ES2538594T3 - Vacuum switch - Google Patents

Abstract

A vacuum interrupter assembly comprising at least one vacuum interrupter (10), the or each vacuum interrupter including a vacuum-tight enclosure; first and second electrically conductive rods (26, 28), a first end of each rod being adapted to be connected, in use, to an electrical network (42, 44); a first electrode (30) being mounted near or at a second end of the first rod (26); a slotted coil (38); and a second electrode (32); wherein the first electrode and slotted coil are located within the vacuum-tight case and the rods are positioned to locate at least a portion of the first electrode within the slotted coil; characterized in that the slotted coil is operatively mounted on a second end of the second rod and that the second electrode is mounted on an inner surface of the slotted coil.

Description

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DESCRIPTION

Vacuum switch

The present invention relates to a vacuum switch assembly and an apparatus incorporating the vacuum switch assembly.

The operation of high-voltage high-voltage transmission and distribution networks (HVDC) of multiple terminals involves the switching of load current and faults / short-circuits in DC power networks. The availability of switching components to perform such conversion allows flexibility in the planning and design of HVDC applications such as parallel HVDC lines with a branch line or a closed loop circuit.

A known solution for switching load current and faults / short circuit is the use of switches

15 based on semiconductors, which are typically used in high-power point-to-point HVDC transmission. The use of semiconductor-based switches results in faster switching and smaller passing fault current values. The disadvantages of using such switches however include high direct losses, sensitivity to transients and lack of tangible isolation when the devices are in their disconnected state.

Another known solution for switching load current and faults / short circuit is a vacuum switch. The operation of the vacuum switch is based on the mechanical separation of the conductive contacts of electricity to open the associated electrical circuit. A vacuum switch as such is capable of allowing the maximum magnitude of the continuous AC current with a high short-circuit current interruption capability.

The conventional vacuum switch however shows a poor development in the interruption of the DC current, due to the absence of zero current. Although it is feasible to use the conventional vacuum switch to interrupt low DC currents of up to a few hundred amps due to the instability of an arc at low currents, such a procedure is not only unreliable, but also incompatible with current levels which are typically found in HVDC applications.

It is possible to perform the DC current interruption using conventional vacuum switches by applying a zero forced current or artificially creating a null current. This procedure of interrupting the DC current consists of connecting an auxiliary circuit in parallel through the vacuum switch

35, the auxiliary circuit comprising a capacitor or a combination of a capacitor and an inductor. The auxiliary circuit remains isolated by a separation of the spark during normal operation of the idle switch.

When the contacts of the vacuum switch begin to separate, the ignition separation of the spark is switched on to introduce an oscillating current of sufficient magnitude through the vacuum switch and thereby force the current through the switch to pass through a null current. This allows the vacuum switch to successfully interrupt the DC current. Such an arrangement however becomes complex, expensive and space consuming due to the need to integrate the additional components of the auxiliary circuit. Document DE 3818510 A1 discloses a vacuum switch assembly according to the preamble of claim 1.

According to a first aspect of the invention, there is provided a vacuum switch assembly comprising at least one vacuum switch, including the vacuum switch or each vacuum switch a vacuum sealed case; first and second electricity conductive rods, a first end of each rod being adapted to be connected, during use, to an electrical network; a first electrode being mounted near or at a second end of the first rod; a slotted coil being operatively mounted at a second end of the second rod; and a second electrode being mounted on an inner surface of the grooved coil, in which the first electrode and the grooved coil are inside the vacuum sealed case and the rods are positioned to place at least a part of the first electrode in the grooved coil inside.

The previous arrangement of the first electrode and the slotted coil in the vacuum switch allows the generation of

A self-induced axial magnetic field that is perpendicular to the arc current drawn between the first and second electrodes during the current interruption process. In the presence of the axial magnetic field, the arc voltage begins to rise, while the arc current begins to fall rapidly until it reaches a value lower than the cut-off current value of the electrode material. At this point the current drops instantly to zero, resulting in complete dielectric recovery and the successful interruption of the current. The ability to create a null current in this way, therefore, returns to the compatible vacuum switch assembly for use as a load break switch or a circuit breaker in both AC and DC networks.

The generation of the self-induced axial magnetic field eliminates the need to incorporate additional equipment into the

65 vacuum switch assembly to generate the required axial magnetic field and thereby reduce the complexity of the arrangement of the vacuum switch assembly. As such, the comparatively simpler design

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The vacuum switch assembly has the effect of reducing the amount of space required for assembly and the associated installation costs, while the reduced number of components in the vacuum switch assembly improves the reliability of the current interruption process .

