Controlling the temperature of a vacuum interrupter

Abstract

The invention relates to a device (3) for controlling the temperature of a vacuum interrupter (1), comprising a housing (5) and two switch contact elements (7, 8) which are movable relative to each other and which are arranged in the housing (5) and are surrounded by a metal housing central region (9) of the housing (5). According to the method, a first alternating voltage (U1) with a first frequency (f1) is applied to a first switch contact element (7), a second alternating voltage (U2) with a second frequency (f2) is applied to the second switch contact element (8), and a third alternating voltage (Uk) with a third frequency (fk) is applied to the housing central region (9), wherein at least two frequencies (f1, f2, fk) differ from each other.

Description

[0001] Description

[0002] Conditioning a vacuum interrupter

[0003] The invention relates to a method and a device for conditioning a vacuum interrupter.

[0004] A vacuum interrupter comprises a housing and two switching contact elements which are movable relative to one another and are arranged in the housing and surrounded by a metallic central region of the housing. Conditioning a vacuum interrupter, which is also referred to as forming the vacuum interrupter, is a work step to generate sufficient dielectric strength of the vacuum interrupter after the vacuum interrupter has been manufactured. During conditioning, unevenness and inhomogeneities, for example micro-peaks and micro-particles, on electrically conductive surfaces of the vacuum interrupter are removed and the surfaces are homogenized. The steps carried out in this process usually comprise conditioning the surfaces of the switching contact elements (so-called contact path conditioning) and conditioning surfaces of the housing, in particular the central region of the housing (so-called chamber conditioning).In addition, shield sections of the vacuum interrupter can also be conditioned individually or simultaneously.

[0005] When conditioning a vacuum interrupter, the dielectrically loaded areas of the vacuum interrupter are typically subjected to an alternating voltage. The alternating voltage (and thus also the conditioning energy) is typically provided via a transformer, and the conditioning of the switching contact elements or the housing of the vacuum interrupter is achieved by different contacts on the high-voltage side and the ground side of the vacuum interrupter.

[0006] Experience has shown that the type of conditioning has a significant influence on the dielectric properties in the application. If a vacuum interrupter is used in an environment with enveloping earthing (so-called dead tank design, particularly in gas-insulated switchgear), a potential shift in the chamber potential of the vacuum interrupter occurs. Since the earth side is fundamentally not defined in the application, one-sided asymmetrical chamber conditioning cannot provide a remedy. Asymmetrical conditioning on both sides would therefore be desirable. Simultaneous symmetrical chamber conditioning with very high voltages can be damaging.

[0007] During conditioning, a control program, based on various program specifications and stored algorithms, modifies the stroke (spacing) of the switching contact elements and the frequency and voltage amplitude of the alternating current used for conditioning. Continuous control of these three parameters should be aimed for in order to capture as many field situations as possible. Currently, contact path conditioning and chamber conditioning are performed in separate conditioning steps.

[0008] The invention is based on the object of providing an improved method and an improved device for conditioning a vacuum interrupter.

[0009] The object is achieved according to the invention by a method having the features of claim 1 and a device having the features of claim 11.

[0010] Advantageous embodiments of the invention are the subject of the dependent claims. In the method according to the invention, a vacuum interrupter having a housing and two switching contact elements which are movable relative to one another and which are arranged in the housing and surrounded by a metallic central region of the housing is conditioned, wherein

[0011] - a first alternating voltage with a first frequency is applied to a first switching contact element,

[0012] - a second alternating voltage with a second frequency is applied to the second switching contact element and

[0013] - a third alternating voltage with a third frequency is applied to the middle area of ​​the housing,

[0014] - where at least two frequencies differ from one another. The alternating voltages are, for example, temporally varying sinusoidal voltages. For alternating voltages of the same frequency, a phase shift of these alternating voltages relative to one another can be adjusted.

