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EP-4738414-A1 - THREE-POSITION, MEDIUM-VOLTAGE, COMPACT SWITCH-DISCONNECTOR WITH VACUUM INTERRUPTION AND DISCONNECTION IN AIR UP TO 17 KV OR IN A SEALED PRESSURISED ENCLOSURE WITH ISOLATION IN DRY AIR UP TO 36 KV, AND METHOD OF OPERATION

EP4738414A1EP 4738414 A1EP4738414 A1EP 4738414A1EP-4738414-A1

Abstract

A medium-voltage, compact, three-position (closed, open, earthed) switch-disconnector with current interruption in a vacuum-sealed chamber, and insulated between the phases and disconnected in air up to 17 kV or, in a sealed pressure-tight enclosure, insulated between the phases and disconnected in dry air up to 36 kV, said switch-disconnector comprising a three-pole assembly, wherein each pole comprises: a support element (11, 13) of insulating material carrying: - a first male plug-in current-carrying and disconnecting contact in air (23) associated with a fixed upper right-angled contact (21); - a telescopic, movable, current-carrying and disconnecting contact in air (39, 41, 43) arranged on a hollow cylindrical support (37) of insulating material rotatable with respect to the support element (11, 13); and - a second fixed male lower plug-in contact (27) associated with a fixed right-angled earthing contact (25), wherein said support element (11, 13) is T-shaped with curved arms and with a widened hollow base (29) in which said hollow cylindrical support (37) made of insulating material and carrying said movable telescopic contact (39, 41, 43) is rotatably arranged, and wherein said movable current-carrying and disconnecting contact in air (39, 41, 43) is rotatable between a first closed position engaged with said first, male, plug-in current-carrying and disconnecting contact in air (23), a second disconnected position, and a third position connected to earth via said second fixed earth contact (27); said switch further comprising a vacuum extinguishing chamber (57) fixed near one end of the support element (11, 13) near the fixed upper right-angled contact (21), said vacuum-sealed chamber (57) containing two axially aligned contact rods (59, 61), one of which (59) is fixed and connected to said fixed upper right-angled contact (21), and the other (61) is movable for vacuum interruption by means of an electrical connection linkage operatively connected to a free end of said movable current-carrying and disconnecting contact in air (39, 41, 43).

Inventors

  • TOSI, GIAMPIETRO

Assignees

  • Tosi, Giampietro

Dates

Publication Date
20260506
Application Date
20251104

Claims (9)

