CN112074923B - Gas-insulated medium-voltage switch with shielding device - Google Patents
Gas-insulated medium-voltage switch with shielding device Download PDFInfo
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- CN112074923B CN112074923B CN201880065053.8A CN201880065053A CN112074923B CN 112074923 B CN112074923 B CN 112074923B CN 201880065053 A CN201880065053 A CN 201880065053A CN 112074923 B CN112074923 B CN 112074923B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H33/00—High-tension or heavy-current switches with arc-extinguishing or arc-preventing means
- H01H33/70—Switches with separate means for directing, obtaining, or increasing flow of arc-extinguishing fluid
- H01H33/7015—Switches with separate means for directing, obtaining, or increasing flow of arc-extinguishing fluid characterised by flow directing elements associated with contacts
- H01H33/7038—Switches with separate means for directing, obtaining, or increasing flow of arc-extinguishing fluid characterised by flow directing elements associated with contacts characterised by a conducting tubular gas flow enhancing nozzle
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H33/00—High-tension or heavy-current switches with arc-extinguishing or arc-preventing means
- H01H33/70—Switches with separate means for directing, obtaining, or increasing flow of arc-extinguishing fluid
- H01H33/88—Switches with separate means for directing, obtaining, or increasing flow of arc-extinguishing fluid the flow of arc-extinguishing fluid being produced or increased by movement of pistons or other pressure-producing parts
- H01H33/90—Switches with separate means for directing, obtaining, or increasing flow of arc-extinguishing fluid the flow of arc-extinguishing fluid being produced or increased by movement of pistons or other pressure-producing parts this movement being effected by or in conjunction with the contact-operating mechanism
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H1/00—Contacts
- H01H1/12—Contacts characterised by the manner in which co-operating contacts engage
- H01H1/36—Contacts characterised by the manner in which co-operating contacts engage by sliding
- H01H1/38—Plug-and-socket contacts
- H01H1/385—Contact arrangements for high voltage gas blast circuit breakers
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H33/00—High-tension or heavy-current switches with arc-extinguishing or arc-preventing means
- H01H33/70—Switches with separate means for directing, obtaining, or increasing flow of arc-extinguishing fluid
- H01H33/88—Switches with separate means for directing, obtaining, or increasing flow of arc-extinguishing fluid the flow of arc-extinguishing fluid being produced or increased by movement of pistons or other pressure-producing parts
- H01H33/90—Switches with separate means for directing, obtaining, or increasing flow of arc-extinguishing fluid the flow of arc-extinguishing fluid being produced or increased by movement of pistons or other pressure-producing parts this movement being effected by or in conjunction with the contact-operating mechanism
- H01H33/904—Switches with separate means for directing, obtaining, or increasing flow of arc-extinguishing fluid the flow of arc-extinguishing fluid being produced or increased by movement of pistons or other pressure-producing parts this movement being effected by or in conjunction with the contact-operating mechanism characterised by the transmission between operating mechanism and piston or movable contact
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- Arc-Extinguishing Devices That Are Switches (AREA)
- Circuit Breakers (AREA)
Abstract
According to a first aspect of the invention, a gas-insulated medium voltage switch (1, 2) is provided. The switch (1, 2) comprises a first contact element (10), a second contact element (20) and a shield (50), the first contact element (10) having a nominal contact surface (12), wherein the shield (50) and the first contact element (10) are movable relative to each other between an exposed configuration and a shielded configuration, wherein in the exposed configuration the shield (50) and the first contact element (10) are arranged to expose the nominal contact surface (12) to the second contact element (20), and in the shielded configuration the shield (50) and the first contact element (10) are arranged to shield the nominal contact surface (12) from the second contact element (20). According to a second aspect of the invention, a method of performing a current breaking operation by means of a switch (1, 2) is provided.
Description
Technical Field
Aspects of the present invention generally relate to a gas-insulated medium voltage switch with the ability to suppress arc restrike, a power distribution network, ring main unit or secondary distribution gas-insulated switchgear having such a switch, and a method of breaking current using the switch.
Background
The gas-insulated switch includes an electrically insulating gas within its housing. Gas-insulated medium-voltage switches are used in various settings, such as in power distribution networks, ring main units or secondary distribution gas-insulated switchgear. When switching the current, the switch is opened by a relative movement of the contacts (plug and tube) away from each other, whereby an arc may form between the separated contacts.
In order to extinguish the arc generated in the current breaking operation, some types of switches are equipped with an arc extinguishing system. In one type of switch, the arc quenching system operates by releasing a quenching gas toward the arc for cooling the arc and ultimately extinguishing the arc.
Generally, low cost and operational reliability are two major factors of medium voltage switches. It is therefore generally desirable to use a simple and cost effective assembly for each part of the switch. In particular, the design of low cost drivers that implement switches is often welcome. Furthermore, one aspect that affects the operational reliability is that the heating of the electrically insulating gas resulting from the extinguishing of the arc changes the dielectric properties of the heated gas that accumulates in the area around the two contacts. Thus, the risk of undesirable arc reignition or other discharge during or after arc extinction may increase.
