EP3453044A1

EP3453044A1 - Double-contact switch having vacuum switching chambers

Info

Publication number: EP3453044A1
Application number: EP17716245.0A
Authority: EP
Inventors: Gerd Schmitz; Marcel Uedelhoven; Johannes Meissner; Michael Wohlang; Oliver Kreft; Kai Schroeder
Original assignee: Eaton Intelligent Power Ltd
Current assignee: Eaton Intelligent Power Ltd
Priority date: 2016-05-03
Filing date: 2017-04-10
Publication date: 2019-03-13
Anticipated expiration: 2037-04-10
Also published as: DE102016108246A1; WO2017190915A1; EP3453044B1; PL3453044T3

Abstract

The invention relates to a double-contact switch, comprising a first and a second tubular vacuum switching chamber (1, 3), which are designed as partial switching chambers of a switching tube, an electrode (4), which is fastened in the switching tube and arranged between the first and second vacuum switching chambers and which has a first fixed contact protruding into the first vacuum switching chamber (1) and a second fixed contact protruding into the second vacuum switching chamber (3), a first electrode (11), which is arranged in the first vacuum switching chamber (1) and can be moved therein in the axial direction and which has an area bearing a contact (12), which area is sealed off gas-tight from the exterior of the first vacuum switching chamber (1), a second electrode (31), which is arranged in the second vacuum switching chamber (3) and can be moved therein in the axial direction and which has an area bearing a contact (32), which area is sealed off gas-tight from the exterior of the second vacuum switching chamber (3), wherein the gas-tight seal (13') of the area of the first electrode (11) bearing the contact (12) is designed differently from the gas-tight seal (33') of the area of the second electrode (31) bearing the contact (32) in such a way that the opening of the first fixed contact (41) and the contact (12) of the first electrode (11) and the opening of the second fixed contact (42) and the contact (32) of the second electrode (31) occur with a time offset.

Description

Double contact switch with vacuum interrupters

The invention relates to a double-contact switch with vacuum interrupters and a hybrid switching device with such a double-contact switch.

In the German patent application DE 10 2013 1 14 260 A1 discloses a double contact switch is described with vacuum interrupters, in which the mechanical switching component has a double vacuum interrupter chamber with two pairs of contacts arranged in the axial direction, which can be actuated independently.

Furthermore, a hybrid switching device with this double-contact switch is described in DE 10 2013 1 14 260 A1, in which a semiconductor switch, based on an IGBT power semiconductor (Insulated Gate Bipolar Transistor), electrically parallel to one of the two contact pairs of the double contact Switch is arranged. This hybrid switching device is particularly suitable for switching direct currents or low-frequency currents. With the opening of a first contact pair of the double-contact switch, a load current can commutate immediately to the IGBT, where it is led to zero within a few milliseconds. With the second contact pair of the double-contact switch, then, after the load current through the IGBT is zero, the galvanic isolation in the hybrid switching device can be brought about. Ideally, the responsible for the galvanic separation second contact pair (isolating contacts) opens with a certain time delay after opening the first pair of contacts (commutation). This avoids that in the case of simultaneous or premature opening of the isolating contacts, a vacuum arc is briefly formed there, ie for the period in which the load current is still being passed through the IGBT. Especially in the case of high currents mean such short-term vacuum arches after numerous circuits under load such as shooters gradual contact erosion and thus a corresponding reduction in electrical life. Furthermore, there may be mechanical bouncing during the switch-on of conventional purely mechanical switching devices as well as hybrid switchgear. If this occurs immediately after the closing of the second contact pair, it is possible at the moment of rebounding to briefly form a vacuum arc due to the flowing load current, which is associated with a local melting of contact material. In a subsequent Rekontaktierung then in principle the risk of permanent contact welding, which is lost for a hybrid switching device, in particular -Schütz the property of galvanic isolation. Even with only minor welds, which are often referred to as "Verpappungen", which are easily broken up again by the drive of a switching device, there is still the danger, in particular for contactors, that it is due to numerous DC switching operations under load due to repeated local Anschmelzungen Contact material on one of the two pairs of contacts causes material migration, such that a local accumulation of contact material gradually forms on one of the contacts, which reduces the effective separation distance over time, and in the long term this can also mean that the galvanic separation capability is eliminated ,

