EP1672655A1 - Vacuum switch with increased current load capacity - Google Patents

Abstract

A vacuum switch chamber has first and second contact pieces (11;12) for switching an electric current flowing through the vacuum chamber. To remove heat arising from the electric current in the vacuum chamber, at least one heat tube (1) is provided.

Description

Technical area

The invention relates to the field of switch technology, in particular the high and medium voltage switch technology and especially to vacuum interrupters. It relates to a vacuum interrupter chamber and a method for cooling a vacuum interrupter chamber according to the preamble of the independent claims.

State of the art

Vacuum switching chambers are known from the prior art, which are forced to increase the current carrying capacity forced. The vacuum interrupter chamber is arranged in an insulating tube, which is flowed through by means of a blower of air, so that even at high current load too high heating of the vacuum interrupter chamber is avoided.

One problem with such an arrangement is that the blower is active, that is, it has to be driven. It has to be maintained and can fail.

Optionally, the blower can be made redundant, whereby a greater reliability can be achieved. Nevertheless, greater reliability of cooling is desirable.

Presentation of the invention

It is therefore an object of the invention to provide a vacuum interrupter chamber and a method for cooling a vacuum interrupter chamber of the type mentioned, which do not have the disadvantages mentioned above. In particular, a vacuum interrupter chamber with a passive and (almost) maintenance-free cooling system is to be created.

This object is achieved by a device and a method having the features of the independent patent claims.

The inventive vacuum switching chamber has at least one heat pipe. The heat pipe (also known as heat pipe) is used primarily to dissipate heat, which is generated by a flowing in the closed state through the vacuum interrupter chamber electrical current (rated current). In general, the vacuum interrupter chamber has at least two contact pieces, and the current flows through the two contact pieces.

Additional heat is generated during a short period of time by a burning in the case of switching between the contact pieces arc. This additional heat can be dissipated to a part through the heat pipe.

By providing the heat pipe, an efficient dissipation of heat is possible, so that a greater current carrying capacity is achieved.

A heat pipe is a passive cooling device. It requires no power or other supply. As a cooling system with a hermetically closed circuit, there is generally no need for maintenance and generally it can be maintenance free for years and decades.

The size of the vacuum interrupter chamber can be kept very small at large rated current carrying capacity by providing the heat pipe. A compact design with high current carrying capacity is possible. Two or more heat pipes may be provided on a vacuum interrupter chamber.

Advantageously, a heat pipe in close thermal contact with at least one of the contact pieces. Also, two or more heat pipes may be provided in close thermal contact with a contact piece. It may also be two or, if present, even more contact pieces, each with one or more heat pipes in close thermal contact. It may also be a heat pipe with two or more contact pieces in close thermal contact.

The vacuum switching chamber may have RMF and / or AMF contact pieces.

In general, the at least one heat pipe includes a working medium for dissipating the heat by evaporation of the working medium in a section of the heat pipe designated as an evaporator and condensing the working medium in a section of the heat pipe designated as a condenser. The working medium should be enclosed in a hermetically sealed volume that includes the evaporator and the condenser.

The heat pipe can be designed as a thermosyphon. In a heat pipe designed as a thermosiphon, the return transport of the condensed working medium takes place (predominantly) by gravity. Thus, the condenser (in the gravitational field) is located higher than the evaporator, and between these must be a monotonous slope along the heat pipe.

In another embodiment, the heat pipe includes means for returning condensed working fluid to the evaporator by capillary forces. Such an embodiment is preferably used when the condenser is arranged below the evaporator; but it can also be used in conjunction with a thermosyphon. As a means for returning condensed working medium to the evaporator by capillary forces, for example, porous materials come into question. Mesh-like structured and / or fabric-like materials are also suitable. Preferably, such means are provided on the inner surface of the heat pipe. By providing a means for returning condensed working fluid to the evaporator by capillary forces, the heat pipe and the vacuum interrupter chamber can be operated independently of position.

Advantageously, the evaporator is in close thermal contact with the first contact piece. This allows a particularly efficient cooling in the region of this contact piece. It is also possible to arrange the evaporator in less direct thermal contact with the contact piece. For example, if the contact piece is connected to a contact stem, the evaporator may also be in close thermal contact with the Contact stem be provided. As a result, while the thermal contact with the contact piece is generally inferior, it may be easier to make the vacuum interrupter chamber with the heat pipe. Or if the contact stem is in turn connected to a contact carrier, the evaporator can also be provided in the contact carrier or at least in close thermal contact with the contact carrier. Such a contact carrier is generally not movable, so that the heat pipe does not need to be movable. A movable heat pipe would be realized, for example, that, preferably between the evaporator and condenser, a flexible deformable portion of the heat pipe is provided, for example by a bellows or a hose made of elastically deformable material.