Disclosure of Invention
It is an object of the present invention to provide an improved gas-insulated medium voltage switch which allows reliable operation while still maintaining, at least to a certain extent, a relatively low cost and compact design.
In view of the above, a gas-insulated medium voltage switch according to claim 1 and a method of performing a current breaking operation according to claim 14 are provided.
According to a first aspect of the present invention, a gas-insulated medium voltage switch is provided. The switch includes: a first contact element having an arcing contact surface and a nominal contact surface, wherein the first contact element is movable along an axis of the switch for opening and closing the switch; a second contact element configured to make contact with the first contact element for closing the switch; and a shield, wherein the shield and the first contact element are movable relative to each other along an axis between an exposed configuration and a shielded configuration such that the shield and the first contact element are in the exposed configuration when the switch is in the closed state and in the shielded configuration during opening of the switch, wherein in the exposed configuration the shield and the first contact element are arranged to expose the nominal contact surface to the second contact element, and in the shielded configuration the shield and the first contact element are arranged to shield the nominal contact surface of the first contact element from the second contact element.
According to a second aspect of the invention, a method of performing a current breaking operation by means of a switch is provided, wherein the switch comprises a first contact element having an arcing contact surface and a nominal contact surface, the arcing contact surface defining an arcing zone, a second contact element, and a shield, wherein the shield and the first contact element are movable relative to each other along an axis. The method comprises the following steps: separating the first contact element from the second contact element by relative movement along the axis of the switch away from each other such that an arc is formed in the arc region; and moving the first contact element and the shield relative to each other from an exposed configuration, in which the nominal contact surface is exposed to the second contact element, to a shielded configuration, in which the nominal contact surface is shielded from the second contact element.
According to another aspect, the switch is a load break switch. As defined herein, a loadbreak switch has the ability to switch load current, but does not have short circuit switching capability. The load current is also referred to as the rated current or nominal current of the switch and is at most 2000A, preferably at most 1250A, more preferably at most 1000A. The current in this range is a typical rated current for distribution networks, ring main units and secondary distribution gas insulated switches. On the other hand, the rated current may be greater than 1A, more preferably greater than 100A, more preferably greater than 400A. In the case of an AC load breaker, the rated current is here represented by the root mean square current.
Here, the medium voltage is defined as a voltage in the range of 1kV to 72 kV. Medium voltage switches therefore have a rated voltage of at most 72 kV. In particular, the rated voltage may be at most 52kV, or preferably at most 36kV, or more preferably at most 24kV, or most preferably at most 12 kV.
Embodiments of the present invention enable current breaking operations to be performed with reduced occurrences of arc reignition (particularly between the nominal contacts of the switch) as compared to conventional designs, thereby achieving more reliable operation. These embodiments are particularly advantageous for thermally interrupting load current in a wide range of possible load short circuit scenarios and environmental conditions. Also, these embodiments are particularly applicable to the alternative quench gases mentioned herein.
Further advantages, features, aspects and details, which can be combined with the embodiments described herein, are apparent from the dependent claims, the description and the drawings.
Drawings
The invention will be explained in more detail with reference to the drawings, in which
Fig. 1a to 1d show cross-sectional views of a load break switch according to an embodiment of the present invention in a closed (closed) state (fig. 1a), an opening (opening) state (fig. 1b), an opening (opening) state (fig. 1c) and a closing (closing) state (fig. 1 d);
fig. 2a to 2d show cross-sectional views of a load break switch according to an embodiment of the present invention in a closed state (fig. 2a), in an open state (fig. 2b), in an open state (fig. 2c) and in a closed state (fig. 2 d); and
fig. 3 shows a flow chart of a method of performing a current breaking operation according to an embodiment of the invention.
Detailed Description
In the following description of the embodiments illustrated in the drawings, like reference numerals designate the same or similar components. Generally, only the differences of individual embodiments are described. Unless otherwise specified, descriptions of parts or aspects in one embodiment apply equally to corresponding parts or aspects in another embodiment.
Fig. 1A to 1D show cross-sectional views of a load break switch 1 according to an embodiment of the present invention. Fig. 1A shows the switch in a closed state, fig. 1B shows the switch in an open state during a current breaking operation, fig. 1C shows the switch in an open state, and fig. 1D shows the switch in a closed state.
The switch 1 has a gas-tight housing 5, the inner volume of which is filled at an ambient pressure p0The lower electrically insulating gas.
Within the housing 5 there is a first contact element 10 and a second contact element 20. The first contact element 10 is a movable tube contact and the second contact element 20 is a fixed pin contact. The first contact element 10 has an arcing contact surface 11 and a nominal contact surface 12.
The switch 1 further comprises a shield 50. The shield 50 may have a flat disc shape extending radially outward from the axis 6 of the switch 1 such that the shield 50 divides the interior volume of the housing 5 into a first region 3 and a second region 4. The shield 50 further comprises an opening in its centre for surrounding the first contact element 10 such that an inner surface of the opening is in sliding contact with the nominal contact surface 12 of the first contact element 10.
