ES2374019T3 - MEDIUM AND HIGH VOLTAGE ELECTRICAL SECTIONING SWITCH. - Google Patents

Abstract

The disconnector has a tubular fixed contact (1), and a rotary movable contact (2) movable along a determined direction for assuring passage and interruption of electric current in respective current passage and interruption positions. One of fixed and movable contacts is established successively in a determined direction of displacement of the contact (2), a fixed polyoxymethylene homopolymer washer (11) and a protection band (15) i.e. fixed plate, that is made of PTFE, so that a new electric arc is initially confronted to the washer and to the band, during interruption of the current.

Description

Medium and high voltage electrical disconnect switch

Field of the Invention

The invention relates to the field of distribution of medium and high voltage electrical current and, in particular, to the disconnecting switchgear devices used in the transport lines of medium voltage electrical energy.

Prior technique and problem raised

Currently, there are different types of disconnect switches in the market. They differ, among others, by their principle of cutting the electric current.

A first type of disconnecting switch functions in an environment of sulfur hexafluoride SF6 where, most of the time, the interruption or sectioning functions of the electric current are performed simultaneously by the mechanical separation of moving contacts from each other, to over a sufficient distance to ensure sectioning. In general, the cells in which these switches are installed are of reduced width, for example 375 mm for 24 kV.

Another technology is to use the interruption of the current in the ambient air. There also, the functions of interruption or sectioning of the electric current are performed simultaneously by the mechanical separation of the contacts. In this technology, the cells in which these switches are installed have a large width, for example 600 to 700 mm for 24 kV.

Another technology consists in using the sectioning of the electric current in a vacuum, for example by means of a vacuum bulb placed in series with a sectioning located in the transmission line of the electric current. This solution is expensive and not widely used.

Another technology is to use the interruption of the electric current in oil. This is the case of the devices of previous generations.

Other technologies consist in using the sectioning of the electric current in other gases, such as N2, CO2. The current interruption functions are performed simultaneously by the mechanical separation of the contact. It is observed that these devices have a much smaller impact on the greenhouse effect than those that work with the SF6.

However, these different technologies have drawbacks.

The disconnecting switches that work in the SF6, of medium voltage, can interrupt electrical currents of the order of 600 to 800 amps. Above 800 amps and especially for the value of 1,250 amps, the switches made have higher costs than other disconnecting switches.

Electric current cut-off cells operating in the air are large and generally have lower cutting performance than those obtained with devices operating in the SF6.

The objective of the present invention is thus to propose another technology of medium voltage current disconnecting switches, avoiding using the sectioning conditions that are cells of the aforementioned technologies, without presenting a high manufacturing cost and with a reduced impact on The greenhouse effect.

US 2007/0119819 describes a device according to the preamble of claim 1.

Summary of the Invention

To this end, the main object of the invention is a medium and high voltage electrical disconnecting switch, by mechanical separation of the electrical contacts, the disconnecting switch comprising:

•

at least one fixed contact connected to an electric conductor; Y

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a mobile contact according to a certain direction in order to guarantee the passage and cutting of the electric current through two respective positions; a first current passage position in which the mobile contact is brought into contact with the at least one fixed contact and a second current cut-off position, offset from the current passage position and in which the mobile contact is separate from the fixed contact.

According to the invention, a first type of contact is completed between the two types of mobile fixed contact (s), successively and in the determined direction of travel of the mobile contact (s) by a first polyoxymethylene element and by a second polytetrafluoroethylene element, so that, during a current cut-off operation, the incipient electric arc first faces the first polyoxymethylene element, and then the second polytetrafluoroethylene element.

In a first considered embodiment of the disconnecting switch according to the invention:

•

the fixed contacts are two and are spaced apart from each other;

•

The mobile contact is rotatable, of length very slightly greater than the distance that separates the two fixed contacts and is mounted on a rotation axis located halfway between the two fixed contacts in order to guarantee the passage and cut of the electric current by the two respective positions, a first current passage position in which the mobile contact is in contact at each of its ends with a fixed contact a second current cut-off position, angularly offset with respect to the first current passage position and in which the ends of the mobile contact are separated from the fixed contact;

•

each first polyoxymethylene element is fixed and is a washer surrounding its corresponding fixed contact; Y

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Each second polytetrafluoroethylene element is a fixed plate, adjacent to the washer that constitutes the first element that extends in an arc of circumference along the circumference defined by the rotation of the two ends of the mobile contact.