In double-contact vacuum interrupters in a cylindrical arrangement with movable electrodes on the end faces, as in the embodiment shown in Fig. 1 from DE 10 2013 1 14 260 A1 known, can generally be assumed that by the pressure difference vacuum - air conditional contact pressure forces for both pairs of contacts of the interrupter are about the same size. Since in vacuum switching devices usually one of the electrodes of the vacuum interrupters is connected directly to the mechanical switching drive, and the other electrode fixed to the housing of the switching device, the desired time difference when opening the two pairs of contacts without additional design measures is often so small that at The separation contacts in principle, the possibility of welding as well as a gradual migration of contact material consists. In DE 10 2013 1 14 260 A1 a hybrid switching device with the embodiment of a double-contact vacuum tube shown in Fig. 1 is described, are used in the contact pressure springs with different high spring constants, in order to achieve that at a switch-off initially the commutation of a Partial switching chamber of the vacuum tube open, while the body of the vacuum tube is initially held by the contact pressure acting on it with the larger spring constant in the on position and thus the isolating contacts remain closed. Only by relaxing this spring with the larger spring constant gradually comes the effect of the contact pressure spring with the smaller spring constant to bear, causing the tube body is moved in the axial direction until it reaches a mechanical stop. During this movement process of the tube body, the release contacts of the right-hand sub-switching chamber then open with a delay in time.

Object of the present invention is therefore to propose a double-contact switch with vacuum interrupters, which requires a smaller space than the known from DE 10 2013 1 14 260 A1 solution for staggered opening of the contact pairs.

This object is solved by the subject matters of the independent claims. Further embodiments of the invention are the subject of the dependent claims.

One of the present invention, the underlying idea is to propose a compact double contact switch with trained as a partial switching chambers a switching tube vacuum switching chambers, which is structurally designed such that when switching off a current flowing through the switch load current, the two pairs of contacts in the interrupter open with a time lag be dimensioned at least larger than a typical current flow time through a parallel to a contact pair semiconductor switch. This is inventively achieved in that gas-tight barriers of the contact-carrying areas of the movable electrodes are designed differently such that the opening of the contacts of the two pairs of contacts is delayed or delayed. As a result, the double-contact switch according to the invention is present all suitable for use in a hybrid switch, in which a power semiconductor switch is connected in parallel to the time first opening first contact pair. When opening the first pair of contacts can be prevented by turning on the power semiconductor switch that forms an arc between the first time-opening contact pair. By blocking the power semiconductor switch during the opening of the first contact pair of the commutated to the power semiconductor switch load current can be led to zero, in particular before the second pair of contacts is opened. As a result, the load current can be switched off almost without the formation of an arc. The invention enables a particularly compact design of a double-contact switch with vacuum interrupters.

One embodiment of the invention now relates to double-contact switches having first and second tubular vacuum interrupters formed as sub-switching chambers of a interrupter, an electrode fixed in the interrupter and disposed between the first and second vacuum interrupters with a first protruding into the first vacuum interrupter chamber Fixed contact and a second, projecting into the second vacuum interrupter fixed contact, one arranged in the first vacuum interrupter and movable in the axial direction of the first electrode with a contact-carrying area, which is sealed against the outside of the first vacuum interrupter gas-tight, one in the second Vacuum switching chamber arranged and movable in this in the axial direction of the second electrode, with a contact-carrying area which is sealed off gas-tight relative to the exterior of the second vacuum interrupter chamber, wherein the gas-tight Closing of the contact-carrying portion of the first electrode is so different from the gas-tight barrier of the contact-carrying portion of the second electrode is formed, that the opening of the first fixed contact and the contact of the first electrode and the opening of the second fixed contact and the contact of the second electrode offset in time. With this construction, the double-contact switch requires relatively little space, so that it is particularly suitable for the construction of compact switching devices. In addition, the parts requirement for the constructive realization of the staggered contact pair Opening comparatively small, whereby the production cost is lower compared to mechanical construction with multiple components.