The shield 50 can be moved relative to the first contact element 10 and/or the housing 5 in the direction of the axis 6 of the switch 1. The friction element 52 provided on the shield 50 is in frictional contact with the inner surface of the housing 5, so that the shield 50 requires a movement force of a larger magnitude than the movement force for the movement of the first contact element 10. The friction element 52 may comprise a seal, for example a rubber O-ring, such that electrically insulating gas in the first region 3 cannot flow between the shield 50 and the inner surface of the housing 5 into the second region 4.
During the movement of the shield 50 in the direction of the axis 6 of the switch 1, the volume of the first region 3 and the second region 4 will change. At least an opening 51 in the shield 50 allows the flow of electrically insulating gas from the first region 3 to the second region 4 such that the gas pressure is equal between the two regions. The shield 50 may include a plurality of openings 51. The opening 51 will be located closer to the periphery of the shield 50 in the region close to the housing 5, in particular the opening 51 should be located away from the first contact element 10 to avoid that an arc reignites between the nominal contact surface 12 and the second contact element 20 through the opening 51.
As the first contact element 10 and the shield 50 are movable relative to each other, the first contact element 10 and the shield may be configured in one of two configurations.
As shown in fig. 1A and 1D, when the first contact element 10 extends outwardly from the shield 50, the first contact element 10 and the shield 50 may be considered to be in an exposed configuration such that the nominal contact surface 12 is exposed to the second contact element 20. In the exposed configuration, the nominal contact surface 12 may be in contact with the second contact element 20, so that a current may flow through the switch 1.
However, in the exposed configuration, a re-ignition of the arc between the nominal contact surface 12 and the second contact element 20 may occur during the current breaking operation. As shown in fig. 1B and 1C, when the first contact element 10 is retracted behind the shield 50, the first contact element 10 and the shield 50 may be considered to be in a shielding configuration such that the nominal contact surface 12 is shielded from the second contact element 20. In the shielding configuration, the communication between the nominal contact surface 12 and the second contact element 20 via the electrically insulating gas is significantly limited. Limiting the exposure of the nominal contact surface 12 to the second contact element 20 greatly reduces the occurrence of re-ignition of the arc between the nominal contact surface 12 and the second contact element 20.
In the context of the present invention, the term "shielding" is understood as mechanical shielding, i.e. a mechanical (preferably insulating) shield is arranged in a space which is otherwise prone to arcing and/or discharge between conductors on opposite sides of the space.
The first contact element 10 may further comprise at least a contact actuating element 14 and the shield 50 may further comprise at least a shield actuating element 53. The relative movement of the first actuation element 14 and the shield actuation element 53 with respect to the first contact element 10 and the shield 50 defines a mechanical limit or stop. At the limit of the relative movement, the first actuation element 14 engages with the shield actuation element 53, so that any further movement of the first contact element 10 causes the shield 50 to move.
As an example of a current breaking operation or an operation of opening a switch, the first contact element 10 and the shield 50 are moved relative to the second contact element 20.
A first opening movement is performed in which the first contact element 10 is separated from the second contact element 20 and retracted into the shield 50. During this first opening movement, the shield 50 remains stationary with respect to the second contact element 20 and the housing 5 due to the friction element 52. The first contact element 10 is moved along the axis 6 of the switch 1 until the first contact actuating element 14 engages with the shield actuating element 53.
Towards the end of the first opening movement, the first contact element 10 is separated from the second contact element 20. Thus, an arc is formed between the second contact element 20 and the arcing contact surface 11 in the arcing zone 31. Furthermore, the nominal contact surface 12 of the first contact element 10 is moved behind the shield 50 such that the first contact element 10 and the shield 50 are in a shielding configuration. At the end of the first opening movement, the first actuation element 14 engages with the shield actuation element 53, as shown in fig. 1B.
A second opening movement is performed, wherein the first contact element 10 continues to move along the axis 6 of the switch in a direction away from the second contact element 20. The first actuating element 14, which engages with the shield actuating element 53, moves the shield 50 together with the first contact element 10 along the axis 6 of the switch 1.
During the second opening movement, the electrically insulating gas in the second region 4 can flow into the first region 3 through the opening 51, so that the gas pressures are equal. The movement of the first contact 10 continues until the switch is fully opened, as shown in fig. 1C. The insulating gas in the second region is heated by extinguishing the arc formed in the arc region 31. The nominal contact surface 12 continues to be shielded from the second contact element 20 by the shield 50, so that the re-ignition of the arc between the nominal contact surface 12 and the second contact element 20 is suppressed despite the change in the dielectric properties of the heated insulating gas accumulated in the second region 4.
Similarly, as an example of a current-on operation or an operation of closing a switch, the first contact element 10 and the shield 50 are moved relative to the second contact element 20.
A first closing movement is performed in which the first contact element 10 is moved along the axis 6 of the switch 1, 2 towards the second contact element 20. During this first closing movement, the shield 50 is held in a fixed position relative to the second contact element 20 due to the friction element 52. The first contact element 10 is moved along the axis 6 of the switches 1, 2 until the first contact actuating element 14 engages the shield 50.