5 The shape of the slotted coil may vary, depending on the design requirements of the vacuum switch. The grooved coil may, for example, include either a single groove, which preferably extends around the entire perimeter of the bobbin, or a plurality of grooves.

In embodiments of the invention, the first electrode may include a first electrode portion mounted at the second end of the first rod. In such embodiments, the first electrode may further include a second electrode portion mounted around the circumference of the first rod and adjacent to the first electrode portion.

The shape of the first electrode varies depending on the arrangement of the vacuum switch, which can be designed.

15 so that the position of the rods is fixed with respect to each other, or that at least one rod is removable relative to the other rod.

In other embodiments, the slotted coil may include a support base that is mounted on the second end of the second rod.

The use of a support base that is part of the slotted coil not only provides structural support for the slotted coil, but also provides a surface for mounting an additional electrode, if desired.

Preferably each electrode is made of a refractory material, which can be selected from a group of chromium-chromium, copper-tungsten, copper, tungsten carbide, tungsten, chromium or molybdenum.

Such refractory materials are compatible for use as an electrode material in a vacuum switch not only because of its low electrical contact resistance and high cutting current value properties, but also due to its ability to resist the effects of the arc and assist in dielectric strength after the interruption of the current.

In embodiments of the invention, at least one rod may be movable in relation to the other rod to open or close a gap between the second ends of the rods.

In such embodiments that employ a support base mounted on the second end of the second rod, the vacuum switch or each vacuum switch may further include a third electrode mounted on the support base, the first and third electrodes defining surfaces of opposite contact and at least one rod is movable relative to the other rod to open or close a gap between the opposing contact surfaces.

The ability to move at least one rod relative to the other rod allows opposite contact surfaces to come into contact, resulting in a low contact resistance between the rods and thus allows the vacuum switch to carry a charging current through the electrically conductive rods during normal operation of the associated external power grid.

The same capacity also allows the separation of the opposing contact surfaces to interrupt the current flowing through the vacuum switch.

In embodiments that employ at least one mobile rod, the vacuum sealed box or each vacuum sealed box further includes a tubular bellows with a separation hole, the tubular bellows or each tubular bellows being operatively connected to at least one rod and being controllable to expand or contract to move a rod in relation to the other rod to open or close a gap between the second ends of the rods.

Wavy walls of the tubular bellows allow the tubular bellows to undergo expansion or

55 shrinkage in order to increase or decrease the tubular length of the tubular bellows and thereby initiate the movement of one rod relative to the other rod while maintaining the degree of vacuum within the vacuum switch.

In other embodiments that employ at least one movable rod, the vacuum switch or each vacuum switch may further include an auxiliary coil located outside the vacuum sealed box, the auxiliary coil being controllable to provide a pulsed magnetic field within the box. vacuum tight.

Once the arc current drops to a sufficiently low value, the auxiliary coil can be controlled to generate the pulsed magnetic field to increase the axial magnetic field and thereby help accelerate the extinction of any residual arc. In addition, the ability to manipulate the moment of field generation

65 pulsed magnetic and the magnitude of the pulsed magnetic field provides precise control over the process of current interruption.

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In other embodiments that employ the use of an auxiliary coil, the refractory material that forms the electrode may be copper-chrome or silver tungsten carbide.

5 The auxiliary coil arrangement also allows each electrode to be made of material that has a low current cut-off value but is conducive to the high dielectric strength requirements of a vacuum switch when the first and third electrodes are separated.

In embodiments of the invention, the positions of the second ends of the rods can be fixed relative to each other.

This configuration eliminates the need to mechanically move each rod during the power interruption process. This speeds up the process of interrupting the current because the time required to interrupt the current is no longer limited by the time required to mechanically separate the rods.

In embodiments where the positions of the first and second rods are fixed relative to each other, the vacuum switch assembly may further include a switching bypass circuit and an ignition circuit, the vacuum switch or each vacuum switch further including an auxiliary electrode coaxially located in a central hole of the first rod, one end of the auxiliary electrode protruding from the second end of the first rod, the bypass switching circuit being operatively connected to the vacuum switch or to each switch of vacuum and being controllable to derive the current to divert the vacuum switch or each vacuum switch, the ignition circuit being operatively connected to the auxiliary electrode or to each auxiliary electrode and being controllable to establish a discharge current between the first and second electrodes . In such embodiments, the ignition circuit may include a power switch.

