JP7118992B2 - vacuum switch - Google Patents

Description

The present invention relates to a vacuum switch designed to be used as an earthing switch or as a disconnector, in particular for railway applications.

Electrical grounding (or earthing) is required for safety reasons when inspecting, maintaining, repairing, or replacing some electrical equipment such as capacitor banks, circuit breakers, circuit switchers, and the like. Grounding switches or devices are available as stand-alone devices or can be combined with other electrical devices such as disconnectors, circuit breakers, and other switching devices. Grounding devices are typically actuated manually by an operator via a manual gear operator or hookstick, or via electromechanical actuators (coils, electric motors, etc.).

In railroad applications, the standard and simplest solution for electrical grounding is an air-isolated grounding switch containing two moving arms. The moving arms are designed to move between an open position and a closed position in which the arms are plugged into corresponding ground fingers connected to the ground. Typically, such air-isolated grounding switches are designed to meet the following requirements for electrical grounding.
i. provide sufficient clearing distance between the arms and fingers in the open state;
ii. Allows closing/opening in off-road conditions without the need for fast opening/closing movements;
iii. withstand any high short circuit (SC) current in the closed position;
iv. Maintains the switch in the closed position during a short circuit current.

There are two main drawbacks to this type of air-insulated grounding switch for railroad applications: due to the rather large clearance distance required between the arm and the grounding finger (at least 200mm for 25kVAC railcars), the grounding Switches take up a lot of space. This is especially problematic in medium voltage applications. Secondly, positioning the switch on the roof of a rail vehicle in the open means that the switch is exposed to harsh environmental conditions (snow, ice, dust, soot, birds). This can prevent the arms from reliably remaining within their respective ground fingers during closure, which can seriously compromise the safe operation and performance of the ground switch.

Another option is to use a gas such as _SF6 for grounding switch isolation in a closed and sealed housing. However, such gas isolated grounding switches are costly, complex and fragile devices. Because the gas-pressure must be constantly monitored, these switches are not necessarily suitable for rail vehicle roof applications, which are subject to high mechanical stress and harsh environmental conditions. Furthermore, _SF6 is a greenhouse gas that contributes to global warming and therefore its use should be avoided.

Solid insulated switchgear (switchgear) with solid insulated grounding switches is an environmentally friendly option. Such switchgear generally uses epoxy resin as the insulating material instead of _SF6 . They require less maintenance and are generally safer than air-insulated switchgear as any risk of gas leakage is eliminated. However, such solid insulated switchgear is still somewhat bulky and quite heavy and cumbersome.

Another type of switch frequently used in railroad applications is the disconnector (isolation switch). A disconnector is a mechanical switching device that provides an isolation distance at the open position of the contacts according to specified requirements. A disconnector is an offload device that can interface with other switching devices such as circuit breakers and grounding switches. Disconnectors are usually capable of opening and closing circuits when there is no or negligible current to be interrupted or when there is no or a small voltage difference across the terminals of each pole of the disconnector. . Also, the disconnector can conduct current under normal circuit conditions and conduct current for an indicated time under abnormal conditions such as short circuits. The normal requirements for disconnectors are therefore the same as requirements i to iv listed above for earthing switches, and:
v. withstand the permanent load current in the closed position of the contacts;
vi. maintaining the contacts in the open position during circuit maintenance;
is.

With respect to the very similar requirements between grounding switches and disconnectors, the disadvantages mentioned above also apply to disconnectors.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a switch that can be used as a grounding switch or as a disconnector that avoids all of the above disadvantages. The present invention provides a reliable, compact and inexpensive electrical ground suitable for railroad applications for use in the field or in enclosed spaces and for use as a stand-alone device or as part of an electrical protection system for either switchgear or circuits. or intended to provide disconnection solutions.

Objects of the invention are a vacuum switch according to claim 1, a use in railway applications according to claim 14 and an electric circuit comprising said vacuum switch according to claim 15.

Other advantages and features of the invention will become more apparent from the following description of particular embodiments of the invention, given as non-limiting examples only and represented in the accompanying drawings.