Towards the end of the first closing movement, the relative movement of the first contact element 10 moves the first contact element 10 and the shield 50 from the shielding configuration to the exposure configuration, wherein the nominal contact surface 12 moves from behind the shield 50 to be exposed to the second contact element 20. At the end of the first closing movement, the first actuating element 14 engages the shield 50, as shown in fig. 1D.
A second closing movement is performed, wherein the first contact element 10 continues to move along the axis 6 of the switch in a direction towards the second contact element 20. The first actuating element 14, which engages with the shield actuating element 50, moves the shield 50 together with the first contact element 10 along the axis 6 of the switch 1.
During the second closing movement, the electrically insulating gas in the first region 3 can flow into the second region 4 through the opening 51, so that the gas pressures are equal. The movement of the first contact 10 continues until the switch is fully closed, as shown in fig. 1A. The nominal contact surface 12 continues to be exposed to the second contact element 20 by the shield 50, allowing an electrical connection to be established between the nominal contact surface 12 and the second contact element 20.
According to embodiments of the present invention (which may be combined with other embodiments described herein), the first contact element 10 may comprise an insulative tip 13 at a distal axial position relative to the nominal contact surface 12. The insulated terminations 13 may comprise a non-conductive material.
When the first contact element 10 and the shield 50 are in the shielding configuration, the insulative tip 13 may be positioned such that the opening in the center of the shield 50 is in sliding contact with the outer surface of the insulative tip 13. The insulating stub 13 may have a tubular shape, so that the second contact element 20 may protrude through the insulating stub 13 and may be in electrical contact with the first contact element 10 when the switch is in the closed state. According to embodiments of the present invention (which may be combined with other embodiments described herein), the first contact element 10 may have a tubular shape. In this case, the arcing contact surface 11 is the inner surface of the tubular first contact element 10 and the nominal contact surface 12 is the outer surface of the tubular first contact element 10. Furthermore, the second contact element 20 may have a pin shape, such that the pin-shaped second contact element 20 is configured to be inserted into the tube-shaped first contact element 10 when the switch is in the closed state.
Referring now to fig. 2A-2D, the switch 2 may further include a gas pressurization system for actively extinguishing an arc formed in the arc region 31. According to an embodiment of the invention (which may be combined with other embodiments described herein), the switch 2 further comprises a piston 30 for pressurizing the quenching gas during the current breaking operation, wherein the piston is configured to compress the quenching gas, the compressed gas being blown in an axial direction through the inner portion of the first contact element 10 and the insulating end portion 13 towards the second contact element 20 to extinguish an arc formed in the arc region 31. Integrated in the first contact 10 is an arc quenching system for extinguishing an arc. The arc extinguishing system has a pressurization system (air compression system) and a nozzle comprising a tubular first contact element 10 and an insulating tip 13. The pressurized system includes a first zone 3, the first zone 3 having a quench gas contained therein. The quenching gas is part of the electrically insulating gas contained in the housing 5 of the switch. The pressurized chamber is delimited by the housing 5 and by a piston 30, the piston 30 serving to compress the quenching gas within the first region 3 during the current breaking operation. For this purpose, the piston 30 moves together with the first contact element 10, so that the piston 30 pressurizes the quenching gas in the pressurizing chamber when the first contact element 10 moves away from the second contact 20 for opening the switch, as shown in fig. 2B and 2C. The energy for the pressurized quenching gas is thus ultimately provided by the drive driving the first contact element 10.
The nozzle comprising the tubular first contact element 10 and the insulating end 13 is adapted to blow pressurized quenching gas from the pressurized chamber onto the arc formed in the arc region 31 during the current breaking operation. The nozzle has at least a nozzle inlet connected to the first zone 3 for receiving pressurized quenching gas from the first zone 3, and a nozzle outlet connected to the second zone 4 via the arc zone 31.
The pressurization system and the nozzle comprising the tubular first contact element 10 and the insulating tip 13 are dimensioned such that the flow of the quenching gas is subsonic. This subsonic flow corresponds to a relatively low quenching pressure p in the pressure chamberquench(pquench＜1,8*p0As defined herein) and therefore only imposes moderate requirements on the driver of the switch.
The piston 30 may have a flat disk shape extending radially outward from the axis 6 of the switch 1 such that the piston 30 and the shield 50 divide the interior volume of the housing 5 into a first region 3 and a second region 4. The center of the piston 30 is fixed to the first contact element 10 so that the piston 30 moves together with the first contact element 10.
The shield 50 further comprises a shield skirt portion 54, which shield skirt portion 54 extends in a direction parallel to the housing 5 away from the second contact element 20 and comprises a shield actuation element 53. The outer surface of the piston 30 is in sliding contact with the shield skirt portion 54 of the shield 50 so that the first contact element 10 can move freely relative to the shield 50.