25 spark ignition.

The inclusion of the bypass switching circuit in the vacuum switch assembly allows the bypass switching circuit to transport the load current during normal operation of the associated power grid. To change the current, the ignition current is controlled to establish a spark between the auxiliary electrode and the surrounding electrodes to establish a current that passes through the vacuum switch. Once the peak current value is established, the bypass switching circuit is changed to an open state to allow the vacuum switch to carry out the current interruption process.

Preferably, the bypass switching circuit includes at least one semiconductor switch or at least one mechanical switch.

The choice of the switching device for the bypass switching circuit may vary depending on several factors such as the cost, size and weight of the switching device and the performance requirements of the current interruption process.

In other embodiments, the vacuum switch assembly may include a plurality of vacuum switches connected in parallel and / or connected in series.

Multiple vacuum switches can be connected to define different configurations of the set of

45 vacuum switch to vary its operating voltage and current characteristics to match the associated power application requirements.

According to a second aspect of the invention, there is provided an apparatus comprising primary and secondary circuits, the primary circuit including a vacuum switch assembly according to any preceding claim, the secondary circuit including a serial connection of at least one capacitor, at least one inductor and a spark ignition switch, in which the primary and secondary circuits are connected in parallel.

During use, the secondary circuit is controllable to inject an oscillatory current into the primary circuit

55 to force the arc current to zero. This not only provides precise control over the amount of time required to interrupt the current, but also reduces the time required for the extinction of the arc current, since the secondary circuit can be configured to achieve zero current before the primary circuit

Preferably, the primary circuit further includes at least one plasma switch connected in series with the vacuum switch assembly.

The ability of the plasma switch to generate a high arc voltage increases the total arc voltage through the serial connection of the vacuum switch assembly and the plasma switch. This in turn accelerates the reduction of arc current and reduces the total time required for the current interruption process.

65 In addition, the inclusion of or each plasma switch results in the reduction of total power dissipation to

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through the primary circuit. This in turn allows the ratings of the circuit elements to be reduced and, therefore, reduces the costs and the space required for the installation of the device.

Examples of applications that are compatible with the vacuum switch assembly according to the

The invention includes, for example, AC power networks, AC high voltage circuit breakers, AC generator circuit breakers, rail traction, ships, superconducting magnetic storage devices, high energy fusion reactor experiments , stationary power applications and high-voltage DC multi-terminal networks (HVDC).

Preferred embodiments of the invention will now be described, by way of non-limiting examples, with reference to the accompanying drawings in which:

Figure 1 shows a vacuum switch assembly according to a first embodiment of the invention;

Figure 2 shows a vacuum switch assembly according to a second embodiment of the invention;

Figure 3 shows a vacuum switch assembly according to a third embodiment of the invention;

Figure 4 shows, in schematic form, a bypass switching circuit and an ignition circuit connected to the vacuum switch assembly of Figure 3;

Figure 5 shows, in schematic form, the primary and secondary circuits connected in parallel according to the fourth embodiment of the invention.

A vacuum switch assembly according to a first embodiment of the invention is shown in Figure 1.

The vacuum switch assembly comprises a single vacuum switch 10.

The vacuum switch 10 includes a pair of cylindrical housings 12, first and second end tabs 14,16 and an annular structure 18 mounted to define a vacuum sealed case. Each end flange 14,16 is welded to a first end of a respective cylindrical housing 12 to form a seal. The two cylindrical housings 12 are joined together at their second ends through the annular structure 18. The annular structure 18 includes a central shield 20 that overlaps the inner walls of the housings.

35 cylindrical 12 to protect the inner walls of cylindrical housings 12 from metal deposition resulting from arc discharge, while each end flange 14,16 includes an end shield 22 to improve the distribution of the electrostatic field line along the length of the vacuum switch 10.

Each cylindrical housing 12 is metallized and nickel plated. The length and diameter of the respective cylindrical housing 12 vary depending on the nominal operating voltage of the vacuum switch 10, while the dimensions and shapes of the first and second end tabs 14,16 and the annular structure 18 may vary. to match the size and shape of the cylindrical shells 12.

The vacuum switch 10 also includes a tubular bellows 24 and a first and second electrically conductive rods 45 26.28.

