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
• • 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
  • H01H33/12—Auxiliary contacts on to which the arc is transferred from the main contacts
• • 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
• • 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
  • H01H2033/028—Details the cooperating contacts being both actuated simultaneously in opposite directions

Definitions

• aspects of the invention relate to a circuit breaker, in particular a gas insulated type circuit breaker. Further aspects relate to such a circuit breaker having a gas insulation housing, a pair of nominal contacts and a pair of arcing contacts. Further aspects relate to a method of breaking an electrical circuit by a gas insulated circuit breaker, and to a High- Voltage or Medium- Voltage switchgear.
• a gas insulated type circuit breaker is an electrical device which is provided on an electrical line to safely interrupt (break) a current, either in a normal switching operation under normal current, or when a fault current such as ground fault or short circuit occurs.
• the gas insulated type circuit breaker has a housing containing a dielectric gas such as sulphur hexafluoride (SF6), which insulates the voltage-carrying components from one another and from ground voltage, and which reduces the risk of high- voltage breakdown in a compact housing.
• SF6 sulphur hexafluoride
• the circuit breaker has two nominal contact elements, which are arranged such that during normal operation in a closed state of the circuit breaker, the normal current (rated up to a nominal current value) is mainly transported through these nominal contact elements.
• the circuit breaker breaks a current, i.e. performs a trip operation
• the nominal contact elements are separated from one another (by moving e.g. one of the nominal contacts), whereby the current is commutated to two arcing contact elements, which are still in contact with one another during the first phase.
• the arcing contact elements are separated, whereby an electric arc develops.
• the arcing contact elements are further separated from one another, and a portion of the dielectric gas is ejected towards the arc for extinguishing the arc.
• the circuit breaker may include a fixed side and a movable side, so that for separating a pair of contacts only one of the contacts is moved while the other one is fixed.
• circuit breakers for which contacts on both sides are movable.
• This circuit breaker has two movable sides, each side having a nominal contact and an arcing contact. On each side, the nominal contact and arcing contact are rigidly connected to each other so that both contacts of the respective side always move at the same speed. Therefore, a large mass has to be moved for breaking a current.
• such a double-motion breaker has a relatively long break time.
• EP 1211726 describes a switchgear in which a main contact is connected to an arcing contact so that the main contact always moves at the same speed as the arcing contact. Also, it is generally desirable to have a switchgear that allows a coordinated motion of the contacts in a way that is favourable from a dielectric point of view. As can be seen from the above discussion, there is a need for an improved circuit breaker having a shorter break time.
• a gas insulated type circuit breaker comprises a housing defining a gas volume for a dielectric insulation gas; a first nominal contact element and a second nominal contact element adapted for selectively carrying or interrupting a nominal current between them, wherein the first nominal contact element is movable along an axis of the circuit breaker, and the second nominal contact element is fixed relative to the housing; a first arcing contact element and a second arcing contact element adapted for selectively carrying or interrupting an arcing current between them, wherein the first arcing contact element and the second arcing contact element are movable along the axis; a first gear coupling the first nominal contact element and the first arcing contact element to each other such that for circuit breaking the first nominal contact element and the first arcing contact element are both moved in a first direction along the axis; and a second gear coupling the second arcing contact element to one of the first nominal contact element and the first arcing contact element such that for circuit breaking the second arcing contact element
• circuit breaking two elements are both moved in a same direction, this does not imply that the motion in the same direction must be established during the entire circuit breaking. It is sufficient that the elements move in the same direction during some portion of the circuit breaking, e.g. more than 50% of the time or even more than 80% of the time; or, e.g., 50% or even 80% of the path of the element driving the gear connecting the two elements.
