EP4094281A1

EP4094281A1 - Disconnecting device and protective-gas-insulated medium-voltage power switchgear

Info

Publication number: EP4094281A1
Application number: EP21708144.7A
Authority: EP
Inventors: Stefan Kern; Torben-Roland Buß
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2020-03-12
Filing date: 2021-02-15
Publication date: 2022-11-30
Also published as: DE102020203190B3; WO2021180424A1

Abstract

The present invention relates to a disconnecting device, comprising: at least one contact (6), which has a first spring apparatus (13, 16) in order to form a pressing force against a counter contact (7); and a holding device (11, 12) for the contact (6), characterized in that a thermal conduction device (22, 23, 24, 25, 31, 32, 35) is designed to press the holding device (11, 12) and the contact (6) against each other. The present invention further relates to protective-gas-insulated medium-voltage power switchgear having the disconnecting device according to the invention.

Description

description

Isolating switch and inert gas-insulated medium-voltage power switchgear

The invention relates to a disconnector according to the preamble of claim 1 and a medium-voltage power switchgear insulated with protective gas according to claim 11.

Inert gas-insulated medium-voltage power switchgear, for example, can be found in the product brochure "Circuit-breaker fixed-mounted systems, type 8DA and 8DB up to 40.5 kV, gas-insulated", catalog HA 35.112006, Siemens AG, order no .: E50001-K1435-A101-A9, Examples of switchgears which have a separate switchgear for each phase of medium voltage are shown on pages 14 to 18. Each switchgear is arranged in a fluid-tight housing and electrically insulated with the inert gas sulfur hexafluoride.

A vacuum interrupter is provided as the circuit breaker. In series with this is a three-position disconnector with the switching positions off, on and earth. In the ON switch position, the disconnector electrically connects the vacuum interrupter to a busbar.

On page 18 of the brochure, the switch position on is shown in the second picture from the top. In this case, the isolating switch has several contacts which are designed as contact fingers arranged in pairs, a gap being formed between the pairs of contact fingers for receiving a mating contact connected to the busbar. Four pairs of contact fingers are provided so that eight contact points are formed between the contact fingers and the mating contact in accordance with the high currents to be switched. The contact fingers are arranged in a cage or box as a holding device from which the contact fingers protrude. To develop a pressure force on the counter contact, a first spring device is provided, which the contact pressing the clock finger against the mating contact to form a good electrically conductive connection.

Gas-insulated medium-voltage switchgear with current-carrying components, like any electrical device, must be cooled in order to dissipate the power loss generated by the resistor. This is essentially done by transferring the lost heat into the protective gas, i.e. by means of convection. The heat is given off to the environment via the metal housing of the switchgear. High currents and resistances lead to high power dissipation, which increases the temperature inside the switchgear. There are normative limit values to be observed at contact points. This limits the level of the possible currents so that safe operation of the metal-encapsulated, gas-insulated switchgear is ensured. In addition to heat dissipation through the interior atmosphere of the encapsulation by convection, non-current-carrying de components also serve to dissipate heat by conduction in order to transfer the heat to the available border areas to the housing parts, which ultimately dissipate them to the environment. The temperature limits for the corresponding interfaces and connection variants are specified in normative terms and may not be exceeded, for example in accordance with the IEC 62271-1, Edition 20.02017-7 standard.

At the contact transition point from the moving contact fingers to the fixed contact, the narrowing of the current path leads to high contact resistances. With the high current, these cause high power dissipation and generate high temperatures on the contact fingers and the fixed contact. The above-mentioned IEC 62271-1 standard provides for the contact fingers on pages 64 and 65, for example, that the contacts when using low-temperature hexafluoride as EMERGENCY OXIDIZING GAS (NOG, see "Point 5" on page 67) and an ambient temperature If the contacts are made of pure copper or are provided with a silver or nickel coating, the ambient temperature must be taken into account, because heat is always transported depends on a temperature difference inside the housing to the environment. Other standards such as the IEEE standard C37.100.1-2018, page 28, which is valid in the USA, even only stipulate a maximum temperature of 105 ° C for the same conditions. The so-called GBT standard valid in China also provides for 105 ° C.