Figure 3 shows a vacuum switch according to the invention; 1 is a cross-sectional view of a vacuum switch according to a first embodiment of the invention with the contacts in the open position; FIG. FIG. 4 shows the contacts of a vacuum switch according to a first variant of the first embodiment in the open position; FIG. 4 shows the contacts of a vacuum switch according to a first variant of the first embodiment in the closed position; Fig. 3c shows the current flow and the induced attractive force between the contacts in the closed position of Fig. 3b; FIG. 5 shows the contacts of a vacuum switch according to a second variant of the first embodiment in the open position; FIG. 4 shows the contacts of a vacuum switch according to a second variant of the first embodiment in the closed position; Fig. 4c shows the current flow and induced attractive force between the contacts in the closed position of Fig. 4b; Figure 6 shows the contacts of a vacuum switch according to a third variant of the first embodiment of the invention in the closed position; Fig. 3 is a cross-sectional view of a vacuum switch according to a second embodiment of the invention with the contacts in the open position; Fig. 3 shows the contacts of the vacuum switch according to the second embodiment in the closed position; Fig. 3 shows the current flow and induced attractive force between the contacts in the closed position; FIG. 4 is a cross-sectional view of a vacuum switch according to a third embodiment of the invention with the contacts in the open position; FIG. 4 shows the contacts of a vacuum switch according to a first variant of the third embodiment in the open position; FIG. 4 shows the contacts of a vacuum switch according to a first variant of the third embodiment in the closed position; Figure 9c shows the current flow and induced attractive force between the contacts in the closed position of Figure 9b; FIG. 8 shows the contacts of a vacuum switch according to a second variant of the third embodiment in the open position; FIG. 8 shows the contacts of a vacuum switch according to a second variant of the third embodiment in the closed position; Figure 10c shows the current flow and induced attractive force between the contacts in the closed position of Figure 10b; Figure 8 shows the contacts of a vacuum switch according to a variant of the third embodiment of the invention in the open position; Fig. 3 illustrates the use of a vacuum switch according to the invention as a grounding switch in an electrical circuit; Fig. 3 shows a variant of the vacuum switch according to the invention;

The object of the invention is a vacuum switch 1 designed to perform electrical grounding or disconnection in electrical circuits. The vacuum switch 1 according to the invention is preferably configured to operate at high or medium voltages. Preferably, the vacuum switch 1 according to the invention is designed for railway applications.

The structure of the vacuum switch 1 according to the invention is generally similar to that of known vacuum switches designed to act as current circuit breakers in electrical circuits.

The vacuum switch 1 generally includes a sealed chamber 2 preferably dominated by a controlled low pressure of air or another dielectric fluid, ie a vacuum. The chamber 2 is defined by an insulating case made of a suitable insulating material such as ceramic, glass-ceramic or glass. In an exemplary embodiment of the invention, the insulating case is tubular and preferably formed by two insulating cylinders 3,4.

A conductive cap 51 , 52 closes each open end of the seal chamber 2 . Caps 51, 52 are preferably made of metal. Any known technique can be used to effectively seal the caps 51, 52 to the insulating case. For example, in a ceramic insulating case the caps 51, 52 can be fixed to their respective cylinders 3, 4 by brazing followed by metallization.

The seal chamber 2 , bounded by insulating cases 3 , 4 and conductive caps 51 , 52 encloses a pair of operating contacts 101 , 102 movable relative to each other inside the seal chamber 2 . The contacts 101, 102 are movable with respect to each other between a first open position in which they are not in contact with each other and current cannot flow through each other, and a second closed position in which they are in contact with each other and current can flow through each other. is.