[0015] The method according to the invention therefore provides for alternating voltages to be applied simultaneously to the switching contact elements and to the middle region of the housing of a vacuum interrupter, at least two of these alternating voltages having different frequencies. Due to the different frequencies, a conditioning voltage is then applied between the switching contact elements and / or between at least one switching contact element and the middle region of the housing, the temporal characteristic of which is a beat, i.e. an alternating voltage with a periodically fluctuating amplitude. Due to the fluctuating amplitude, different voltage values ​​are covered by this conditioning voltage when conditioning the vacuum interrupter, without the alternating voltages applied to the switching contact elements and the middle region of the housing having to be changed. This enables, in particular, the contact path conditioning and the chamber conditioning to be carried out simultaneously.Furthermore, conditioning can be made significantly more flexible by selecting the individual parameters of the three power supplies. In particular, potential control of the vacuum interrupter housing can be mapped during conditioning, corresponding to the application in a switching device, with a particular focus on the prevailing field conditions in the switching device. Furthermore, symmetrical and asymmetrical chamber conditioning can be performed. Finally, the invention enables the use of transformers with lower nominal voltages or lower dielectric strength.The arrangement or connection of the transformers on both sides of the vacuum interrupter enables a simpler dielectric design of the supply for the conditioning voltages to the vacuum interrupter, since the conditioning voltages result from the superposition of the alternating voltages applied to the switching contact elements and the middle area of ​​the housing and corresponding voltage supplies only have to be designed for these alternating voltages, but not for the conditioning voltages themselves.

[0016] In one embodiment of the invention, the first frequency coincides with the second frequency and is different from the third frequency. This embodiment is particularly suitable for chamber conditioning, since it results in beats of the conditioning voltages between the central region of the housing and the two switching contact elements.

[0017] In a further embodiment of the invention, the first frequency matches the third frequency and is different from the second frequency. This results in beats in the conditioning voltage between the switching contact elements and the conditioning voltage between the middle region of the housing and the second switching contact element. This embodiment is therefore particularly suitable for simultaneous contact path conditioning and chamber conditioning. In a further embodiment of the invention, the three frequencies differ from one another in pairs. This results in beats in the conditioning voltage between the switching contact elements and the conditioning voltages between the middle region of the housing and both switching contact elements. This embodiment of the invention is therefore also particularly suitable for simultaneous contact path conditioning and chamber conditioning.

[0018] In a further embodiment of the invention, at least two of the three alternating voltages have different amplitudes. In particular, all three alternating voltages can have different amplitudes. This allows for particularly flexible conditioning, especially when the amplitudes are varied.

[0019] In a further embodiment of the invention, the ratio of the first frequency to the second frequency is in the range from 0.8 to 1.2.

[0020] In a further embodiment of the invention, the ratio of the maximum of the first frequency and the second frequency to the third frequency is greater than 0.5 and / or the ratio of the minimum of the first frequency and the second frequency to the third frequency is less than 2.

[0021] In a further embodiment of the invention, a fourth alternating voltage with a fourth frequency different from the first frequency is applied to the first switching contact element in series with the first alternating voltage and / or a fifth alternating voltage with a fifth frequency different from the second frequency is applied to the second switching contact element in series with the second alternating voltage and / or a sixth alternating voltage with a sixth frequency different from the third frequency is applied to the housing center region in series with the third alternating voltage. For example, the ratio of the fourth frequency to the first frequency is at most 0.5 and / or the ratio of the fifth frequency to the second frequency is at most 0.5 and / or the ratio of the sixth frequency to the third frequency is at most 0.5.

[0022] The aforementioned embodiment of the invention thus provides up to six alternating voltages for conditioning a vacuum interrupter, with two alternating voltages being electrically applied in series to a switching contact element and / or to the housing's central region. By varying the amplitudes, frequencies, and / or phases of these alternating voltages, this embodiment of the invention offers even greater possibilities and freedom for designing the contact gap conditioning and chamber conditioning. The frequencies of the alternating voltages can be set, for example, in the range from 30 Hz to 70 Hz.

[0023] A device according to the invention for conditioning a vacuum interrupter with a housing and two switching contact elements which are movable relative to one another and which are arranged in the housing and surrounded by a metallic housing central region of the housing, comprises

[0024] - a first voltage supply which is arranged to apply a first alternating voltage with a first frequency to a first switching contact element,

[0025] - a second voltage supply which is arranged to apply a second alternating voltage with a second frequency to the second switching contact element, and

[0026] - a third voltage supply which is arranged to apply a third alternating voltage with a third frequency to the middle region of the housing,

[0027] - wherein at least two frequencies differ from one another or the frequency of at least one voltage supply can be set to different values. In one embodiment of the device according to the invention, the amplitudes of at least two alternating voltages differ from one another or the amplitude of at least one alternating voltage can be set to different values.

