas flows in through the quenching gas channel at the bottom of the cup, the The nozzle element guided in the cup is conveyed by the quenching gas into its position for blowing the switching arc area. If the cup is arranged vertically and the bottom of the cup is at its bottom, the quenching gas lifts the nozzle element against gravity as the contacts are separated. Once the contacts are separated from each other, the nozzle element can sink to the bottom again due to gravity.

Alternatively or in addition to this, means, for example spring elements, can also be provided to retract the at least one nozzle element back into a starting position after the contacts have been separated, in particular when the nozzle element in its position for blowing a switching arc area prevents the contacts from closing. This is completely independent of whether the switching device according to the invention has a cup or not.

It is also advantageous if a stop for the nozzle element is arranged on the side of the cup that is open to the switching chamber. If the stop is not arranged on the contact itself, it is easier to provide the stop in such a way that the nozzle element can be held at approximately the height of the contact head during separation of the contacts.

In principle, it is conceivable and possible to introduce the quenching gas for blowing the switching arc area into the switching chamber from an overpressure chamber or through a pump system. However, the invention is characterized by an quenching chamber and a piston which divides the quenching chamber at least into a compression chamber and the switching chamber, wherein the contacts are arranged in the switching chamber and the quenching gas in the compression chamber is compressed by the piston during the separation of the contacts, and at least one quenching gas channel via which quenching gas can be supplied from the compression chamber to the nozzle during the separation of the contacts. The switching device according to the invention is then a self-blowing switch.

If a cup is provided to guide the nozzle element, it is useful in a self-blowing switch according to the invention if the bottom of the cup is formed by the piston.

In a further embodiment of the invention, an extinguishing gas channel is provided in the nozzle element, which begins at an end of the nozzle element facing the compression chamber and ends in at least one nozzle for blowing the switching arc region in which a switching arc forms when the contacts are separated.

In this design, the nozzle element (also) has the function of an independent nozzle for blowing the switching arc area.

In another preferred embodiment of a self-blowing switch according to the invention, the nozzle element closes all extinguishing gas channels of the piston in relation to the switching chamber in at least one position, in particular during the time in which the contacts of the switch are closed.

In a further preferred embodiment of the self-blowing switch according to the invention, at least one compensation channel is provided between the switching chamber and the compression chamber, which can preferably be closed when the contacts are separated and via which a pressure difference between the switching chamber and the compression chamber can be reduced. Such a compensation channel can be provided, for example, in the outer region of the piston and can be closed via a movable piston seal. The piston can be designed to be at least partially movable relative to the cup, whereby the piston can assume a first position relative to the cup in which the compensation channel is open and a second position in which the compensation channel is closed. For example, part of the piston can be shaped as an annular disk that surrounds the cup to guide the nozzle element and is guided on the cup between two positions. Through holes can be provided in the piston annular disk, which are open in the first position of the coupling annular disk so that the switching chamber and the compression chamber are fluidically connected to one another, and are closed in the second position of the coupling annular disk by a sealing element formed on the cup.

In order to avoid a negative pressure in a cup, for example a field control cup surrounding the second contact, slowing down a rapid opening of the contacts when the contacts are opened, it is advantageous if flow openings are provided in the bottom area of the cup so that quenching gas can flow from the switching chamber into the cup while the contacts are separated from each other.

The switching device according to the invention is not only suitable for use with SF ₆ as an extinguishing gas, but in particular also for the use of an extinguishing gas which contains a fluoroketone and/or a fluoronitrile.

Furthermore, the switching device according to the invention is suitable for use as a load-break switch, in particular for medium voltages in the range of 1 to 52 kV.

In the following, the invention is explained in more detail with reference to figures in which a preferred embodiment of the invention is shown.

