DE102020203190B3 - Isolating device and inert gas-insulated medium-voltage power switchgear - Google Patents

Abstract

The subject of the present invention is a separating device with at least one contact (6) which has a first spring device (13, 16) in order to generate a pressure force on a mating contact (7), and with a holding device (11, 12) for the contact (6), and with a heat-conducting device (22, 23, 24, 25, 31, 32, 35) which is designed to press the holding device (11, 12) and the contact (6) against one another, characterized in that the heat-conducting device (22, 23, 24,25,31,32,35) is designed to produce a pressure force between the holding device (11,12) and the contact (6) by means of a second spring device (25) the separating device according to the invention.

Description

The invention relates to a circuit breaker according to claim 1 as well as a gas-insulated medium-voltage power switchgear according to claim 10 and a gas-insulated medium-voltage power switchgear according to claim 14.

Inert gas-insulated medium-voltage power switchgears are known, for example, from the product brochure "Fixed-Mounted Circuit Breakers, Type 8DA and 8DB up to 40.5 kV, Gas-Insulated", Catalog HA 35.11 2006, Siemens AG, Order No .: E50001-K1435-A101-A9. On pages 14 to 18 examples of switchgear are shown that have a separate switchgear for each phase of the medium voltage. 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 disconnector has a plurality of contacts which are designed as contact fingers arranged in pairs, with 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. A first spring device is provided to generate a pressure force on the mating contact, which presses the contact fingers against the mating contact in order to form a connection with good electrical conductivity.

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 the 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 atmosphere inside the encapsulation by convection, non-current carrying 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 it to the environment. The temperature limits for the corresponding interfaces and connection variants are specified in normative terms and may, for example, according to the IEC 62271-1 standard , Edition 20.0 2017-7, must not be exceeded.

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 IEC 62271-1 standard provides for the contact fingers on pages 64 and 65, for example, that the contacts have a maximum temperature of 115 when using low-temperature hexafluoride as NOT-OXIDIZING GAS (NOG, see "Point 5" on page 67) and an ambient temperature of 40 ° C maximum ° C if the contacts are made of pure copper or have a silver or nickel coating. The ambient temperature must be taken into account here because heat transport always 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 additionally 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 thus 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. With 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 result in compliance with the prescribed temperature limits for contacts and other components may be necessary.

On the other hand, movable assemblies such as fans inside the housing are usually not provided because there are other moving parts inside that 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 designs.

Furthermore, from the publication EP 3 439 009 A1 a gas-insulated switchgear and from the publication DE 32 15 110 A1 a tap switch system is known.

The object of the invention is to use known separating devices as a starting point to specify a separating device which allows a comparatively high amount of heat to be given off to the environment and at the same time can be manufactured inexpensively.

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. 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 expected 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 presses or pulls the contact and mating contact together in the ON position in order to ensure good electrical conductivity. One spring device can preferably be used per contact or contact finger. Alternatively, a single spring can 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 therefore usually ruled out, while copper or aluminum or brass also due to 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, by conduction of heat at the contact points between the contacts and the mating contact, to dissipate heat loss to the holding device in an improved manner. This considerably increases the available surface for heat radiation.

The heat conduction 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 are suitable for their comparatively low cost. The second spring device can, for example, have a spiral spring or a plate spring. A leaf spring can also be used to 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 metal. On its longest side, the contact can have a recess for receiving the heat-conducting device with the second spring device, so that the heat-conducting device does not unnecessarily increase the space required for the contact in the separating device. The heat conduction device is accordingly 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 conducting device has a metallic contact material. Because of its high thermal conductivity, copper is advantageously used, at least in part, for the heat conduction device. Copper has that Another advantage that it can be attached particularly inexpensively by ultrasonic welding. Alternatively, at least some of the 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 comprises 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 are suitable for their comparatively low cost.

In a preferred embodiment of the separating device according to the invention, several 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, with the at least one contact being pressed onto the mating contact in the switching position ON.

The object of the invention is to use known medium-voltage power switchgear insulated with inert gas to specify a switchgear that allows a comparatively high amount of heat to be dissipated 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 10.