During the movement of the first contact element 10 and thus of the piston 30, the volume of the region between the piston 30 and the shield 50 will change in the direction of the axis 6 of the switch 2. At least one opening 51 in the shield 50 allows electrically insulating gas to flow from the second region 3 to the region between the piston 30 and the shield 50, so that the gas pressure is equal between the two regions. Since the movement of the piston 30 relative to the shield 50 occurs substantially before the first contact element 10 is separated from the second contact element 20 and before the arc is formed in the arc zone 31, the insulating gas drawn into the zone between the piston 30 and the shield 50 is in a state substantially not heated by the extinguishing of the arc. Thus, the insulating gas in the region between the piston 30 and the shield 50, in particular the insulating gas surrounding the nominal contact surface 12 when in the shielding configuration, has not changed significantly in dielectric properties due to the extinguishing of the arc, so that an arc reignition between the nominal contact surface 12 and the second contact element 20 is further suppressed.
The piston 30 is configured to engage with the shield actuation element 53 for moving the shield 50. The piston 30 and the shield actuation member 53 define a mechanical limit or stop with respect to the relative movement of the first contact element 10 and the shield 50. At the limit of the relative movement, the piston 30 engages with the shield actuating element 53, so that any further movement of the first contact element 10 causes the shield 50 to move. According to the embodiment shown in fig. 2A to 2D, the first contact element 10 and the shield 50 are moved relative to the second contact element 20 as an example of a current breaking operation or an operation of opening the switch 2.
A first opening movement is performed in which the first contact element 10 is separated from the second contact element 20 and retracted into the shield 50. During this first opening movement, the shield 50 remains stationary with respect to the second contact element 20 and the housing 5 due to the friction element 52. The first contact element 10 is moved along the axis 6 of the switch 1 until the piston 30 engages the shield actuating element 53.
Towards the end of the first opening movement, the first contact element 10 is separated from the second contact element 20. Thus, an arc is formed between the second contact element 20 and the arcing contact surface 11 in the arcing zone 31. Furthermore, the nominal contact surface 12 of the first contact element 10 is moved behind the shield 50 such that the first contact element 10 and the shield 50 are in a shielding configuration. At the end of the first opening movement, the piston 30 engages with the shield actuating member 53, as shown in fig. 2B.
During the first opening movement, the electrically insulating gas in the second region 4 can flow through the opening 51 into the region between the piston 30 and the shield 50, so that the gas pressures are equal.
A second opening movement is performed, wherein the first contact element 10 continues to move along the axis 6 of the switch in a direction away from the second contact element 20. The piston 30, which engages with the shield actuating element 53, causes the shield 50 and the first contact element 10 to move together along the axis 6 of the switch 1.
The movement of the first contact 10 continues until the switch is fully opened, as shown in fig. 1C. The arc formed in the arc zone 31 is extinguished by the pressurized quenching gas forced through the nozzle comprising the tubular first contact element 10 and the insulated end portion 13. The nominal contact surface 12 continues to be shielded from the second contact element 20 by the shield 50, so that the re-ignition of the arc between the nominal contact surface 12 and the second contact element 20 is suppressed despite the change in the dielectric properties of the heated insulating gas that accumulates in the second region 4.
Similarly, as an example of a current-on operation or an operation of closing the switch, the first contact element 10 and the shield 50 are moved relative to the second contact element 20.
A first closing movement is performed in which the first contact element 10 is moved along the axis 6 of the switch 2 towards the second contact element 20. During this first closing movement, the shield 50 is held in a fixed position relative to the second contact element 20 due to the friction element 52. The first contact element 10 is moved along the axis 6 of the switch 2 until the first contact actuating element 14 engages the shield 50.
During the first closing movement, the electrically insulating gas in the region between the piston 30 and the shield 50 can flow through the opening 51 into the second region 4, so that the gas pressures are equal.
Towards the end of the first closing movement, the relative movement of the first contact element 10 moves the first contact element 10 and the shield 50 from the shielding configuration to the exposure configuration, in which the nominal contact surface 12 is moved from behind the shield 50 to be exposed to the second contact element 20. At the end of the first closing movement, the first actuating element 14 engages the shield 50, as shown in fig. 2D.
A second closing movement is performed, wherein the first contact element 10 continues to move along the axis 6 of the switch in a direction towards the second contact element 20. The first actuating element 14, which engages with the shield actuating element 50, moves the shield 50 together with the first contact element 10 along the axis 6 of the switch 2.
The movement of the first contact 10 continues until the switch is fully closed, as shown in fig. 1A. The nominal contact surface 12 continues to be exposed to the second contact element 20 by the shield 50, allowing an electrical connection to be established between the nominal contact surface 12 and the second contact element 20.
General preferred aspects of the invention
These advantages are not limited to the embodiments shown in fig. 2a to 3, but the switch may be modified in a number of ways. In the following, some generally preferred (i.e., optional) aspects of the invention are described. This description is explained using the reference numerals of fig. 1A to 1D and fig. 2A to 2D, but the aspect is not limited to this embodiment. Each of these aspects may be used alone or in combination with any other aspect(s) described herein.