[0028] A further embodiment of the device according to the invention comprises

[0029] - a fourth voltage supply which is arranged to apply a fourth alternating voltage having a fourth frequency different from the first frequency to the first switching contact element in series with the first alternating voltage, and / or

[0030] - a fifth voltage supply which is arranged to apply a fifth alternating voltage with a fifth frequency different from the second frequency to the second switching contact element in series with the second alternating voltage, and / or

[0031] - a sixth voltage supply which is arranged to apply a sixth alternating voltage having a sixth frequency different from the third frequency to the middle region of the housing in series with the third alternating voltage.

[0032] A device according to the invention enables the implementation of the method according to the invention. Therefore, the advantages of the device correspond to the above-mentioned advantages of the method according to the invention.

[0033] The above-described properties, features, and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more readily understood in connection with the following description of exemplary embodiments, which are explained in more detail in conjunction with the drawings.

[0034] FIG. 1 shows a vacuum interrupter and a first exemplary embodiment of a device for conditioning the vacuum interrupter, FIG. 2 shows a time profile of a conditioning voltage between two switching contact elements of a vacuum interrupter according to a first exemplary embodiment of the method according to the invention,

[0035] FIG 3 shows time profiles of conditioning voltages between a housing center region and two switching contact elements of a vacuum interrupter according to the first embodiment of the method according to the invention,

[0036] FIG 4 shows a time profile of a conditioning voltage between two switching contact elements of a vacuum interrupter according to a second embodiment of the method according to the invention,

[0037] FIG 5 shows time profiles of conditioning voltages between a housing center region and two switching contact elements of a vacuum interrupter according to the second embodiment of the method according to the invention,

[0038] FIG 6 a vacuum interrupter and a second embodiment of a device for conditioning the vacuum interrupter.

[0039] Corresponding parts in the figures are provided with the same reference symbols.

[0040] Figure 1 (FIG. 1) shows a vacuum interrupter 1 and a first exemplary embodiment of a device 3 for conditioning the vacuum interrupter 1. The vacuum interrupter 1 comprises a housing 5 and two switching contact elements 7, 8 which are movable relative to one another and are arranged in the housing 5. The housing 5 has a metallic housing central region 9, two opposing metallic end regions 11, 12 and two insulator regions 13, 14 made of an electrically insulating material, for example a ceramic material. Each insulator region 13, 14 connects an end region 11, 12 to the housing central region 9. A first switching contact element 7 is arranged on a first electrically conductive contact pin 15 which is fixedly connected to a first end region 11.The second switching contact element 8 is arranged on a second electrically conductive contact pin 16, which is guided through an opening 20 in the second end region 12 and is axially displaceable relative to the housing 5, that is to say along its longitudinal axis. The position of the first switching contact element 8 in the housing 5 is thus fixed, while the second switching contact element 9 is movable relative to the housing 5 and the first switching contact element 7 by axially displacing the second contact pin 16. Two shielding elements 17, 18 are arranged in the housing 5. A first shielding element 17 surrounds a section of the first contact pin 15 in a ring shape, starting from the housing center region 9. The second shielding element 18 surrounds a section of the second contact pin 16 in a ring shape, starting from the housing center region 9.Furthermore, a bellows 19 is arranged in the housing 5, which is firmly connected at one end to the second end region 12 of the housing 5 and at a second end to the second contact pin 16. The bellows 19 seals the interior of the housing 5 against a gas that, without the bellows 19, could enter the interior of the housing 5 through the opening 20 in the second end region 12.

[0041] The housing 5 with the exception of the first end region 11, the shielding elements 17, 18 and the bellows 19 are shown in Figure 1 in a sectional view.

[0042] The device 3 for conditioning the vacuum interrupter 1 comprises three voltage supplies 31, 32, 33. A first voltage supply 31 is set up to apply a first alternating voltage Ul with a first frequency fl to the first switching contact element 7. For this purpose, the first end region 11 of the housing 5 is connected to the first voltage supply 31. The first switching contact element 7 is electrically connected to the first end region 11 via the first contact pin 15. A second voltage supply 32 is set up to apply a second alternating voltage U2 with a second frequency f2 to the second switching contact element 8. For this purpose, the second contact pin 16 is connected to the second voltage supply 32. The third voltage supply 33 is set up to apply a third alternating voltage Uk with a third frequency fk to the housing middle region 9.At least two frequencies fl , f2 , fk differ from one another or the frequency fl , f2 , fk of at least one voltage supply 31 , 32 , 33 can be set to different values.