Fig. 1

einen Längsschnitt durch eine erfindungsgemäße Schaltvorrichtung mit Düsenscheibe in geschlossener Schaltstellung;

Fig. 2 a

einen vergrößerten Ausschnitt der in Fig. 1 dargestellten Schaltvorrichtung in geschlossener Stellung;

Fig. 2b

einen vergrößerten Ausschnitt der in Fig. 1 dargestellten Schaltvorrichtung in einer ersten Stellung während des Trennens;

Fig. 2c

einen vergrößerten Ausschnitt der in Fig. 1 dargestellten Schaltvorrichtung in einer zweiten Stellung während des Trennens;

Fig. 2d

einen vergrößerten Ausschnitt der in Fig. 1 dargestellten Schaltvorrichtung in einer dritten Stellung während des Trennens;

Fig. 2e

einen vergrößerten Ausschnitt der in Fig. 1 dargestellten Schaltvorrichtung in geöffneter Stellung;

Fig. 2f

einen vergrößerten Ausschnitt der in Fig. 1 dargestellten Schaltvorrichtung in einer Stellung während des Schließens

Fig. 3a

einen Längsschnitt durch eine andere erfindungsgemäße Schaltvorrichtung in einer ersten Stellung während des Trennens;

Fig. 3b

die in Fig. 3a dargestellte erfindungsgemäße Schaltvorrichtung in einer zweiten Stellung während des Trennens;

Fig. 3c

die in Fig. 3a dargestellte erfindungsgemäße Schaltvorrichtung in einer Stellung während des Schließens.

They show:

Fig. 1

a longitudinal section through a switching device according to the invention with nozzle disk in closed switching position;

Fig. 2 a

an enlarged section of the Fig. 1 switching device shown in the closed position;

Fig. 2b

an enlarged section of the Fig. 1 illustrated switching device in a first position during separation;

Fig. 2c

an enlarged section of the Fig. 1 illustrated switching device in a second position during separation;

Fig. 2d

an enlarged section of the Fig. 1 shown switching device in a third position during separation;

Fig. 2e

an enlarged section of the Fig. 1 switching device shown in the open position;

Fig. 2f

an enlarged section of the Fig. 1 shown switching device in one position during closing

Fig. 3a

a longitudinal section through another switching device according to the invention in a first position during separation;

Fig. 3b

the in Fig. 3a illustrated switching device according to the invention in a second position during separation;

Fig. 3c

the in Fig. 3a illustrated switching device according to the invention in a position during closing.

In Figure 1 a load-break switch according to the invention is shown in the closed switching position. The load-break switch has an encapsulated quenching chamber 1 containing an quenching gas. A lower, movable contact with a contact pin 2 and an upper, fixed contact are arranged in the quenching chamber 1. The fixed contact has a tulip contact 4 arranged within a field control cup 3. An arc contact 3a made of a burn-resistant material is provided at the lower end of the field control cup 3 facing the movable contact. In addition, lateral flow openings 3b are provided in the area of the field control cup near the bottom. The contact pin 2 is at the upper end of a Bolt 5 is arranged, which is guided through the bottom wall 6 of the extinguishing chamber 1 and whose lower end forms a first switch pole 7. The tulip contact 4 is electrically connected to a switch pole 8 arranged outside the extinguishing chamber 1.

Both contacts are arranged concentrically to a longitudinal axis L, in the direction of which the bolt 5 is axially movable, so that the contact pin 2 can be inserted into the tulip contact 4 in order to establish a conductive connection, and the contact pin 2 and tulip contact 4 can be separated from each other again. The head of the contact pin has a hemispherical contact head 9 made of a burn-resistant material.

At the transition of the bolt 5 to the contact pin 2, a shoulder is formed on which a piston 12 sits. The piston 12 separates the arcing chamber into a switching chamber 13, in which the contact pin 2 and tulip contact 4 are arranged, and a compression chamber 14. The piston 12 is connected to a sleeve 15, which extends concentrically around the contact pin 2 and projects beyond it. The inner diameter of the sleeve 15 is such that it encloses the field control cup 3 when the contact pin 2 is inserted into the tulip contact 4.