According to another aspect of the invention, the switch 2 may further comprise at least one gas outlet 32, the at least one gas outlet 32 being for exhausting the quenching gas from inside the housing 5 to outside the housing 5. The gas outlet 32 is positioned in the housing 5 in the second region 4 and is configured to discharge a portion of the quench gas from inside the housing 5. During extinguishing of the arc generated in the arc region 31, the quenching gas is heated and expands in the second region 4, which may allow a portion of the heated quenching gas to flow through the opening 51 in the shield 50. Venting such heated quench gas reduces the effects of changes in the dielectric properties of the quench gas during current interruption operations to further inhibit arc reignition between the nominal contact surface 12 and the second contact element 20.
According to another aspect of the invention, the loadbreak switches 1, 2 are of single-action type. According to one aspect, the first contact element 10 is a movable contact and is movable along the axis 6 away from the second contact element 20 for opening the switch. The second contact element 20 may be stationary, e.g. fixed to the housing 5. The first contact element 10 is driven by a driver.
According to another aspect, the first contact element 10 and the second contact element 20 have a maximum contact spacing of at most 150mm (preferably at most 110mm) and/or at least 10mm, preferably a maximum contact spacing of 25mm to 75 mm.
According to another aspect, the housing 5 has a (radial) diameter of 40mm to 80mm and/or a maximum (axial) length of 40mm to 200 mm.
In another aspect, the pressurization system may be configured to pressurize the quench gas to a quench pressure p during a circuit breaking operationquench＜1,8*p0Wherein p is0Is the ambient (equilibrium) pressure of the insulating gas in the total volume 6 of the housing, and pquenchIs the (maximum overall) pressure of the insulating gas (also referred to as quenching gas) which is pressurized in the pressurization chamber during the current breaking operation. This condition of the quench pressure ensures that the flow of the quench gas is subsonic and at the same time limits the requirements of the actuators that are normally responsible for pressurizing the quench gas.
More preferably, the quenching pressure satisfies pquench＜1,5*p0Or pquench＜1,3*p0Or even pquench＜1,1*p0. On the other hand, the quenching pressure preferably satisfies pquench>1,01*p0So that the pressure rises enough to extinguish the arc.
According to another aspect, the quench pressure satisfies pquench＜p0+800mbar, preferably satisfying pquench＜p0+500mbar, more preferably satisfying pquench＜p0+300mbar, and even more preferably satisfies pquench＜p0+100 mbar. On the other hand, the quenching pressure preferably satisfies pquench>p0+10mbar。
Typically, the ambient pressure p of the (total) insulating gas in the housing0Is that<3bar, more preferably p0<1,5bar, and even more preferably p0<＝1,3bar。
The pressure difference that meets at least one of these conditions not only allows a subsonic flow pattern of the quenching gas, but also keeps the requirements of the actuator of the switch low, thus keeping the costs low. Nevertheless, these limits still allow reasonable arc quenching performance within the rating of the medium voltage loadbreak switch. In general, p is0<3bar, preferably p0<1,5bar, more preferably p0<＝1,3bar。
These pressure conditions are very different from the typical flow conditions of high voltage circuit breakers (rated voltages higher than 72 kV). In these high-voltage circuit breakers (puffer and self-venting), the flow conditions are sonic in order to cool the arc to the maximum. Thus, a much higher pressure rise, p, is requiredquenchMuch greater than 1,8 × p0(and much greater than p)0+800 mbar). This puts high demands on the drivers of these high-voltage circuit breakers, which are disadvantageous, even prohibitive, from a cost point of view to the medium-voltage load circuit breakers considered herein. These medium voltage load circuit breakers are completely different types of switches than high voltage circuit breakers for completely different applicationsUse, design and market.
Next, aspects regarding the insulating gas are described.
In the switch according to the invention, the electrically insulating gas may comprise SF 6. SF6 has excellent dielectric and arc extinguishing properties and is therefore commonly used in gas insulated switchgear. However, due to their high global warming potential, great efforts have been made to reduce emissions and eventually to stop using this greenhouse gas, finding an alternative gas that can replace SF 6.
Such alternative gases have been proposed for use in other types of switches. For example, WO2014154292a1 discloses a switch without SF6 with an alternative to electrically insulating gas. Replacing SF6 with this replacement gas is technically challenging because SF6 has excellent switching and insulation properties due to its inherent ability to cool the arc.
According to one aspect, the present configuration allows the use of a replacement gas (e.g., as described in WO2014154292a 1) having a lower global warming potential than SF6 in the loadbreak switch, even if the replacement gas does not fully comply with the interrupt performance of SF 6.
The electrically insulating gas preferably has a lower global warming potential than SF6 at 100 year intervals. For example, the insulating gas may be included in a mixture with a hydrocarbon or organofluorine compound selected from the group consisting of CO2、O2、N2、H2Air, N2O, at least one background gas component of a group. For example, the dielectric insulating medium may comprise dry air or technical air. The dielectric insulating medium may especially comprise an organofluorine compound selected from the group consisting of: fluoroethers, oxiranes, fluoroamines, fluoroketones, fluoroolefins, fluoronitriles and mixtures and/or decomposition products thereof. Specifically, the insulating gas may include at least CH4Perfluorinated and/or partially hydrogenated organofluorine compounds and mixtures thereof as hydrocarbons. The organofluorine compound is preferably selected from the group consisting of: fluorocarbons, fluoroethers, fluoroamines, fluoronitriles, and fluoroketones; and is preferably a fluoroketone and/or a fluoroether, more preferably a perfluoroketoneAnd/or hydrofluoroethers, more preferably perfluoroketones having 4 to 12 carbon atoms, and even more preferably perfluoroketones having 4, 5, or 6 carbon atoms. The insulating gas preferably comprises a component (such as N) with air or air2、O2And/or CO2) Mixed fluoroketones.