[0043] A conditioning voltage Us=Ul-U2 is thus applied between the switching contact elements 7, 8. A conditioning voltage Uu=Ul-Uk is applied between the first switching contact element 7 and the housing center region 9. A conditioning voltage Uo=Uk-U2 is applied between the housing center region 9 and the second switching contact element 8. The conditioning voltage Us is primarily used for contact path conditioning, while the conditioning voltages Uo and Uu are primarily used for chamber conditioning.

[0044] Figure 2 (FIG 2) and Figure 3 (FIG 3) show the conditioning voltages Us, Uo and Uu as a function of time t according to a first embodiment of the method according to the invention. In this embodiment, the frequencies fl, f2 and the amplitudes of the alternating voltages Ul and U2 match, but the alternating voltage U2 is 180° out of phase with the alternating voltage Ul. The frequency fk of the alternating voltage Uk is slightly lower than the frequencies fl, f2 of the alternating voltages Ul and U2. For example, the frequencies fl and f2 are each 50 Hz and the frequency fk is 49 Hz. The amplitude of the alternating voltage Uk can also differ from the amplitudes of the alternating voltages Ul and U2 and can, for example, be only 40 percent of the amplitudes of the alternating voltages Ul and U2.As a result, the time courses of the conditioning voltages Uo and Uu are beats that have the same beat periods but are 180 ° out of phase with each other.

[0045] Figure 4 (FIG 4) and Figure 5 (FIG 5) show the conditioning voltages Us, Uo and Uu as a function of time t according to a second exemplary embodiment of the method according to the invention. In this exemplary embodiment, the frequencies fl, f2, fk of all three alternating voltages Ul, U2 and Uk differ slightly from one another, where fk is the mean value of fl and f2. For example, the frequencies are selected or set according to fl=49 Hz, f2=51 Hz and fk=50 Hz. The amplitudes of the alternating voltages Ul and U2 match; the amplitude of the alternating voltage Uk is smaller than the amplitudes of the alternating voltages Ul and U2 and is, for example, 40 percent of the amplitudes of the alternating voltages Ul and U2. The alternating voltage U2 is phase-shifted by 180° with respect to the alternating voltage Ul and by 90° with respect to the alternating voltage Uk.As a result, the time courses of the conditioning voltages Us , Uo and Uu are beats, where the beat periods of the conditioning voltages Uo and Uu are the same and are twice as long as the beat period T of the conditioning voltage Us , tl and t2 denote times at which the amplitude of the conditioning voltage Us is zero .

[0046] Figure 6 (Fig. 6) shows a vacuum interrupter 1 and a second exemplary embodiment of a device 3 for conditioning the vacuum interrupter 1. The vacuum interrupter 1 is designed like the vacuum interrupter 1 shown in Figure 1. The device 3 for conditioning the vacuum interrupter 1 differs from the device 3 shown in Figure 1 in that, in addition to the voltage supplies 31, 32, 33, it has a fourth voltage supply 34, a fifth voltage supply 35 and a sixth voltage supply 36. The fourth voltage supply 34 is set up to apply a fourth alternating voltage U4 with a fourth frequency f4 different from the first frequency f1 to the first switching contact element 7 in series with the first alternating voltage U1.The fifth voltage supply 35 is configured to apply a fifth alternating voltage U5 having a fifth frequency f5 different from the second frequency f2 to the second switching contact element 8 in series with the second alternating voltage U2. The sixth voltage supply 36 is configured to apply a sixth alternating voltage U6 having a sixth frequency f6 different from the third frequency fk to the housing center region 9 in series with the third alternating voltage Uk.

[0047] Although the invention has been illustrated and described in detail by means of preferred embodiments, the invention is not limited by the disclosed examples and other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention.

[0048] Regardless of the grammatical gender of a particular term, persons with male, female or other gender identity are included.