In the second considered embodiment of the disconnecting interior according to the invention,

•

the fixed contacts are two, spaced apart from each other

•

The mobile contact is rotatable, of length very slightly greater than the distance between the two fixed contacts and is rotatably mounted on a rotation axis located in a first of the two fixed contacts to ensure the passage and cut of the electric current by the two respective positions, the first current passage position in which the mobile contact is in contact by a rotating end with the second fixed contact opposite to the one on which it is rotatably mounted and the second current cut-off position, offset angularly with respect to the current passage position and in which the rotating end of the mobile contact is separated from the fixed contact;

•

The polyoxymethylene element is a fixed washer surrounding the corresponding second contact, and

•

The second polytetrafluoroethylene element is a fixed plate, adjacent to the washer that constitutes the first element and which extends in an arc of circumference along the circumference defined by the displacement of the rotating end of the movable contact.

In the third embodiment of the disconnecting switch according to the invention,

•

the fixed contact is unique and tubular, with a determined outer diameter;

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the mobile contact is also tubular and the inner diameter very slightly smaller than the determined outer diameter of the fixed contact and is coaxial thereto longitudinally moving along the axis of revolution that defines the tubular shapes;

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The first polyoxymethylene element and the second polytetrafluoroethylene element are revolution-shaped parts, coaxial with the fixed and mobile contacts and with an inner diameter slightly larger than the determined outer diameter of the fixed contact.

In this case, it is considered to position the first polyoxymethylene element and the second polytetrafluoroethylene element in the mobile contact.

Preferably, the polyoxymethylene is of the homopolymer type.

Preferably, polytetrafluoroethylene (PTFE) is selected from the group of PTFE loaded in SiO2, PTFE loaded in CaF2 and PTFE loaded in MoS2.

List of figures

The invention and its different technical characteristics will be better understood with the following description, accompanied by several figures that represent respectively:

• Figure 1, a representative scheme of a first embodiment of the invention;

5 • Figure 2, a detailed view of this first embodiment according to the invention;

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3 shows a perspective view of this first embodiment, in three different current phases;

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Figure 4, in industrial section, the assembly of an installation using the invention in the three different phases of current corresponding to Figure 3;

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Figure 5, a representative scheme of a second embodiment of the invention; Y

10 • Figure 6, in semi-section, the principle of a third embodiment of the invention.

Detailed description of two embodiments of the invention

With reference to FIG. 1, an insulating enclosure 14 is distinguished mainly on the edge of which two fixed contacts 1 are diametrically opposed and inside which it is rotatably mounted around an axis A concentrically to the envelope 14, a mobile contact 2. It comes in the form of a rod of

15 length very slightly less than the inside diameter of the insulating shell 14, and whose ends 21 can simultaneously come into contact at the ends 17 of the contacts 1 leading into the interior of the insulating shell 14.

The arrival of the electric current is symbolized by a first arrow 12, applied to a first fixed contact 1 and the output is schematized by a second arrow 13 leaving the other fixed contact 1, diametrically opposite to the

20 first.

The invention provides, around the end 17 of each fixed contact 1, a first polyoxymethylene element, preferably homopolymer, in the form of a polyoxymethylene washer 11, called the POM washer. These POM 11 washers are located at the level of the inner wall of the insulating shell 14 so that the end 17 of each fixed contact can flow into the insulating shell 14. The complete assembly in the inner wall 25 of the shell insulator 14 of two second elements of polytetrafluoroethylene in the form of two protective bands 15 of polytetrafluoroethylene (PTFE) 15, which are each in the form of a band in the form of an arc of circumference, applied against the inner surface of the insulating shell 14 , of which a first end practically touches the POM washer 11, the other end being at a non-negligible distance from the end 21 of the movable contact 1. The two protection bands 15 are thus diametrically opposite and have a

30 which corresponds to the displacement of the ends 21 of the movable contact 2, which is rotatably mounted around the central axis A. Preferably, a natural PTFE or loaded in SiO2, or loaded in CaF2 or loaded in MoS2 will be chosen.

It will be better understood in this way that a rotation of one or two tens of degrees of the movable contact 2 around its axis of rotation A allows to pass a first current passage position, in which these ends 21

35 are in contact with one end 17 of a fixed contact 1, at a current cut-off position, after the rotation of the movable contact 2, when the ends 21 of the movable contact 2 are away from the ends 17 of the two fixed contacts one.