The first end flange 14 includes a spacing hole sized to accommodate the tubular bellows 24, while the second end flange 16 includes a spacing hole sized to accommodate the second rod 28 within its spacing hole. The tubular bellows 24 also includes a separation hole for retaining the first rod 26.

The first and second rods 26,28 are respectively retained within the separation holes of the tubular bellows 24 and the second end flange 16 so that the second ends of the rods 26,28 are located inside the case and the first Rod ends 26, 28 are outside the box. The

First and second rods 26,28 can be made from, for example, high oxygen free conductivity copper (OFHC).

The vacuum switch 10 also includes first, second and third electrodes 30, 32, 34 and a coil with multiple slots 38. The coil with multiple slots 38 includes a plurality of slots (not shown).

It is envisioned that, in other embodiments, the coil with multiple slots may be replaced by a slotted coil that includes only a single slot. Preferably said single groove would extend completely around the entire perimeter, for example the circumference, of the coil.

65 The first electrode 30 is composed of first and second electrode portions 30a, 30b. The first electrode portion 30a is in the form of a rounded electrode portion that is mounted at the second end of

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the first rod 26. The second electrode portion 30b is in the form of an annular electrode portion that is mounted around the circumference of the first rod 26 and is adjacent to the first electrode portion 30a.

5 The second electrode 32 is mounted on an inner surface of the coil with multiple slots 38.

The multi-slot coil 38 includes a support base 36. The support base 36 is mounted on the second end of the second rod 28.

10 The third electrode 34 is mounted in the center of the support base 36. The rods 26,28 are coaxially aligned such that the first and third electrodes 30,34 define opposite contact surfaces. The third electrode 34 includes a recess 40 for receiving the first electrode portion 30a and the shape of the cavity 40 corresponds to the rounded shape of the first electrode portion 30a in order to maximize contact between the first and third electrodes 30 ,3. 4.

Each electrode 30, 32, 34 is made of a refractory material, which can be selected from a group of, for example, chromium-chromium, copper-tungsten, copper tungsten carbide, tungsten, chromium or molybdenum. These refractory materials not only exhibit excellent electrical conductivity, but also show high dielectric strength in the presence of the arc during the current interruption process. In addition, these

20 refractory materials have relatively high current interruption values, which helps to extinguish the arc quickly once the current has fallen below the cut-off current value.

The wavy walls of the tubular bellows 24 allow the tubular bellows 24 to undergo expansion or contraction in order to increase or decrease the tubular length of the tubular bellows 24. This allows the first rod 26 to move

25 with respect to the second rod 28 between a first position in which the first and third electrodes 30,34 are kept in contact and a second position where only a portion of the first electrode portion 30a remains located within the coil with multiple slots 38. The second rod 28 is held in a fixed position.

In use, the first end of the first rod 26 is connected to a positive terminal 42 of a DC network, while the first end of the second rod 28 is connected to a negative terminal 44 of the DC network.

During normal operation of the connected DC network, the tubular bellows 24 is controlled to move the first rod 26 to the first position to put the first and third electrodes 30.34 in contact. This allows the

Current flows between the positive and negative terminals 42.44 of the DC network connected through the electrically conductive rods 26,28. The low contact resistance resulting from the contact between the first and third electrodes 30,34 means that there is no current flow through the coil with multiple slots 38.

In the case of a fault that results in a high fault current flowing in the connected DC network, the current

40 must be interrupted to prevent high fault current from damaging components of the DC network. The interruption of the fault current allows isolation and subsequent repair of the fault in order to restore the DC network to normal operating conditions.

The process of interrupting the current is started by controlling the tubular bellows 24 to move the first

45 rod 26 towards its second position in order to separate the opposing contact surfaces of the first and third electrodes 30,34. The separation of the opposing contact surfaces results in the formation of a separation between the first electrode 30 and the second and third electrodes 32,34, which leads to the formation of an arc in this separation. The arc is composed of metal vapor plasma, which continues to conduct the current that flows between the first and third electrodes 30,34.