[0049] List of reference symbols

[0050] 1 vacuum switch tube

[0051] 3 Device for conditioning a

[0052] Vacuum circuit tube

[0053] 5 housings

[0054] 7, 8 Switching contact element

[0055] 9 Middle housing area

[0056] 11, 12 End area

[0057] 13, 14 Insulator area

[0058] 15, 16 contact bolts

[0059] 17, 18 Screen element

[0060] 19 Bellows

[0061] 20 Opening

[0062] 31 to 36 Voltage Supply fl, f2, fk, f4, f5, f6 Frequency t Time tl, t2 Time

[0063] T beat period

[0064] Ul, U2, Uk, U4, U5, U6 Alternating voltage Us, Uo, Uu, Us ' condition! voltage

Claims

Patent claims 1. Method for conditioning a vacuum interrupter (1) with a housing (5) and two switching contact elements (7, 8) which are movable relative to one another and which are arranged in the housing (5) and are surrounded by a metallic Housing middle area (9) of the housing (5), wherein - to a first switching contact element (7) a first alternating voltage (Ul) with a first frequency (fl) is applied, - a second alternating voltage (U2) with a second frequency (f2) is applied to the second switching contact element (8) and - a third alternating voltage (Uk) with a third frequency (fk) is applied to the middle region of the housing (9), - where at least two frequencies (fl, f2, fk) differ from each other.

2. The method according to claim 1, wherein the first frequency (fl) is the same as the second frequency (f2) and is different from the third frequency (fk).

3. The method according to claim 1, wherein the first frequency (fl) coincides with the third frequency (fk) and is different from the second frequency (f2).

4. The method according to claim 1, wherein the three frequencies (fl, f2, fk) are pairwise different from each other.

5. Method according to one of the preceding claims, wherein at least two of the three alternating voltages (Ul, U2, Uk) have different amplitudes from one another.

6. Method according to one of claims 1 to 4, wherein all three alternating voltages (Ul, U2, Uk) have different amplitudes from one another.

7. Method according to one of the preceding claims, wherein the ratio of the first frequency (f1) to the second frequency (f2) is in the range from 0.8 to 1.

2.

8. Method according to one of the preceding claims, wherein the ratio of the maximum of the first frequency (fl) and the second frequency (f2) to the third frequency (fk) is greater than 0.5 and / or the ratio of the minimum of the first frequency (fl) and the second frequency (f2) to the third frequency (fk) is less than 2.

9. Method according to one of the preceding claims, wherein - a fourth alternating voltage (U4) with a fourth frequency (f4) different from the first frequency (f1) is applied to the first switching contact element (7) in series with the first alternating voltage (Ul) and / or - a fifth alternating voltage (U5) with a fifth frequency (f5) different from the second frequency (f2) is applied to the second switching contact element (8) in series with the second alternating voltage (U2) and / or - a sixth alternating voltage (U6) with a sixth frequency (f6) different from the third frequency (fk) is applied to the housing middle region (9) in series with the third alternating voltage (Uk).

10. The method according to claim 9, wherein - the ratio of the fourth frequency (f4) to the first frequency (fl) is at most 0.5 and / or - the ratio of the fifth frequency (f5) to the second frequency (f2) is at most 0.5 and / or - the ratio of the sixth frequency (f6) to the third frequency (fk) is at most 0.

5.

11. Device (3) for conditioning a vacuum interrupter (1) with a housing (5) and two switching contact elements (7, 8) which are movable relative to one another and which are arranged in the housing (5) and surrounded by a metallic housing central region (9) of the housing (5), the Device comprising - a first voltage supply (31) which is arranged to apply a first alternating voltage (Ul) with a first frequency (fl) to a first switching contact element (7), - a second voltage supply (32) which is arranged to apply a second alternating voltage (U2) with a second frequency (f2) to the second switching contact element (8), and - a third voltage supply (33) which is arranged to apply a third alternating voltage (Uk) with a third frequency (fk) to the housing central region (9), - wherein at least two frequencies (fl, f2, fk) differ from one another or the frequency (fl, f2, fk) of at least one voltage supply (31, 32, 33) can be set to different values.

12. Device (3) according to claim 11, wherein the amplitudes of at least two alternating voltages (Ul, U2, Uk) differ from one another or the amplitude of at least one alternating voltage (Ul, U2, Uk) can be set to different values.

13. Device (3) according to claim 11 or 12 with - a fourth voltage supply (34) which is arranged to apply a fourth alternating voltage (U4) with a fourth frequency (f4) different from the first frequency (f1) to the first switching contact element (7) in series with the first alternating voltage (U1), and / or - a fifth voltage supply (35) which is arranged to apply a fifth alternating voltage (U5) with a fifth frequency (f5) different from the second frequency (f2) to the second switching contact element (8) in series with the second alternating voltage (U2), and / or - a sixth voltage supply (36) which is arranged to supply to the housing middle region (9) in series with the third alternating voltage (Uk) a sixth alternating voltage (U6) with a sixth frequency (f6) different from the third frequency (fk).

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