EP0920705B2 - Load interrupter switch - Google Patents

Abstract

The invention concerns a load interrupter switch (1) for voltages in the kV range, with a vacuum interrupter chamber (2) which is surrounded in a gap-free manner by a sleeve (4) formed from elastomer material having high dielectric strength. The sleeve (4) is in turn clamped by the two halves (11 and 12) of the housing of the load interrupter switch (1). In this way, external flashover of the high voltage between the end plates (24 and 25) of the vacuum interrupter chamber (2) is effectively prevented during switching operations without the need for liquid or gaseous media. In this way, in contrast to conventional load interrupter switches, complicated monitoring is unnecessary and the load interrupter switch is not harmful to the environment.

Description

The invention relates to a load switch according to the preamble of claim 1.

Such load switches - see for example DE-U-93 14 754- are e.g. as switch disconnector in Railway operation known. The vacuum interrupter is located here in the on position with that in an insulating housing housed switching mechanism electrical in the bypass to that for the full nominal device current designed main current path. When switching off first open the main contacts without power and commutate the current to the shunt horizontal series connection of vacuum interrupter and auxiliary switching point, which has an operating fork. Once the main contacts are far enough apart have removed the vacuum interrupter quickly operated via a tilt mechanism and the in Switch-off arc occurring inside the interrupter in the first current zero crossing without any external appearance safely deleted.

In practice, however, it has been shown that the used vacuum interrupters or chambers relatively have large dimensions and high ones Manufacturing costs are connected. Therefore, since some time vacuum interrupters of a lower one Voltage series than that for which the switch was designed is used. This allows both the dimensions as well as reducing manufacturing costs the active part in the vacuum interrupter such use is usually allowed.

Decreased with the reduction in size but also the distance between the metal end plates the housing of the vacuum interrupter. Therefore is the external insulation, which occurs during and after the shutdown is claimed in the open air in the area but not enough.

To solve this problem, the vacuum interrupters are placed in a medium with higher dielectric strength. Among other things, insulating oil, e.g. B. mineral or silicone oil, various esters or an insulating gas such as sulfur hexafluoride (SF ₆ ) for use. These media displace the air in the vicinity of the vacuum interrupters and because they have a high dielectric strength, an external flashover is prevented.

However, these media have the disadvantage that they are not harmless with regard to their environmental compatibility are. Because such load switches over many Years in use can cause leaks due to aging of components and due to external Influences cannot be completely excluded. On The medium may therefore escape into the environment. possible.

Another disadvantage of such media is that they require ongoing control. When using of insulating oil e.g. the oil level can be checked and because such load switches in most applications are installed on high masts, here is a corresponding one Effort required. The same applies in the case of Insulating gas with which the pressure must be checked.

Furthermore, it is also known the external insulation of the vacuum interrupters by encapsulation e.g. Improve epoxy resin. However, it can through aging processes to an air gap and thus to an external rollover of the vacuum interrupter in the area between the epoxy resin shell and the outer housing come. Such aging processes cause z. B. Stress cracks due to post-contraction of the cast resin jacket, embrittlement through ineffective flexibilizers, which in the Pouring was used or gap formation Detachment of the resin jacket from the outer housing of the vacuum interrupter due to different material expansion with frequent hot-cold alternating loads. This danger can therefore not be completely eliminated become. Another disadvantage is that a such a molded vacuum interrupter at one Disassembly only accessible if the casing is destroyed is.

The previously known embodiments are therefore complex, for universal use, e.g. on Transmission tower, only conditionally useful or become often because of a possible danger to the environment declined.

Document FR-2 698 481 A1 discloses one Load switch with a vacuum interrupter, where between the housing of the vacuum interrupter and an outer housing an electrically insulating Body made of silicone. This silicone body is tubular and faces either the outside or on the inside, elastically deformable ribs on. It is made in such a way that it is intimate at the same time Contact with the outer surface of the interrupter housing and inner surface of the outer housing. Thereby should be a gap-free to avoid electrical Rollover can be achieved. In addition can during assembly in the area between the interrupter housing and the inside of the silicone body An insulating grease can be introduced while the ribs on the outside to create a seal be compressed at least to a small extent.