With great advantage at least part of the evaporator is integrated in the first contact piece. This ensures a very good thermal contact between evaporator and contact piece. Additionally or alternatively, at least a part of the evaporator may also be integrated in a contact stem connected to the first contact piece.

Advantageously, at least a part of the evaporator may be formed by a cavity in the first contact piece. For example, the cavity may be formed by a blind hole.

Advantageously, the heat pipe in close thermal contact with a fixed contact piece. As explained above, this allows a simplified construction of the heat pipe. In addition, the mass to be moved during a switching operation is lower.

With great advantage, the capacitor has a device for heat dissipation. The device for heat dissipation can, for example a heat exchanger, a radiator or a cooling fin arrangement include or be. If cooling fins are provided, these are advantageously arranged so that they are oriented substantially vertically when the vacuum interrupter is aligned in the intended manner. In general, a vacuum switching chamber is substantially rotationally symmetrical with an axis, and the vacuum interrupter chamber is generally provided for mounting with a vertically aligned axis. In this case, the cooling fins of the cooling fin arrangement are advantageously aligned substantially parallel to the axis.

In general, a vacuum interrupter chamber has an evacuated volume containing the contacts. Advantageously, the capacitor or at least a part of the capacitor and in particular a device for heat dissipation outside this volume is arranged.

Advantageously, the evaporator and the capacitor are arranged at the same electrical potential. However, a heat pipe according to the invention can have a hollow insulating body (for example a ceramic or glass tube) to bridge a potential difference between the evaporator and the condenser, in particular if the capacitor (and in particular a cooling rib arrangement of the capacitor) is to be touchable when electrical high voltage is applied to the vacuum switching chamber and thus should be at ground potential. If the heat pipe is to form such an electrical insulation gap, an electrically insulating working medium is also to be provided.

Advantageously, in particular if only one heat pipe is provided, the evaporator is arranged near the middle of the vacuum interrupter chamber. As a result, a particularly efficient cooling of the vacuum interrupter chamber is achieved.

A switching device according to the invention, for example a high-power switch, high-voltage power switch, generator switch, medium-voltage switch or the like, has at least one vacuum interrupter chamber according to the invention.

The inventive method for cooling a vacuum interrupter chamber is characterized in that a working medium is vaporized at a location called evaporator by absorbing heat and is condensed with release of heat at a designated capacitor location and the condensed working fluid is returned to the evaporator. The absorbed and dissipated heat is essentially generated by a current flowing through the vacuum interrupter in the closed state (rated current).

Further preferred embodiments and advantages will become apparent from the dependent claims and the figure.

Brief description of the drawings

Fig. 1

einen Schnitt durch eine in einem äusseren Isolierrohr angeordnete Vakuumschaltkammer;

Fig. 2

einen Kondensator mit Kühlrippenanordnung, geschnitten senkrecht zur Achse;

Fig. 3

einen Kondensator mit integrierter Kühlrippenanordnung, geschnitten parallel zur Achse.

In the following, the subject invention will be explained in more detail with reference to preferred embodiments, which are illustrated in the accompanying drawings. They show schematically:

Fig. 1

a section through a arranged in an outer insulating vacuum interrupter chamber;

Fig. 2

a condenser with cooling fin arrangement, cut perpendicular to the axis;

Fig. 3

a condenser with integrated cooling fin arrangement, cut parallel to the axis.

The reference numerals used in the drawings and their meaning are listed in the list of reference numerals. Basically, the same or equivalent parts are provided with the same or similar reference numerals. For the understanding of the invention non-essential parts are not shown in part. The described embodiments are exemplary of the subject invention and have no limiting effect.

Ways to carry out the invention

Fig. 1 shows schematically and cut a vacuum interrupter chamber in the open state. For the invention insignificant details are not discussed and are largely not shown.

The vacuum interrupter chamber is substantially rotationally symmetrical with an axis A and includes two contact pieces 1 1 and 12. The contact piece 12 is movable by means of a non-illustrated drive. Contact piece 1 1 is fixed. The contact pieces 1 1 and 12 are attached to contact stems 21 and 22, respectively.