In particular, the gas-tight shut-off of the contact-carrying region of the first electrode and the gas-tight shut-off of the contact-bearing region of the second electrode are each formed by a flexible bellows, in particular metal bellows. Diameters, wall thicknesses, wavenumbers and / or stiffnesses of the bellows may be different, in particular to cause different forces acting on the contact pairs, which cause the time delay in opening the contact pairs in the interrupter. To provide the different forces on the contact pairs, the outer diameter of the bellows can be different sizes. As a result, the forces acting on the contact pairs due to the vacuum pressure can be set differently, so that the opening of the contact pairs results in a time delay due to the different forces. For example, the radius Ri of the bellows of the first vacuum interrupter chamber may be smaller by a quarter than the radius R _{2 of} the bellows of the second vacuum interrupter chamber. As a result, by a factor of about 1, 8 different sized forces can be adjusted, which act on the contact pairs in the interrupter.

Different forces acting on the pairs of contacts can also be realized in that the bellows of the first vacuum interrupter chamber has a greater wave number and / or a smaller wall thickness than the bellows of the second vacuum interrupter chamber. As a result, a different Federsteif ig speed of the two bellows is effected, which can lead directly to a time-delayed opening of the contact pairs. In order to be able to use the double-contact switch in particular as a component in a switching device, the first electrode can be coupled to a switching drive and the second electrode can be connected to a switch housing wall. For example, the first electrode may be provided with a connection for a switching drive, and the second electrode may be formed so that the at one Switch housing wall can be attached, for example by a screw.

A further embodiment of the invention relates to a hybrid switching device having a first and a second power connection, a double-contact switch according to the invention and as described herein, a switching drive with an electromechanical drive for moving switching contacts in the direction of the axis of the vacuum switching chambers of the double-contact switch and a parallel to a temporally first opening contact pair of the double contact switch switched power semiconductor switch having a first and a second terminal, wherein the first terminal of the power semiconductor switch and the first movable electrode of the double-contact switch to the first power terminal of Hybrid switchgear are connected and the first movable electrode is fixedly connected to a housing wall of the hybrid switching device, wherein the fixed electrode of the double-contact switch is connected to the second terminal of the power semiconductor switch, wherein the second movable electrode of the double-contact switch is electrically connected to a movable part of the switching drive, and wherein the switching tube of the double-contact switch is slidably mounted along its longitudinal axis to a stop in the housing of the hybrid switching device. Further advantages and possible applications of the present invention will become apparent from the following description in conjunction with the embodiments illustrated in the drawings.

In the description, in the claims, in the abstract and in the drawings, the terms and associated reference numerals used in the list of reference numerals recited below are used.

The drawings show in

1 is a perspective view of a sectional view of a Doppelkontakt- switch with vacuum interrupters according to the prior art. Fig. 2 is a block diagram of an embodiment of a hybrid switching device according to the prior art;

Fig. 3 is a sectional view of a first embodiment of a double-contact switch with vacuum interrupters according to the invention, which is particularly suitable for use in the hybrid switching device of Fig. 2; and

Fig. 4 is a sectional view of a second embodiment of a double-contact switch with vacuum interrupters according to the invention, which is particularly suitable for use in the hybrid switching device of Fig. 2.

In the following description, identical, functionally identical and functionally connected elements may be provided with the same reference numerals. Absolute values are given below by way of example only and are not to be construed as limiting the invention.