• a method of breaking an electrical circuit by a gas insulated circuit breaker comprises moving, by a drive unit, a driven contact element in a first direction along an axis of the circuit breaker, the driven contact element being one of a first nominal contact element and a first arcing contact element of the circuit breaker, transmitting the movement of the driven contact element, by a first gear coupling the first nominal contact element and the first arcing contact element to each other, to the other one of the first nominal contact element and the first arcing contact element, thereby moving the other contact element in the first direction along the axis, transmitting the movement of the driven contact element, by means of a second gear coupling a second arcing contact element of the circuit breaker to the driven contact element, thereby moving the second arcing contact element in a second direction along the axis opposite to the first direction, separating the first nominal contact element from a second nominal contact element which is held at a fixed position relative to a housing of the circuit breaker throughout the
• both arcing contacts are movable, a high relative speed between the arcing contacts may be obtained with relatively less work from the driving source as compared to a circuit breaker for which only one of the contacts is moved. Further, since the second nominal contact is fixed, the moved masses are reduced compared to a full double-motion circuit breaker. Further, especially due to the first gear, the speeds of the contacts may be selected and, in particular, be preselected, individually, thus allowing an advantageous movement of the contacts.
• Fig. 1 is a schematic cross-sectional side view of a circuit breaker according to a first embodiment
• Fig. 2 is a schematic cross-sectional side view of portions of a circuit breaker according to a second embodiment
• Figs. 3a to 3e are schematic enlarged side views of contact elements of a circuit breaker during different phases of breaking a current.
• the circuit breaker 1 is of the gas-insulated type and correspondingly has a housing 4, which defines a gas volume for a dielectric insulation gas.
• the housing 4 allows the insulation gas to be held therein in an gas-tight manner.
• the circuit breaker 1 has a first nominal contact assembly 40, a second nominal contact assembly 50, a first arcing contact assembly 60 and a second arcing contact assembly 70. All these elements and more elements described herein are, according to the first embodiment, arranged inside the housing 4.
• the first nominal contact assembly 40 is cylindrically shaped and has a first nominal contact element 42, typically at an end thereof.
• the second nominal contact assembly 50 is cylindrically shaped and has a second nominal contact element 52, typically at an end thereof.
• the contact elements 42, 52 can be parts of the cylindrically shaped contact assemblies and may, e.g., be surface-treated or otherwise adapted in a known manner, e.g. by spring members, for improving the contact and for reducing contact resistance.
• the first and second nominal contact elements 42, 52 are in direct mechanical and electrical contact with each other, for carrying a nominal current between them.
• the first and second nominal contact elements 42, 52 are separated from one another, and thereby the electrical contact is interrupted.
• the nominal contact elements are adapted for selectively carrying or interrupting a nominal current between them, i.e. carrying the current when the circuit breaker is in a closed configuration and interrupting it when the circuit breaker is in an open configuration.
• the first arcing contact assembly 60 has a first arcing contact element 62, which is shaped e.g. as a tulip, and is typically arranged at an end thereof.
• the second arcing contact assembly 70 has a second arcing contact element 72, which is shaped e.g.
• a nozzle system 64 in particular a self- blasting nozzle system 64, is present, which can typically be connected to the first arcing contact assembly 60, so that the self-blasting nozzle system 64 is jointly movable along the axis 2 with the first arcing contact element 62.
• the first and second nominal contact elements 42, 52 and the first and second arcing contact elements 62, 72 can advantageously be arranged co-axially about an axis 2 of the circuit breaker.
• the first nominal contact element 42, the first arcing contact element 62 and the second arcing contact element 72 are movable along the axis 2, along with their respective contact assemblies 40, 60, 70.
• a drive unit 10 is connected, e.g. via a rod 12, to the first nominal contact assembly 40 and thereby to the first nominal contact element 42. Thereby, for circuit breaking the drive unit 10 can pull, via the rod 12, the first nominal contact element 42 to the left.
• a first gear 20 couples the first nominal contact assembly 40 to the first arcing contact assembly 60, and thereby the first nominal contact element 42 to the first arcing contact element 62.
• the first gear 20 couples the first nominal contact element 42 to the first arcing contact element 62 in such a manner that when the first nominal contact element 42 is pulled to the left, the first arcing contact element 62 is also pulled to the left.
• the first gear 20 has a positive transmission ratio, at least for some position of the first nominal contact element 42, and possibly for all positions.