50 As the separation between the opposing contact surfaces increases and the magnitude of the current increases, the coil with multiple slots 38 begins to conduct the current through the second electrode 32. The shape of the coil with multiple slots 38 causes the conducted current flows in a preferential direction within the coil 38 with multiple slots, resulting in the generation of an axial magnetic field in the

55 separation between the first electrode 30 and the second electrode 32. The direction of the generated axial magnetic field is perpendicular to the direction of the current that is conducted between the first electrode 30 and the second electrode

32

In the presence of the axial magnetic field, the metal vapor plasma is forced away from the separation between the

60 first electrode 30 and second and third electrodes 32.34. Subsequently the arc voltage begins to rise while the magnitude of the extracted current begins to decrease rapidly. When the magnitude of the current consumed reaches a value less than the cut-off current value of the electrode material, the arc energy becomes insufficient to maintain the current, which leads to the arc becoming highly unstable since the Current drops instantly to zero. This allows full dielectric recovery and that

65 the successful power interruption takes place.

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The duration of the interruption of the current is limited by the time required to mechanically move the first rod 26 from the first position to the second position, which is typically a few milliseconds. Once the first rod 26 reaches the second position, the current will typically drop to zero by approximately 10 to 20 µs.

5 The arrangement of the first rod 26 and the coil with multiple grooves 38 therefore allows the separation of the first and third electrodes 30,34 to result in the generation of a self-induced axial magnetic field to aid in arc extinction. formed between the first electrode 30 and the second and third electrodes 32,34. This eliminates the need to incorporate additional equipment in the vacuum switch assembly to generate the required axial magnetic field and therefore reduces the complexity of the arrangement of the vacuum switch assembly.

The comparatively simpler design of the vacuum switch assembly has the effect of reducing the amount of space required for assembly and the associated installation costs, while the reduced number of

15 components in the vacuum switch assembly improves the reliability of the current interruption process.

A vacuum switch assembly according to a second embodiment of the invention shown in Figure 2. The structure and operation of the vacuum switch assembly of Figure 2 are the same as those of the vacuum switch assembly of Figure 2, except that the second embodiment includes an auxiliary coil 46 that is located outside the vacuum-tight box of the vacuum switch 110 and above the protruding end 14.

The auxiliary coil 46 is associated with a DC power supply 48. In use, the DC power supply 48 is controlled to supply a pulsed DC current to the auxiliary coil 46 so that the auxiliary coil

25 46 generates a pulsed magnetic field inside the vacuum sealed case.

During the current drop after the generation of the axial magnetic field, the auxiliary coil 46 is controlled to generate the pulsed magnetic field once the current reaches a low value. These results in the pulsating magnetic field overlap in the axial magnetic field and therefore increase the strength of the axial magnetic field. This helps reduce the time required to extinguish the residual arc.

The provision of the auxiliary coil 46 in the vacuum switch assembly allows each electrode 30, 32, 34 to be made of a material that has a low cut-off current value, but is conducive to the requirements of high dielectric strength in the vacuum switch 110 during open condition. Examples of this type of material

35 electrode include copper-chrome and tungsten carbide silver.

The provision of the auxiliary coil 46 in the vacuum switch assembly also allows precise control over the moment of injection of the pulsed DC current in the auxiliary coil 46 and the magnitude and duration of the pulsed DC current injected and by Therefore, it improves the performance of the current interruption process.

A vacuum switch assembly according to the third embodiment of the invention is shown in Figure 3. The structure and operation of the vacuum switch assembly of Figure 3 are the same as those of the vacuum switch assembly. of Figure 1, except that, in the third embodiment of the invention, the tubular bellows of the vacuum switch 210 and the separation hole of the first end flange 14 are omitted

45 is sized to accommodate the first rod 26. The omission of the tubular bellows means that the positions of the first and second rods 26,28 are fixed relative to each other. Since the position of the first rod 26 is fixed, the third electrode can be omitted from the vacuum switch assembly of Figure 3.

The first and second rods 26,28 are positioned so that only a part of the first rod 26 is located just inside the coil with multiple slots 38.

The vacuum switch assembly further includes an auxiliary electrode 50, a switching bypass circuit 52 and an ignition circuit 54.

55 The auxiliary electrode 50 is coaxially located in a central hole of the first rod (26), so that one end of the auxiliary electrode 50 protrudes from the second end of the first rod 26. The auxiliary electrode 50 is hermetically sealed by vacuum welding against the first rod 26 using metallized ceramic spacers.

As shown in Figure 4, the bypass switching circuit 52 is connected in parallel with the vacuum switch 210, while the ignition circuit 54 is connected in series with the auxiliary electrode

50. The ignition circuit 54 includes a spark ignition switch.

During normal operation of the connected DC network, the bypass switching circuit 52 is

65 switches to a closed state to allow the load current to flow through the bypass switching circuit 52 and thereby bypass the vacuum switch 210.

