WO2023174675A1 - Interrupter unit for gas-insulated high or medium voltage device and gas-insulated high or medium voltage device - Google Patents

Interrupter unit for gas-insulated high or medium voltage device and gas-insulated high or medium voltage device Download PDF

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Publication number
WO2023174675A1
WO2023174675A1 PCT/EP2023/055014 EP2023055014W WO2023174675A1 WO 2023174675 A1 WO2023174675 A1 WO 2023174675A1 EP 2023055014 W EP2023055014 W EP 2023055014W WO 2023174675 A1 WO2023174675 A1 WO 2023174675A1
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WO
WIPO (PCT)
Prior art keywords
nozzle
heating channel
flow
guiding direction
section area
Prior art date
Application number
PCT/EP2023/055014
Other languages
French (fr)
Inventor
Bernardo Galletti
Marcelo Buffoni
Branimir Radisavljevic
Angelos Garyfallos
Paulo Cristini
Original Assignee
Hitachi Energy Switzerland Ag
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hitachi Energy Switzerland Ag filed Critical Hitachi Energy Switzerland Ag
Publication of WO2023174675A1 publication Critical patent/WO2023174675A1/en

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Classifications

    • 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
    • H01H33/7023—Switches with separate means for directing, obtaining, or increasing flow of arc-extinguishing fluid characterised by flow directing elements associated with contacts characterised by an insulating tubular gas flow enhancing nozzle
    • 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
    • H01H33/91—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 the arc-extinguishing fluid being air or gas
    • 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
    • H01H33/02—Details
    • H01H33/04—Means for extinguishing or preventing arc between current-carrying parts
    • H01H33/22—Selection of fluids for arc-extinguishing