The vacuum switching arrangement comprises, for example, a vacuum interrupter in order to quickly achieve arc quenching when it is disconnected. In a preferred embodiment of the medium-voltage power switchgear insulated with protective gas according to the invention, the medium-voltage power switchgear has a fluid-tight housing which is designed to be filled with a sulfur hexafluoride-free electrically insulating protective gas. For example, so-called “clean air”, ie essentially moisture-free compressed air, or a mixture of essentially nitrogen and carbon dioxide, can be used. This is an advantage because the replacement of the climate-damaging sulfur hexafluoride gas usually results in a lower electrical insulation capacity. The energy consumption and energy output is also often comparatively lower. The solution according to the invention can thus be used to advantage in order to facilitate the removal of heat from the contacts to the housing. By using the heat conduction device, the system is able to transfer the power loss to the cooler housing very efficiently through heat conduction. The process of heat conduction takes place regardless of the insulating gas used and the gas pressure set. The switchgear can therefore be designed to be more cost-effective and at the same time high currents can be transmitted.

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 holding device to the housing. On the one hand, this enables heat to be conducted to the outside; on the other hand, an additional possibility is created to transfer heat to the protective gas inside by convection via the surface of the holding means. 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.

Furthermore, an inert gas-insulated medium-voltage power switchgear according to claim This is an advantage because this design is simple and 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.

• 1 einen bekannten 3-Stellungstrennschalter einer schutzgasisolierte Mittelspannungs-Leistungsschaltanlage, und
• 2 ein erstes Ausführungsbeispiel einer erfindungsgemäßen Trennvorrichtung, und
• 3 eine zweite Ansicht der Trennvorrichtung gemäß 2, und
• 4 Bestandteile einer demontierte Trennvorrichtung gemäß 2, und
• 5 ein erstes Ausführungsbeispiel einer Wärmeleitvorrichtung, und
• 6 eine zweite schematische Ansicht der Wärmeleitvorrichtung gemäß 5, und
• 7 ein zweites Ausführungsbeispiel einer Wärmeleitvorrichtung, und
• 8 ein zweites Ausführungsbeispiel einer erfindungsgemäßen Trennvorrichtung.

For a better explanation of the invention show in a schematic representation

• 1 a known 3-position disconnector of an inert gas-insulated medium-voltage power switchgear, and
• 2 a first embodiment of a separating device according to the invention, and
• 3 a second view of the separating device according to 2 , and
• 4th Components of a dismantled separating device according to 2 , and
• 5 a first embodiment of a heat conduction device, and
• 6th a second schematic view of the heat conduction device according to 5 , and
• 7th a second embodiment of a heat conduction device, and
• 8th a second 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.

the 1 shows, in extracts, a known gas-insulated medium-voltage power switchgear with a fluid-tight metal housing 1 made of cast aluminum (Alsi10Mg), for example, which is designed to be filled with an electrically insulating protective gas. A busbar 2 is with a counter contact 7th connected, which is formed essentially as a flat forged part.

The separator 3 has a holding device 5 with 4 pairs of contacts, the so-called separating fingers or contact fingers 6th are trained. The switched-on state is shown, in which the contacts 6th the mating contact 7th touch and connect a current path through a joint 3 and a ladder 8th to the vacuum circuit breaker (not shown). An earth contact 4th serves to ground the disconnection device or the vacuum circuit-breaker. The holding device 5 with the contacts 6th can move in a semicircular arc from the illustrated switching position ON via OFF (holding device 5 perpendicular and in one axis with a ladder 8th ) to earth contact 4th for the switching position EARTH.

2 and 3 show two views of a separating device according to the invention 6,9,10-16 with an electrically non-conductive and non-magnetic holding means 9 from the housing 1 is spaced. The holding means 9 is designed for heat transport from the holding device to the housing. At the same time, it provides a large surface area for heat dissipation by convection to the surrounding protective gas. The holding means 9 is rotatably attached to the housing. It is by means of a drive device arranged outside the housing 14th movable to set the switch positions EARTH, OFF and ON of the disconnection device. A slide bearing with high thermal conductivity is also provided as a contact transfer point to the housing.

The holding means 9 has a substantially shoe shape; it tapers towards the plain bearing or the drive device 14th there. The sole 15th is shaped to be used as a fastening for a box-shaped holding device 11, 12, 13, 14 for the eight contacts 6th that act as contact fingers with contact points 10 are designed for the mating contact to serve. Any pair of contact fingers 6th is spaced apart by a gap which is bridged by two first spring devices 13, 14, which are designed as spiral springs. Will the holding means 9 rotated, the holding device rotates 11 with and pushes the contact fingers 6th at their contact points 10 on a mating contact. The holding device 11 is essentially box-shaped and has the contact points 10 remote end two webs 12th on; it consists of cast aluminum (Alsi10Mg).