POM polyoxymethylene is a gazgenic material. However, during the beginning of the rotation of the mobile contact 2, from the first current passage position, an electric arc is generated between the ends 17 of the fixed contacts 40 and the ends 21 of the mobile contact 2. Each washer POM 11 surrounding each end 17 of the fixed contact 1, the electric arc therefore sublimates a part of this POM washer 11, causing a partial sublimation of this POM washer thereby releasing an "CH2O formaldehyde" electrophilic gas. In other words, under the effect of heat linked to the electric arc, there is a passage from the solid state to the gaseous state of the POM surface in contact with the electric arc. The gas generated by this chemical transformation is a gas of

45 decomposition of the PPO; when this is modified by an elevated temperature. The gas generated in this way will interfere with the electric arc plasmas, cool it and participate to its extension for its properties. Other materials such as polypropylene, polystyrene, polyethylene and polymethyl methacrylate, etc ... produce "formaldehyde" under the effect of heat.

The function of the protection plates 15 allows this phenomenon to continue to lead to rapid suppression.

50 and complete the two electric arcs between the ends 17 of the fixed contacts and the ends 21 of the movable contact.

The tests under CO2 gas have shown the remarkable efficiency of more than 50% with respect to the amperage of the electric current, allowing the presence of POM 11 washers to cut electric currents of the order of 630 amps, at 12 kV with respect to 400 amps, at 12 kV, without the presence of POM.

During tests carried out under SF6 gas, improvements were also observed, at the level of the cutting time.

In figure 2, the PTFE protection band 15, associated with the POM washer 111, which surrounds the end 17 of a fixed contact 1 is shown. A cantilever fixing pin 18 is distinguished from the inside. of the insulating envelope and penetrating a hole 19 of the PTFE protection band 15.

Figure 3 shows the assembly of a disconnecting switch, according to the invention, according to the technology described above, applied in three electrical phases, for example three three-phase current lines. The insulating envelope 14 is mainly distinguished in which the inner wall contains three PTFE protection bands 15, each fixed by a tab 18. Inside these semi-craters of insulating envelopes 14, the rotation axis A is rotatably mounted, which is a carrier of the movable contacts 2, one end being distinguished 17. This rotation shaft A also carries protective elements 19 of the movable contacts 2. It is thus understood that, after a rotation of a dozen degrees of the shaft A of rotation, the ends 17 of the movable contact 2 each travel an arc of circumference along a PTFE protection band 15.

Figure 4 shows a device in the form of an industrial design type cut with numerous details. It is enough to distinguish therein the sealed envelope 14 in which the rotation shaft A is mounted. Three pairs of fixed contacts 1 are distinguished that protrude inside the cavity of the insulating enclosure 14 by its end 17. Each one is surrounded by a POM washer 11 and are in contact with current arrivals 21. The PTFE protective bands 15 are represented in thinner strokes behind the mobile contract 2, which are made here by a double plate that surrounds through the end 21, the end 17 of a mobile contact 1.

With reference to Figure 5, a second embodiment of the invention, which can be described as rotating, is comparable to the first embodiment. It includes, like her, two fixed contacts 50 and 57, opposite or facing each other, but separated by a certain distance. A POM washer 51 is generally used, placed around the contact end of a second contact 50, in a manner analogous to the first embodiment, a curved PTFE protective band 55 is placed adjacent to the POM 512 washer. diameter of this protective band 55 is equal to the length of a movable contact 52, itself rotatably mounted around a rotation axis 5A placed on or in contact with a first fixed contact 57. Thus, the movable contact 52, by a turn, it can be separated from the end of the second contact 50, its distal end extending along the inner wall of the protection band 55.

Figure 6 represents a third embodiment of the invention that will be described as longitudinal while the first can be described as circular or tubular.

A contact 31 is distinguished therein which has a tubular shape of a longitudinal axis B. Along the latter, there is always, according to a conception of revolution, a mobile assembly 40 comprising, among others, a mobile contact 42 partially surrounded , at least on the side where the fixed contact 31 is located, by a POM jacket 41. Between the fixed contact 31 and the POM jacket 41 is a PTFE band 45 whose inner diameter corresponds to the inner diameter of the POM jacket 41. It will also be noted that the external diameter of the fixed contact 31 is very slightly smaller than the internal diameter of the PTFE protective band 45 and that of the POM jacket 41. However, the minimum internal diameter of the mobile contact 42 must be slightly smaller than the external diameter of the fixed contact 31 so that these two elements can be in contact with a sufficient pressure during a translation of the mobile assembly 40 towards the fixed contact 31. The co The mobile assembly 40 can be assembled by means of a crankcase 43 or a clamping plate 44.

It will be understood, that after a relative translation of the mobile assembly 40 with respect to the fixed contact 31, that the mobile assembly 40 with respect to the fixed contact 31, that the mobile contact 42 moves away from one end 32 of the fixed contact 31, that the jacket of POM 41 produces a partial sublimation effect in contact with the electric arc and that the PTFE protection band contributes to the complete extinction of the latter, during the prolongation of the relative separation movement.