Fig. 1 shows a longitudinal section through a double contact switch with a vacuum interrupter, which has a rotationally symmetrical, cylindrical shape with two separate Teilschaltkammern 1, 3, in particular of similar or identical structure, for mechanical contact pairs 10, 30 of the switch. Both sub-switching chambers 1, 3 can either be designed as completely separate vacuum chambers or partially connected to each other so that they have a common vacuum. As shown in Fig. 1, both sub-switching chambers 1 and 3 are separated in the middle of the vacuum interrupter by a partition wall 4, which consists of an electrically conductive material and two centrally disposed, fixed switching contacts 41, 42 of the mechanical contact pairs 10 and 30 carries whose end faces each face the interior of one of the switching chambers. Likewise, the partition can be designed in a geometry that it itself serves as a double contact arrangement. The contact surface of the partition can be designed so that it consists of a low-burning material with good resistance to welding. When used in a completely arc-free working hybrid contactor is the use of a low-burning contact material is not mandatory; In this case, a material of good electrical conductivity and adequate resistance to welding is appropriate.

The opening and closing of the switching contacts via axially movable copper electrodes 1 1, 31, at the inner end faces switching contacts 12, 32 of the mechanical contact pairs 10 and 30 of a suitable material, v.a. of adequate resistance to welding and good electrical conductivity. The areas of the two movable electrodes 1 1, 31 carrying the switching contacts are each sealed off from the exterior of the respective switching chamber via a flexible metal bellows 13, 33. Each metal bellows 13, 33 is in particular soldered over two circumferential, vacuum-tight solder joints on the one hand to the respective electrode 1 1 and 31, on the other hand with a respective cover 14 and 34, which closes the respective part switching chamber 1, 3.

The bellows 13, 33 in this case form gastight shut-off of the switching contacts 12, 32 supporting portions of the electrodes 1 1, 31 relative to the exterior of the sub-switching chambers 1, 3, so that a vacuum is maintained in these chambers.

The two movable electrodes 1 1, 31 opposite a common fixed electrode in the form of the aforementioned disc-shaped switching chamber partition 4, which is connected along its entire circumference with the wall of the respective part switching chamber 1, 3 either as a separate part or preferably in the peripheral area itself Part of the switching chamber wall 43 represents.

To guide the load current, the fixed electrode 4 has a correspondingly sized, sufficient wall thickness. For electrical insulation with respect to the two movable electrodes 1 1, 31, the fixed electrode 4 is connected at its peripheral end faces 43 in the direction of their respective switching chamber 1, 3 with an annular insulating ring 15, 35, for example made of ceramic, vacuum-tight. In a hybrid switching device, this double-contact switch with vacuum interrupters - as shown in Fig. 2 - be involved in such a way that one of the two movable electrodes, such as the electrode 1 1 is rigidly connected via a flat power connection to a power connector of the hybrid switching device. The fixed electrode 4 of the vacuum interrupter is also connected via a flat power connection to the hybrid switching device, in such a way that the so-connected mechanical contacts 10 of the first part switching chamber 1 are arranged electrically parallel to a power semiconductor switch 20 of the hybrid switching device. The second movable electrode 31 is connected to the movable part of the hybrid-electric hybrid drive via another surface current connection. Electrically, the mechanical contacts 30 of the second partial switching chamber 3 are connected in series with the parallel arrangement of the power semiconductor switch 20 and the mechanical contacts 10 of the first partial switching chamber 1. During switching operations, the electromechanical drive 40 of the hybrid switching device ensures a movement of the movable contacts in the direction of the interrupter axis. The power semiconductor switch 20 is controlled by a switching electronics 50, which in turn exchanges signals with the electromechanical drive 40. The switching electronics 50 are configured to control the timing of switching on and off of the power semiconductor switch 20 depending on the switching states of the double-contact switch depending on respective signals of the electromechanical actuator 40.

In Fig. 3, a double-contact switch is shown with a vacuum tube in which the outer diameter of the bellows for the two sub-switching chambers 1 and 3 were chosen to be different sizes. For example, if the radius Ri of the bellows 13 'of the right Teilschaltkammer 1 by 1/4 smaller than the radius R2 of the bellows 33' of the left Teilschaltkammer 3, then due to the vacuum pressure p _Vak acting on the contacts 32, 4 of the left Teilschaltkammer 3 Force F ₂ = pva _k x TR ₂ ² approximately 1, 8 times higher than the force acting on the contacts 12, 4 of the right part of switching chamber 1 vacuum force Fi = p _Vak x 9 / 16nR ₂ ² .