So far, measures for cooling particularly heated components have been implemented by enlarging the cooling surfaces by means of additional Lich mounted heat sinks within the system encapsulation. Materials with particularly good thermal conductivity properties such as aluminum or copper are used for the heat sinks. The heat is given off to the housing parts by pure convection and thermal radiation. Alternatively, the resistance of the main current path is lowered and the resulting power loss is reduced, which enables higher currents. However, this usually means an increase in cross-section in the conductive main current path, which is only possible to a very limited extent with a given installation space. In the case of particularly high currents, such as a current of 3150A to be tested in accordance with the above-mentioned standard IEC 62271-1, high temperatures occur inside the switchgear enclosure and active cooling of the switchgear housing by external fans could ensure compliance with the prescribed temperature limits for contacts and other components may be necessary.

On the other hand, moving assemblies such as fans are usually not provided inside the housing, because further moving parts inside generally require a higher susceptibility to errors and thus possibly shorter lifetimes and shorter maintenance intervals. For this reason, operators of medium-voltage switchgear reject such constructions.

The object of the invention is based on known separating devices to provide a separating device that provides a comparatively high heat dissipation to the environment and at the same time is inexpensive to manufacture. The invention solves this problem with a separating device according to claim 1.

The disconnector is preferably designed for use in a medium-voltage power switchgear. The so-called primary distribution level for medium voltage usually has voltages between 12 kV and 40.5 kV, which makes vacuum switching technology necessary in such systems, for example. In addition, there are isolating switches that guarantee safe galvanic isolation.

So-called contact fingers arranged in pairs can be provided as contacts, for example. Depending on the level of the currents to be switched, up to five or more contact finger pairs can be used between a single contact finger.

The first spring device can, for example, have a spiral spring or a plate spring. A leaf spring can also be used to advantage. The spring device pushes or pulls the contact and mating contact in the ON position together to ensure good electrical conductivity. One spring device can preferably be used per contact or contact finger. Alternatively, a single spring can also be selected for all contacts.

The holding device positions the contacts within the housing and is, for example, rotatably mounted in order to be able to assume the various switching positions.

The first spring device and / or the holding device are preferably formed from a non-magnetic material in order to avoid additional heating and disruptive effects from magnetic fields and induced currents. Steel and iron are usually ruled out, while copper or aluminum or brass also because of this. are suitable for their comparatively low cost. The holding device can be designed, for example, as a box or cage which engages around the contacts or contact fingers and is resiliently supported.

The heat conduction device with the second spring device makes it possible, through conduction of heat at the contact points between the contacts and the mating contact, to dissipate heat loss in an improved manner to the holding device. This he increases the available surface for heat radiation considerably.

In a preferred embodiment of the separating device according to the invention, the heat-conducting device is designed to produce a pressing force between the holding device and the contact by means of a second spring device. This is an advantage because in this way a connection with high thermal conductivity is ensured.

The second spring device is preferably formed from a non-magnetic material in order to avoid additional heating and disruptive effects from magnetic fields and induced currents. Steel and iron are therefore usually ruled out, while copper or aluminum or brass also due to their comparatively low cost are suitable. The second Federeinrich device can, for example, have a spiral spring or a plate spring. A leaf spring can also be used with advantage.

In a preferred embodiment of the separating device according to the invention, the heat conduction device is arranged on the holding device.

In a preferred embodiment of the separating device according to the invention, the heat conduction device is arranged on the contact. For example, the contact can be designed as a contact finger essentially as a flat, cuboid workpiece made of Me tall. Contact can be at its longest Side have a recess for receiving the heat conduction device with the second spring device, so that the heat conduction device does not unnecessarily increase the space required for the contact in the separating device. The heat conduction device is pressed out of the recess only to bridge a small gap over the contour of the contact. For example, the gap is smaller than 10 mm, preferably smaller than 5 mm.

In a preferred embodiment of the separating device according to the invention, the heat conduction device has a metallic contact material. Because of its high thermal conductivity, it is advantageous to use copper, at least in part, for the thermal conduction device. Copper has the further advantage that it can be attached particularly inexpensively by ultrasonic welding. Alternatively, at least a proportion of aluminum or brass can be used.