Claims (6)

1.- Medium and high voltage electrical disconnector switch, by mechanical separation of electrical contacts comprising:

•

at least one fixed contact (1, 31) connected to an electric conductor (21); Y

•

a mobile contact (2, 42) according to a certain direction in order to guarantee the passage and cutting of the electric current through two respective positions; a first current passage position in which the mobile contact (2, 42) is in contact with the at least one fixed contact (1, 31) and a second current cut-off position relative to the current passage position and in which the mobile contact (2, 42) is separated from the fixed contact (1, 31).

characterized in that a first type of contact is completed between the two types of fixed fixed contacts (s), successively and in the determined direction of travel of the mobile contact (s) by a first polyoxymethylene (POM) element (11, 41) and by a second polytetrafluoroethylene (PTFE) element (15, 45), so that, during an electrical power cut operation, the incipient arc first faces the first polyoxymethylene (POM) element (11, 41 ), and then to the second element of polytetrafluoroethylene (PTFE) (15, 45). 2.- Medium and high voltage disconnecting switch according to claim 1, characterized in that:

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the fixed contacts (1) are two, spaced apart from each other;

•

The mobile contact (2) is rotatable, of length very slightly longer than the distance between the two fixed contacts (1) and mounted rotatably on a rotation axis (A) located halfway between the two fixed contacts (1) in order to guarantee the passage and the cut of the current through the two respective positions, the first current passage position in which the mobile contact (2) is in contact at each of its ends (21) with a fixed contact ( 1) and the second current cut-off position, angularly offset with respect to the current passage position and in which the ends of the movable contact (21) are separated from the fixed contact (1);

•

each first polyoxymethylene (POM) element (11) is a fixed washer surrounding its corresponding fixed contact; Y

•

each second polytetrafluoroethylene (PFTE) element (15) is a fixed plate, adjacent to the washer (11) that constitutes the first element that extends in an arc of circumference along the circumference defined by the rotation of the two ends of the mobile contact (2).

3.- Medium and high voltage electrical disconnecting switch according to claim 1, characterized in that:

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the fixed contacts (50, 57) are two, spaced apart from each other;

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the mobile contact (52) is pivotal, of length very slightly longer than the distance between the two fixed contacts (50, 57) and is rotatably mounted on a rotation axis located on a first (57) of the two fixed contacts for to be able to guarantee the passage and the cut of the current through the two respective positions, the first current passage position in which the mobile contact (52) is in contact by a pivoting end with the second fixed contact (50) opposite to that on which it is pivotally mounted, and the second current cut-off position, angularly offset with respect to the current passage position and in which the pivoting end of the movable contact (52) is separated from the second fixed contact (50);

•

The polyoxymethylene element (POM) is a fixed washer (51) surrounding the corresponding second contact (50), and

•

The second polytetrafluoroethylene (PTFE) element is a fixed plate (55), adjacent to the washer constituting the first element and extending in an arc of circumference along the circumference defined by the displacement of the pivoting end of the mobile contact ( 52).

4. Electric switch of medium and high voltage according to claim 1, characterized in that:

•

the fixed contact (31) is unique and tubular of a determined outer diameter;

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the mobile contact (42) is also tubular and of an inner diameter very slightly smaller than the determined outer diameter of the fixed contact (31) and coaxial thereto moving longitudinally along an axis of revolution (B) defining the tubular shapes;

•

the first polyoxymethylene (POM) element (41) and the second polytetrafluoroethylene (PTFE) element

5 (45) are in the form of a revolution piece, coaxial with the fixed and mobile contacts and with an inner diameter slightly greater than the determined outer diameter of the fixed contact (31). 5. Electric switch disconnector according to claim 4, characterized in that the first polyoxymethylene (POM) element (41) and the second polytetrafluoroethylene (PTFE) element, that is, the protective band (45) are in solidarity with the mobile contact (42). 6. Electrical switch disconnector according to claim 5, characterized in that the polyoxymethylene (POM) used is of the homopolymer type. 7. Electric switch disconnector according to claim 5, characterized in that the polytetrafluoroethylene (PTFE) is of the type of materials that are part of the group comprising the natural polytetrafluoroethylene (PTFE), the polytetradluoroethylene (PTFE) charged in SiO2, the polytetradluoroethylene charged in CaF2 and the 15 polytetradluoroethylenes loaded in MoS2.  FIGURE 1 FIGURE 2