The piston 12 is sealed to the inner wall of the extinguishing chamber 1 with a movable piston ring 16. The piston ring 16 also acts as a valve closure for compensation channels 17, which are arranged on the outer circumference of the piston 12. In addition, extinguishing gas channels 18 are provided in the piston 12 near the bolt 5 as a fluidic connection between the compression chamber 14 and the interior of the sleeve 15.

The sleeve 15, together with the base formed by the piston 12, forms a type of cup in which a nozzle ring disk 19 is guided, which surrounds the contact pin 2 and whose inner diameter corresponds to the outer diameter of the contact pin 2 and whose outer diameter corresponds to the inner diameter of the sleeve. When switched on, the nozzle ring disk 19 rests on the extinguishing gas channels 18 in the area of the base of the cup and covers them when the load break switch is switched on. The sleeve 15 has a radially inward-facing rim 15a at its upper end, which limits an axial movement of the nozzle ring disk 19 upwards. The nozzle ring disk 19 serves to cover the arcing contact 4 at the beginning of the switching movement and to control and concentrate the extinguishing gas flow during the separation process on an area of the arcing zone between the contact head 9 of the movable contact and the arcing contact 3a of the fixed contact.

The load-break switch shown operates according to the principle of a blow-piston switch as a self-blowing switch.

In the Figures 2a - 2f is the functionality of the Figure 1 shown load-disconnector.

In Figure 2a the load break switch is in the switched-on state. The contact pin 2 is inserted into the tulip contact 4. The movable piston ring 16 lies in the lower end of a circumferential groove in the piston 12 and the compensation channels 17 from the top of the piston to the bottom of the piston are open. The movable nozzle ring disk 19 lies on the extinguishing gas channels 18 of the piston 12 and closes them.

To separate the contact, the contact pin 2 moves as shown in Figure 2b shown with an arrow in the bolt 5, downwards out of the tulip contact 4. This movement causes the piston ring 16 to move to the upper end of the circumferential groove in the piston 12 and thus closes the compensation channels 17. The extinguishing gas volume in the compression chamber is compressed and the overpressure causes the movable nozzle disk 19 in the sleeve 15 to be raised and pressed against the arc contact 3a. The fit of the sleeve 15 and nozzle disk 19 initially prevents a flow of extinguishing gas from the compression chamber to the contact head 9 of the movable contact. The path of the extinguishing gas flow is in the Figures 2b to 2d and 2f indicated by arrows.

As soon as the contact head 9 passes the arc contact 3a with its contact surface, an arc ignites between the contact head 9 and the arc contact 3a. Almost simultaneously, an annular gap forms between the inner surface of the movable nozzle ring disk 19 and the contact head 9. In Figure 2c it can be seen how the quenching gas subsequently flows from the compression chamber into the switching chamber. The flow runs through the quenching gas channels 18, along the contact pin 2, through the annular gap between the movable nozzle ring disk 19 and the contact head 9, past the arc contact 3a into the tulip contact 4 and out of the upper flow openings 3b in the field control cup 3. The nozzle ring disk 19 is pressed against the rim 15a of the sleeve 15 by the quenching gas flow, so that its position is fixed in relation to the contact head 9. The nozzle effect is particularly high in the area of the contact head.

Figure 2d shows the same load break switch in a further advanced separation movement. A concentrated flow of the extinguishing gas occurs over the entire switching path along the path described above. Re-ignition of the arc After its extinguishing, this is prevented until the isolating distance between the contacts is sufficiently large for permanent dielectric strength.

Figure 2e shows the load break switch in the switched off state. In this state, the maximum separation distance between the contacts is reached and the pressure difference between the top and bottom of the piston has been equalized by the extinguishing gas flow. Due to the lack of dynamic pressure on the movable nozzle ring disk 19, it falls down under its own weight within the sleeve 15 and closes the extinguishing gas channels 18 again.

