EP1928065B1

EP1928065B1 - Medium voltage gas-insulated switch-disconnector

Info

Publication number: EP1928065B1
Application number: EP06125177.3A
Authority: EP
Inventors: Roberto Capitanio; Francesco Belloni
Original assignee: ABB Schweiz AG
Current assignee: ABB Schweiz AG
Priority date: 2006-11-30
Filing date: 2006-11-30
Publication date: 2017-01-04
Anticipated expiration: 2026-11-30
Also published as: EP1928065A1; ES2630405T3; CN201163710Y

Description

The present invention relates to a medium voltage gas-insulated switch-disconnector, in particular a three-phase, three positions general purpose switch-disconnector with integrated earthing switch suitable for medium voltage. The switch-disconnector of the invention are typically used in medium voltage switchgear within secondary distribution substations for supplying lines, power transformers and networks.
Medium voltage gas-insulated switch-disconnector are well known in the art. They usually consist of a gas-tight casing that defines an internal space filled with an insulating gas and houses, for each phase, one or more moving contacts and one or more corresponding fixed contacts. In a typical application, a switch-disconnector comprises for each phase, a moving contact, a fixed contact and an earthing contact, the moving contact being able to move between open, closed and earthed positions.
Depending on the intended application, the switch-disconnectors need to satisfy a number of requirements which often cannot be met by the same switch-disconnector. For instance, in general it is desirable to have a switch-disconnector which is as compact as possible so as to occupy the minimum possible space within the unit it is installed in. In some cases, it is necessary to have a metal earthed segregation between the upper and lower compartment of the unit and this is generally achieved by using a switch-disconnector provided with a stainless steel casing. On the other hand, in such a case, the need of maintaining a minimum electrical distance with respect to the busbar does not allow to put the switch-disconnector too close to the busbars themselves, with a consequent waste of internal space on the unit.
It is therefore necessary to have a number of switch-disconnectors tailored according to the intended application, in terms of size and performances, with a consequent increase of design and manufacturing costs. This lack of standardization has a further drawback on the manufacturing costs, as well as on the maintenance costs, since it is necessary to have a number of different components and spare parts according to the different types of switch-disconnector.
It is therefore an object of the present invention to provide a switch-disconnector which is highly standardized (in terms of features, size and performances), in the sense that it can satisfy a number of different requirements thereby making possible its use in a number of different applications that cannot be covered nowadays by a single apparatus.
More in particular, it is an object of the present invention to provide a switch-disconnector which allows to minimize the occupied space inside the unit it is installed in, and at the same time can satisfy the requirements of the relevant Standards, e.g. the metal earthed segregation between the compartments of the unit.
As a further object, the present invention is aimed at providing a switch-disconnector having the highest possible number of standardized components, thereby reducing manufacturing and maintenance costs.
EP 0 485 306 A1 discloses a two shell plastic housing for a Medium Voltage gas-insulated switch-disconnector.
FR 2 259 459 discloses a Medium Voltage gas-insulated switch-disconnector according to the pre-amble of claim 1.
Thus, the present invention relates to a Medium Voltage gas-insulated switch-disconnector as defined by claim 1.
In this way, it is possible to overcome some of the disadvantages and drawbacks of the gas-insulated switch-disconnectors of the known art. Thanks to the fact that one of the half shells is made of polymeric material, it is possible to have a reasonably compact size of the overall housing, particularly if the bushings are integrated with said half-shell made of polymeric material, as better described below. In addition, being that the polymeric material is insulating, it is possible to reduce the electrical distance with respect to, e.g., the busbars, thereby reducing the occupied volume within a panel.
On the other end, being that one of the half shell is made of mental material and earthed, due to which a metal earthed segregation between the upper part and the lower part of the unit in which the is switch-disconnector is installed, is achieved e.g. between the busbar compartment and the feeder compartment of a metal-enclosed switchgear. Furthermore, the metal earthed segregation, provided by the half-shell made of metal material, considerably reduces the possibility of a short-circuit between the phases and between the upper and lower contacts of the same phase due to leakage currents. Also, the metal material guarantee safe performance in case of internal fault.
A Medium Voltage switchgear, including a switch-disconnector according to the general definition given above, is also part of the present invention
Further characteristics and advantages of the invention will emerge from the description of preferred, but not exclusive embodiments of the switch-disconnector according to the invention, non-limiting examples of which are provided in the attached drawings, wherein:

Figure 1 is a perspective view of a possible embodiment of a switch-disconnector according to the invention;
Figure 2 is a perspective view of the housing of the switch-disconnector of figure 1, showing the first-half shell separated from the second half-shell;
Figure 3 is a detailed view of the first, upper, half shell of the switch-disconnector according to figure 2;
Figure 4 is a detailed view of the second, lower, half-shell of the switch-disconnector according to figure 2;
Figure 5 is a view of the second, lower, half-shell of the switch-disconnector of figure 4, with the lower bushing disassembled from the half-shell itself;
Figure 6 is a partial front view of a Medium Voltage switchgear into which a switch-disconnector according to the invention has been installed.

With reference to the above mentioned figures, the gas-insulated medium voltage switch-disconnector according to the invention, designated with the reference number 1, comprises a gas-tight housing 2 which contains an insulating gas. Insulating gases, such as SF6, are well-known and generally used in the art and will not further described here. The switch-disconnector also comprises, for each phase, a moving contact, a fixed contact and an earthing contact (not shown in the attached figures) which are positioned inside said housing. In the embodiments of the attached figures, a three-phase switch-disconnector is shown, having a corresponding number moving contacts, fixed contacts and earthing contacts.
An operating mechanism 3 (shown only in figure 6) is generally used for moving said moving contact between open, closed and earthed positions, according to well known procedures. The housing may also include a pressure indicator, an exhaust valve or, in general, a pressure relief system for any gas overpressure, as well as one or more inspection windows for visual check of the contacts position.
As clearly shown in the figures, the gas-tight housing 2 comprises a first, upper, half-shell 21 and a second, lower, half shell 22, which are coupled to each other in a gas-tight manner. In the switch-disconnector of the invention one of two half shells 21, 22 is made of metal material, while the other is made of polymeric material.
The upper half-shell 21 and the lower half shell 22, advantageously comprise a flanged-portion, respectively 210 and 220, for the mutual interface between them. Said flanged portions 210 and 220 may comprise one or more seats for sealing means, such as gaskets, and may be provided with coupling and fixing means for keeping the two half- shells 21 and 22 joined in a gas-tight manner. As an example, screw means can be used for fixing the two- half shells 21, 22.
Preferably, for each phase, the switch-disconnector comprises a first bushing 41 associated with said first, upper, half-shell 21 and a second bushing 42 associated with said second, lower, half-shell 22.
According to a preferred embodiment, the first, upper, half-shell 21 is made of polymeric material and the second, lower, half-shell 22 is made of metal material. In this way, due to the earthed metal segregation provided for by the lower half-shell made of metal, it is possible to access the lower compartment even if the busbars are under voltage.
As for the material, the polymeric material used for one of the two half-shells can be an epoxy resin; other kinds of polymeric materials can obviously be used, according to the needs. The metal material used for the other of the two half-shells can be steel, for example stainless steel or pre-galvanized steel.
With reference to figures 2 and 3, in a particularly preferred embodiment of the switch-disconnector 1 according to the invention, the half-shell made of polymeric material comprises, for each phase, an integral-made bushing, i.e. the half-shell 21 and the three bushings 41 are made in a single piece. As shown in the above-mentioned figures, in this way it is possible to have a very compact structure of the half shell 21, maintaining at the same time the requirements of electrical distance with respect to the busbar.
Conversely, as shown in figures 4 and 5, the switch-disconnector 1 of the invention, comprises, for each phase, a bushing 42 assembled with said half-shell 22 made of metal material, i.e. three bushing 42 for the three-phase switch-disconnector of the attached figures. In such a case, holes are provided in the bottom part of the lower half-shell, allowing free passage of the contact terminals, and the bushing is assembled to the half-shell 22 so as to keep gas-tight conditions. Advantageously, the bushing may comprise, integrated in their structure, a voltage indicator.
According to a preferred embodiment, the first bushings 41 support the fixed contact (not shown) positioned inside the housing 2, while the second bushings 42 support the moving contact (not shown) also positioned inside the housing 2. For example, the moving contact can be a blade pivotally supported by the terminal 420 of the bushing 42, said blade being capable to move between a close position, in which it is engaged with the corresponding fixed contact, an earthed position in which it is engaged with a corresponding earthing contact, and an open position, in which it not engaged with said fixed or earthing contacts.
A driving shaft (not shown) is normally provided and connects the three moving contacts to the operating mechanism 3 which, as shown in figure 6, is positioned externally to the housing 2.
Preferably, said half-shell 22 made of metal material is earthed. In such a case, the earthing contact (not shown) is connected to said half-shell 22 made of metal material.
With reference to figure 6, the present invention, according to a second aspect, also relates to a medium voltage switchgear 10, said switchgear comprising a switch-disconnector 1 according to what defined above.
Preferably, the medium voltage switchgear 10 according to the invention comprises a casing 101 which defines defining an internal space. The switch-disconnector 1 is generally positioned inside said casing 101 so as to divide said internal space in a first, upper, compartment 110 and a second, lower, compartment 120. The operating mechanism 3, for moving the moving contacts of the switch-disconnector between open, closed and earthed positions, is normally positioned outside the casing 101 and is connected to said moving contact through a driving shaft. The upper compartment 110 can be for instance the busbar compartment, while the lower compartment 120 can be the feeder, or cable, compartment.
Being that one of the two half shells, e.g. the lower half-shell 22, is made of metal material, the switch-disconnector 1 provides a metal-earthed segregation between said first, upper, compartment 110 and said second, lower, compartment 120. At the same time, as shown in figure 6, the extremely compact structure of the first half shell 21 made of insulating polymeric material, e.g. epoxy resin, allows reducing the electrical distance with respect to the busbar, thereby minimizing the occupied volume inside the casing itself.
The switch-disconnector thus conceived may undergo numerous modifications and come in several variants, all coming within the scope of the invention as defined by the claims. Moreover, all the component parts described herein may be substituted by other, technically equivalent elements. In practice, the component materials and dimensions of the device may be of any nature, according to need and the state of the art.