Definitions

  • Interrupter unit for gas-insulated high or medium voltage device and gas-insulated high or medium voltage device
  • the invention relates to an interrupter unit for a gas-insulated high or medium voltage device.
  • the present invention also relates to a gas-insulated high or medium voltage device comprising the above interrupter unit.
  • High or medium voltage devices such as circuit breakers and switchgears are essential for the protection of technical equipment, especially in the high voltage range.
  • circuit breakers are predominantly used for interrupting a current, when an electrical fault occurs.
  • circuit breakers have the task of opening arcing contacts, quench an arc, and keeping the arcing contacts apart from one another in order to avoid a current flow even in case of high electrical potential originating from the electrical fault itself.
  • Circuit breakers may break medium to high short circuit currents of typically 1 kA to 80 kA at medium to high voltages of 12 kV to 72 kV and up to 1200 kV.
  • high or medium voltage devices accommodate high-voltage conductors such as lead conductors to which a high voltage is applied.
  • Some high or medium voltage devices namely gas-insulated high or medium voltage devices comprise an insulation gas, for example SFe, in order to shield and insulate the high-voltage conductor from other component and/or to improve quenching of an arc, when operating arcing contacts.
  • an insulation gas for example SFe
  • the insulation gas is used for extinguishing the arc generated in an arcing region between the arcing contacts when a current is interrupted and is thus also called arc extinguishing gas.
  • the arcing region is typically surrounded by an insulating nozzle.
  • the nozzle typically also serves for guiding a stream of the insulation gas for extinguishing, or blowing off, the arc.
  • the insulation gas is typically guided by a dedicated passage in the nozzle, also called heating channel, which ends close to the arcing region.
  • the insulation gas is guided directly onto the developing arc.
  • An electric arc is made up by a flux of electrons and a flux of ions which circulate in opposite directions between the arcing contacts.
  • ions and electrons recombine and the insulation gas resumes its isolating properties.
  • a gaseous mantle surrounds a core of the arc. The temperature of the gaseous mantle decreases as the distance from the arc axis is increased. The current flow is interrupted when an efficient blast of insulation gas is applied to cool the arc and extinguish it.
  • Sulphur hexafluoride is widely used as arc extinguishing gas, as it is known for its high dielectric strength and thermal interruption capability.
  • SFe Sulphur hexafluoride
  • SFe might have some environmental impact when released into the atmosphere, in particular due to its relatively high global warming potential and its relatively long lifetime in the atmosphere.
  • WO 2013/153112 A1 describes a circuit breaker including two contacts, a pressurization chamber, a nozzle arrangement designed to blow an arc in a quenching region, with a narrowest passage of a pressurization chamber outflow channel to be passed by outflowing quenching gas defining a pressurization chamber outflow limiting area, a narrowest passage of a nozzle channel to be passed by outflowing quenching gas defining a nozzle outflow limiting area, the smaller area of which defining an absolute outflow limiting area, with quenching gas having a global warming potential lower than the one of SFe over an interval of 100 years; wherein a ratio of the pressurization chamber outflow limiting area to the nozzle outflow limiting area is less than 1.1 :1.
  • an interrupter unit for a gas-insulated high or medium voltage device comprising a first arcing contact and a second arcing contact, wherein at least one of the arcing contacts is axially movable along a switching axis, a nozzle, wherein the nozzle at least partially encloses one of the arcing contacts, wherein the nozzle comprises a heating channel for guiding an arc extinguishing gas in a flow-guiding direction to an arcing region formed between the first and the second arcing contact during an opening operation of the arcing contacts, wherein the heating channel comprises at an opening of the heating channel into the arcing region a terminal section, where a radial component of the flow-guiding direction is equal to or greater than an axial component of the flow-guiding direction, wherein the terminal section is rotationally symmetric around the switching axis, and wherein the terminal section comprises a segment, in which a cross-section area orthogonal to the flow-guiding direction is constant with respect to the flow-
  • the arc extinguishing gas is selected from CO2, mixtures with CO2, SFe, mixtures of SFe with a carrier gas and/or mixtures of fluoroketons and/or fluoronitriles with a carrier gas.
  • the carrier gas for use with fluoroketons and/or fluoronitriles and/or SFe may comprise air, N2, CO2, and mixtures thereof.
  • the insulation gas may have a reduced fluorine content or may even be essentially fluorine free.
  • the gas-insulated high or medium voltage device is preferably a circuit breaker and more preferably the gas-insulated high or medium voltage device is configured as a puffer-type circuit breaker, a self-blast circuit breaker, or a combined puffer-type and self-blast circuit breaker.
  • medium to high voltages means voltages of 12 kV to 72 kV (medium voltage) and up to 1200 kV (high voltage).
  • the cross-section area of the heating channel orthogonal to the flow-guiding direction in the segment in the terminal section of the heating channel is constant with respect to the flow-guiding direction of the heating channel. Due to the rotational symmetry of the heating channel in the terminal section, a form of the cross-section area preferably corresponds to a surface of revolution.
  • the heating channel preferably links a pressurization chamber of the arc extinguishing gas, which is also called insulation gas, with the arcing region during movement of the at least one arcing contact along the switching axis and is also known as pressurization chamber outflow channel.
  • a pressurization chamber of the arc extinguishing gas which is also called insulation gas
  • the heating channel comprises at the opening of the heating channel into the arcing region the terminal section, where a radial component of the flow-guiding direction is equal to or greater than an axial component of the flow-guiding direction.
  • the axial component of the flow-guiding direction is colinear to the switching axis.
  • the radial component of the flow-guiding direction is orthogonal to the switching axis and defined by the rotational symmetry of the terminal section of the heating channel around the switching axis.
  • Being rotationally symmetric around the switching axis preferably means that the terminal section of the heating channel is such that the switching axis is with respect to the terminal section an infinite rotational symmetry axis C ⁇ .
  • the flow-guiding direction is preferably defined by sidewalls of the nozzle encompassing the heating channel.
  • the flow-guiding direction at a point in the heating channel is parallel or antiparallel to the direction of the normal vector of a plane through that point, wherein said plain corresponds to a sectional plane of least area through the heating channel.
  • Having the radial component of the flow-guiding direction being equal to or greater than the axial component of the flow-guiding direction in the terminal section of the heating channel preferably means in other words that a course of the heating channel is predominantly towards the switching axis - i.e. an angle of the flow-guiding direction with respect to the switching axis is 90° ⁇ 45° in the terminal section.
  • the insulation gas preferably flows along the flow-guiding direction towards the arcing region and passes the terminal section of the heating channel before it enters the arcing region.
  • the fluid dynamics of the insulation gas are particularly influenced by the cross-section area of the heating channel orthogonal to the flow-guiding direction.
  • the segment with the constant cross-section area with respect to the flow-guiding direction in the terminal section of the heating channel is preferably the narrowest passage the insulation gas passes during its flow from the pressurization chamber to the arcing region and thus preferably constitutes a pressurization chamber outflow limiting area.
  • the insulation gas After the insulation gas has reached the arcing region, it preferably flows out of the arcing region by passing a nozzle outflow limiting area.
  • the nozzle outflow limiting area can be formed by several channels.
  • the constant cross-section area of the heating channel in the segment within the terminal section leads to a situation wherein a ratio of the pressurization chamber outflow limiting area to the nozzle outflow limiting area decreases more and more pronounced as the current duties of the medium or high voltage device are increased, due to nozzle ablation.
  • the decrease of such an area ratio establishes more favourable conditions for the quenching of the arc in high current duties, thus improving the thermal interruption capability of the high to medium voltage device in short-line-fault (SLF) test duties.
  • SPF short-line-fault
  • the nozzle gets severely worn by ablation of material due to the large current, which normally results in a decrease of the quenching capacity of the insulation gas flow, as it changes the pressurization chamber outflow limiting area and thus decreases the driving force that moves the gas flow inside the nozzle. Hence, the gas is flushed less effectively from the nozzle. In turn this leads to a reduction of the safety margin with which the current is interrupted throughout a prescribed breaking sequence.
  • the described segment of the terminal section of the heating channel which has a constant cross-section area with respect to the flow-guiding direction, allows to increase the safety margin. This is possible as the ablation does not decrease the pressurization chamber outflow limiting area, as it is constant with respect to the flow-guiding direction.
  • the decrease of the ratio of the pressurization chamber outflow limiting area to the nozzle outflow limiting area helps defer the decrease of the thermal interruption performance of the high or medium voltage device due to the change in the nozzle’s contours brought about by ablation.
  • the nozzle comprises an auxiliary nozzle and an insulating nozzle arranged around the auxiliary nozzle, wherein the heating channel is formed in between the insulating nozzle and the auxiliary nozzle, wherein in a unworn state of the interrupter unit, axial side walls of the auxiliary nozzle and the insulating nozzle facing the arcing region are rotationally symmetric around the switching axis, and are configured such that a sum of a first narrowest cross-section area orthogonal to the switching-axis encompassed by the ax- ial side wall of the auxiliary nozzle with a second narrowest cross-section area orthogonal to the switching-axis encompassed by the axial side wall of the insulating nozzle is lower than the cross-section area of the heating channel orthogonal to the flow-guiding direction in the segment within the terminal section of the heating channel.