Preferably, the first contact 101, called the fixed contact, is fixed and rigidly attached to one of the caps 51, as shown. A second contact 102, called a movable contact, is mounted inside the chamber 2 so that it can be moved through another cap 52 between closed and open positions of the contact. A sealing metal bellows 16 is mounted between the movable contact 102 and the corresponding cap 52 to enable the movable contact 102 to move and maintain a controlled vacuum inside the seal chamber 2, thereby allowing the chamber 2 to move. Ensure a proper seal. A metal bellows shield may be mounted around the sealing bellows 16 at the level of the end of the bellows 106 coupled to the movable contact 102 . However, as will become apparent below, this bellows shield is not essential for the vacuum switch according to the invention when used as a grounding switch or disconnecting switch.

The movable contact 102 has an open position (FIGS. 2, 3a, 4a, 6, 8, 9a, 10a, 11 and 13) in which the movable contact 102 is not in contact with the fixed contact 101, and It moves between the contacting closed position (Figs. 3b, 3c, 4b, 4c, 5, 7a, 7b, 9b, 9c, 10b and 10c).

The tightly sealed chamber 2 also preferably includes a main shield 20 positioned at the contact area of the movable contact 101 and the fixed contact 102 around the contacts. In a conventional vacuum switch used as a circuit breaker, this primary shield 20 is primarily exposed to metal deposition or to any potential arcing when the contacts open to a load or short circuit current break. It is designed to protect the insulating cases 3, 4 against such emissions. The main shield 20 of the vacuum switch 1 according to the present invention does not need to protect the insulating cases 3, 4 against vapor deposition or emission since no arcing activity is expected during grounding or disconnecting operations and can therefore be removed. (The same applies to bellows shields). However, the shield 20 can be used and designed to create electric fields and electric potential line distributions when the vacuum switch 1 is in the open position. In this case, less requirements are placed on the design of the main shield 20 of the vacuum switch 1 according to the invention than the conventional shields of known vacuum switches used for current breaks. For example, a low cost material such as steel can be used for the main shield 20 .

When the vacuum switch 1 according to the invention is used in an electrical circuit, the movable contact 102 is connected to an actuating mechanism M (shown in FIG. 12) designed to displace the movable contact 102 between open and closed positions. be.

In railroad applications, the actuation mechanism M is preferably manually operated by an operator via a manual gear operator such as a coil or electric motor or any other suitable mechanism or a hook-stick or electromechanical actuator.

When used as a grounding switch, the vacuum switch 1 according to the invention is connected with one contact to an electrical circuit and the other contact to ground. Preferably, the fixed contact 101 of the vacuum switch 1 is connected to the electrical circuit and the movable contact 102 is connected to ground, as shown in FIG. Thus, in this case, electrical grounding occurs when the fixed contact 101 and the movable contact 102 of the vacuum switch 1 are in the closed position, and no electrical grounding exists when the fixed and movable contacts 101, 102 are in the open position.

When used as a disconnector, both contacts 101, 102 are connected to the ends of an electrical circuit.

A vacuum switch according to the invention can be air-insulated or liquid-insulated. In particular, due to the insulating case 3, 4, the vacuum switch 1 can be placed directly on the roof of a rail vehicle for railway applications, where the insulating case protects the switch from the external environment (dust, birds, soot, snow). to protect A vacuum switch according to the invention can be placed inside a metal-clad hermetic switchgear as a compact component for grounding or disconnecting. This presents a significant problem for conventional earthing switches operating in air which are not suitable for being placed in such enclosed switchgear.

In order to perform electrical grounding or disconnection, especially for railway applications, the vacuum switch 1 according to the invention must fulfill the following requirements.
• Pass BIL and power frequency tests for dielectric withstand voltage (examples of conditions required by these tests are BIL>170 kV, PF>75 kV for 25 kV VCB).
• Withstand short-circuit current in the closed (ie, grounded) position of the contacts for a specified time (eg, withstand 25 kA for 1 second).
• Maintaining the contacts in the closed position at high short circuit currents.
• Conducting the nominal current in the closed position for disconnection.

It is known from electrical contact theory that the current flow between two electrical contacts passes through a small contact spot. The tiny current flow path is confined to a very small area at the interface of contacts 101,102. This current line distribution creates a repelling or blow-off electromagnetic force between the contacts that tends to break the contacts and prevent them from remaining in the closed position. These electromagnetic blow-off forces F _b are proportional to the square of the flowing current.