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In the event of a failure in the connected DC network, the bypass switching circuit 52 is switched to an open state to prevent current from flowing through the bypass switching circuit 52 and the ignition circuit 54 is controlled to establish a discharge current between the first and second electrodes 30,32. 5 This is done by establishing a radiofrequency discharge between the auxiliary electrode 50 and the surrounding conductors. The generated plasma spreads rapidly between the separation between the first and second electrodes 30,32 and begins to conduct a current. This in turn causes the current to flow through the coil with multiple slots 38 and therefore leads to the generation of an axial magnetic field. As in the first and second embodiments, the presence of the axial magnetic field increases the arc tension and

10 decreases the arc current until it is extinguished.

The switching of the bypass switching circuit 52 between the open and closed states can be performed using a semiconductor switch or a mechanical switch depending on the requirements of availability, cost and performance.

The time required for the vacuum switch assembly in Figure 4 to interrupt the current is limited by the time necessary for the switching bypass circuit 52 to achieve an open state. The switching time for a mechanical circuit breaker is normally a few milliseconds, while the switching time for a semiconductor switch is typically less than 10 µs.

The time required to fully open the mechanical switch, therefore, may require multiple ignitions through the vacuum switch 210 to maintain the arc until the mechanical switch is fully open.

It is envisioned that the vacuum switch assembly according to embodiments of the invention can be used to carry out the current interruption process for conditions other than high fault current conditions.

Apart from the interruption of the current in the DC networks, the vacuum switch assembly in Figures 1 to 4 can also be used to interrupt the current in the AC power networks, high voltage alternating current switches and AC circuit breaker generators.

An apparatus according to the fourth embodiment of the invention is shown in Figure 5.

The apparatus comprises primary and secondary circuits 56.58, whereby the primary and secondary circuits 56.58 are connected in parallel.

The primary circuit 56 includes a serial connection of a vacuum switch assembly according to the first or second embodiment and a plasma switch 60 connected in series with the vacuum switch 10, 110, 210 according to any of the first , second and third embodiments. The plasma switch 60

40 may be, for example, a hydrogen plasma switch.

The secondary circuit 58 includes a series connection of a capacitor 62, an inductor 64 and a spark ignition switch 66.

During use, the plasma switch 60 is controllable to generate a high arc voltage, which is combined with the arc voltage through the vacuum switch assembly to increase the total arc voltage through the serial connection of the vacuum switch 10, 110, 210 and plasma switch 60. Increasing the total arc voltage in turn accelerates the reduction of the arc current and thereby reduces the total time required for the process of interrupting the arc. stream.

50 On the other hand, the inclusion of the plasma switch 60 results in the reduction of the total power dissipation through the primary circuit 56. This in turn allows the ratings of the circuit elements of the primary circuit 56 to be reduced and by therefore decreases the costs and space necessary for the installation of the device.

55 During use, the secondary circuit 58 is controllable to inject an oscillatory current into the primary circuit 56 to force the arc current to zero. The ability to force the arc current to zero not only provides precise control over the amount of time required to interrupt the current, but also accelerates the time required for the extinction of the arc current, since the secondary circuit 58 It can be configured to achieve zero current before primary circuit 56.

60 It is envisioned that, in other embodiments, the plasma switch can be omitted from the apparatus so that the secondary circuit is connected in parallel with the vacuum switch 10, 110, 210.

In other embodiments, it is envisioned that a vacuum switch assembly may include a plurality of vacuum switches 65 connected in series and / or connected in parallel.

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Multiple vacuum switches can be connected to define different configurations of the vacuum switch assembly to improve its operating voltage and current characteristics. For example, the connection of several vacuum switches in series increases the dielectric strength of the vacuum switch assembly and therefore allows the use of the vacuum switch assembly with higher operating voltages,

5 while connecting several vacuum switches in parallel allows the vacuum switch to interrupt the highest current levels.

The vacuum switch assembly in Figures 1 to 4 and the apparatus of Figure 5 are compatible for use in, but are not limited to, applications such as traction of trains, ships, magnetic storage devices 10 superconductors, experiments High-power reactor fusion, stationary power applications and multi-terminal networks (HVDC) of high voltage current.