  • the nozzle preferably comprises two parts, the insulating nozzle, which is also called the main nozzle, and the auxiliary nozzle.
  • the insulating nozzle is preferably arranged around the auxiliary nozzle and forming the heating channel in between the insulating nozzle and the auxiliary nozzle.
  • the insulating nozzle and the auxiliary nozzle are preferably at least in the terminal part of the heating channel rotationally symmetric about the switching axis.
  • the arcing region preferably comprises two outlets through which the insulation gas can flow out.
  • the nozzle outflow limiting area is formed by the sum of the first narrowest cross-section area and of the second narrowest crosssection area.
  • the nozzle preferably comprises the insulating nozzle and the auxiliary nozzle.
  • the axial side walls of the auxiliary nozzle facing the arcing region preferably define the auxiliary nozzle channel, wherein at an auxiliary nozzle throat the auxiliary nozzle channel has a narrowest cross-section with the first narrowest cross-section area.
  • the axial side walls of the insulating nozzle facing the arcing region preferably define the insulating nozzle channel, wherein at an insulating nozzle throat the insulating nozzle channel has a narrowest crosssection with the second narrowest cross-section area.
  • the described configuration that the sum of the first narrowest cross-section area (also called auxiliary nozzle throat cross section area) and the second narrowest cross-section area (also called insulating nozzle throat cross section area) is lower than the cross-section area of the heating channel in the segment within the terminal section of the heating channel combines the advantage of having the ratio of the pressurization chamber outflow limiting area to the nozzle outflow limiting area >1 in low current duty operations, thereby reducing the risk of dielectric breakdown, with the advantage of having the ratio of the pressurization chamber outflow limiting area to the nozzle outflow limiting area ⁇ 1 towards the end of the prescribed breaking sequence in SLF duties.
  • the nozzle wear caused by the high-current arc in SLF duties induces a decrease of the ratio of the pressurization chamber outflow limiting area to the nozzle outflow limiting area towards lower values, since the numerator remains constant by design while the denominator increases due to wear, which in turn leads to an increased thermal interruption performance.
  • the cross-section area of the heating channel within the segment is at least 1.05 times greater, and preferably at least 1.1 times greater than the sum of the first narrowest cross-section area orthogonal to the switching-axis encompassed by the axial side wall of the auxiliary nozzle with the second narrowest cross-section area orthogonal to the switching-axis encompassed by the axial side wall of the insulating nozzle.
  • the pressurization chamber outflow limiting area defined by the cross-section area of the heating channel within the segment is at least 1.05 times greater, and preferably at least 1.1 times greater than the sum of the auxiliary nozzle throat cross section area with the insulating nozzle throat cross section area, which constitutes the nozzle outflow limiting area.
  • the pressurization chamber outflow limiting area is greater than the nozzle outflow limiting area, but also that the pressurization chamber outflow limiting area is only slightly greater than the nozzle outflow limiting area. This makes it especially easy to lower the ratio of the pressurization chamber outflow limiting area to the nozzle outflow limiting area ⁇ 1 towards the end of the prescribed breaking sequence in high current duties.
  • the crosssection area of the heating channel within the segment is not more than 1 .25 times greater, and preferably not more than 1 .2 times greater than the sum of the first narrowest cross-section area orthogonal to the switching-axis encompassed by the axial side wall of the auxiliary nozzle with the second narrowest cross-section area orthogonal to the switching-axis encompassed by the axial side wall of the insulating nozzle.
  • Having a pressurization chamber outflow limiting area that is more than 1 .25 times greater than the nozzle outflow limiting area makes it hard to achieve a ratio of the pressurization chamber outflow limiting area to the nozzle outflow limiting area ⁇ 1 towards the end of the prescribed breaking sequence due to nozzle ablation.
  • the ration between the cross-section area of the heating channel within the segment to the sum of the first narrowest cross-section area orthogonal to the switching-axis encompassed by the axial side wall of the auxiliary nozzle with the second narrowest cross-section area orthogonal to the switching-axis encompassed by the axial side wall of the insulating nozzle is 1 .05 to 1 .25, and more preferably 1.1 to 1 .2, further preferably 1 .15 ⁇ 8% and even more preferably 1 .15 ⁇ 5%.
  • an interrupter unit wherein in the unworn state of the interrupter unit, the axial side walls of the auxiliary nozzle and the insulating nozzle facing the arcing region and adjacent to the opening of the heating channel into the arcing region extend at least partially parallel to the switching axis.
  • the auxiliary nozzle throat and the insulating nozzle throat have at least at the opening of the heating channel a form corresponding to a right cylinder.
  • the diameter of the auxiliary nozzle throat is equal to or smaller than the diameter of the insulating nozzle throat.
  • the course of the heating channel from the pressurization chamber to the opening at the arcing region can in principle have any form, as long as within the terminal section of the heating channel the radial component of the flow-guiding direction is equal to or greater than the axial component of the flow-guiding direction.
  • the heating channel can first have a course parallel to the nozzle throat and then change its direction in order to have in the terminal section a course perpendicular to the nozzle throat.
  • the terminal section comprises a subsection where the flow-guiding direction of the heating channel exclusively has a radial component, and wherein the segment with the constant cross-section area extends at least in part along said subsection.
  • the segment with the constant cross-section area extends along the whole subsection.
  • an interrupter unit is provided, wherein with respect to the flow-guiding direction the segment with the constant cross-section area starts at the beginning of the terminal section, or wherein with respect to the flow-guiding direction the segment with the constant cross-section area starts at the beginning of the subsection where the flow-guiding direction of the heating channel exclusively has a radial component.
  • the segment in the terminal part of the heating channel with the constant cross-section area can start at different points in the terminal section.
  • the nozzle comprises the auxiliary nozzle and the insulating nozzle arranged around the auxiliary nozzle, wherein the heating channel is formed in between the insulating nozzle and the auxiliary nozzle and wherein the segment with the constant cross-section area starts, where a sidewall of the auxiliary nozzle facing the heating channel has its maximal axial extent.
  • the sidewall of the auxiliary nozzle facing the heating channel may at a start of the heating channel be predominantly oriented parallel to the switching axis.
  • the orientation of the sidewall of the auxiliary nozzle changes.
  • the sidewall of the auxiliary nozzle facing the heating channel may be such that the sidewall comprises a turning point, where with respect to the switching axis the sidewall reaches a maximum.
  • the segment with the constant cross-section area starts at said turning point.
  • the nozzle comprises the auxiliary nozzle and the insulating nozzle arranged around the auxiliary nozzle, wherein the heating channel is formed in between the insulating nozzle and the auxiliary nozzle and wherein sidewalls of the insulating nozzle and auxiliary nozzle facing the heating channel within the segment with the constant cross-section area are not parallel to each other.
  • the area of the cross-section is constant with respect to the flowguiding direction and as the flow-guiding direction comprises a radial component, the sidewalls of the heating channel within the segment are preferably not parallel to each other. In case of parallel sidewalls, the area of the cross-section would indeed decrease along the flow-guiding direction as a radius of a surface of revolution describing the cross-section area decreases.
  • the nozzle comprises the auxiliary nozzle and the insulating nozzle arranged around the auxiliary nozzle, wherein the heating channel is formed in between the insulating nozzle and the auxiliary nozzle and wherein within the segment with the constant cross-section area a shortest distance between a sidewall of the insulating nozzle facing the heating channel and a sidewall of the auxiliary nozzle facing the heating channel increases with respect to the flow-guiding direction.
  • An end of the segment with the constant cross-section area within the terminal section of the heating channel can in general be at different points of the terminal section.
  • an interrupter unit is provided, wherein with respect to the flow-guiding direction the segment with the constant cross-section area ends at the opening of the heating channel into the arcing region, or wherein with respect to the flow-guiding direction the segment with the constant cross-section area ends at the beginning of a fillet region at the opening of the heating channel into the arcing region.
  • the segment with constant cross-section area preferably extends until the opening of the heating channel at the arcing region.
  • edges of the opening of the heating channel may be rounded and/or may be configured as fillet edges, it is also possible that the segment with the constant cross-section area ends with the beginning of the fillet region.
  • the course of the heating channel from the pressurization chamber to the opening at the arcing region can in principle have any form, as long as within the terminal section of the heating channel the radial component of the flow-guiding direction is equal to or greater than the axial component of the flowguiding direction.