The German utility model G 93 14 754 UI discloses a vacuum interrupter with one against internal pressure durable encapsulation. Encapsulating this Vacuum interrupter consists of an inner one Layer of hard plastic foam and one outer burstproof coat. The preferably from a polyurethane foam inner Layer is evenly porous in order according to the teaching of this The best possible thermal insulation to enable, so in the event of a fault, no ignition sufficient temperature of the surrounding gas can be achieved. The burstproof coat is as Formed winding body and consists of threads or Tapes impregnated with a hardened plastic are. It is close to the foam layer trained and dimensioned so that he bursting force can accommodate that within an error the vacuum interrupter occurs.

The casing of the tube also contains this state of the art a foam Plastic material, which due to aging in its properties can be affected. In particular can embrittlement or detachment of the Foam layer appear from the outer casing of the tube. There is also a disassembly of this encapsulated Vacuum interrupter only if the Wrapping possible.

The invention is therefore based on the object to create a load switch that is out of control Safe to use for a long time and also removable is.

This object is achieved according to the invention solved the features of claim 1.

The main advantage here is that due to the elastic properties of the cuff no gap remains on the periphery of the housing. An external rollover on the vacuum interrupter It is therefore not possible to have such an air gap.

It is also advantageous that the edges of the two End plates of the vacuum interrupter from the Be cuffed behind and thereby the Path essential for a possible rollover extended. This makes this case even more reliable prevented.

Because the use of the cuff an insert of liquid or gaseous media makes, the load switch according to the invention has numerous further advantages.

This eliminates the costly control activities to check the liquid level or the Pressure state. The load switch can therefore have many Years in continuous operation without the sleeve acting as a dielectric medium must be checked.

It also affects the Environment avoided by escaping media, which the load switch according to the invention e.g. also in water protection areas be used without hesitation can. This makes a permanent load switch provided that is universally applicable.

Another advantage is that the Assembly of the circuit breaker according to the invention essential simplified. This is how training with a pre-assembled cuff a pre-assembly of the Arrangement, which is why no effort for a final assembly or a filling e.g. necessary high up on the mast is. Because with no liquid or gaseous medium is handled, the effort for the Transport and installation of the invention Load switch essential.

The circuit breaker according to the invention is here easy to manufacture and allows disassembly if necessary. In addition, the space requirements and costs kept low for the vacuum interrupter become.

It is also advantageous if on the outside the cuff a complementary Pressure housing made of insulating material is provided, which the outer circumference of the cuff in the elastic range biases. On the one hand, this ensures that the cuff is firmly attached to the vacuum interrupter presses and further that also on the outer circumference of the No air gap is created in the cuff, causing an external rollover could enable. The possible route for an external rollover, this means a Dimension enlarged, in which this practically no longer is possible. Operational safety and reliability the load switch is thereby further increased. Further the vacuum interrupter in the pressure housing centered and fixed.

Advantageous developments of the invention result derive from the features of the subclaims.

Because the dimensions of the cuff are chosen so that the cuff has a preload on the vacuum interrupter, is reliably prevented that an air gap between the sleeve and the housing of the vacuum interrupter results. So that can also be relative large dimensional tolerances of the vacuum interrupter be balanced. This increases reliability of the circuit breaker.

If the cuff at least one in Axial direction of the pressure housing sealing bead has in the assembly joint of the pressure housing comes to rest, also becomes a seal of the pressure housing against external influences. This reliably prevents e.g. Dirt and especially water in the pressure housing can penetrate. Failure of the circuit breaker can so effectively avoided. Furthermore, the one-piece design of the sleeve with the sealing bead the assembly of the arrangement.

If the sealing bead also has a thickening on, which can be squeezed in the assembly joint of the pressure housing the reliability of this increases Sealing on the pressure housing continues.

The fact that on the outer circumference of the cuff projecting essentially parallel to the stimulus plates and circumferential screens are arranged, the risk of a rollover is even greater reduced.

It is a further advantage if the cuff at least one recess for receiving material of the cuff displaced under pressure having. It is achieved that the cuff clean on the peripheral surface of the vacuum interrupter creates without damaging the Cuff occurs due to the applied compressive forces. The reliability of the circuit breaker increases thereby further.