4th shows components of a disassembled separating device, in particular contacts 6th with the first spring devices 13, 16 and contact points 10 . Fastening plates 21, 26 are used to attach the contacts 6th in the holding device 11 . The contacts point to heat dissipation by conduction 6th one heat conduction device each 22nd on, the holding device in the assembled state 11 and connects the contacts.

5 shows a first embodiment of a heat conduction device 22nd having a first flat area 26th , a bundle of stranded copper wires 23 and a termination clip 24 having. The terminating clamp 24 brings the individual strands of the strand bundle back together.

6th and 7th show a schematic detailed view of the embodiment according to 5 . The contact finger 22nd has a contact area 10 as well as a recess 33 at the longest edge of the essentially cuboid contact 22nd on. In the recess 33 The second spring device is a non-magnetic, metallic spring plate - preferably a copper spring plate 25th - for clamping the copper braid 22nd arranged against the cage or box inside of the holding device. It is used to connect copper spring steel sheets 25th and contact fingers 22nd Rivets 32 or screws used. Stranded copper tapes have a high thermal conductivity of approx. 370 W / (m * K). They are preferred by the very inexpensive ultrasonic welding at the point of attachment 32 arranged. Alternatively, the more expensive method of electron beam welding can also be used.

The direct heat dissipation through conduction is made possible by the newly inserted solids 22nd allows within the separation device. Due to the large surface of the holding device 11 or the so-called disconnector cage, there is already a medium single-digit temperature drop on the contact fingers 6th achieved. 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 that 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.

Alternative to the flat spring 25th could the braided straps 22nd with the holding device 11 be screwed, which, however, means a higher installation effort, because typically up to 10 stranded strips have to be screwed together manually.

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

8th shows an alternative embodiment of the separating device, in which the heat conduction device with copper braided tape 22nd and spring plate 25th is firmly connected to the inside of the holding device.

Claims (14)

Separating device with at least one contact (6), which has a first spring device (13, 16) to form a pressure force on a mating contact (7), and with a holding device (11, 12) for the contact (6), and with a heat conduction device (22,23,24,25,31,32,35) which is designed to press the holding device (11,12) and the contact (6) against one another, characterized in that the heat conduction device (22,23,24, 25, 31, 32, 35) is designed to produce a pressing force between the holding device (11, 12) and the contact (6) by means of a second spring device (25). Separating device according to Claim 1 , characterized in that the heat conduction device (22,23,24,25,31,32,35) is arranged on the holding device (11,12). 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). 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). Separating device according to Claim 4 , characterized in that the metallic contact material has several stranded conductors (23). Separating device according to Claim 4 or 5 , characterized in that the metallic contact material (23) is at least partially formed from copper. Separating device according to one of the preceding claims, characterized in that the heat-conducting device (22, 23, 24, 25, 31, 32, 35) comprises essentially non-magnetic material. Separating device according to one of the preceding claims, characterized in that a plurality of contacts (6) are designed as contact fingers arranged in pairs, a gap for receiving the mating contact (7) being formed between the pairs of contact fingers. Separating device according to one of the preceding claims, characterized in that the separating device is designed as a three-position separating device with the switching positions EARTH, OFF and ON, the at least one contact (6) being pressed onto the mating contact (7) in the switching position ON. Inert gas-insulated medium-voltage power switchgear with a vacuum switching arrangement and a separating device according to one of the Claims 1 until 9 . Inert gas-insulated medium-voltage switchgear according to Claim 10 , 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. Inert gas-insulated medium-voltage switchgear according to Claim 11 , characterized in that the separating device is spaced apart from the housing (1) by an electrically non-conductive and non-magnetic holding means (11). Inert gas-insulated medium-voltage switchgear according to Claim 12 , characterized in that the holding means (9) is designed for heat transport from the holding device (11) to the housing (1). Inert gas-insulated medium-voltage power switchgear with a fluid-tight housing and with a vacuum switching arrangement and a separating device, characterized in that the separating device according to Claim 9 is formed, and that the separating device with an electrically non-conductive and non-magnetic holding means (11) is spaced from the housing (1), and that the holding means (11) is rotatably attached to the housing (1) and by means of an outside of the housing (1) arranged drive device (14) is movable in order to set the switching positions EARTH, OFF and ON of the separating device.

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