  • an interrupter unit comprising with respect to the flow-guiding direction upstream to the terminal section and adjacent to the terminal section, a further section, where the radial component of the flowguiding direction is lower than the axial component of the flow-guiding direction, wherein the further section is rotationally symmetric around the switching axis, and wherein the further section is configured such that the further section comprises a further segment, where a cross-section area of the heating channel orthogonal to the flow-guiding direction is constant with respect to the flow-guiding direction.
  • the further segment with the constant cross-section area in the further section of the heating channel is preferably adjacent to the segment with the constant cross-section area in the terminal section of the heating channel.
  • an interrupter unit is provided, wherein with respect to the flow-guiding direction the further segment with the constant cross-section area ends at the beginning of the terminal section. Further preferably the cross-section area within the further segment and within the segment are the same.
  • the further section comprises a further subsection, where the flow-guiding direction of the channel exclusively has an axial component.
  • the cross-section area of the heating channel orthogonal to the flow-guiding direction within the segment with the constant cross-section area has a form corresponding to a lateral surface of a right circular cylinder or to a lateral surface of a conical frustum, and/or wherein the cross-section area of the heating channel orthogonal to the flow-guiding direction within the further segment with the constant cross-section area has a form corresponding to a lateral surface of a conical frustum or to an annulus.
  • the cross-section area preferably has a form that corresponds to a surface of revolution.
  • the surface of revolution can have different forms and/or can correspond to lateral surfaces of different bodies of revolution.
  • the form of the cross-section area corresponds to the lateral surface of a right circular cylinder or to the lateral surface of a conical frustum.
  • the form of the cross-section area corresponds to the lateral surface of a right circular cylinder.
  • the form of the cross-section area corresponds to the lateral surface of a conical frustum or to an annulus. Further preferably, in the further subsection of the further section, where the flow-guiding direction of the heating channel exclusively has an axial component, the form of the cross-section area corresponds to an annulus.
  • Fig. 1 schematically shows an interrupter unit for a gas-insulated high voltage circuit breaker, according to a preferred embodiment.
  • FIG. 2 schematically shows the interrupter unit of figure 1 in an unworn state and in a worn state
  • Fig. 3 schematically shows two exemplary cross-sectional areas of a heating channel within a segment of the heating channel of the interrupter unit of figure 1 , and
  • Fig. 4 schematically shows an interrupter unit for a gas-insulated high voltage circuit breaker, according to another preferred embodiment.
  • Fig. 1 schematically shows an interrupter unit 10 for a gas-insulated high or medium circuit breaker, according to a preferred embodiment.
  • the interrupter unit 10 comprising a first arcing contact 12 and a second arcing contact 14.
  • the first arcing contact 12 has the form of a plug contact 12 and the second arcing contact 14 is configured as tulip contact 14.
  • the plug contact 12 is axially movable along a switching axis 16.
  • the tulip contact 14 is configured to engage around a proximal portion of the plug contact 12, in the closed position of the contacts 12, 14 (not shown in figure 1 ). In the open position of the contacts 12, 14 the plug contact 12 and tulip contact 14 are apart from each other, as shown in figure 1 .
  • the interrupter unit 10 further comprises a nozzle 18, wherein the nozzle 18 at least partially encloses the arcing contacts 12, 14.
  • the nozzle 18 comprises a heating channel 20 for guiding an arc extinguishing gas in a flow-guiding direction 22 to an arcing region 24 formed between the first arcing contact 12 and the second arcing contact 14 during the opening operation of the arcing contacts 12, 14.
  • the heating channel 20 links a pressurization chamber of the arc extinguishing gas (not shown in figure 1 ), with the arcing region 24 during the relative movement of the arcing contacts 12 and 14 along the switching axis 16.
  • the nozzle 18 comprises an auxiliary nozzle 26 and an insulating nozzle 28 arranged around the auxiliary nozzle 26 and the heating channel 20 is formed in between the insulating nozzle 28 and the auxiliary nozzle 26.
  • the heating channel 20 comprises at an opening 30 of the heating channel 20 into the arcing region 24 a terminal section 32, where a radial component of the flow-guiding direction 22 is equal to or greater than an axial component of the flow-guiding direction 22.
  • the terminal section 32 of the heating channel 20 is rotationally symmetric around the switching axis 16.
  • the axial component of the flow-guiding direction 22 is the component colinear to the switching axis 16.
  • the radial component of the flowguiding direction 22 is orthogonal to the switching axis 26 and defined by the rotational symmetry of the terminal section 32 around the switching axis 16.
  • the terminal section 32 comprises a segment 34, in figure 1 the shaded area 34, where a cross-section area of the heating channel 20 orthogonal to the flow-guiding direction 22 is constant with respect to the flow-guiding direction 22 of the heating channel 20.
  • the terminal section 32 further comprises a subsection 38, where the flow-guiding direction 22 of the heating channel 20 exclusively has a radial component.
  • this subsection 38 the course of the heating channel 20 is such that the flow-guiding direction 22 is orthogonal to the switching axis 26.
  • the segment 34 with the constant cross-section area extends at least in part along said subsection 38.
  • the cross-section area of the heating channel 20 orthogonal to the flow-guiding direction 22 within the segment 34 with the constant cross-section area has a form 36 corresponding to a lateral surface of a cylinder.
  • Figure 3 illustrates two exemplary forms 36 of the cross-section areas, which correspond to the cross-sections indicated by the arrows 40, 42 in figure 1 .
  • the height of the cylinders, which are also indicated by the arrows 40, 42 increases when the radius of the cylinder decreases.
  • figure 3 and 1 also illustrate that in the segment 34 the heating channel 20 is formed such that the shortest distance increases with respect to the flow guiding direction 22.
  • the course of the heating channel 20 in the terminal section 32 is different from the embodiment as shown in figure 1.
  • the course of the heating channel 20 in the terminal section 32 is such that the flow guiding direction 22 has in addition to the radial component also an axial component.
  • the form of the constant crosssection area would correspond to a lateral surface of a conical frustrum.
  • the segment 34 starts with respect to the flow-guiding direction 22 at a point 44, where a sidewall 46 of the auxiliary nozzle 26 facing the heating channel 20 has its maximal axial extent.
  • a sidewall 46 of the auxiliary nozzle 26 facing the heating channel 20 has its maximal axial extent.
  • the sidewall 46 of the auxiliary nozzle 26 facing the heating channel 20 is predominantly oriented parallel to the switching axis 16.
  • the orientation of the sidewall 46 changes.
  • the segment 34 starts at the point 44, where the sidewall 46 has a turning point and the axial extent of the sidewall 46 reaches its maximum.
  • the edges of the opening 30 of the heating channel 20 into the arcing region 24 are rounded and configured as fillet edges.
  • the end of the segment 34 with the constant cross-section area within the terminal section 32 of the heating channel 20 ends in this embodiment at the beginning of the fillet region 48 at the opening 30 of the heating channel 20 into the arcing region 24.
  • FIG 2 which shows the interrupter unit 10 of figure 1 in an unworn state (indicated by a continuous line of the contour) and in a worn state, where sidewalls 50, 50’, 52, 52’ of the nozzle 18 are ablated (indicated by a dashed line of the contour), axial side walls 50 of the auxiliary nozzle 26 and axial side walls 52 of the insulating nozzle 28 facing the arcing region 24 and adjacent to the opening 30 of the heating channel 20 extend at least partially parallel to the switching axis 16 in the unworn state of the nozzle 18.
  • the axial side walls 50 of the auxiliary nozzle 26 define an auxiliary nozzle channel 54 and the axial side walls 52 of the insulating nozzle 28 define an insulating nozzle channel 56.
  • a diameter 58 of the auxiliary nozzle channel 54 and a diameter 60 of the insulating nozzle channel 56 are the same.
  • the segment 34 with the constant cross-section area within the terminal section 32 of the heating channel 20 is the narrowest pas- sage the arc extinguishing gas passes during its flow from the pressurization chamber to the arcing region 24 and constitutes a pressurization chamber outflow limiting area.
  • a nozzle outflow limiting area is defined by the sum of a first narrowest cross-section area defined by the the diameter 58 of the auxiliary nozzle channel 54 and encompassed by the axial side wall 50 of the auxiliary nozzle 26 with a second narrowest cross-section area defined by the the diameter 60 of the insulating nozzle channel 56 and encompassed by the axial side wall 52 of the insulating nozzle 28.
  • the nozzle outflow limiting area is defined by the sum of a first narrowest cross-section area defined by the the diameter 58’ of the auxiliary nozzle channel 54 and encompassed by the axial side wall 50’ of the auxiliary nozzle 26 with a second narrowest cross-section area defined by the the diameter 60’ of the insulating nozzle channel 56 and encompassed by the axial side wall 52’ of the insulating nozzle 28.
  • the interruption unit 10 is configured such that in the unworn state a ratio between the pressurization chamber outflow limiting area to the nozzle outflow limiting area is >1 and changes to ⁇ 1 in the worn state.
  • the ratio between the the pressurization chamber outflow limiting area to the nozzle outflow limiting area is 1.1. Due to nozzle ablation and due to the constant cross-section area in the segment 34 of the heating channel 20, the ratio between the pressurization chamber outflow limiting area to the nozzle outflow limiting area changes to to ⁇ 1 in the worn state.
  • the heating channel 20 comprises with respect to the flow-guiding direction 22 upstream to the terminal section 32 and adjacent to the terminal section 32, a further section 62, where the radial component of the flowguiding direction 22 is lower than the axial component of the flow-guiding direction 22.
  • the further section 62 is rotationally symmetric around the switching axis 16, and comprises a further segment, where a cross-section area of the heating channel 20 orthogonal to the flow-guiding direction 22 is constant with respect to the flow-guiding direction 22.