  1. A medium-voltage compact, three-position (closed, open, earthed) switch-disconnector with current interruption in a vacuum-sealed chamber, and insulated between the phases and disconnected in air up to 17 kV or, in a sealed pressure-tight enclosure, insulated between the phases and disconnected in dry air up to 36 kV, said switch-disconnector comprising a three-pole assembly, wherein each pole comprises: - a support element (11, 13) of insulating material carrying: - a first, male, plug-in, current-carrying and disconnecting contact in air (23) associated with a fixed upper right-angled contact (21), - a telescopic, movable, current-carrying and disconnecting contact in air (39, 41, 43) arranged on a hollow cylindrical support (37) of insulating material and rotatable with respect to the support element (11, 13); and - a second. fixed, male, lower plug-in contact (27) associated with a fixed right-angled earthing contact (25), wherein said support element (11, 13) is T-shaped with curved arms and with a widened hollow base (29) in which said hollow cylindrical support (37) made of insulating material and carrying said movable telescopic air isolation and flow contact (39, 41, 43) is rotatably arranged, and wherein said movable current-carrying and disconnecting contact in air (39, 41, 43) is rotatable between a first position engaged with said first, male, plug-in current-carrying and disconnecting contact in air (23), a second disconnected position, and a third position connected to earth via said second fixed earth contact (27), and - a vacuum extinguishing chamber (57) which, by interrupting the arc in the vacuum-sealed environment, maintains the insulating capacity of the free ambient air or dry air in the sealed pressurised enclosure, which is fixed at one end of the support element (11, 13) near the fixed upper right-angled contact (21), said vacuum-sealed chamber (57) containing two axially aligned contact rods (59, 61), one contact rod (59) of which is fixed and connected to said fixed upper right-angled contact (21), and the other contact rod (61) is movable for vacuum interruption so as to slide within the extinguishing chamber (57) by means of an electrical connection linkage operatively connected to a free end of said movable current-carrying and disconnecting contact in air (39, 41, 43).
  2. Switch-disconnector according to claim 1, characterised in that said telescopic movable contact (39, 41, 43) arranged on said hollow cylindrical support (37) made of insulating material comprises a first, fixed, expandable, elastic, outer cylindrical portion (39), which is electrically connected to a connection contact (31) for connection to a medium voltage circuit, and within which there is slidably mounted a second, inner, cylindrical portion (41) carrying near its free end, rigidly joined to its inside, a tulip-shaped contact element (43) acting as a female contact.
  3. Switch-disconnector according to one or more of the preceding claims, characterised in that said free end of said second cylindrical portion (41) is supported inside an annular support element (45) which is made of insulating material and pivotably mounted (at 47) inside a first end of two half-arms (49, 51) made of insulating material and forming an end fork, a second opposite end of the two half-arms (49, 51) being pivotably mounted on said support element (11, 13) and a hollow central shaft (55) being provided for actuation of the isolator.
  4. Switch-disconnector according to one or more of the preceding claims, characterised in that a first upper end of said chamber (57) is integrally mounted on said fixed upper right-angled contact (21), while another lower end of said chamber (57) extends downwardly within a U-shaped insulating support-piece (63) fastened by screws (65) to said support element (11, 13).
  5. Switch-disconnector according to one or more of the preceding claims, characterised in that an annular support member (45) made of insulating material is arranged at a free end of said movable telescopic current-carrying and disconnecting contact in air (39, 41, 43) and, extending from said annular support member (45), there is a metal recessed contact extension (75) which engages with two bosses (77) internally arranged on a hollow finger (79) extending from a U-shaped bar (69) pivotably mounted (at 67) on a U-shaped insulating support-piece (63) fastened by screws (65) to the support element (11, 13).
  6. Switch-disconnector according to claim 5, characterised in that said U-shaped bar (69) has a slot (71) inside which a spindle (73) connected to one end of said contact rod (61), sliding inside the chamber (57), is arranged.
  7. Switch-disconnector according to claim 6, characterised in that said U-shaped bar (69) is pivotably mounted on a U-shaped insulating support-piece (63) by means of a spindle (67) on which there is wound a spring (81) which reacts against said U-shaped bar (69) and keeps it normally in contact with a lower part of the chamber (57) as well as keeping said two contact rods (59, 61) in contact.
  8. Switch-disconnector according to claim 2, characterised in that said connection contact (31) is attached to said support element (11, 13) together with a U-shaped member (33) closed at the bottom and provided with pin-like extensions (35) which engage rotatably with said first, fixed, expandable, elastic outer cylindrical portion (39) of said telescopic arm.
  9. Method for operating a switch-disconnector according to one or more of the preceding claims 1 to 8, wherein, when said switch-disconnector is in the closed position, the movable current-carrying and disconnecting contact in air (41), (43) is closed on the fixed current-carrying and disconnecting contact in air (21), (23), the recessed metal contact extension (75) of the movable current-carrying and disconnecting contact in air (41), (43) is engaged with the bosses (77) and by means of the electrical connection linkage (69), (73), (75) the movable current-carrying and disconnecting contact in air (41), (43) is connected to the movable vacuum breaker contact (61) closed on the fixed vacuum breaker contact (59), which in turn is connected to the fixed current-carrying and disconnecting contact in air (21), (23), so that the current passes through both the current-carrying and disconnecting contact in air and the vacuum breaker contacts; and when it is required to break the current flow, with a single opening operation, there is in a first moment the disconnection of the movable current-carrying and disconnecting contact in air (41), (43) from the fixed current-carrying and disconnecting contact in air (21), (23), while maintaining the current flow between the two contact rods (59), (61) in a vacuum, the electrical connection linkage (69), (73), (75) in the air and the movable current-carrying and disconnecting contact in air (41), (43); in a second moment, when the movable current-carrying and disconnecting contact in air is sufficiently far from the fixed current-carrying and disconnecting contact in air, there is interruption in the vacuum-sealed chamber (57) with the movement away of the breaker contact rod (61) from the breaker contact rod (59); and in a third moment with the disengagement of the recessed metal contact extension (75) from the bosses (77), the movable current-carrying and disconnecting contact in air (75), (37), (39), (41), (43) separates completely from the movable vacuum breaker contact (59), and moves into the horizontal isolated/open position, and simultaneously the movable vacuum breaker contact rod (61) closes back onto the fixed vacuum breaker contact rod (59), inside the vacuum chamber (57), setting up the vacuum breaker contacts (59), (61) for the next closing operation.