The at least one recess is advantageously as a circumferential ring groove in the inner periphery the cuff. This will make one even pressure distribution over the entire circumference of the vacuum interrupter.

If the cuff is on at least one End face in the area of at least one end plate at least one pocket is provided in the assembled State an adjustment of the length of the vacuum interrupter possible without the material of the cuff is damaged since it is in at least one pocket can dodge. The reliability of the cuff and thus the operational safety of the circuit breaker thus increased.

The at least one pocket is also ring-shaped is formed, an even distribution of Pressure load on the front of the cuff reached.

The cuff according to the invention is preferred made of EPDM (ethylene-propylene terpolymer) or Made of silicone rubber, which has good elastic properties have and not compressible are. Such materials allow a secure seal the interface between the vacuum interrupter and the cuff or between the cuff and the pressure housing of the circuit breaker. On Outside rollover can be avoided safely.

The fact that the load switch as a load break switch is formed in the series connection to Vacuum interrupter a visible isolating distance is arranged, can also from a greater distance visual inspection can be done to determine whether the load switch is closed.

If parallel to the vacuum interrupter or parallel to the series connection vacuum interrupter / visible Isolation section when switched on the circuit breaker has a current path for high continuous current carrying capacity is switched on, the vacuum tube relieved when the load switch (switch disconnector) is in the closed state. This has the Advantage that the vacuum interrupter only in the Switching operations with the present high voltages is applied. This can be a continuous current which are higher than the nominal current of the Switching chamber or series connection from a vacuum switching chamber and visible separation distance. The lifespan the load switch increases significantly.

Fig. 1 eine Schnittdarstellung eines erfindungsgemäßen Lastschalters, wobei auf der linken Seite der Hauptachse ein Schnitt in der Trennebene des Druckgehäuses und rechts von der Hauptachse ein Schnitt in einer anderen Ebene durch eine Gehäusehälfte des Druckgehäuses dargestellt ist; und

Fig. 2 eine vereinfachte Schnittdarstellung gemäß der Linie A-A in Fig. 1.

The invention is explained in more detail below in an exemplary embodiment with reference to the figures of the drawing. It shows:

Figure 1 is a sectional view of a circuit breaker according to the invention, wherein on the left side of the main axis, a section in the parting plane of the pressure housing and to the right of the main axis, a section in another plane through a housing half of the pressure housing is shown. and

FIG. 2 shows a simplified sectional illustration along the line AA in FIG. 1.

As shown in the figures a load switch 1 a pressure housing with two housing halves 11 and 12, which are made of insulating material and are essentially mirror images. In the Housing halves 11 and 12 include a vacuum interrupter 2 and a switching mechanism 3 arranged. The arrangement and function of the vacuum interrupter 2 and the switching mechanism 3 corresponds the known versions, which is why on a detailed Explanation on this is dispensed with. Essential is that the vacuum interrupter 2 has switching contacts inside has closed by the switching mechanism 3 or be opened. This is the switching mechanism 3 with an eccentric actuator 31 trained, which on a movable Contact 21 of the vacuum interrupter 2 acts.

The vacuum interrupter 2 has in addition the movable contact 21 a fixed contact 22 on the opposite of the movable contact 21 is arranged. The vacuum interrupter 2 also has a housing 23 which is metallic End plates 24 and 25 is provided which is cylindrical Complete middle section of housing 26. The middle part of the housing 26 is made of electrically insulating material manufactured. Inside the vacuum interrupter 2 there is a high vacuum, which when switched off for a safe arc break and when switched off Condition for safe voltage maintenance provides.

To make sure there is no rollover the tension between the end plates 24 and 25 of the vacuum interrupter 2 occurs is all around Vacuum interrupter 2 a sleeve 4 made of EPDM (Ethylene-propylene terpolmer) arranged. The cuff 4 is designed such that it has the edges of the two end plates 24 and 25 of the vacuum interrupter 2 embraces. Furthermore, the dimensions the cuff 4 chosen so that tolerance deviations the vacuum interrupter 2 balanced can be and the cuff 4 still under Preload on the peripheral surface of the vacuum interrupter 2 is present. As a result, there is no continuous Air gap between the end plates 24 and 25 before.