In a preferred embodiment of the separating device according to the invention, the metallic contact material has several stranded conductors. Stranded conductors have the advantage that they are flexible and can accordingly easily be bent and pressed on by the second spring device. The stranded conductors can preferably be combined to form a stranded bundle, e.g. by twisting. Alternatively, the strands in the bundle can be essentially parallel and provided with a closure cap or welded at their free end.

In a preferred embodiment of the separating device according to the invention, the metallic contact material is at least partially formed from copper. Because of its high thermal conductivity, copper is advantageously used, at least in part, for the heat conduction device. Copper has the further advantage that it can be attached particularly inexpensively by ultrasonic welding. In a preferred embodiment of the separating device according to the invention, the heat-conducting device essentially has a non-magnetic material. In this way, additional heating and disruptive effects from magnetic fields and induced currents can be avoided. Steel and iron are therefore usually ruled out, while copper or aluminum or brass are non-magnetic and especially due to the fact that they are not magnetic. their comparatively low cost are suitable.

In a preferred embodiment of the separating device according to the invention, a plurality of contacts are designed as contact fingers arranged in pairs, with a gap for receiving the mating contact being formed between the pairs of contact fingers.

In a preferred embodiment of the separating device according to the invention, the separating device is designed as a three-position separating device with the switching positions EARTH, OFF and ON, the at least one contact being pressed onto the counter contact in the switching position ON.

The object of the invention is based on known medium-voltage protective gas insulated

Power switchgear to specify a switchgear that allows a comparatively high heat dissipation to the environment and at the same time is inexpensive to manufacture.

The invention solves this problem by means of an inert gas-insulated medium-voltage power switchgear according to claim 11.

The vacuum switching arrangement includes, for example, a vacuum interrupter in order to quickly quench the arc when it is disconnected.

In a preferred embodiment of the protective gas-insulated medium-voltage power switchgear according to the invention, the medium-voltage power switchgear has a fluid-tight housing that is used for filling with a sulfur-containing xafluoride-free electrically insulating protective gas is ausgebil det. For example, so-called "clean air", i.e. essentially moisture-free compressed air, or a mixture of essentially nitrogen and carbon dioxide, can be used. This is an advantage because replacing the climate-damaging sulfur hexafluoride gas generally results in a lower electrical insulation capacity Consumption and energy dissipation is often comparatively lower. The solution according to the invention can therefore be used to advantage in order to facilitate the removal of heat from the contacts to the housing The process of heat conduction takes place independently of the insulating gas used and the gas pressure set. The switchgear can therefore be designed more cost-effectively and high currents can be transmitted at the same time.

In a preferred embodiment of the inert gas-insulated medium-voltage power switchgear according to the invention, the separating device is spaced apart from the housing by an electrically non-conductive and non-magnetic holding means. This is an advantage because electrical insulation of the current path from the housing is ensured. The holding means can for example comprise a plastic or a ceramic or a casting resin.

In a preferred embodiment of the inert gas-insulated medium-voltage power switchgear according to the invention, the holding means is designed for heat transport from the Haltevor device to the housing. On the one hand this is made possible by conduction of heat to the outside, on the other hand an additional possibility is created to transfer heat to the protective gas inside via the surface of the holding means by convection. The holding means preferably has a thermal conductivity of at least 2.5 W / (m * K). A thermal conductivity of more than 3.5W / (m * K) is particularly advantageous. In a preferred embodiment of the gas-insulated medium-voltage power switchgear according to the invention, the holding means is rotatably attached to the housing and can be moved by means of a drive device arranged outside the housing in order to set the switching positions EARTH, OFF and ON of the isolating device. This is an advantage because this design has been tried and tested for a long time. For example, a motor for automatic control of the separating device and / or a hand crank for manual operation can be provided.