Description

The present invention relates to a medium-voltage compact switch-disconnector with three positions, i.e. closed, open and earthed, with current interruption in a vacuum-sealed chamber, and insulated between the phases and disconnected in air up to 17 kV, or, in a sealed pressure-tight enclosure, insulated between the phases and disconnected in dry air up to 36 kV, said switch-disconnector up to 36 kV being isolated in dry air inside a sealed pressure-tight enclosure. For particular location and operational requirements various types of load-breaking switch-disconnectors isolated in SF6 (sulphur hexafluoride) for medium voltages up to 36 kV are known. The gas SF6, owing to its electric arc extinguishing and isolating properties, is used very much in high-voltage and medium-voltage equipment and is considered to be difficult to replace, but its potential greenhouse effect is high because its global heating potential is equal to 23,900 times that of carbon dioxide (CO2) and the time it remains in the atmosphere is 3,200 years and it is the most powerful greenhouse gas known. SF6 is not toxic and it is a stable gas from a chemical and thermal point of view, but during operation of the switches owing to the supply of energy, in particular in the presence of moisture, it may lose its dielectric resistance, decompose and become toxic and corrosive and damaging for the equipment and for human beings. The gas, if it spreads into the environment, owing to its heavy weight, is deposited on the ground, but in confined spaces, if it is breathed in, even if not decomposed and therefore not toxic, again because of its weight, is deposited on the bottom of the lungs and displaces the oxygen and causes respiratory problems for the maintenance personnel working in the environment. One object of the present invention is to provide a medium-voltage switch-disconnector and/or isolator with three positions which, combining the use of air or dry air and vacuum for disconnecting and extinguishing of the arc, satisfies the particular location and operational requirements of equipment isolated in SF6, but protects the environment and, owing to its extreme constructional simplicity, also represents a valid alternative from a technical and cost point of view, to equipment in SF6. A further aim is to provide a switch-disconnector which is constructionally simple, easy to use and safe and does not involve the presence of gas. Last but not least, a further aim is to provide a switch-disconnector, the components of which do not require special positioning within the containment frame, but which may be entirely mounted far therefrom before insertion. Moreover, such a switch-disconnector is made so that the mechanical and electrical operation is not influenced by the enclosure which, however, in the case of use in conditions higher than 17 kV is pressure-sealed so as to preserve the presence of dry air which ensures the established electrical insulation and extinguishing of the arc. These objects are achieved according to the present invention by a medium-voltage switch-disconnector and/or isolator with three positions, provided in accordance with the independent claim 1 and the following dependent subclaims. According to the invention, the medium-voltage compact switch-disconnector disconnected in air or in dry air with vacuum interruption having three positions, i.e. closed, isolated and earthed, comprises a series of three poles, wherein each pole is provided with a double fixed contact and a double movable contact. Said double fixed contact consists of a fixed current-carrying and disconnecting contact in air, joined via an electrical connection to a fixed contact situated in a vacuum-sealed chamber where the interruption occurs. Said double movable contact consists of a movable current-carrying and disconnecting contact in air, arranged on an arm pivotably mounted and rotatable between a closed position engaged with a fixed current-carrying and disconnecting contact in air, a second isolated position, and a third position connected to earth via a fixed earth contact, said movable current-carrying and disconnecting contact in air being joined, by means of a simple electrical connection linkage, to a movable breaker contact situated in the vacuum-sealed chamber, said vacuum-sealed chamber being integrally mounted on the fixed insulating part which supports the rotatable, insulating, pivotably mounted arm which carries the movable contact device. Operation anti-clockwise in the direction of the arrow in Figure 2 detaches in air the movable current-carrying and disconnecting contact in air from the fixed current-carrying and disconnecting contact in air and immediately an electrical connection linkage, connected to the movable current-carrying and disconnecting contact in air, causes the breaking of the load, guiding the separation of the movable and fixed contacts located inside the vacuum-sealed chamber, said movable current-carrying and