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  • Circuit Breakers (AREA)

Abstract

The invention relates to an interrupter unit (10) for a gas-insulated high or medium voltage device comprising a first arcing contact (12) and a second arcing contact (14), wherein at least one of the arcing contacts (12,14) is axially movable along a switching axis (16), a nozzle (18), wherein the nozzle (18) comprises a heating channel (20) for guiding an arc extinguishing gas in a flow-guiding direction (22) to an arcing region (24) formed between the first (12) and the second arcing contact (14) during an opening operation of the arcing contacts (12,14), wherein the heating channel (20) comprises at an opening (30) of the heating channel (20) into the arcing region (24) a terminal section (32), where a radial component of the flow-guiding direction (22) is equal to or greater than an axial component of the flow-guiding direction (22), wherein the terminal section (32) is rotationally symmetric around the switching axis (16), and wherein the terminal section (32) comprises a segment (34), in which a cross-section area orthogonal to the flow-guiding direction (22) is con- stant with respect to the flow-guiding direction (22) of the heating channel (20). Furthermore, the invention relates to a gas-insulated high or medium voltage device comprising the above interrupter unit (10).

Description

Description
Interrupter unit for gas-insulated high or medium voltage device and gas-insulated high or medium voltage device
Technical Field
The invention relates to an interrupter unit for a gas-insulated high or medium voltage device.
The present invention also relates to a gas-insulated high or medium voltage device comprising the above interrupter unit.
Background Art
High or medium voltage devices, such as circuit breakers and switchgears are essential for the protection of technical equipment, especially in the high voltage range. For example, circuit breakers are predominantly used for interrupting a current, when an electrical fault occurs. As an example, circuit breakers have the task of opening arcing contacts, quench an arc, and keeping the arcing contacts apart from one another in order to avoid a current flow even in case of high electrical potential originating from the electrical fault itself. Circuit breakers, may break medium to high short circuit currents of typically 1 kA to 80 kA at medium to high voltages of 12 kV to 72 kV and up to 1200 kV. Thus, high or medium voltage devices accommodate high-voltage conductors such as lead conductors to which a high voltage is applied.
Some high or medium voltage devices, namely gas-insulated high or medium voltage devices comprise an insulation gas, for example SFe, in order to shield and insulate the high-voltage conductor from other component and/or to improve quenching of an arc, when operating arcing contacts.
In particular the insulation gas is used for extinguishing the arc generated in an arcing region between the arcing contacts when a current is interrupted and is thus also called arc extinguishing gas. The arcing region is typically surrounded by an insulating nozzle. The nozzle typically also serves for guiding a stream of the insulation gas for extinguishing, or blowing off, the arc. Thereby, the insulation gas is typically guided by a dedicated passage in the nozzle, also called heating channel, which ends close to the arcing region. Thus, the insulation gas is guided directly onto the developing arc.
An electric arc is made up by a flux of electrons and a flux of ions which circulate in opposite directions between the arcing contacts. When the temperature of the arc decreases, ions and electrons recombine and the insulation gas resumes its isolating properties. In a gas insulated circuit breakers, a gaseous mantle surrounds a core of the arc. The temperature of the gaseous mantle decreases as the distance from the arc axis is increased. The current flow is interrupted when an efficient blast of insulation gas is applied to cool the arc and extinguish it.
Sulphur hexafluoride (SFe) is widely used as arc extinguishing gas, as it is known for its high dielectric strength and thermal interruption capability. However, SFe might have some environmental impact when released into the atmosphere, in particular due to its relatively high global warming potential and its relatively long lifetime in the atmosphere.
Thus, efforts have been made to substitute SFe with different more environmentally friendly arc extinguishing gases or to reduce the SFe content in the arc extinguishing gas mixture. For example, one candidate for substituting SFe as insulation gas is CO2. However, the arc extinguishing capability of CO2 is inferior to that of SFe. Thus, for a circuit breaker of a conventional design, a sufficient interruption performance is thus often not achieved when CO2 is used as a quenching gas instead of SFe. This is particularly the case for relatively high short-circuit currents and voltage ratings.
However, the thermal interruption capacity of the high or medium voltage device is not only influenced by the type of insulation gas. Also, the design of the nozzle influences the thermal interruption capacity of the high or medium voltage device. WO 2013/153112 A1 describes a circuit breaker including two contacts, a pressurization chamber, a nozzle arrangement designed to blow an arc in a quenching region, with a narrowest passage of a pressurization chamber outflow channel to be passed by outflowing quenching gas defining a pressurization chamber outflow limiting area, a narrowest passage of a nozzle channel to be passed by outflowing quenching gas defining a nozzle outflow limiting area, the smaller area of which defining an absolute outflow limiting area, with quenching gas having a global warming potential lower than the one of SFe over an interval of 100 years; wherein a ratio of the pressurization chamber outflow limiting area to the nozzle outflow limiting area is less than 1.1 :1.
Summary of invention
It is an object of the invention to provide means to improve the thermal interruption performance of gas-insulated high or medium voltage devices, particularly during high current duties.
The object of the invention is solved by the features of the independent claims. Modified embodiments are detailed in the dependent claims.
Thus, the object is solved by an interrupter unit for a gas-insulated high or medium voltage device comprising a first arcing contact and a second arcing contact, wherein at least one of the arcing contacts is axially movable along a switching axis, a nozzle, wherein the nozzle at least partially encloses one of the arcing contacts, wherein the nozzle comprises a heating channel for guiding an arc extinguishing gas in a flow-guiding direction to an arcing region formed between the first and the second arcing contact during an opening operation of the arcing contacts, wherein the heating channel comprises at an opening of the heating channel into the arcing region a terminal section, where a radial component of the flow-guiding direction is equal to or greater than an axial component of the flow-guiding direction, wherein the terminal section is rotationally symmetric around the switching axis, and wherein the terminal section comprises a segment, in which a cross-section area orthogonal to the flow-guiding direction is constant with respect to the flow-guiding direction of the heating channel. Furthermore, the object is solved by a gas-insulated high or medium voltage device comprising the above interrupter unit, and wherein the high or medium voltage device comprises an arc extinguishing gas.
Preferably the arc extinguishing gas is selected from CO2, mixtures with CO2, SFe, mixtures of SFe with a carrier gas and/or mixtures of fluoroketons and/or fluoronitriles with a carrier gas. The carrier gas for use with fluoroketons and/or fluoronitriles and/or SFe may comprise air, N2, CO2, and mixtures thereof. Further preferably the insulation gas may have a reduced fluorine content or may even be essentially fluorine free.
According to another preferred embodiment of the invention the gas-insulated high or medium voltage device is preferably a circuit breaker and more preferably the gas-insulated high or medium voltage device is configured as a puffer-type circuit breaker, a self-blast circuit breaker, or a combined puffer-type and self-blast circuit breaker. In the context of this invention medium to high voltages means voltages of 12 kV to 72 kV (medium voltage) and up to 1200 kV (high voltage).
In the present interruption unit, the cross-section area of the heating channel orthogonal to the flow-guiding direction in the segment in the terminal section of the heating channel is constant with respect to the flow-guiding direction of the heating channel. Due to the rotational symmetry of the heating channel in the terminal section, a form of the cross-section area preferably corresponds to a surface of revolution.
The heating channel preferably links a pressurization chamber of the arc extinguishing gas, which is also called insulation gas, with the arcing region during movement of the at least one arcing contact along the switching axis and is also known as pressurization chamber outflow channel.
The heating channel comprises at the opening of the heating channel into the arcing region the terminal section, where a radial component of the flow-guiding direction is equal to or greater than an axial component of the flow-guiding direction. The axial component of the flow-guiding direction is colinear to the switching axis. The radial component of the flow-guiding direction is orthogonal to the switching axis and defined by the rotational symmetry of the terminal section of the heating channel around the switching axis.
Being rotationally symmetric around the switching axis preferably means that the terminal section of the heating channel is such that the switching axis is with respect to the terminal section an infinite rotational symmetry axis C~.
The flow-guiding direction is preferably defined by sidewalls of the nozzle encompassing the heating channel. Preferably the flow-guiding direction at a point in the heating channel is parallel or antiparallel to the direction of the normal vector of a plane through that point, wherein said plain corresponds to a sectional plane of least area through the heating channel.
Having the radial component of the flow-guiding direction being equal to or greater than the axial component of the flow-guiding direction in the terminal section of the heating channel preferably means in other words that a course of the heating channel is predominantly towards the switching axis - i.e. an angle of the flow-guiding direction with respect to the switching axis is 90° ± 45° in the terminal section.
During circuit breaking operation of the high or medium voltage device, the insulation gas preferably flows along the flow-guiding direction towards the arcing region and passes the terminal section of the heating channel before it enters the arcing region. The fluid dynamics of the insulation gas are particularly influenced by the cross-section area of the heating channel orthogonal to the flow-guiding direction.
The segment with the constant cross-section area with respect to the flow-guiding direction in the terminal section of the heating channel is preferably the narrowest passage the insulation gas passes during its flow from the pressurization chamber to the arcing region and thus preferably constitutes a pressurization chamber outflow limiting area. After the insulation gas has reached the arcing region, it preferably flows out of the arcing region by passing a nozzle outflow limiting area. The nozzle outflow limiting area, as will be described in more detail later, can be formed by several channels. The constant cross-section area of the heating channel in the segment within the terminal section leads to a situation wherein a ratio of the pressurization chamber outflow limiting area to the nozzle outflow limiting area decreases more and more pronounced as the current duties of the medium or high voltage device are increased, due to nozzle ablation. The decrease of such an area ratio establishes more favourable conditions for the quenching of the arc in high current duties, thus improving the thermal interruption capability of the high to medium voltage device in short-line-fault (SLF) test duties.
In high current duties the nozzle gets severely worn by ablation of material due to the large current, which normally results in a decrease of the quenching capacity of the insulation gas flow, as it changes the pressurization chamber outflow limiting area and thus decreases the driving force that moves the gas flow inside the nozzle. Hence, the gas is flushed less effectively from the nozzle. In turn this leads to a reduction of the safety margin with which the current is interrupted throughout a prescribed breaking sequence. The described segment of the terminal section of the heating channel, which has a constant cross-section area with respect to the flow-guiding direction, allows to increase the safety margin. This is possible as the ablation does not decrease the pressurization chamber outflow limiting area, as it is constant with respect to the flow-guiding direction. Thus, the decrease of the ratio of the pressurization chamber outflow limiting area to the nozzle outflow limiting area helps defer the decrease of the thermal interruption performance of the high or medium voltage device due to the change in the nozzle’s contours brought about by ablation.