In particular cases, the above fluoronitriles are perfluoronitriles, in particular perfluoronitriles comprising 2 carbon atoms and/or 3 carbon atoms and/or 4 carbon atoms. More particularly, the fluoronitrile may be a perfluoroalkylnitrile, in particular perfluoroacetonitrile, perfluoropropionitrile (C)2F5CN) and/or perfluorobutanenitrile (C)3F7CN). More specifically, the fluoronitrile may be perfluoroisobutyronitrile (according to formula (CF)3)2CFCN) and/or perfluoro-2-methoxypropionitrile (according to formula CF)3CF(OCF3) CN). Among them, perfluoroisobutyronitrile is preferable because of its low toxicity.
Further aspects
The switch may further include other components, such as drivers, controllers, etc., which have been omitted from the drawings and are not described herein. These components are provided to simulate a conventional medium voltage loadbreak switch.
The loadbreak switch may be used as a medium voltage loadbreak switch. This includes use as a disconnector in settings where arcing cannot be excluded and/or use as a combined switch-fuse switch.
A loadbreak switch may be provided as part of the gas insulated ring main unit. Thus, according to another aspect of the present invention, there is provided a power distribution network, ring main unit or secondary distribution gas insulated switchgear having a load break switch as described herein.
Claims (14)
1. Gas-insulated medium voltage switch (1, 2) comprising:
a first contact element (10) having an arcing contact surface (11) and a nominal contact surface (12), wherein the first contact element (10) is movable along an axis (6) of the switch (1, 2) for opening and closing the switch (1, 2);
a second contact element (20) configured to be in contact with the first contact element (10) for closing the switch (1, 2); and
a shield (50) for shielding the magnetic field,
wherein the shield (50) and the first contact element (10) are movable relative to each other along the axis (6) between an exposed configuration and a shielded configuration, such that the shield (50) and the first contact element (10) are in the exposed configuration when the switch (1, 2) is in a closed state and in the shielded configuration during opening of the switch (1, 2),
wherein in the exposed configuration the shield (50) and the first contact element (10) are arranged to expose the nominal contact surface (12) to the second contact element (20), and in the shielded configuration the shield (50) and the first contact element (10) are arranged to shield the nominal contact surface (12) of the first contact element (10) from the second contact element (20), and
wherein the shield (50) is configured to: is moved along the axis (6) of the switch (1, 2) between the exposed configuration and the shielded configuration during a current breaking operation.
2. The switch (1, 2) according to claim 1, wherein the first contact element (10) comprises an insulating tip (13), the insulating tip (13) being at a distal axial position with respect to the nominal contact surface (12).
3. The switch (1, 2) according to claim 2, wherein the shield (50) defines a first region (3) and a second region (4) of the housing (5), and wherein the shield (50) further comprises at least one opening (51), the at least one opening (51) being located closer to a periphery of the shield (50) than the axis (6) of the switch (1, 2) for balancing a pressure between the first region (3) and the second region (4).
4. Switch (1, 2) according to claim 3, wherein the shield (50) comprises a friction element (52) positioned between the shield (50) and the housing (5).
5. The switch (1, 2) according to any of claims 1 to 4, wherein the shield (50) comprises at least a shield actuation element (53) and the first contact element (10) comprises at least a first contact actuation element (14), wherein the shield actuation element (53) engages with at least one of the first contact element (10) and the first contact actuation element (14) to move the shield (50).
6. The switch (1, 2) according to claim 3, wherein the first contact element (10) forms a tube, the second contact element (20) forms a pin, the first and second contact elements defining an arc region (31), and the second contact element (20) is configured to be inserted into the first contact element (10) when the switch (1, 2) is in a closed state, wherein the arc contact surface (11) is an inner surface of the tube and the nominal contact surface (12) is an outer surface portion of the tube, wherein the shield (50) extends outwardly from the nominal contact surface (12) in a radial direction and an inner surface of the shield (50) is in sliding contact with the nominal contact surface (12).
7. The switch (1, 2) according to claim 6, further comprising:
a piston (30) for pressurizing a quenching gas during the current breaking operation,
wherein the piston is configured to compress the quenching gas, the compressed quenching gas being blown in an axial direction through an interior of the first contact element (10) and the insulating tip (13) towards the second contact element (20) to extinguish an arc formed in the arc region (31).
8. Switch (1, 2) according to claim 7, further comprising at least one gas outlet (32) for discharging quenching gas from inside the housing (5) to outside the housing (5).
9. Switch (1, 2) according to any of claims 7 and 8, wherein the shield (50) comprises at least a shield actuation element (53), wherein the shield actuation element (53) engages with at least one of the first contact element (10) and the piston (30) to move the shield (50).