The cuff 4 is in turn from the housing halves 11 and 12 of the switch 1 and biased. Due to the preload too between the sleeve 4 and the assembled housing halves 11 and 12 no air gap in front of which an external rollover the tension between the end plates 24 and 25 would allow the vacuum interrupter 2.

As shown in Fig. 1, the cuff has 4 ring-shaped screens 41 on the in corresponding recesses in the housing halves 11 and 12 are included. The screens 41 serve in a known manner to extend the route (Creepage distance) along the surface.

The cuff 4 also has four recesses 42 arranged on the inner peripheral surface are and have an annular shape. At the Closing the housing halves 11 and 12 will apply pressure the cuff 4 exercised and since this is made of an elastomeric material is made, which is elastic but in essential is not compressible, allow the Recesses 42 a dodge of the material of the Cuff 4 in the spaces thus formed. On this will damage the cuff 4 prevents and a good seal of the interface between the sleeve 4 and the vacuum interrupter 2 reached.

At the end of the cuff 4, which is the face plate 25 in the area of the fixed contact 22 overlaps, an annular pocket 43 is also formed. Since vacuum interrupters 2 have relatively large length tolerances may be a Length adjustment or positioning of the vacuum interrupter 2 in load switch 1 necessary. To the necessary deformation of the cuff 4 in this The frontal area serves to enable the annular Pocket 43 as a chamber for volume compensation of the displaced material.

As shown in Fig. 2, the cuff has 4 further a sealing bead 44 with a thickening 45 on. These are on the two assembly joints the housing halves 11 and 12 of the circuit breaker 1 for sealing against external influences arranged. The thickening 45 is accordingly trained recesses or grooves on the Joint surfaces of the housing halves 11 and 12 added and when closing the housing halves 11 and 12 crimped. The sealing bead 44 with the thickening 45 has a length which is essentially the total length corresponds to the cuff 4. But he can also in the entire assembly joint area of the housing halves 11 and 12 in one piece with the cuff 4 as Round cord designed to seal the pressure housing his.

When the load switch 1 is opened during operation will be pre-tensioned by springs Contacts 21 and 22 through the switching mechanism 3 released, so that the switch contacts in the Open vacuum interrupter 2. Because of the high applied voltage, which depending on the application z. B. 45 kV, the arrangement tends to Way through for a potential voltage discharge to seek an arc. Inside the vacuum interrupter 3 this is not due to the vacuum possible.

Since the cuff 4 under tension on Housing 23 of the vacuum interrupter 2 abuts and equally under tension with the pressure housing of the load switch 1 is connected, there is no air gap before that allow a flashover would. A rollover through the material of the cuff 4 is due to the high dielectric strength of the material used for the cuff 4 also not possible. Such a rollover is therefore prevented.

In an application example, the load switch used as switch disconnector and in series arranged with a visible separation distance. It is a main current path designed for the continuous operating current parallel to the vacuum interrupter and one connected with this auxiliary switching point in series, whereby the vacuum tube when switched on Switch disconnector is relieved. To switch off the switch disconnector is initially in a known manner the main contact opens, causing the voltage completely passed through the vacuum interrupter 2 becomes. Then the contacts 21 and 22 of the Vacuum interrupter 2 disconnected and the connection is completely interrupted without arcing can train in the load switch 1.

In addition to what is shown here, the invention allows Embodiment further design approaches to.

The dimensions and shape of the cuff 4 can, depending on the construction and type of the vacuum interrupter 2 vary. In any case, it is essential that the cuff 4 so on the vacuum interrupter 2 is present that there is no air gap between them is possible.

The cuff 4 does not have to be 41 be trained, but can also be designed differently or have a smooth outer peripheral surface, if the safety of the load switch 1 e.g. by virtue of of low existing voltages.

The recesses 42 in the cuff 4 have in the example shown semicircular cross sections and are in four places around the vacuum interrupter 2 trained. Both the shape as also the number of annular recesses 42 can deviate from this. It is also possible that Cutouts 42 instead of the shown embodiment with an annular shape to provide the inner peripheral surface of the sleeve 4.

The pocket 43 in the cuff 4 can also be provided on both end faces. Furthermore can also change the shape and number of pocket 43 in vary in a manner similar to the recesses 42.