According to a preferred embodiment of the invention, the nozzle comprises an auxiliary nozzle and an insulating nozzle arranged around the auxiliary nozzle, wherein the heating channel is formed in between the insulating nozzle and the auxiliary nozzle, wherein in a unworn state of the interrupter unit, axial side walls of the auxiliary nozzle and the insulating nozzle facing the arcing region are rotationally symmetric around the switching axis, and are configured such that a sum of a first narrowest cross-section area orthogonal to the switching-axis encompassed by the ax- ial side wall of the auxiliary nozzle with a second narrowest cross-section area orthogonal to the switching-axis encompassed by the axial side wall of the insulating nozzle is lower than the cross-section area of the heating channel orthogonal to the flow-guiding direction in the segment within the terminal section of the heating channel.
In other words, the nozzle preferably comprises two parts, the insulating nozzle, which is also called the main nozzle, and the auxiliary nozzle. The insulating nozzle is preferably arranged around the auxiliary nozzle and forming the heating channel in between the insulating nozzle and the auxiliary nozzle. The insulating nozzle and the auxiliary nozzle are preferably at least in the terminal part of the heating channel rotationally symmetric about the switching axis.
Furthermore, the arcing region preferably comprises two outlets through which the insulation gas can flow out. Thus, the nozzle outflow limiting area is formed by the sum of the first narrowest cross-section area and of the second narrowest crosssection area.
Although it might be possible - e.g. for medium voltage applications - that only one nozzle with one nozzle outlet is provided, the nozzle preferably comprises the insulating nozzle and the auxiliary nozzle. The axial side walls of the auxiliary nozzle facing the arcing region preferably define the auxiliary nozzle channel, wherein at an auxiliary nozzle throat the auxiliary nozzle channel has a narrowest cross-section with the first narrowest cross-section area. The axial side walls of the insulating nozzle facing the arcing region preferably define the insulating nozzle channel, wherein at an insulating nozzle throat the insulating nozzle channel has a narrowest crosssection with the second narrowest cross-section area.
The described configuration that the sum of the first narrowest cross-section area (also called auxiliary nozzle throat cross section area) and the second narrowest cross-section area (also called insulating nozzle throat cross section area) is lower than the cross-section area of the heating channel in the segment within the terminal section of the heating channel combines the advantage of having the ratio of the pressurization chamber outflow limiting area to the nozzle outflow limiting area >1 in low current duty operations, thereby reducing the risk of dielectric breakdown, with the advantage of having the ratio of the pressurization chamber outflow limiting area to the nozzle outflow limiting area <1 towards the end of the prescribed breaking sequence in SLF duties. Indeed, the nozzle wear caused by the high-current arc in SLF duties, induces a decrease of the ratio of the pressurization chamber outflow limiting area to the nozzle outflow limiting area towards lower values, since the numerator remains constant by design while the denominator increases due to wear, which in turn leads to an increased thermal interruption performance.
In connection to this and according to another preferred embodiment of the invention the cross-section area of the heating channel within the segment is at least 1.05 times greater, and preferably at least 1.1 times greater than the sum of the first narrowest cross-section area orthogonal to the switching-axis encompassed by the axial side wall of the auxiliary nozzle with the second narrowest cross-section area orthogonal to the switching-axis encompassed by the axial side wall of the insulating nozzle. In other words, the pressurization chamber outflow limiting area defined by the cross-section area of the heating channel within the segment is at least 1.05 times greater, and preferably at least 1.1 times greater than the sum of the auxiliary nozzle throat cross section area with the insulating nozzle throat cross section area, which constitutes the nozzle outflow limiting area. Thus, it is not only preferred that the pressurization chamber outflow limiting area is greater than the nozzle outflow limiting area, but also that the pressurization chamber outflow limiting area is only slightly greater than the nozzle outflow limiting area. This makes it especially easy to lower the ratio of the pressurization chamber outflow limiting area to the nozzle outflow limiting area <1 towards the end of the prescribed breaking sequence in high current duties.
Furthermore, and according to a further embodiment of the invention, the crosssection area of the heating channel within the segment is not more than 1 .25 times greater, and preferably not more than 1 .2 times greater than the sum of the first narrowest cross-section area orthogonal to the switching-axis encompassed by the axial side wall of the auxiliary nozzle with the second narrowest cross-section area orthogonal to the switching-axis encompassed by the axial side wall of the insulating nozzle. Having a pressurization chamber outflow limiting area that is more than 1 .25 times greater than the nozzle outflow limiting area makes it hard to achieve a ratio of the pressurization chamber outflow limiting area to the nozzle outflow limiting area <1 towards the end of the prescribed breaking sequence due to nozzle ablation.
Particularly preferred the ration between the cross-section area of the heating channel within the segment to the sum of the first narrowest cross-section area orthogonal to the switching-axis encompassed by the axial side wall of the auxiliary nozzle with the second narrowest cross-section area orthogonal to the switching-axis encompassed by the axial side wall of the insulating nozzle is 1 .05 to 1 .25, and more preferably 1.1 to 1 .2, further preferably 1 .15 ± 8% and even more preferably 1 .15 ± 5%.
According to another preferred embodiment of the invention, an interrupter unit is provided, wherein in the unworn state of the interrupter unit, the axial side walls of the auxiliary nozzle and the insulating nozzle facing the arcing region and adjacent to the opening of the heating channel into the arcing region extend at least partially parallel to the switching axis. Preferably, in the unworn state the auxiliary nozzle throat and the insulating nozzle throat have at least at the opening of the heating channel a form corresponding to a right cylinder. Further preferably the diameter of the auxiliary nozzle throat is equal to or smaller than the diameter of the insulating nozzle throat.
The course of the heating channel from the pressurization chamber to the opening at the arcing region can in principle have any form, as long as within the terminal section of the heating channel the radial component of the flow-guiding direction is equal to or greater than the axial component of the flow-guiding direction. For example, the heating channel can first have a course parallel to the nozzle throat and then change its direction in order to have in the terminal section a course perpendicular to the nozzle throat. In this regard and according to preferred embodiment of the invention, the terminal section comprises a subsection where the flow-guiding direction of the heating channel exclusively has a radial component, and wherein the segment with the constant cross-section area extends at least in part along said subsection. Preferably the segment with the constant cross-section area extends along the whole subsection. According to another preferred embodiment of the invention, an interrupter unit is provided, wherein with respect to the flow-guiding direction the segment with the constant cross-section area starts at the beginning of the terminal section, or wherein with respect to the flow-guiding direction the segment with the constant cross-section area starts at the beginning of the subsection where the flow-guiding direction of the heating channel exclusively has a radial component. The segment in the terminal part of the heating channel with the constant cross-section area can start at different points in the terminal section.
In this regard and according to another embodiment of the invention the nozzle comprises the auxiliary nozzle and the insulating nozzle arranged around the auxiliary nozzle, wherein the heating channel is formed in between the insulating nozzle and the auxiliary nozzle and wherein the segment with the constant cross-section area starts, where a sidewall of the auxiliary nozzle facing the heating channel has its maximal axial extent. The sidewall of the auxiliary nozzle facing the heating channel may at a start of the heating channel be predominantly oriented parallel to the switching axis. Preferably, as the course of the heating channel changes towards the switching axis also the orientation of the sidewall of the auxiliary nozzle changes. The sidewall of the auxiliary nozzle facing the heating channel may be such that the sidewall comprises a turning point, where with respect to the switching axis the sidewall reaches a maximum. Preferably, the segment with the constant cross-section area starts at said turning point.
According to another preferred embodiment the nozzle comprises the auxiliary nozzle and the insulating nozzle arranged around the auxiliary nozzle, wherein the heating channel is formed in between the insulating nozzle and the auxiliary nozzle and wherein sidewalls of the insulating nozzle and auxiliary nozzle facing the heating channel within the segment with the constant cross-section area are not parallel to each other. As the area of the cross-section is constant with respect to the flowguiding direction and as the flow-guiding direction comprises a radial component, the sidewalls of the heating channel within the segment are preferably not parallel to each other. In case of parallel sidewalls, the area of the cross-section would indeed decrease along the flow-guiding direction as a radius of a surface of revolution describing the cross-section area decreases.
In this regard and according to another preferred embodiment the nozzle comprises the auxiliary nozzle and the insulating nozzle arranged around the auxiliary nozzle, wherein the heating channel is formed in between the insulating nozzle and the auxiliary nozzle and wherein within the segment with the constant cross-section area a shortest distance between a sidewall of the insulating nozzle facing the heating channel and a sidewall of the auxiliary nozzle facing the heating channel increases with respect to the flow-guiding direction.
An end of the segment with the constant cross-section area within the terminal section of the heating channel can in general be at different points of the terminal section. According to another preferred embodiment of the invention an interrupter unit is provided, wherein with respect to the flow-guiding direction the segment with the constant cross-section area ends at the opening of the heating channel into the arcing region, or wherein with respect to the flow-guiding direction the segment with the constant cross-section area ends at the beginning of a fillet region at the opening of the heating channel into the arcing region.
In other words, the segment with constant cross-section area preferably extends until the opening of the heating channel at the arcing region. However, as edges of the opening of the heating channel may be rounded and/or may be configured as fillet edges, it is also possible that the segment with the constant cross-section area ends with the beginning of the fillet region.
As already mentioned, the course of the heating channel from the pressurization chamber to the opening at the arcing region can in principle have any form, as long as within the terminal section of the heating channel the radial component of the flow-guiding direction is equal to or greater than the axial component of the flowguiding direction. However, according to another preferred embodiment of the invention an interrupter unit is provided, wherein the heating channel comprises with respect to the flow-guiding direction upstream to the terminal section and adjacent to the terminal section, a further section, where the radial component of the flowguiding direction is lower than the axial component of the flow-guiding direction, wherein the further section is rotationally symmetric around the switching axis, and wherein the further section is configured such that the further section comprises a further segment, where a cross-section area of the heating channel orthogonal to the flow-guiding direction is constant with respect to the flow-guiding direction.
Further preferably the further segment with the constant cross-section area in the further section of the heating channel is preferably adjacent to the segment with the constant cross-section area in the terminal section of the heating channel.