To better explain the invention show in the schematic representation

Figure 1 shows a known 3-position disconnector of a gas-insulated medium-voltage power switchgear, and

FIG. 2 shows a first exemplary embodiment of a separating device according to the invention, and

FIG. 3 shows a second view of the separating device according to FIG. 2, and

FIG. 4 components of a dismantled separating device according to FIG. 2, and

Figure 5 shows a first embodiment of a Wärmeleitvor direction, and

Figure 6 is a second schematic view of the Wärmeleitvor direction according to Figure 5, and

Figure 7 shows a second embodiment of a Wärmeleitvor direction, and FIG. 8 shows a second exemplary embodiment of a separating device according to the invention.

For a person skilled in the art, it becomes clear in the context of the preceding description and the following illustration of preferred exemplary embodiments that different variants of the embodiments and exemplary embodiments can be freely combined in order to constructively implement the inventive basic idea of improved heat dissipation from the contacts of the separating device.

Figure 1 shows extracts of a known medium-voltage power switchgear insulated with protective gas with a fluid-tight metal housing 1 made, for example, of cast aluminum (AlsilOMg), which is designed to be filled with an electrically insulating protective gas. A busbar 2 is connected to a Gegenkon clock 7, which is essentially designed as a flat Schmie deteil.

The separating device 3 has a holding device 5 with 4 pairs of contacts, which are designed as so-called separating fingers or contact fingers 6. Shown is the switched-on state in which the contacts 6 touch the mating contact 7 and provides a current path via a joint 3 and a Lei ter 8 to the vacuum circuit breaker (not shown) be. A ground contact 4 is used to ground the Trennvor direction or the vacuum circuit breaker. The Haltvor device 5 with the contacts 6 can be moved in a semicircular arc from the illustrated switching position ON via OFF (holding device 5 perpendicular and in an axis with conductor 8) to ground contact 4 for the switching position EARTH.

FIG. 2 and FIG. 3 show two views of a separating device 6, 9, 10-16 according to the invention, which is spaced apart from the housing 1 by an electrically non-conductive and non-magnetic holding means 9. The holding means 9 is formed out for a heat transport from the holding device to the housing. At the same time it provides a large surface Heat dissipation by convection to the surrounding protective gas ready. The holding means 9 is rotatably attached to the housing. It is movable by means of a drive device 14 arranged outside the housing in order to set the switching positions EARTH, OFF and ON of the separating device. There is also a sliding bearing with high thermal conductivity provided as a contact transfer point to the housing.

The holding means 9 has essentially the shape of a shoe; it tapers towards the slide bearing or towards the drive device 14. The sole 15 is shaped in order to serve as a fastening for a box-shaped holding device 11, 12, 13, 14 for the eight contacts 6, which are designed as contact fingers with contact points 10 for the mating contact. Each pair of contact fingers 6 is spaced apart by a gap which is bridged by two first spring devices 13, 14, which are designed as spiral springs. If the Haltemit tel 9 rotated, the holding device 11 rotates with and pushes the contact fingers 6 at their contact points 10 onto a mating contact. The holding device 11 is essentially box-shaped and has two webs 12 at the end facing away from the contact points 10; it is made of cast aluminum (AlsilOMg).

FIG. 4 shows components of a disassembled separating device, in particular contacts 6 with the first spring devices 13, 16 and contact points 10. Fastening plates 21, 26 serve to attach the contacts 6 in the holding device 11 which connects the holding device 11 and the contacts in the assembled state.

Figure 5 shows a first embodiment of a Wärmeleitvor device 22, which has a first flat area 26, a bundle of litz wires made of copper 23 and a terminating terminal 24 on. The end clamp 24 brings the individual strands of the strand bundle back together. FIGS. 6 and 7 show a schematic detailed view of the embodiment according to FIG. 5. The contact finger 22 has a contact area 10 and a recess 33 on the longest edge of the essentially cuboid contact 22. In the recess 33, a non-magnetic, metallic spring plate - preferably a copper spring plate 25 - is arranged as a second spring device for clamping the copper braided strip 22 against the inside of the cage or box of the holding device. There are used to connect the copper spring plate 25 and contact fingers 22 rivets 32 or screws. Kup ferlitzenband have a high thermal conductivity of approx. 370 W / (m * K). They are preferably arranged by the very inexpensive ultrasonic welding at the attachment point 32 is. Alternatively, the more expensive method of electron beam welding can also be used.