Upon actuation of the switching drive to open the contacts, which is for example directly connected to the switching electrode 31 of the left part of switching chamber 3, then first, the load on the contacts 12, 4 of the right Teilschaltkannnner 1 compensated force Fi, while the on the contacts 32, 4 of the left part of the switching chamber 3 larger force F _2, the contacts 32, 4 still holds closed.

As a result, when the switching electrode 1 1 of the right-hand sub-switching chamber 1 is mechanically firmly connected to the housing of the switching device, the entire vacuum tube body is set in motion so that the contacts 12, 4 provided in the hybrid switch for commutation open first.

Upon reaching a mechanical stop by the vacuum tube, the end position of the vacuum tube body and thus the desired contact opening distance for the commutation 12, 4 is reached. With the further movement of the switching drive is then delayed in time and on the contacts 32, 4 of the left part of the switching chamber 3 vacuum vacuum force F ₂ compensated, so that finally also provided for the electrical isolation of the hybrid switch contact pair 32, 4 opens.

Differently high contact pressure forces in the two sub-switching chambers of a double-contact vacuum interrupter can also be realized via different wall thicknesses of the bellows and furthermore also via their wavenumbers. 4, a double-contact switch is shown with a vacuum tube, in which the bellows 33 "of the left Teilschaltkammer 3, a greater wall thickness and a lower wave number (three waves 36) than the bellows 13" of the right Teilschaltkammer 1 (four shafts 37) having. As a result, the bellows 33 "of the partial switching chamber 3 receives a higher spring stiffness than the bellows 13" of the partial switching chamber 1.

To the on the contact pairs 12, 4 and 32, 4 of the two sub-switching chambers 1 and 3-charged vacuum forces, which are due to the same diameter of the bellows 13 "and 33" in this example the same size, thus comes another Component in the form of the spring forces of the bellows 13 "and 33" to bear, which fails for the two sub-switching chambers 1 and 3 different levels.

The effective contact pressure force F _e tf is thus composed as

F _e ff = Fvak ⁺ Fßalg where F _Va k is the vacuum force and F _Ba _{g is} the spring force of a bellows.

For the effective contact pressure forces in the two partial switching chambers 1 and 3 of the illustrated double-contact switch, F _e tf_i <F _e ff_ ₃ , so that due to the different high spring constant of the two bellows 13 ", 33" the contact opening movement analogous to in FIG. 3 case expires. The pairs of contacts 32, 4 of the left part of switching chamber 3 thus open again delayed in time with respect to the contact pairs 12, 4 of the right part of switching chamber. 1

The time delay when opening the pairs of contacts 32, 4 and 12, 4 can also be effected by a different choice of material in the bellows or generally the gas-tight barriers, for example by a bellows made of a spring steel with a high Federsteif ig speed and another bellows of a Spring steel is produced with a low spring stiffness.

The present invention is particularly suitable for almost arc-free switching high DC and low-frequency currents. Switching operations can be carried out almost free of burn-off, which leads to an extended life of the switch. The double-contact switch according to the invention can be used in contactors, circuit breakers, motor protection switches, in particular for switching direct currents and low-frequency currents. reference numeral

1 first sub-switch

10 mechanical contacts (isolating contacts) first part switching chamber

1 1 movable electrode first part switching chamber

12 movable contact first part switching chamber

13 bellows

13 'bellows of smaller diameter

13 "bellows with lower wall thickness

14 cover first part switching chamber

15 Isolierstoffring first part switching chamber

2 vacuum interrupters

20 power semiconductor switch

3 second part switching chamber

30 mechanical contacts (isolating contacts) second part switching chamber

31 movable electrode second part switching chamber

32 movable contact second part switching chamber

33 bellows

33 'bellows with larger diameter

33 "bellows with greater wall thickness

34 cover second part switching chamber

35 Isolierstoffring second part switching chamber

36 three waves of the bellows 33 "