• a second gear 30 couples, e.g. via a rod 14, the second arcing contact element 72 to the first arcing contact element 62 (preferably via the blast nozzle system 64, as shown in Fig. 1).
• the second gear 30 has a negative transmission ratio, such that when the first arcing contact element 62 is moved to the left, the second arcing contact element 72 is moved to the right and vice versa, respectively.
• the drive unit 10 is connected, e.g. via the rod 12, to the first nominal contact element 42 and is coupled, e.g. via the gear 20, to the first arcing contact element 62. Further, the drive unit 10 is also coupled, via the first gear 20 and the second gear 30, to the second arcing contact element 72.
• the second nominal contact element 52 (and the entire second contact assembly 50) is fixed relative to the housing 4, as is schematically indicated by the shaded portion in Fig. 1.
• the drive unit 10 is provided at that side of the circuit breaker 1, on which the first nominal contact element 42 and the first arcing contact element 62 are provided.
• the first nominal contact element 42 is located, along the axis 2, more towards or closer to the drive unit 10 than the second nominal contact element 52, and the first arcing contact element 62 is located more towards or closer to the drive unit 10 than the second arcing contact element 72.
• Fig. 1 shows the circuit breaker in a closed state.
• the first arcing contact element 62 here e.g. a tulip contact 62
• the second arcing contact element 72 here e.g. a rod contact 72
• the drive unit 10 pulls, e.g. via the rod 12, the first nominal contact element 42 towards the left, or more generally speaking in a first direction. Therefore, the first nominal contact element 42 is also referred to as the driven contact element 42. By this movement, the first nominal contact element 42 is separated from the second nominal contact element 52. At this time, the arcing contact elements 62, 72 are still in mechanical and electrical contact with each other, and a current is commutated from the nominal contact elements 42, 52 to the arcing contact elements 62, 72.
• the first gear 20 couples the movement of the first nominal contact element 42 to the first arcing contact element 62, which is thereby also pulled towards the left, i.e. towards the first direction.
• the second gear 30 coupling the second arcing contact element 72 to the first arcing contact element 62, the second arcing contact element 72 is pulled in the opposite direction, i.e. to the right, or more generally speaking in a second direction.
• the first arcing contact element 62 is separated from the second arcing contact element 72.
• An arc appearing between the arcing contact elements 62, 72 is then extinguished within the nozzle system 64 by gas blowing in a manner recognizable by the person skilled in the art.
• the second nominal contact element 52 is held at a fixed position relative to the housing 4. As an advantage of this arrangement, because the second nominal contact element 52 is fixed, the reaction forces acting on the driving unit 10 are reduced. Thereby, the kinetic energy necessary for highspeed operation is reduced. Also, the mechanical reliability of the interrupter is improved.
• the first gear 20 is a pivot gear having a lever 21 which is mounted to the housing 4 pivotably about a pivot axis 22.
• lever 21, as well as below mentioned lever 31, are two-armed levers with a fixed angle between their lever arms.
• a linkage 23 is pivotably mounted at one lever arm 24a, in particular end 24a, to the lever 21, and at the other end 24b to the first nominal contact assembly 40.
• a further linkage 25 is pivotably mounted at one other lever arm 26a, in particular end 26a, to the lever 21, and at the other end 26b to the first arcing contact assembly 60.
• the second gear 30 is provided in an analogous manner, with a lever 31 mounted to the housing 4 pivotably about a pivot axis 32, a linkage 33 pivotably mounted at one lever arm 34a, in particular end 34a, to the lever 31 and at the other end 34b to a rod 14, and with a further linkage 35 pivotably mounted at one other lever arm 36a, in particular end 36a, to the lever 31, and at the other end 36b to the second arcing contact assembly 70.
• the first gear 20 and the second gear 30 shown in Fig. 1 have variable transmission ratios, i.e. transmission ratios that depend on the positions of the elements coupled via the gears 20, 30.
• the transmission ratio of a gear is defined as the distance by which the unit driving the gear moves, divided by the distance by which the unit driven by the gear moves.