According to another preferred embodiment of the invention an interrupter unit is provided, wherein with respect to the flow-guiding direction the further segment with the constant cross-section area ends at the beginning of the terminal section. Further preferably the cross-section area within the further segment and within the segment are the same.
According to another preferred embodiment the further section comprises a further subsection, where the flow-guiding direction of the channel exclusively has an axial component.
According to another preferred embodiment of the invention, the cross-section area of the heating channel orthogonal to the flow-guiding direction within the segment with the constant cross-section area has a form corresponding to a lateral surface of a right circular cylinder or to a lateral surface of a conical frustum, and/or wherein the cross-section area of the heating channel orthogonal to the flow-guiding direction within the further segment with the constant cross-section area has a form corresponding to a lateral surface of a conical frustum or to an annulus.
As already mentioned, the cross-section area preferably has a form that corresponds to a surface of revolution. Depending on the course of the heating channel, the surface of revolution can have different forms and/or can correspond to lateral surfaces of different bodies of revolution. Preferably in connection to the terminal section of the heating channel, the form of the cross-section area corresponds to the lateral surface of a right circular cylinder or to the lateral surface of a conical frustum. Further preferably, in the subsection of the section, where the flow-guiding direction of the heating channel exclusively has a radial component, the form of the cross-section area corresponds to the lateral surface of a right circular cylinder.
Further preferably in connection to the further section of the heating channel, the form of the cross-section area corresponds to the lateral surface of a conical frustum or to an annulus. Further preferably, in the further subsection of the further section, where the flow-guiding direction of the heating channel exclusively has an axial component, the form of the cross-section area corresponds to an annulus.
These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.
In the drawings:
Fig. 1 schematically shows an interrupter unit for a gas-insulated high voltage circuit breaker, according to a preferred embodiment.
Fig. 2 schematically shows the interrupter unit of figure 1 in an unworn state and in a worn state,
Fig. 3 schematically shows two exemplary cross-sectional areas of a heating channel within a segment of the heating channel of the interrupter unit of figure 1 , and
Fig. 4 schematically shows an interrupter unit for a gas-insulated high voltage circuit breaker, according to another preferred embodiment.
Description of embodiments Fig. 1 schematically shows an interrupter unit 10 for a gas-insulated high or medium circuit breaker, according to a preferred embodiment. The interrupter unit 10 comprising a first arcing contact 12 and a second arcing contact 14. In this embodiment the first arcing contact 12 has the form of a plug contact 12 and the second arcing contact 14 is configured as tulip contact 14. The plug contact 12 is axially movable along a switching axis 16. The tulip contact 14 is configured to engage around a proximal portion of the plug contact 12, in the closed position of the contacts 12, 14 (not shown in figure 1 ). In the open position of the contacts 12, 14 the plug contact 12 and tulip contact 14 are apart from each other, as shown in figure 1 .
The interrupter unit 10 further comprises a nozzle 18, wherein the nozzle 18 at least partially encloses the arcing contacts 12, 14. The nozzle 18 comprises a heating channel 20 for guiding an arc extinguishing gas in a flow-guiding direction 22 to an arcing region 24 formed between the first arcing contact 12 and the second arcing contact 14 during the opening operation of the arcing contacts 12, 14. The heating channel 20 links a pressurization chamber of the arc extinguishing gas (not shown in figure 1 ), with the arcing region 24 during the relative movement of the arcing contacts 12 and 14 along the switching axis 16.
In this embodiment the nozzle 18 comprises an auxiliary nozzle 26 and an insulating nozzle 28 arranged around the auxiliary nozzle 26 and the heating channel 20 is formed in between the insulating nozzle 28 and the auxiliary nozzle 26. The heating channel 20 comprises at an opening 30 of the heating channel 20 into the arcing region 24 a terminal section 32, where a radial component of the flow-guiding direction 22 is equal to or greater than an axial component of the flow-guiding direction 22. The terminal section 32 of the heating channel 20 is rotationally symmetric around the switching axis 16. The axial component of the flow-guiding direction 22 is the component colinear to the switching axis 16. The radial component of the flowguiding direction 22 is orthogonal to the switching axis 26 and defined by the rotational symmetry of the terminal section 32 around the switching axis 16.
The terminal section 32 comprises a segment 34, in figure 1 the shaded area 34, where a cross-section area of the heating channel 20 orthogonal to the flow-guiding direction 22 is constant with respect to the flow-guiding direction 22 of the heating channel 20.
In this embodiment the terminal section 32 further comprises a subsection 38, where the flow-guiding direction 22 of the heating channel 20 exclusively has a radial component. In other words, and as can be seen in figure 1 , in this subsection 38, the course of the heating channel 20 is such that the flow-guiding direction 22 is orthogonal to the switching axis 26. The segment 34 with the constant cross-section area extends at least in part along said subsection 38.
Furthermore, and as is also illustrated in figure 3, in the embodiment shown in figure 1 the cross-section area of the heating channel 20 orthogonal to the flow-guiding direction 22 within the segment 34 with the constant cross-section area has a form 36 corresponding to a lateral surface of a cylinder. Figure 3 illustrates two exemplary forms 36 of the cross-section areas, which correspond to the cross-sections indicated by the arrows 40, 42 in figure 1 . As can also be seen in figure 3, is that the height of the cylinders, which are also indicated by the arrows 40, 42 increases when the radius of the cylinder decreases. As the height of the cylinder corresponds to a shortest distance between the sidewall of the insulating nozzle 28 facing the heating channel 20 and a sidewall 46 of the auxiliary nozzle 26 facing the heating channel 20, figure 3 and 1 also illustrate that in the segment 34 the heating channel 20 is formed such that the shortest distance increases with respect to the flow guiding direction 22.
In another preferred embodiment shown in figure 4 the course of the heating channel 20 in the terminal section 32 is different from the embodiment as shown in figure 1. In the embodiment shown in figure 4 the course of the heating channel 20 in the terminal section 32 is such that the flow guiding direction 22 has in addition to the radial component also an axial component. For simplicity only one halve of the rotationally symmetric part of the interrupter unit 10 is shown in figure 4 and also only the second arcing contact 14 of the first and second arcing contacts 12, 14 is shown in figure 4. In the embodiment shown in figure 4, the form of the constant crosssection area would correspond to a lateral surface of a conical frustrum. Furthermore, and with regard to the segment 34 with the constant cross-section area, in the embodiments shown in figures 1 and 4 the segment 34 starts with respect to the flow-guiding direction 22 at a point 44, where a sidewall 46 of the auxiliary nozzle 26 facing the heating channel 20 has its maximal axial extent. As can be seen in figures 1 and 3, at a beginning of the heating channel 20 the sidewall 46 of the auxiliary nozzle 26 facing the heating channel 20 is predominantly oriented parallel to the switching axis 16. However, as the course of the heating channel 20 changes towards the switching axis 16 also the orientation of the sidewall 46 changes. The segment 34 starts at the point 44, where the sidewall 46 has a turning point and the axial extent of the sidewall 46 reaches its maximum.
As can also be seen in figure 1 , the edges of the opening 30 of the heating channel 20 into the arcing region 24 are rounded and configured as fillet edges. The end of the segment 34 with the constant cross-section area within the terminal section 32 of the heating channel 20 ends in this embodiment at the beginning of the fillet region 48 at the opening 30 of the heating channel 20 into the arcing region 24.
With respect to figure 2, which shows the interrupter unit 10 of figure 1 in an unworn state (indicated by a continuous line of the contour) and in a worn state, where sidewalls 50, 50’, 52, 52’ of the nozzle 18 are ablated (indicated by a dashed line of the contour), axial side walls 50 of the auxiliary nozzle 26 and axial side walls 52 of the insulating nozzle 28 facing the arcing region 24 and adjacent to the opening 30 of the heating channel 20 extend at least partially parallel to the switching axis 16 in the unworn state of the nozzle 18.
The axial side walls 50 of the auxiliary nozzle 26 define an auxiliary nozzle channel 54 and the axial side walls 52 of the insulating nozzle 28 define an insulating nozzle channel 56. In the embodiment shown in figure 2, in the unworn state of the interrupter unit 10, a diameter 58 of the auxiliary nozzle channel 54 and a diameter 60 of the insulating nozzle channel 56 are the same.
In the embodiment shown in figure 2 the segment 34 with the constant cross-section area within the terminal section 32 of the heating channel 20 is the narrowest pas- sage the arc extinguishing gas passes during its flow from the pressurization chamber to the arcing region 24 and constitutes a pressurization chamber outflow limiting area.
Furthermore, in the unworn state, a nozzle outflow limiting area is defined by the sum of a first narrowest cross-section area defined by the the diameter 58 of the auxiliary nozzle channel 54 and encompassed by the axial side wall 50 of the auxiliary nozzle 26 with a second narrowest cross-section area defined by the the diameter 60 of the insulating nozzle channel 56 and encompassed by the axial side wall 52 of the insulating nozzle 28.
In the worn state the nozzle outflow limiting area is defined by the sum of a first narrowest cross-section area defined by the the diameter 58’ of the auxiliary nozzle channel 54 and encompassed by the axial side wall 50’ of the auxiliary nozzle 26 with a second narrowest cross-section area defined by the the diameter 60’ of the insulating nozzle channel 56 and encompassed by the axial side wall 52’ of the insulating nozzle 28.
In the embodiment shown in figure 2 the interruption unit 10 is configured such that in the unworn state a ratio between the pressurization chamber outflow limiting area to the nozzle outflow limiting area is >1 and changes to <1 in the worn state. In particular in the unworn stat the ratio between the the pressurization chamber outflow limiting area to the nozzle outflow limiting area is 1.1. Due to nozzle ablation and due to the constant cross-section area in the segment 34 of the heating channel 20, the ratio between the pressurization chamber outflow limiting area to the nozzle outflow limiting area changes to to <1 in the worn state.
As can be further seen in figure 1 , the heating channel 20 comprises with respect to the flow-guiding direction 22 upstream to the terminal section 32 and adjacent to the terminal section 32, a further section 62, where the radial component of the flowguiding direction 22 is lower than the axial component of the flow-guiding direction 22. Furthermore, in the embodiment shown in figure 1 , the further section 62 is rotationally symmetric around the switching axis 16, and comprises a further segment, where a cross-section area of the heating channel 20 orthogonal to the flow-guiding direction 22 is constant with respect to the flow-guiding direction 22.
While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments. Other variations to be disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosed, and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting scope.
Reference signs list
10 interrupter unit
12 first arcing contact, plug contact
14 second arcing contact, tulip contact
16 switching axis
18 nozzle
20 heating channel
22 flow guiding direction
24 arcing region
26 auxiliary nozzle
28 insulating nozzle
30 opening of heating channel
32 terminal section
34 segment
36 form of cross-section area of segment 34
38 subsection
40 arrow
42 arrow
44 point where sidewall of heating channel has maximal axial extent
46 sidewall of auxiliary nozzle facing heating channel
48 fillet region
50 side wall of auxiliary nozzle facing arcing region in unworn state
50’ side wall of auxiliary nozzle facing arcing region in worn state
52 side wall of insulating nozzle facing arcing region in unworn state
52’ side wall of insulating nozzle facing arcing region in worn state
54 auxiliary nozzle channel
56 insulating nozzle channel
58 diameter of auxiliary nozzle channel in unworn state
58’ diameter of auxiliary nozzle channel in worn state
60 diameter of insulating nozzle channel in unworn state
60’ diameter of insulating nozzle channel in worn state
62 further section