At the Figure 2f As the switch-on movement begins, the bolt 5 and the contact pin move in the direction of the fixed tulip contact 4. This causes the piston ring 16 to move to the lower end of the circumferential groove of the piston 12 and the compensation channels 17 open. The volume of extinguishing gas displaced by the piston 12 during switching on increases the pressure in the switching chamber and an extinguishing gas flow is formed through the compensation channels 17 into the compression chamber. At the end of this movement, the load break switch is switched on again and the extinguishing gas pressure in the switching chamber and compression chamber is equalized.

In the Figure 3a In the preferred embodiment of the self-blow switch shown, the piston 12 has a piston ring disk 20 and a coupling ring disk 21. The piston 12 is sealed to the inner wall of the arcing chamber 1 by means of the piston ring disk 20. The coupling ring disk 21 is arranged inside the piston ring disk 20 and sits on a shoulder formed at the transition of the bolt 5 to the contact pin 2. Furthermore, the coupling ring disk 21 is connected to the sleeve 15 so that the sleeve 15 and the coupling ring disk 21 form a cup, with at least part of the coupling ring disk 21 projecting beyond the sleeve 15 on the outer surface such that a rim 21a is formed on the cup. The inner diameter of the piston ring disk 20 is larger than the outer diameter of the bolt 5 so that the clear area between the bolt 5 and the piston ring disk 20 serves as a compensation channel. The cup then acts as a valve closure for the compensation channel. For this purpose, the coupling ring disc 21 can have a sealing element (not shown) on the underside.

In the area of the upper inner edge of the piston ring disk 20, locking lug pins 22 are formed in the circumferential direction, which interact with the rim 21a of the cup, so that the cup and the piston ring disk 20 are connected and the piston ring disk 20 is guided axially movable relative to the cup along a predetermined distance. As a result, the piston ring disk 20 is locked in position when the The clutch ring disk 21 is carried along by the latter, whereby it can assume two end positions relative to the cup. In the first end position, the compensation channels 17 are open. In the second end position, the clutch ring disk 21 rests against a sealing surface 20a formed on the piston ring disk 20 in such a way that the compensation channels 17 are closed.

It is sensible to provide at least three, preferably 5 or 7 locking lug pins 22, which are evenly distributed around the circumference. However, an even number of locking lug pins can also be provided, and the distribution does not necessarily have to be even.

Figure 3a shows the load break switch during contact separation, whereby the contact pin 2 is moved downwards by the bolt 5, as shown by the arrow. Due to the movement of the bolt 5 and the resulting overpressure in the compression chamber 14, the piston disk ring 20, which is in the first end position before contact separation, moves to the second end position and remains in this position during the entire separation movement. In this position, the cup takes the piston ring disk 20 with it during its movement, so that the piston 12 compresses the extinguishing gas volume in the compression chamber 14, creating an overpressure in it. Due to the overpressure, the piston ring disk 20 with the sealing surface 20a and the coupling ring disk 21 are pressed against one another in such a way that the compensation channel formed by the central area of the piston ring disk 20 is closed. At the same time, the extinguishing gas flows through the extinguishing gas channels 18, so that the movable nozzle disk 19 in the sleeve is lifted by the excess pressure and pressed against the lower edge of the arc contact 3a, whereby the extinguishing gas initially does not flow into the switching chamber 13. Figure 3b shows the same load break switch in a more advanced separation movement. An annular gap is formed between the inner surface of the movable nozzle ring disk 19 and the contact head 9 so that the quenching gas flows into the switching chamber 13, as shown by the arrows.