The vacuum interrupter chamber further has an insulating body 50, typically made of ceramic, which is formed as a hollow cylinder and is closed at its ends by a cover 41, 42. The enclosed volume 10 is evacuated. The movable contact stem 22 is attached to the lid 42 with the interposition of a bellows 70. The fixed contact stem 21 is on the lid 41st attached. A shield 60 prevents the insulating body 50 loses its insulating properties by vapor deposition, especially with metal vapor from an arc zone between the contact pieces 11,12 and becomes electrically conductive.

The contact pieces 11, 12 as well as the contact posts 21, 22 are advantageously made of copper, and the contact pieces 11, 12 are provided on their mutually facing side with a coating 15 made of an erosion-resistant material, for example Cu / Cr. A contact piece 11, 12 can also be formed in one piece with a contact stem 21, 22.

For dissipating heat that arises in the vacuum interrupter chamber, a heat pipe 1 integrated in the vacuum interrupter chamber is provided. The heat is mainly due to ohmic losses that occur when the vacuum interrupter chamber (and the contact pieces) are traversed in the closed switching state of an electric current (rated current).

For electrically contacting the vacuum interrupter chamber, a beam-like fixed contact carrier 31 is connected to the contact stem 21, for example by means of a thread 36, and a likewise bar-like drive contact carrier 32 is slidably connected to the contact stem 22. To produce the electrical contact between the movable contact piece 22 and the drive contact carrier 32, spring contact rings or multi-contact blades (not shown) can be provided, for example, in recesses 35.

Substantial parts of the vacuum interrupter chamber are disposed within an outer insulating tube 80 which serves for electrical shielding and mechanical stabilization.

The heat pipe 1 has a volume that includes a working medium 2. Advantageously, the volume of the heat pipe 1 can be evacuated prior to filling the working medium 2, so that it contains only the working medium.

The volume is formed by a plurality of sub-volumes, which are provided in the contact piece 11, the contact piece 21, a flange 5 and a pipe 7. An arranged in the contact piece 11 and the contact stem 21 region of the heat pipe 1 serves as an evaporator 3: By absorbing heat of the contact piece 11, the first liquid working medium 2 is evaporated. In a designated section 4 of the heat pipe 1 as a condenser 4, the gaseous working medium 2 absorbs absorbed heat energy and condenses, whereupon it is returned to the evaporator 3.

The unilaterally closed tube 7 is preferably made of copper and, for example, welded to the flange 5, which advantageously has a socket for receiving the tube 7. The flange 5 is screwed, for example, with the contact stem 21 and has to ensure a gas and pressure-tight connection to a cutting ring 6, which cooperates with the contact stem 21.

Preferably, the contact stem 21 is annealed copper, which is generally the case anyway due to the manufacturing process of the vacuum interrupter chamber. The flange 5 is made of a harder material, preferably also of copper, for example, copper in die-hard quality.

It could also be provided that the material of the contact stem 21 would be harder than that of the flange 5, in which case the cutting ring 6 would advantageously be provided on the contact stem 21.

The tube 7 or at least its upper part serves as the condenser 4. In order to increase the surface area available for the condensation of the working medium 2, it is also possible to provide a tube system of the heat pipe 1 in the condenser. To improve the heat absorption in the evaporator 3, a tube system of the heat pipe 1 can also be provided there.

For efficient removal of heat at the condenser 4, a cooling fin arrangement 8 is provided on the tube 7. Advantageously, the cooling fins aligned substantially parallel to the axis A can be arranged approximately in a star-shaped (radial) manner around the tube. Fig. 2 shows schematically and parallel to the axis A cut such a possible cooling fin arrangement. The individual cooling fins can also be branched (not shown).

It is possible to provide a forced cooling of the cooling fin arrangement 8, for example by means of blowers.

Fig. 3 shows schematically and parallel to the axis A cut another possible embodiment of a capacitor 4. There are cooling fins in the capacitor 4 integrated. The condenser 4 has a multiplicity of elongate and / or areally extending cavities 8a. In this way, on the one hand a large surface for cooling the capacitor 4 from the outside by air (ambient air, optionally forced) realized and on the other hand, a large surface area, on which working fluid from the inside can condense.