• infinitesimally small distances are used, and distances in the first direction along the axis are positive and distances in the opposite direction are negative.
• the transmission ratio of the first gear 20 is the distance by which the first arcing contact assembly 60 is moved, divided by the distance by which the first nominal contact assembly 40 is moved.
• the transmission ratio of the first gear 20, also referred to as first transmission ratio varies with the position of the first nominal contact element 42 and/or of the first arcing contact element 62 along the axis 2.
• the transmission ratio of the second gear 30, also referred to as second transmission ratio varies with the position of the first nominal contact element 42 and/or of the second arcing contact element 62 along the axis 2.
• the ends 22, 26a and 26b essentially form a straight line in the closed position shown in Fig. 1.
• the first gear 20 couples the first nominal contact element 42 and the first arcing contact element 62 to each other such that the first nominal contact element 42 and the first arcing contact element 62 are moved in the same direction (here to the left) during the entire circuit breaking.
• the first gear 20 has a positive (or possibly temporarily zero) transmission ratio during the entire circuit breaking.
• This embodiment illustrates a further general aspect, in that the transmission ratio of the first gear 20 is gradually increasing during the circuit breaking.
• the geometry of the lever 21 and the linkages 23, 25 is chosen such that the transmission ratio is small at first, i.e. in the beginning the arcing contact assembly 60 is moved by a small distance only.
• the transmission ratio gradually increases.
• the first nominal contact 42 may move with higher velocity than the arcing contacts 62, 72 (gear ratio ⁇ 1), until the current is commutated from the nominal contact elements 42, 52 to the arcing contact elements 62, 72.
• the arcing contact elements 62, 72 can be separated from each other after the nominal contact elements 42, 52 without needing to have a long overlap of the arcing contact elements 62, 72 along the axial direction. This means a shorter break time and a decrease of friction force during opening and closing operation can be achieved.
• the main phases of accelerating the nominal contact element 42 and of accelerating the arcing contact element 62 occur at different times, i.e. in different time windows, so that an efficient acceleration can be achieved even with a limited power of the drive unit 10.
• a circuit breaking operation can be achieved within two AC cycles.
• the first and second gears 20 and 30 are shown by example only. Other types of gears coupling two linear movements can be used instead of the lever-type first and second gears 20 and 30 shown in Fig. 1.
• the rod 14 which drives the gear 30 is connected to the blast nozzle system 64.
• this does not necessarily mean that the elements are directly attached to one another. Instead, it can also mean that the elements are connected via intermediate elements.
• the rod 14 since the rod 12 is connected to the blast nozzle system 64, the rod 14 may equally be regarded as being connected to the first arcing contact element 62, since the arcing contact element 62 is itself connected to the blast nozzle system 64.
• a gear couples a first element and a second element to each other, this includes the case that the gear couples an element connected to the first element and an element connected to the second element to each other.
• the rod 14 can also be connected to the rod 12 or (equivalently in the embodiment of Fig. 1) to the first nominal contact assembly 40 and thereby to the first nominal contact element 42.
• Fig. 2 shows a portion of a circuit breaker according to a second embodiment.
• the circuit breaker is similar to the circuit breaker of Fig. 1, except for the first gear 20.
• the first gear 20 is dimensioned such that in a first phase of circuit breaking (first movement of the first nominal contact element 42 to the left with associated counter-clockwise pivoting of the lever 21), the first arcing contact element 62 is moved to the right. Only after the lever 21 has pivoted to a degree such that the joint 26a has moved past the line connecting the joints 22 and 26b, i.e. past the axis 2 in Fig.
• the direction of the first arcing contact element 62 is reversed such that the first arcing contact element 62 moves to the left.
• the first gear 20 defines a dead point for the motion of the first arcing contact, at which the transmission ratio of the first gear 20 changes sign from negative to positive.
• the dead point is obtained at a position of the first nominal contact element 42 which is before the separation of the first and second nominal contact elements 42 and 52 (see Fig. 1).