On the other hand, it is known that the contact resistance _Rc is inversely proportional to the square root of the instantaneous closing force _Fc . The instantaneous closing force F _c is the difference between the external force F _ext exerted by the actuating mechanism M and the external pressure (atmospheric pressure) while the contacts are in the closed position and the blow-off force F _b is

The effect of this blow-off force F _b is amplified in the case of short-circuit currents, significantly increasing the contact resistance or, under severe conditions, causing the contacts to pull apart. In order for the vacuum switch according to the invention to ground or disconnect safely, these blow-off forces F _b must be limited.

ここで、短絡事象（接地又は断路）中にも閉鎖位置に接点が維持されることが要求されるので、Ｆ_c＞０という条件が追加される。 The macroscopic design of the contacts of the vacuum switch 1 according to the invention is adapted to counteract or reduce the effect of the blow-off force _Fb . The geometry of the contacts is shaped to alter the current path through the contacts to create an electromagnetic attractive force F _a to balance or reduce the effect of the blow-off force F _b . With these attractive forces F _a , the instantaneous closing force F _c can be expressed as follows.

Here, the condition F _c >0 is added since it is required that the contacts remain in the closed position during a short circuit event (grounded or disconnected).

Figures 2 to 11 show various embodiments of the vacuum switch 1 according to the invention having different possible geometries of the movable and fixed contacts 102, 101 capable of generating an attractive force F _a to satisfy equation (2) above. indicates

In the first embodiment and this variant shown in FIGS. 2 to 5, the movable and fixed contacts 102, 101 exhibit a so-called "closed front" shape. In this first embodiment, the stationary contact 101 presents a trumpet-shaped cavity 103 at its open end. The contact surface 105 of the fixed contact 101 is flat but has a hole 107 communicating with the cavity 103 . Similarly, the movable contact 102 has a neck 104 , a flange 106 and a trumpet-shaped free end designed to contact the contact surface 105 of the stationary contact 101 and having a flat contact surface 108 . Preferably, there is a mechanical support element 110 around neck 104 of movable contact 102 . This support element 110 is preferably made of stainless steel.

In a first variant of this first embodiment, shown in FIGS. 3a to 3c, there is a spring 109 which is arranged inside the cavity 103 of the first contact 101 and directly below the hole 107 . A spring 109 can be made of stainless steel to prevent the cavity 103 from collapsing during closure of the contacts 101,102. Another method of strengthening the cavity 103 of the fixed contact 101 is to provide a spring washer 111 inside the cavity 103, as shown in the variant of FIG.

In a second variant of the first embodiment shown in FIGS. 4a and 4b, the contact surface 108 of the movable contact is furthermore a rim 108 designed to be in contact 102 with the contact surface 105 of the stationary contact 101. ' and contact surface 105 of fixed contact 101 includes a rim 105' around hole 107 of cavity 103 designed to contact contact surface 108 of movable contact 102. As shown in FIG. Thus, in this variant, while in the closed position (FIGS. 4b, 4c and 5), contact between fixed contact 101 and movable contact 102 is restricted to rims 108' and 105'. This helps to alter and conduct the current flow I through the contacts in the closed position.

As shown in Figures 3c and 4c, the geometry according to the first embodiment alters the current flow I in the contacts in the closed position, allowing the attractive electromagnetic force to balance or reduce the effect of the blow-off force _Fb . F _a is generated.

In this first embodiment, the gap G between contacts 101, 102 is preferably longer than the required clearance distance. For example, a 16mm gap is sufficient to meet the requirements of a 25kV grounding switch or disconnector used in railroad applications (eg such requirements may be BIL > 170kV and PF > 75kV). . Also in this embodiment, the stroke of the movable contact 102 to the closed position is equal to the gap G. Thus, in this first embodiment, a very small air- or liquid-insulated grounding switch or disconnector that is much smaller than known air-insulated grounding switches with very large clearing distances and thus stroke distances (typically about 200 mm). can be obtained.