The direct dissipation of heat by conduction is made possible by the newly inserted solid body 22 within the separating device. Due to the large surface of the holding device 11 or the so-called disconnector cage, a medium single-digit temperature drop on the contact fingers 6 is already sufficient. In addition, there is the transfer of heat via the holding means 9 to the housing 1.

The simultaneous retention of the insulation to the current path ensures that no additional components have to be installed in the critical dielectric field area. The heat transport takes place in what is known as the field shadow, so that no further constructive measures have to be taken which increase the distances to the inside of the housing. In comparison to an embodiment with alternative heat sinks, which are usually mounted on the outside of the housing parts of heated components, this variant is to be considered cost-neutral due to the complexity of the assembly sequence.

As an alternative to the flat spring 25, the stranded strips 22 could be screwed to the holding device 11, but this is a This means higher assembly costs, because typically up to 10 stranded straps have to be screwed together manually.

Instead of braided strips 23, copper lamellar strips produced by resistance welding (small current strips), which are screwed together, could alternatively be used.

FIG. 8 shows an alternative embodiment of the separating device, in which the heat-conducting device is firmly connected to the inside of the holding device by means of stranded copper tape 22 and spring plate 25.

Claims

1. Separating device with at least one contact (6) which has a first Federeinrich device (13, 16) to form a pressure force on a mating contact (7), and with a holding device (11, 12) for the contact (6), characterized in that a heat conduction device (22, 23, 24, 25, 31, 32, 35) is designed to press the holding device (11, 12) and the contact (6) against one another.

2. Separating device according to claim 1, characterized in that the heat conduction device (22,23,24,25,31,32,35) is formed out by means of a second spring device (25) a pressure force between the holding device (11,12) and to establish the contact (6).

3. Separating device according to claim 1 or 2, characterized in that the heat conduction device

(22,23,24,25,31,32,35) on the holding device (11,12) is arranged.

4. Separating device according to claim 1 or 2, characterized in that the heat conduction device

(22,23,24,25,31,32,35) is arranged on the contact (6).

5. Separating device according to one of the preceding claims, characterized in that the heat conducting device (22,23,24,25,31,32,35) has a metallic contact material (23).

6. Separating device according to claim 5, characterized in that the metallic contact material has a plurality of stranded conductors (23).

7. Separating device according to claim 5 or 6, characterized in that the metallic contact material (23) is at least partially formed from copper.

8. Separating device according to one of the preceding claims, characterized in that the heat conduction device (22,23,24,25,31,32,35) comprises essentially non-magnetic material.

9. Separating device according to one of the preceding claims, characterized in that a plurality of contacts (6) are designed as pairs of contact fingers, wherein between tween the pairs of contact fingers, a gap for receiving the mating contact (7) is formed.

10. Separating device according to one of the preceding claims, characterized in that the separating device (6,9,10-16) is designed as a three-position separating device with the switching positions EARTH, OFF and ON, wherein at the switching position ON the at least one contact ( 6) is pressed onto the mating contact (7).

11. Inert gas-insulated medium-voltage power switchgear with a vacuum switching arrangement and a disconnecting device

(6,9,10-16) according to any one of claims 1 to 10.

12. Inert gas-insulated medium-voltage power switchgear according to claim 11, characterized in that the medium-voltage power switchgear has a fluid-tight housing (1) which is designed to be filled with a sulfur hexafluoride-free electrically insulating protective gas.

13. Inert gas-insulated medium-voltage power switchgear according to claim 12, characterized in that the separating device (6,9,10-16) is spaced apart from the housing (1) with an electrically non-conductive and non-magnetic holding means (11) .

14. Inert gas-insulated medium-voltage power switchgear according to claim 13, characterized in that the Haltemit tel (9) is designed for heat transport from the holding device (11) to the housing (1).

15. Inert gas-insulated medium-voltage power switchgear according to one of claims 10 to 14, characterized in that the holding means (11) is rotatably attached to the housing (1) and is movable by means of a drive device (14) arranged outside the housing (1) is to set the switch positions EARTH, OFF and ON of the isolating device (6,9,10-16).