In Figure 3c a beginning switching-on movement is shown, in which the bolt 5 moves in the direction of the fixed tulip contact 4. Due to the overpressure that develops in the switching chamber 13, the piston ring disk 20 is moved in the direction of its first end position. This opens up a gap between the piston ring disk 20 and the coupling ring disk 21, so that the extinguishing gas can flow into the compression chamber 14, as shown by the arrow.

reference sign

1

quenching chamber

2

contact pin

3

field tax cup

3a

arc contact

3b

flow openings

4

tulip contact

5

bolt

6

floor of the extinguishing chamber

7

first switch pole

8

second switch pole

9

contact head

12

Pistons

13

switching chamber

14

compression chamber

15

sleeve

15a

brim

16

piston ring

17

compensation channels

18

extinguishing gas channels

19

nozzle ring disk

20

piston ring disc

20a

sealing surface

21

clutch ring disc

21a

brim

22

Hook

Claims (14)

1. Switching device, in particular for medium-voltage switchgear, having an encapsulated switching chamber (13) containing an extinguishing gas, having a first contact and a second contact which are arranged in the switching chamber (13), at least the first contact being movable relative to the second contact and the contacts being able to be connected to one another or separated from one another, and having a blowing device, comprising a nozzle device with at least one nozzle, for blowing on a region, in which a switching arc is formed when the contacts are separated, with the extinguishing gas, and having at least one nozzle element which is movable relative to the contacts and which at least partially forms the nozzle, the mobility of the nozzle element being limited at least by a stop, characterized by an extinguishing chamber (1) and a piston (12) which divides the extinguishing chamber (1) at least into a compression chamber (14) and the switching chamber (13), the contacts being arranged in the switching chamber (13) and the extinguishing gas in the compression chamber (14) being compressed by the piston (12) during the separation of the contacts, and at least one extinguishing gas duct (18) via which extinguishing gas from the compression chamber (14) can be supplied to the nozzle during the separation of the contacts.
2. Switching device according to claim 1, characterized in that the at least one movable nozzle element is guided along one of the contacts.
3. Switching device according to claim 1 or 2, characterized in that the at least one nozzle element is plate-like or disc-like and, in particular, is an annular disc (19).
4. Switching device according to claim 3, characterized in that the contact on which the nozzle element is guided is a contact pin (2) and interacts with the nozzle element as a nozzle at least at one point in time during the separation of the contacts, a contact head (9) of the contact pin (2) preferably being hemispherical.
5. Switching device according to one of the preceding claims, characterized in that the nozzle element is guided inside a cup, in the base of which at least one extinguishing gas channel (18) is provided for supplying the extinguishing gas for blowing on the region in which a switching arc is formed when the contacts are separated.
6. Switching device according to claim 5, characterized by a stop for the nozzle element on the side of the cup open to the switching chamber.
7. Switching device according to one of claims 5 or 6, characterized in that the bottom of the cup is formed by the piston (12).
8. Switching device according to one of the preceding claims, characterized by an extinguishing gas duct in the nozzle element, which preferably begins at an end of the nozzle element facing the compression chamber (14) and ends in at least one nozzle for blowing on the region in which a switching arc is formed when the contacts are separated.
9. Switching device according to one of the preceding claims, characterized in that the nozzle element in at least one position closes all extinguishing gas channels (18) of the piston (12) with respect to the switching chamber (13).
10. Switching device according to one of the preceding claims, characterized by a compensation channel (17) between the switching chamber (13) and the compression chamber (14), which can preferably be closed during the separation of the contacts and via which a pressure difference between the switching chamber (13) and the compression chamber (14) can be reduced.
11. Switching device according to claim 10, which is related back to one of claims 5 or 6, characterized in that the piston (12) is at least partially movable relative to the cup, wherein the piston (12) can assume, relative to the cup, a first position, in which the compensation channel (17) is open, and a second position, in which the compensation channel (17) is closed.
12. Switching device according to one of the preceding claims, characterized in that the second contact has a cup, in particular a field control cup (3), in the base region of which flow openings (3b) are provided.
13. Switching device according to one of the preceding claims, characterized in that the extinguishing gas contains a fluoroketone and/or a fluoronitrile.
14. Switching device according to one of the preceding claims, characterized in that it is a load break switch.

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