In a second embodiment of the vacuum switch 1 according to the invention, the contacts exhibit a geometry called "tulip closure" as shown in Figures 6 and 7a, 7b. In this second embodiment, the free end of the movable contact 102 has a basically cylindrical shape with a preferably rounded contact surface 112 and a corresponding recess 113 in the free end of the stationary contact 101. designed to be inserted into Thus, recess 113 has a similar cylindrical shape with a concave rounded bottom 117 . As soon as the movable contact 102 touches the wall of the fixed contact 101, the wall of the recess 1113 of the fixed contact 101 is elastic to facilitate the insertion of the movable contact 102 into the recess 113 and the electrical contact. is preferred. The walls of the recess 113 are preferably made from a plurality of flexible lugs 115, as shown in Figures 6, 7a and 7b.

As shown in FIG. 7b, in this second embodiment the current flow I of the contacts 101, 102 in the closed position is altered and the attractive force F _a is applied via the flexible lugs 115 to the fixed contacts 115 It is generated from the stationary contact 101 that "clamps" the movable contact 102 inside the recess 113 of 101 . These attractive forces F _a , or pinch forces in this embodiment, can balance and overcome the effect of the blow-off force F _b .

Due to the overlapping fixed and movable contacts 101, 102, the vacuum switch according to the second embodiment provides a very safe closure.

In this second embodiment, the gap G between contacts 101, 102 is also preferably greater than the required clearance distance. As with the first embodiment, a 16mm gap is sufficient to meet the requirements of a 25kV grounding switch or disconnector used in railroad applications. However, due to this second geometry, the matching stroke for moving contact 102 into the closed position inside recess 113 of fixed contact 101 is longer than gap G. FIG. For example, as shown in FIG. 6, the stroke is 25 mm for a gap G of 16 mm. The vacuum switch according to the second embodiment of the invention used as a grounding switch or disconnector remains smaller than many of the known air-insulated grounding switches with a stroke of 200mm.

In a third embodiment shown in Figures 8 to 11, the fixed and movable contacts 101, 102 exhibit a so-called "conical closed" shape. In this third embodiment, the movable contact 102 has an “arrow” shaped free end with a neck 104 terminated by an inverted cone 114 . This inverted cone 114 is designed to be inserted into a corresponding recess 113 in the free end of the fixed contact 101 . As in the first embodiment, fixed contact 101 provides cavity 103 below recess 113 with hole 107 linking cavity 103 to recess 113 .

The inner wall of recess 113 is contact surface 105 of fixed contact 101 designed to contact contact surface 108 of moving contact 102 , which is the outer wall of inverted cone 114 .

A mechanical support element 110 is preferably present around neck 104 of movable contact 102 . This support element 110 is preferably made from stainless steel.

In a first variant of the third embodiment shown in FIGS. 9a to 9c, there is a spring 109 inside the cavity 103 of the first contact 101 and arranged directly below the hole 107 . Spring 109 can be made from stainless steel and prevents cavity 103 from collapsing during closure of contacts 101,102. Another way to strengthen the cavity 103 of the fixed contact 101 is to provide a spring washer 111 inside the cavity 103 as shown in the variant of FIG.

In a second variant of the third embodiment shown in FIGS. 10a to 10c, the contact surface 108 of the movable contact 102 comprises around it a rim 108' designed to contact the contact surface 105 of the fixed contact 101, Contact surface 105 of stationary contact 101 includes a rim 105' around hole 107 in cavity 103 designed to contact contact surface 108 of movable contact 102. As shown in FIG. Thus, in this variant, while in the closed position (FIGS. 10b, 10c), contact between fixed contact 101 and movable contact 102 is limited to rims 108' and 105'. This alters the current flow I to help alter and conduct the current flow I through the contacts in the closed position.

As shown in FIGS. 9c and 10c, the geometry according to the third embodiment alters the current flow I in the contacts in the closed position, allowing the effect of the blow-off force F _b to be balanced or reduced. A force F _a is generated.