37 four waves of bellows 13 "

4 partition / fixed electrode

40 electromechanical drive

41 fixed contact first part switching chamber

42 fixed contact second part switching chamber

43 switching chamber wall fixed electrode

50 switching electronics

Claims

claims

1 . Double contact switch with

- A first and a second tubular

Vacuum switching chamber (1, 3), which are designed as Teilschaltkammern a switching tube (2),

- A stationary in the interrupter, arranged between the first and second vacuum interrupter electrode (4) with a first, in the first vacuum interrupter chamber (1) projecting fixed contact (41) and a second, in the second vacuum interrupter chamber (3) projecting fixed contact (42) .

- One in the first vacuum interrupter chamber (1) arranged and movable in this in the axial direction of the first electrode (1 1) having a, a contact (12) bearing region which is sealed against the outside of the first vacuum interrupter chamber (1) gas-tight

- One in the second vacuum interrupter chamber (3) arranged and movable in this in the axial direction of the second electrode (31), with a, a contact (32) supporting area which is sealed against the outside of the second vacuum interrupter chamber (3) gas-tight, wherein

- The gas-tight barrier (13 ', 13 ") of the contact (12) bearing

Area of the first electrode (1 1) is so different to the gas-tight barrier (33 ', 33 ") of the contact (32) supporting portion of the second electrode (31) is formed such that the opening of the first

Fixed contact (41) and the contact (12) of the first electrode (1 1) and the opening of the second fixed contact (42) and the contact (32) of the second electrode (31) offset in time takes place.

2. Switch according to claim 1, characterized in that the gastight barrier (13 ', 13'') of the contact (12) carrying portion of the first electrode (1 1) and the gas-tight barrier (33', 33 '') of the contact (32) carrying portion of second electrode (31) in each case by a flexible bellows, in particular metal bellows (1 3 ', 33', 1 3 "33") are formed.

3. Switch according to claim 2, characterized in that the diameters, wall thicknesses, wavenumbers and / or rigidities of the bellows (13 ', 33', 13 "33") are different.

4. Switch according to claim 3, characterized in that the outer diameter of the bellows (13 ', 33') are different in size.

5. A switch according to claim 4, characterized in that the radius Ri of the bellows (1 3 ') of the first vacuum interrupter chamber (1) by about a quarter smaller than the radius R _{2 of} the bellows (33') of the second vacuum interrupter chamber (3 ') is.

6. Switch according to claim 3, 4 or 5, characterized in that the bellows (13 ") of the first vacuum interrupter chamber (1) has a greater wave number and / or a smaller wall thickness than the bellows (33") of the second vacuum interrupter chamber (3).

7. Switch according to one of the preceding claims, characterized in that the second electrode (31) with a switching drive (40) can be coupled and the first electrode (1 1) is connectable to a switch housing wall.

8. Hybrid switching device with

a first and a second power connection,

- A double-contact switch according to one of the preceding

Claims,

- A switching drive with an electromechanical drive (40) for

Moving switch contacts in the direction of the axis of the

Vacuum switch chambers (1, 3) of the double-contact switch, and

a power semiconductor switch (20) having a first and a second connection connected in parallel with a contact pair (12, 41) of the double-contact switch that opens at first in time;

- Wherein the first terminal of the power semiconductor switch (20) and the first movable electrode (1 1) of the double-contact switch are connected to the first power terminal of the hybrid switching device and the first movable electrode (1 1) fixed to a housing wall of the hybrid - Switching device is connected, wherein the fixed electrode (4) of the double-contact switch is connected to the second terminal of the power semiconductor switch (20), - Wherein the second movable electrode (31) of the double-contact switch is electrically connected to a movable part of the switching drive, and

- wherein the interrupter of the double contact switch displaceable along its longitudinal axis up to a stop in the housing of the hybrid

Switching device is stored.