10. A switch (1, 2) according to any of claims 1 to 4 and 6 to 8, wherein the switch (1, 2) is configured for a rated system voltage in the range of 1kV to 72kV, and for a rated current of at most 2000A.
11. The switch (1, 2) according to any of claims 1 to 4 and 6-8, wherein the switch (1, 2) is a load break switch.
12. A power distribution network, ring main unit or secondary distribution switchgear having a load break switch (1, 2) according to claim 11.
13. A method (3) of performing a current breaking operation by a switch (1, 2), the switch (1, 2) comprising a first contact element (10), a second contact element (20) and a shield (50), the first contact element (10) having an arcing contact surface (11) and a nominal contact surface (12), the arcing contact surface (11) defining an arcing zone (31), wherein the shield (50) and the first contact element (10) are movable relative to each other along an axis (6), the method comprising:
-a first movement (301): -separating the first contact element (10) from the second contact element (20) by relative movement away from each other along the axis (6) of the switch (1, 2) such that an arc is formed in the arc region (31);
-a second movement (302): moving the first contact element (10) and the shield (50) relative to each other from an exposed configuration, in which the nominal contact surface (12) is exposed to the second contact element (20), to a shielded configuration, in which the nominal contact surface (12) is shielded from the second contact element (20), the second movement (302) comprising: -moving the shield (50) along the axis (6) of the switch (1, 2) between the exposed configuration and the shielded configuration; and
-starting to shield (303) the nominal contact surface (12) from the second contact element (20) during opening of the switch (1, 2).
14. The method (3) according to claim 13, further comprising:
-compressing (304) a quenching gas; and
-blowing (305) the quenching gas in an axial direction through the first contact element (10) towards the second contact element (20) to extinguish the arc formed in the arc region (31).
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP17199202.7 | 2017-10-30 | ||
| EP17199202.7A EP3477675B1 (en) | 2017-10-30 | 2017-10-30 | Gas-insulated medium-voltage switch with shield device |
| PCT/EP2018/078665 WO2019086268A1 (en) | 2017-10-30 | 2018-10-19 | Gas-insulated medium-voltage switch with shield device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN112074923A CN112074923A (en) | 2020-12-11 |
| CN112074923B true CN112074923B (en) | 2022-05-17 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201880065053.8A Active CN112074923B (en) | 2017-10-30 | 2018-10-19 | Gas-insulated medium-voltage switch with shielding device |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP3477675B1 (en) |
| CN (1) | CN112074923B (en) |
| ES (1) | ES2913627T3 (en) |
| WO (1) | WO2019086268A1 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP4421836A1 (en) * | 2023-02-27 | 2024-08-28 | Siemens Aktiengesellschaft | Switchgear device with arc management arrangement |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0016983A1 (en) * | 1979-03-09 | 1980-10-15 | Licentia Patent-Verwaltungs-GmbH | Puffer-type gas circuit breaker |
| CN1259753A (en) * | 1999-01-07 | 2000-07-12 | 富士电机株式会社 | Buffer type gas circuit breaker |
| CN102945768A (en) * | 2012-11-07 | 2013-02-27 | 中国西电电气股份有限公司 | Arc-control device of breaker |
| CN103151216A (en) * | 2013-02-01 | 2013-06-12 | 中国科学院电工研究所 | Fluorocarbon mixed gas insulation arc extinction switching device provided with external absorption device |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2011104902A1 (en) * | 2010-02-26 | 2011-09-01 | 三菱電機株式会社 | Electric current switching apparatus |
| CN105283939B (en) | 2013-03-28 | 2017-07-07 | Abb 技术有限公司 | Switch module, the switchgear including switch module, the switchgear including switching device and cooling means |
-
2017
- 2017-10-30 ES ES17199202T patent/ES2913627T3/en active Active
- 2017-10-30 EP EP17199202.7A patent/EP3477675B1/en active Active
-
2018
- 2018-10-19 WO PCT/EP2018/078665 patent/WO2019086268A1/en active Application Filing
- 2018-10-19 CN CN201880065053.8A patent/CN112074923B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0016983A1 (en) * | 1979-03-09 | 1980-10-15 | Licentia Patent-Verwaltungs-GmbH | Puffer-type gas circuit breaker |
| CN1259753A (en) * | 1999-01-07 | 2000-07-12 | 富士电机株式会社 | Buffer type gas circuit breaker |
| CN102945768A (en) * | 2012-11-07 | 2013-02-27 | 中国西电电气股份有限公司 | Arc-control device of breaker |
| CN103151216A (en) * | 2013-02-01 | 2013-06-12 | 中国科学院电工研究所 | Fluorocarbon mixed gas insulation arc extinction switching device provided with external absorption device |
Also Published As
| Publication number | Publication date |
|---|---|
| CN112074923A (en) | 2020-12-11 |
| EP3477675A1 (en) | 2019-05-01 |
| EP3477675B1 (en) | 2022-03-02 |
| WO2019086268A1 (en) | 2019-05-09 |
| ES2913627T3 (en) | 2022-06-03 |
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