As with the other embodiments, in this third embodiment the gap G between contacts 101, 102 is preferably longer than the required clearance distance. For example, a 16 mm gap is sufficient to meet the requirements of a 25 kV grounding switch or disconnector used in railroad applications (eg such requirements may be BIL>170 kV and PF>75 kV). However, due to this third shape, the matching stroke of the movable contact 102 to the closed position inside the recess 113 of the fixed contact 101 is longer than the gap G. FIG. The vacuum switch according to the third embodiment of the invention, used as a grounding switch or disconnector, remains much smaller than most of the known air-insulated grounding switches with a 200mm stroke.

As can be seen above, a vacuum switch according to the present invention used as an electrical grounding or disconnecting switch can be made even more compact than conventional vacuum switches used for current interrupting because no arcing contacts are required. For example, a vacuum switch according to the invention used for grounding or disconnecting in railroad applications can have a very small total diameter of 60 mm or less.

There are many advantages that result from using the vacuum switch according to the invention as a grounding switch or disconnector. A vacuum switch according to the present invention uses the same basic principles as conventional vacuum switches, but does not need to interrupt current or close under load conditions when used as a grounding switch or disconnector. Therefore, the overall design of the vacuum switch according to the invention can be simpler and more cost effective than conventional vacuum switches.

As can be seen above, the geometry of the contacts can be fairly simple. For generating a transverse or axial magnetic field (TMF or AMF) to control the vacuum arc generated during contact opening, especially under short-circuit conditions, although the grounding switch requirements described above must be met. No special geometry is required.

Expensive CuCr contacts are also not required, instead cost effective materials can be used for the contacts. For example, the contacts can be made of copper or iron, one copper and one iron. Iron or any other ferromagnetic material can be used in one or both of the contacts to extend the attractive or pinch force F _a between contacts having all of the above geometries. For example, with the tulip-closed geometry of the second embodiment described above, it has been found that advantageous configurations correspond to copper moving contacts and iron or ferromagnetic stationary contacts with a tulip shape.

As previously mentioned, another advantage of using a vacuum switch according to the present invention as a grounding action or disconnector arises from the fact that arcing activity between the fixed contact 101 and the movable contact 102 is not expected during contact opening. Accordingly, the main shield 20 surrounding the contact area between the fixed contact 101 and the movable contact 102 can be eliminated or designed to serve only dielectric purposes. In this latter case, it can therefore be made from cost effective materials such as stainless steel.

Furthermore, the insulating case of the vacuum switch according to the invention can be made of ceramic or glass-ceramic, like conventional vacuum switches used for current interruption, but can also simply be made of glass. The insulating case can be transparent (glass, ceramic or glass-ceramic) and with a transparent or translucent primary shield 20 or even without a primary shield at all, the operator can determine the status of the vacuum switch (open or closed). can be visually confirmed. FIG. 13 shows such a grounding switch with a transparent insulating case, the main shield 20 being made as a similar quasi-transparent mesh of suitable material to form a Faraday cage to meet the required dielectric objectives. (forming an electric field and electric potential line distribution when the contacts are in the open position).

A vacuum switch according to the present invention may also include any suitable sensing mechanism capable of indicating to the operator the state of the switch and the position of the contacts, ie open or closed. This can be useful in some applications, for example when the switch is placed inside a metal clad closed switchgear.

Figure 12 shows the use of the vacuum switch 1 according to the invention for electrical grounding of electrical circuits for railway applications. The vacuum switch 1 is held in the frame 7 of the main circuit breaker of the electrical circuit. The actuating mechanism M and the external conductors 61, 62 attached to the movable contact 102 of the vacuum switch 1 and connected to ground can be seen in detail in this figure. In the closed position of the vacuum switch 1 according to the invention, current flow through the outer conductors 61, 62 can be used to provide an additional attractive force _Fca between the fixed contact 101 and the movable contact 102 during a short circuit. .