A heat pipe 1 can advantageously be designed so that the internal pressure in the heat pipe 1 is approximately between 900 mbar and 1300 mbar, when the contact pieces 11, 12 are current-carrying. But there are also pressures of several bar possible, especially if the heat pipe 1 is substantially metallic and thus can easily withstand high pressures and remains gas-tight.

Suitable working media 2 are, for example, water, acetone, fluorinated hydrocarbons such as "FC-72" from 3M, or hydro-fluoro ethers such as "HFE-7100" from 3M.

The production of a vacuum interrupter chamber according to FIG. 1 can take place in two separate steps, wherein in a first step the parts forming the volume 10 and the parts arranged in the volume 10 are joined together and advantageously also the contact carriers 31, 32 and the outer insulating tube 80 can, for example be added. In a second step, the working medium 2 can then be filled and the other parts belonging to the heat pipe 1 (flange 5, pipe 7, cooling rib arrangement 8) are added.

An advantage of the illustrated embodiment is that the vacuum interrupter chamber can be optionally used with or without heat pipe simply by performing or omitting the second production step.

By integrating a heat pipe or a part of a heat pipe 1 in a current-carrying conductor of the vacuum interrupter chamber, a vacuum interrupter chamber of small size can be realized with high current carrying capacity.

LIST OF REFERENCE NUMBERS

1

heat pipe

2

Working medium, working fluid

3

Evaporator

4

capacitor

5

flange

6

Cutting ring, cutting edge

7

Pipe, one-sided closed pipe

8th

Device for heat emission, heat exchanger, cooling fin arrangement, radiator

8a

elongated or flat erstrecker cavity

10

evacuated volume, vacuum

11

Contact piece, fixed contact piece

12

Contact piece, movable contact piece

1 5

Coating made of erosion-resistant material

21

Contact stem, fixed contact stem

22

Contact stem, moving contact stem

31

Contact carrier, fixed contact carrier, beams

32

Contact carrier, drive contact carrier, beams

35

Recess, recess for multi-contact blades, recess for contact spring

36

thread

41

Lid, upper chamber lid

42

Lid, lower chamber lid

50

Insulating body, insulating tube, ceramic

60

shielding

70

Bellows, bellows

80

outer insulating tube

A

Axis, axis of rotation

Claims (12)

Vacuum switching chamber (1) having a first (11) and a second contact piece (12) for switching a flowing in the closed state through the vacuum interrupter electrical stoma, characterized in that for discharging caused by the electric current in the vacuum interrupter heat chamber at least one heat pipe (1 ) is provided. Vacuum switching chamber (1) according to claim 1, characterized in that the at least one heat pipe (1) contains a working medium (2) for removing the heat by evaporation of the working medium (2) in a section of the heat pipe (1) designated as evaporator (3). and condensing the working medium (2) in a section of the heat pipe (1) designated as a condenser (4). Vacuum switching chamber according to claim 2, characterized in that the evaporator (3) is in close thermal contact with the first contact piece (11). Vacuum switching chamber according to claim 2 or claim 3, characterized in that at least a part of the evaporator (3) in the first contact piece (11) is integrated. Vacuum switching chamber according to one of claims 2 to 4, characterized in that at least part of the evaporator (3) is formed by a cavity in the first contact piece (11). Vacuum switching chamber according to one of the preceding claims, characterized in that the first contact piece (11) a fixed contact piece (11). Vacuum switching chamber according to one of claims 2 to 6, characterized in that the capacitor (4) has a device for heat dissipation (8). Vacuum switching chamber according to claim 7, characterized in that the device for heat dissipation (8) includes a cooling fin arrangement (8). Vacuum switching chamber according to claim 8, characterized in that it is formed substantially rotationally symmetrical with an axis (A), and that cooling fins of the cooling fin arrangement (8) are aligned substantially parallel to the axis (A). Vacuum switching chamber according to one of claims 2 to 9, characterized in that it comprises the contact pieces (11,12) containing evacuated volume (10), and that at least a part of the capacitor (4) outside this volume (10) is arranged. Switching device, comprising at least one vacuum switching chamber according to one of the preceding claims. Method for cooling a vacuum interrupter chamber, characterized in that a working medium (2) is evaporated at a location designated as evaporator (3) by taking up heat generated in the vacuum interrupter chamber and condensing with release of heat at a location designated as condenser (4) and the condensed working medium (2) is returned to the evaporator (3).

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