• An advantage of this dead point is that the overlap of the arcing contact elements 62, 72 along the axial direction can be reduced even further, and that the main phases of accelerating the nominal contact element 42 and of accelerating the arcing contact element 62 can be decoupled even further, because around the dead point there is only very little acceleration of the arcing contact element 62.
• Fig. 3a shows the circuit breaker in a closed configuration, analogous to the configuration of Figs. 1 and 2.
• the nominal contact elements 42, 52 are in contact with one another, and also the arcing contact elements 62, 72 are in contact with one another.
• a current is mainly transported via the nominal contact elements 42, 52, as opposed to the arcing contact elements 62, 72.
• a speed of the first nominal contact element 42 is faster than a speed of the first arcing contact element 62, and correspondingly the first nominal contact element 42 has moved a sizable distance with respect to the second nominal contact element 52, whereas there is almost no relative movement between the arcing contact elements 62 and 72.
• the nominal contact elements 42, 52 are separating from one another and any remaining current which has flown between them is commutated to the arcing contact elements 62, 72.
• Fig. 3e shows the circuit breaker in a fully open position, in which the nominal contact elements 42, 52 as well as the arcing contact elements 62, 72 are maximally separated from one another, and in which the arc has been extinguished.
• Figs. 3a to 3e also illustrate some general advantageous aspects of the embodiment: Namely, at a first time (e.g. the time of Fig. 3c), the first nominal contact element 42 is moved farther towards the first direction than the first arcing contact element 62. Thereafter, during a second time (e.g. the time of Fig. 3e), the first arcing element 62 is moved equally or farther towards the first direction than the first nominal contact element 42. This reflects the non-constant transmission ratio of the first gear 20. Thereby, the electrical field at the arcing contact elements 62, 72 is exposed during the making of the arc, but is shielded thereafter such that the risk of subsequent high-voltage breakdown is reduced. In other words, the movement of the contacts is coordinated, in particular due to the first gear 20, in such a way that dielectrically desirable properties at each stage of movement are obtained.
• the second arcing contact element 72 in a final position (see Fig. 3e), is moved further to the second direction than the second nominal contact element 52.
• the second arcing contact element 72 is positioned further to the second direction than the second nominal contact element 52 during at least from the time of arc formation or even during the entire circuit breaking. This again leads to favourable dielectric shielding of the retracted second arcing contact element 72 by the radially surrounding and axially protruding second nominal contact element 52.
• the circuit breaker 1 described herein is particularly advantageous for High- Voltage or Medium- Voltage applications.
• medium voltage is defined as a voltage above lkV
• high voltage is defined as a voltage above e.g. 35 kV, such as 52 kV and more.
• Figs. 1 and 2 may be varied in that the rod 12 connects the drive unit 10 to the first arcing contact element 62, instead of connecting the drive unit 10 to the first nominal contact element 42 as in Fig. 1. Then, the drive unit 10 drives the first arcing contact element 62 directly and the first nominal contact element 42 indirectly via the first gear 20. Also, independently thereof, the rod 14 may connect the second gear 30 to the first arcing contact element 62, instead of connecting it to the rod 12 as mentioned with respect to Fig. 1.
• the second gear 30 couples the second arcing contact element 72 to the first arcing contact element 62.
• first arcing contact element 62 has been shown in the shape of a tulip and the second arcing contact element 72 has been shown in the shape of a rod, different shapes may also be used.
• first arcing contact element 62 can be a rod and the second arcing contact element 72 can be a tulip.

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• Circuit Breakers (AREA)
• Arc-Extinguishing Devices That Are Switches (AREA)

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ID=44626588

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Cited By (1)

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• 2011
  • 2011-05-13 EP EP11721282.9A patent/EP2707891A1/en not_active Withdrawn
  • 2011-05-13 KR KR1020137033124A patent/KR20140044822A/ko not_active Application Discontinuation
  • 2011-05-13 WO PCT/EP2011/057792 patent/WO2012155952A1/en active Application Filing
  • 2011-05-13 CN CN201180070877.2A patent/CN103518246A/zh active Pending

Non-Patent Citations (1)

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