Claims

A Medium Voltage gas-insulated switch-disconnector (1):
- a gas-tight housing (2) containing an insulating gas;

- for each phase, a moving contact, a fixed contact and an earthing contact positioned inside said housing;

- an operating mechanism (3) for moving said moving contact between open, closed and earthed positions;
said gas-tight housing (2) comprising a first, upper, half-shell (21) and a second, lower, half shell (22) coupled in a gas-tight manner, one of said first and second half shells (21, 22) being made of metal material, the other being made of polymeric material,
characterised in that said half-shell made of metal material is earthed, said switch-disconnector (1) comprising, for each phase, a first bushing (41) associated with said first, upper, half-shell (21) and a second bushing (42) associated with said second, lower, half-shell (22), said first bushing supporting said fixed contact and said second bushing supporting said moving contact.
The switch-disconnector (1) of claim 1, characterized in that said first, upper, half-shell (21) is made of polymeric material and said second, lower, half-shell (22) is made of metal material.
The switch-disconnector (1) according to one or more of the preceding claims, characterized in that said polymeric material is an epoxy resin and said metal material is steel.
The switch-disconnector (1) according to one or more of the preceding claims, characterized in that said half-shell made of polymeric material comprises, for each phase, an integral-made bushing.
The switch-disconnector (1) according to one or more of the preceding claims, characterized in that it comprises, for each phase, a bushing assembled with said half-shell made of metal material.
The switch-disconnector (1) according to claim 1, characterized in that said earthing contact is connected to said half-shell made of metal material.
A Medium Voltage switchgear (10), characterized in that it comprises a switch-disconnector (1) according to any of claims 1-6.
The Medium Voltage switchgear (10) according to claim 7, characterized in that it comprises a casing (101) defining an internal space, said switch-disconnector (1) being positioned inside said casing (101) and dividing said internal space in a first, upper, compartment (110) and a second, lower, compartment (120).
The Medium Voltage switchgear (10) according to claim 10, characterized in that said switch-disconnector (1) provides a metal-earthed segregation between said first, upper, compartment (110) and said second, lower, compartment (120).