Claims

Claims
1 . Interrupter unit (10) for a gas-insulated high or medium voltage device comprising a first arcing contact (12) and a second arcing contact (14), wherein at least one of the arcing contacts (12,14) is axially movable along a switching axis (16), a nozzle (18), wherein the nozzle (18) at least partially encloses one of the arcing contacts (12,14), wherein the nozzle (18) comprises a heating channel (20) for guiding an arc extinguishing gas in a flow-guiding direction (22) to an arcing region (24) formed between the first (12) and the second arcing contact (14) during an opening operation of the arcing contacts (12,14), wherein the heating channel (20) comprises at an opening (30) of the heating channel (20) into the arcing region (24) a terminal section (32), where a radial component of the flow-guiding direction (22) is equal to or greater than an axial component of the flow-guiding direction (22), wherein the terminal section (32) is rotationally symmetric around the switching axis (16), and wherein the terminal section (32) comprises a segment (34), in which a cross-section area orthogonal to the flow-guiding direction (22) is constant with respect to the flow-guiding direction (22) of the heating channel (20).
2. The interrupter unit (10) according to claim 1 , wherein the nozzle (18) comprises an auxiliary nozzle (26) and an insulating nozzle (28) arranged around the auxiliary nozzle (26), wherein the heating channel (20) is formed in between the insulating nozzle (28) and the auxiliary nozzle (26), wherein in a unworn state of the interrupter unit (10), axial side walls (50,52) of the auxiliary nozzle (26) and the insulating nozzle (28) facing the arcing region (24) are rotationally symmetric around the switching axis (16), and are configured such that a sum of a first narrowest cross-section area orthogonal to the switching-axis (16) encompassed by the axial side wall (50) of the auxiliary nozzle (26) with a second narrowest cross-section area orthogonal to the switching-axis (16) encompassed by the axial side wall (52) of the insulating nozzle (28) is lower than the cross-section area of the heating channel (20) within the segment (34). The interrupter unit (10) according to claim 2, a) wherein the cross-section area of the heating channel (20) within the segment (34) is at least 1 .05 times greater, and preferably at least 1.1 times greater than the sum of the first narrowest cross-section area orthogonal to the switching-axis (16) encompassed by the axial side wall (50) of the auxiliary nozzle (26) with the second narrowest cross-section area orthogonal to the switching-axis (16) encompassed by the axial side wall (52) of the insulating nozzle (28); and/or b) wherein the cross-section area of the heating channel (20) within the segment (34) is not more than 1 .25 times greater, and preferably not more than 1 .2 times greater than the sum of the first narrowest cross-section area orthogonal to the switching-axis (16) encompassed by the axial side wall (50) of the auxiliary nozzle (26) with the second narrowest cross-section area orthogonal to the switching-axis (16) encompassed by the axial side wall (52) of the insulating nozzle (28). The interrupter unit (10) according to claims 2 or 3, wherein in the unworn state of the interrupter unit (10), the axial side walls (50,52) of the auxiliary nozzle (26) and the insulating nozzle (28) facing the arcing region (24) and adjacent to the opening (30) of the heating channel (20) into the arcing region (24) extend at least partially parallel to the switching axis (16). The interrupter unit (10) according to any of the previous claims, wherein the terminal section (32) comprises a subsection (38) where the flow-guiding direction (22) of the heating channel (20) exclusively has a radial component, and wherein the segment (34) with the constant cross-section area extends at least in part along said subsection (38).
6. The interrupter unit (10) according to any of the previous claims, wherein with respect to the flow-guiding direction (22) the segment (34) with the constant cross-section area starts at the beginning of the terminal section (32), or wherein with respect to the flow-guiding direction (22) the segment (34) with the constant cross-section area starts at the beginning of the subsection (38) where the flow-guiding direction (22) of the heating channel (20) exclusively has a radial component.
7. The interrupter unit (10) according to any of the previous claims, wherein the nozzle (18) comprises an auxiliary nozzle (26) and an insulating nozzle (28) arranged around the auxiliary nozzle (26), wherein the heating channel (20) is formed in between the insulating nozzle (28) and the auxiliary nozzle (26), and a) wherein the segment (34) with the constant cross-section area starts, where a sidewall (46) of the auxiliary nozzle (26) facing the heating channel (20) has its maximal axial extent, and/or b) wherein sidewalls (46) of the insulating nozzle (28) and auxiliary nozzle (26) facing the heating channel (20) within the segment (34) with the constant crosssection area are not parallel to each other.
8. The interrupter unit (10) according to any of the previous claims, wherein the nozzle (18) comprises an auxiliary nozzle (26) and an insulating nozzle (28) arranged around the auxiliary nozzle (26), wherein the heating channel (20) is formed in between the insulating nozzle (28) and the auxiliary nozzle (26), and wherein within the segment (34) with the constant cross-section area a shortest distance between a sidewall of the insulating nozzle (28) facing the heating channel (20) and a sidewall (46) of the auxiliary nozzle (26) facing the heating channel (20) increases with respect to the flow-guiding direction (22).
9. The interrupter unit (10) according to any of the previous claims, wherein with respect to the flow-guiding direction (10) the segment (34) with the constant cross-section area ends at the opening (30) of the heating channel (20) into the arcing region (24) or wherein with respect to the flow-guiding direction (22) the segment (34) with the constant cross-section area ends at the beginning of a fillet region (48) at the opening (30) of the heating channel (20) into the arcing region (24).
10. The interrupter unit (10) according to any of the previous claims, wherein the heating channel (20) comprises with respect to the flow-guiding direction (22) upstream to the terminal section (32) and adjacent to the terminal section (32), a further section (62), where the radial component of the flow-guiding direction (22) is lower than the axial component of the flow-guiding direction (22), wherein the further section (62) is rotationally symmetric around the switching axis (16), and wherein the further section (62) is configured such that the further section (62) comprises a further segment, where a cross-section area of the heating channel (20) orthogonal to the flow-guiding direction (22) is constant with respect to the flow-guiding direction (22).
11 . The interrupter unit (10) according to the previous claim, wherein with respect to the flow-guiding direction (22) the further segment with the constant cross-section area ends at the beginning of the terminal section (32).
12. The interrupter unit (10) according to any of claims 10 or 11 , wherein the further section comprises a further subsection, where the flow-guiding direction (22) of the heating channel (20) exclusively has an axial component.
13. The interrupter unit (10) according to any of the previous claims, wherein the cross-section area of the heating channel (20) orthogonal to the flow-guiding direction (20) within the segment (34) with the constant cross-section area has a form (36) corresponding to a lateral surface of a right circular cylinder or to a lateral surface of a conical frustum, and/or wherein the cross-section area of the heating channel (20) orthogonal to the flow-guiding direction (22) within the further segment with the constant crosssection area has a form corresponding to a lateral surface of a conical frustum or to an annulus.
14. Gas-insulated high or medium voltage device comprising an interrupter unit (10) according to any of the previous claims, and wherein the high or medium voltage device comprises an arc extinguishing gas. 15. Gas-insulated high or medium voltage device according to the previous claim, wherein the gas-insulated high or medium voltage device is configured as a circuit breaker and more preferably as a puffer-type circuit breaker, a self-blast circuit breaker, or a combined puffer-type and self-blast circuit breaker.
PCT/EP2023/055014 2022-03-15 2023-02-28 Interrupter unit for gas-insulated high or medium voltage device and gas-insulated high or medium voltage device WO2023174675A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP22162161.8 2022-03-15
EP22162161.8A EP4246548A1 (en) 2022-03-15 2022-03-15 Interrupter unit for gas-insulated high or medium voltage device and gas-insulated high or medium voltage device

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19936987C1 (en) * 1999-07-30 2001-01-25 Siemens Ag High-voltage (HV) switch with arcing contacts and single electrode
US20080314873A1 (en) * 2006-02-28 2008-12-25 Abb Research Ltd Switching chamber for a high-voltage switch having a heating volume for holding quenching gas produced by switching arcs
WO2013153112A1 (en) 2012-04-11 2013-10-17 Abb Technology Ag Circuit breaker
WO2018177824A1 (en) * 2017-03-31 2018-10-04 General Electric Technology Gmbh A switching chamber for a gas-insulated circuit breaker comprising an optimized thermal channel

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19936987C1 (en) * 1999-07-30 2001-01-25 Siemens Ag High-voltage (HV) switch with arcing contacts and single electrode
US20080314873A1 (en) * 2006-02-28 2008-12-25 Abb Research Ltd Switching chamber for a high-voltage switch having a heating volume for holding quenching gas produced by switching arcs
WO2013153112A1 (en) 2012-04-11 2013-10-17 Abb Technology Ag Circuit breaker
WO2018177824A1 (en) * 2017-03-31 2018-10-04 General Electric Technology Gmbh A switching chamber for a gas-insulated circuit breaker comprising an optimized thermal channel

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