In the closed position of the contacts, current flow through the outer conductors 61, 62 held in place by the pushrod 63 of the actuating mechanism M provides a greater blow-on force (attractive force) F _ca , which causes the conductors It is the repulsive force between conductors 61, 62 that pushes 61, 62 away from each other. As a result, these blow-on forces _Fca tend to keep the first and second contacts 101, 102 in the closed position. These forces F _ca , like the blow-off force F _b , are proportional to the square of the flowing current.

短絡事象（接地又は断路）中の閉鎖位置事象に接点がとどまることが必要になるので、追加の条件はＦ_c＞０である。 With these additional attractive forces F _ca , the instantaneous closing force F _c can be expressed as:

An additional condition is F _c >0, as it requires the contacts to remain in the closed position event during a short circuit event (grounded or disconnected).

Figure 12 is an embodiment in which the loop formed by conductors 61, 62 is restricted by a mechanism box. When a short circuit current occurs, the current in the loop gives the contacts an additional attractive force F _ca . In this type of arrangement, only a very small closing contact spring force is required from the actuation mechanism M for satisfactory grounding action during full short circuit current.

In one variant, a vacuum switch according to the invention can be used alone, or two or more of such vacuum switches can be used in series. Two or more switches in series are used because the total gap (distance to the closed/open position of the pole contact) of such a series vacuum switch is the sum of the gaps of each vacuum switch in the series. This allows for greater safety during operation. Thus, the gap between the contacts connected to each end of the circuit can be increased without having to build a large and expensive vacuum switch.

Generally speaking, the present invention provides a vacuum switch that includes an insulating case made from a suitable insulating material and closed at its ends by two conductive caps to form a sealed vacuum chamber. Inside the sealed vacuum chamber, the vacuum switch has first and second movable relative to each other between a first open position in which the contacts are not in contact and a second closed position in which the contacts are in contact. Including contacts. The vacuum switch and in particular the first and second contacts are designed to remain in the closed position and pass through the vacuum switch in the event of high short circuit currents in the electrical circuit. In particular, the vacuum switch and contacts tend to develop between the first and second contacts during high short circuit currents in the electrical circuit and move the contacts away from each other through the vacuum switch while in the closed position. Some electromagnetic repulsion is designed to be minimized or reduced.

Preferably, these electromagnetic repulsive forces are reduced by adapting the geometry of the first and second contacts to create an electromagnetic attractive force that opposes the repulsive forces, tending to push the contacts together into the closed position. be done.

The resulting vacuum switch can be used as a grounding switch or as a disconnector and is an expensive switch that must withstand opening or closing under load, similar to vacuum switches required to interrupt current in an electrical circuit. Since no materials are required, it is highly reliable, compact, durable and cost effective. Further, the vacuum switch according to the invention can be used particularly in railroad applications as an air or liquid insulated grounding or disconnecting switch in the main electrical circuit, the insulating case of the vacuum switch according to the invention being suitable for use in harsh environments found on top of railcars. provide the best protection against harsh environmental conditions and provide the durability of the grounding switch.

Claims (13)