Claims (19)

1. A vacuum switch assembly comprising at least one vacuum switch (10), including the vacuum switch or each vacuum switch a vacuum sealed case; first and second rods electrically 5 conductors (26, 28), a first end of each rod being adapted to be connected, in use, to an electrical network (42, 44); a first electrode (30) being mounted near or at a second end of the first rod (26); a slotted coil (38); and a second electrode (32); wherein the first electrode and the grooved coil are located inside the vacuum sealed case and the rods are positioned to place at least a part of the first electrode inside the grooved coil; characterized in that the slotted coil is operatively mounted on a second end of the second rod and that the second electrode is mounted on an inner surface of the slotted coil. 2. A vacuum switch according to claim 1, wherein the slotted coil includes only a single groove. fifteen

3.

A vacuum switch according to claim 1, wherein the slotted coil includes a plurality of grooves.

Four.

A vacuum switch assembly according to any preceding claim, wherein the first electrode includes a first electrode portion (30a) mounted on the second end of the first rod.

5.

A vacuum switch assembly according to claim 4, wherein the first electrode further includes a second electrode (30b) mounted around the circumference of the first rod and adjacent to the first electrode portion.

25

6.

A vacuum switch assembly according to any preceding claim, wherein the slotted coil includes a support base (36) mounted on the second end of the second rod.

7.

A vacuum switch assembly according to any preceding claim, wherein each electrode is made of a refractory material.

8.

A vacuum switch assembly according to claim 7, wherein the refractory material is selected from a group of chromium-chromium, copper-tungsten, tungsten carbide copper, tungsten, chromium or molybdenum.

35

9.

A vacuum switch assembly according to any preceding claim, wherein at least one rod is removable relative to the other rod to open or close a gap between the second ends of the rods.

10.

A vacuum switch assembly according to claim 9 when it depends on claim 6, wherein the switch or each vacuum switch further includes a third electrode (34) mounted on the support base, defining the first and third electrodes opposite contact surfaces, and at least one rod is movable relative to the other rod to open or close a gap between the opposing contact surfaces.

A vacuum switch assembly according to claim 9 or claim 10, wherein the or each vacuum sealed case further includes a tubular bellows (24) with a separation hole, the tubular bellows being or each tubular bellows operatively connected to at least one rod and being controllable to expand or contract to move a rod relative to the other rod to open or close a gap between the second ends of the rods. 12. A vacuum switch assembly according to any one of claims 9 to 11, wherein the switch or each vacuum switch further includes an auxiliary coil (46) located outside the vacuum sealed case, the auxiliary coil being controllable to provide a pulsed magnetic field inside the vacuum sealed case. 55

13.

A vacuum switch assembly according to claim 12 when it depends on claim 7, wherein the refractory material is copper and chrome, copper and tungsten, tungsten carbide copper, tungsten, chromium, molybdenum or tungsten carbide silver .

14.

A vacuum switch assembly according to any one of claims 1 to 8, wherein the positions of the second ends of the rods are fixed relative to each other.

fifteen.

A vacuum switch assembly according to claim 14, further including a bypass switching circuit (52) and an ignition circuit (54), including the switch or each vacuum switch

65 also an auxiliary electrode (50) coaxially located in a central hole of the first rod (26), one end of the auxiliary electrode protruding from the second end of the first rod, the switching circuit being 10 bypass operatively connected to or each vacuum switch and being controllable to divert the current to deviate from the switch or each vacuum switch, the ignition circuit being operatively connected to or each auxiliary electrode and being controllable to establish a discharge current between The first and second electrodes. 5

16.

A vacuum switch assembly according to claim 15, wherein the ignition circuit includes a spark ignition switch (66).

17.

A vacuum switch assembly according to claim 15 or claim 16, wherein the

Bypass switching circuit includes at least one semiconductor switch or at least one mechanical switch. 18. A vacuum switch assembly according to any preceding claim that includes a plurality of vacuum switches connected in series and / or connected in parallel. fifteen 19. An apparatus comprising primary and secondary circuits, including the primary circuit (56) a vacuum switch assembly according to any preceding claim, the secondary circuit (58) including a serial connection of at least one capacitor (62) , at least one inductor (64) and a spark ignition switch (66), in which the primary and secondary circuits are connected in parallel. twenty 20. An apparatus according to claim 19, wherein the primary circuit further includes at least one plasma switch connected in series with the vacuum switch assembly. eleven