The cuff 4 can in any way Connection with vacuum interrupters 2 used be what other switching elements than switch disconnectors includes. It is also used in circuit breakers and the like conceivable.

The pressure housing can also consist of more than two housing parts exist, the number of Sealing beads 44 adapted to the number of assembly joints is.

Furthermore, parallel to the vacuum interrupter 2 also a continuous current or main current contact system be provided, which allows the load switch 1 using a specific vacuum interrupter 2 for different nominal or continuous currents interpreted.

The invention thus creates a load switch 1 for voltages in the kV range with a vacuum interrupter 2, which by a made of elastomer material trained with high dielectric strength Cuff 4 is gripped without gaps. The cuff 4 is in turn through the housing halves 11 and 12 of the load switch 1 clamped. That way a high tension outside flashover between the end plates 24 and 25 of the vacuum interrupter 2 effectively prevented during the switching process without liquid or gaseous media are necessary for this. This is in contrast to conventional circuit breakers no high control effort required and the Load switch is harmless to the environment.

Claims (12)

1. Load interrupter switch (1) for voltages above 1 kV, having a vacuum interrupter chamber (2) whose contacts (21, 22) are closed or opened by means of a switching mechanism (3), the vacuum interrupter chamber (2) having a housing (23) with metallic end plates (24, 25) which encloses the switching contacts situated in the vacuum, and a cylindrical housing middle part (26) made from an electrically insulating material, which housing is surrounded by a coating which is made from a dielectric material and grips the edges of the two end plates (24, 25) behind, it being the case that provided on the outside of the dielectric coating is a jacket of complementary construction, which is made from insulating material and pressurizes the outer circumference of the dielectric coating, characterized in that the dielectric coating is formed by a prefabricated sleeve (4) which consists of an elastomeric material of high dielectric strength which is pressed against the housing (23) without a gap by a pressure housing (11, 12) serving as the jacket, wherein said pressure housing (11, 12) consists of at least two part housings which in mounted condition constitude the closed pressure housing (11, 12).
2. Load interrupter switch according to Claim 1, characterized in that the dimensions of the sleeve (4) are selected such that the sleeve (4) bears in a pretensioned fashion against the circumference of the vacuum interrupter chamber (2).
3. Load interrupter switch according to Claim 2, characterized in that the sleeve (4) has at least one sealing bead (44) which runs in the axial direction of the pressure housing (11, 12) and comes to lie in the mounting joint of the pressure housing (11, 12).
4. Load interrupter switch according to Claim 3, characterized in that the sealing bead (44) has a thickened part (45) which can be pinched in the mounting joint of the pressure housing (11,12).
5. Load interrupter switch according to one of Claims 1 to 4, characterized in that circumferential shields (41) are provided which project on the outer circumference of the sleeve (4) in a fashion essentially parallel to the end plates (24, 25) of the vacuum interrupter chamber (2).
6. Load interrupter switch according to one of Claims 1 to 5, characterized in that the sleeve (4) has at least one cut-out (42) for holding material displaced during the pressure loading by the pressure housing (11, 12).
7. Load interrupter switch according to Claim 6, characterized in that the at least one cut-out (42) is constructed as a circumferential annular groove.
8. Load interrupter switch according to one of Claims 1 to 7, characterized in that at least one pocket (43) is constructed on the sleeve (4) in the region of the end plate (25) and/or the end plate (24).
9. Load interrupter switch according to Claim 8, characterized in that the at least one pocket (43) is constructed as an annular groove.
10. Load interrupter switch according to one of Claims 1 to 9, characterized in that the sleeve (4) is constructed from silicone rubber or from EPDM (Ethylene-Propylene-Terpolymer).
11. Load interrupter switch according to one of Claims 1 to 10, characterized in that it is constructed as a switch-disconnector in the case of which a visible isolating distance is arranged in series with the vacuum interrupter chamber.
12. Load interrupter switch according to one of Claims 1 to 11, characterized in that in the closed state of the load interrupter switch a circuit for high continuous current-carrying capacity is connected in parallel with the vacuum interrupter chamber or in parallel with the series circuit of the vacuum interrupter chamber/visible isolating distance.

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