an insulating case (3, 4) made from a suitable insulating material;
two conductive caps (51, 52) each rigidly fixed to a hole in said insulating case (3, 4) to form a sealed vacuum chamber (2);
a first contact (101) and a second contact (102) inside said sealed vacuum chamber (2) in an open position in which said first and second contacts (101, 102) are not in contact; a first contact (101) and a second contact (102) movable relative to each other between a closed position in which said first and second contacts (101, 102) are in contact;
A vacuum switch (1) comprising
The first and second contacts (101, 102) are designed to remain in the closed position in the event of a short circuit current passing through the first and second contacts (101, 102) when in the closed position. ,
Said first contact (101) comprises a flat contact surface (105) with a hole (107) and presents a trumpet-shaped cavity (103) at its free end, said hole (107) opening into said cavity (103). ), said second contact (102) being in contact with the neck (104), flange (106) and contact surface (105) of said first contact (101) in said closed position. A vacuum switch (1), characterized in that it exhibits a corresponding trumpet-shaped free end with a designed flat contact surface (108 ). an insulating case (3, 4) made from a suitable insulating material;
two conductive caps (51, 52) each rigidly fixed to a hole in said insulating case (3, 4) to form a sealed vacuum chamber (2);
a first contact (101) and a second contact (102) inside said sealed vacuum chamber (2) in an open position in which said first and second contacts (101, 102) are not in contact; a first contact (101) and a second contact (102) movable relative to each other between a closed position in which said first and second contacts (101, 102) are in contact;
A vacuum switch (1) comprising
The first and second contacts (101, 102) are designed to remain in the closed position in the event of a short circuit current passing through the first and second contacts (101, 102) when in the closed position. ,
Said first contact (101) has a recess (113) at its free end and below said recess (113) with a hole (107) linking the cavity (103) to said recess (113). and the cavity (103) of
The inner wall of said recess (113) is the contact surface (105) of said first contact (101) and said second contact (102) is said contact surface (105) of said free end of said first contact (101). having an arrow-shaped free end with a neck (104) terminated by an inverted cone (114) designed to be inserted into the recess (113);
The outer wall of said inverted cone (114) is a contact surface of said second contact (102) designed to contact said contact surface (105) of said first contact (101) in said closed position. A vacuum switch (1) characterized in that (108). Said first and second contacts (101, 102) are generated between said contacts (101, 102) upon a short circuit current passing through said contacts (101, 102) while in said closed position, said Claim 1 or claim 2 , characterized in that it is designed so that the electromagnetic repulsion forces ( _Fb ) tending to move the contacts (101, 102) away from each other are minimized or cancelled. A vacuum switch (1) according to claim 1. Said first and second contacts (101, 102) have an electromagnetic attraction force (F _a ) is generated, said electromagnetic attraction force (F _a ) tending to keep said contacts (101, 102) in said closed position . A vacuum switch (1) according to any one of the preceding claims. Claim characterized in that there is an elastic element (109, 111) inside said cavity (103) to prevent said cavity from collapsing upon closure of said contacts (101, 102). Vacuum switch (1) according to any one of claims 1 to 4 . Vacuum switch (1) according to any one of the preceding claims , characterized in that there is a support element (110) around the neck (104) of the second contact (102). that the contact surfaces between said contacts (101, 102) in the closed position are limited by rims (105', 108') present at each free end of said first and second contacts (101, 102); A vacuum switch (1) according to any one of claims 1 to 6 , characterized in that: Vacuum switch (1) according to any one of the preceding claims , characterized in that the insulating case (3, 4) is made of ceramic, glass-ceramic or glass. Vacuum switch (1) according to any one of the preceding claims , characterized in that said insulating casing (3, 4) is transparent. 10. The method according to any one of claims 1 to 9 , characterized in that both or one of said first and second contacts (101, 102) are made from copper, iron or any other ferromagnetic material. vacuum switch (1). Further comprising a main shield (20) positioned inside said sealed vacuum chamber (2) around said first and second contacts (101, 102), said main shield (20) 11. A vacuum switch (1) according to any one of the preceding claims , characterized in that it is designed as a semi-transparent mesh so that the positions of the and second contacts (101, 102) are visible. 12. Use of a vacuum switch (1) according to any one of claims 1 to 11 as an air or liquid insulated earthing switch or as a disconnecting switch for railway applications. An electrical circuit comprising a vacuum switch (1) according to any one of claims 1 to 11, wherein said second contact (102) comprises at least two conductors (61, 62) arranged in a loop. ) and the length of said conductors (61, 62) and the distance between said conductors (61, 62), in the closed position of the contacts (101, 102) of said vacuum switch (1), are: a secondary attractive force (F _ca ) is generated by the current flowing through said vacuum switch (1) and said conductors (61, 62) tending to push said conductors (61, 62) away from each other; An electrical circuit, characterized in that it is arranged so that it tends to maintain said first and second contacts (101, 102) in the closed position during short-circuit currents in said electrical circuit.

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