EP2120242B1 - Middle- and high-voltage electrical switch disconnector - 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

Field of the invention

The invention relates to the field of the distribution of the electric current under medium and high voltage and, in particular, the switch disconnector devices used in the transmission lines of electrical energy under medium voltage.

Prior art and problem

At present, there are different types of disconnect switches on the market. They are differentiated, among other things, by their principle of breaking the electric current.

A first type of disconnector switch operates in a sulfur hexafluoride SF _{6 environment} where, most often, the functions of interruption or sectioning of the electric current are carried out at the same time by the mechanical separation of movable contacts, one by relative to others, a distance sufficient to ensure sectioning. In general, the cells in which these switches are installed are of small width, for example 375 mm for 24 kV.

Another technology is to interrupt the current in the ambient air. Again, the functions of interruption or sectioning of the electric current are performed at the same time 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 technique is to cut the electric current in the vacuum, for example by means of a vacuum interrupter placed in series with a disconnector placed on the transmission line of the electric current. This solution is expensive and is not widely used.

Another technology is to operate the interruption of the electric current in oil. This is the case of older generation devices.

Other technologies consist in cutting the electric current in other gases, such as N ₂ , CO ₂ . The current interruption functions are performed at the same time by the mechanical separation of the contact. These devices have a much lower impact on the greenhouse effect than those with SF ₆ .

However, these different technologies have disadvantages.

The disconnecting switches operating in the medium voltage SF ₆ can interrupt electrical currents of the order of 600 to 800 amperes. Above 800 amps and especially for the value of 1,250 amps, the switches made have costs much higher than other disconnecting switches.

The electric power cutoff cells operating in the air are large and generally have lower cutoff performance than those obtained with devices operating in the SF ₆ .

The object of the present invention is therefore to propose another technology of medium voltage switch disconnectors, avoiding using the sectioning conditions which are those of the technologies listed above, without presenting a high manufacturing cost and having a low impact on the greenhouse effect.

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

Summary of the invention

• au moins un contact fixe relié à un conducteur électrique ; et
• un contact mobile selon une direction déterminée, pour pouvoir assurer le passage et la coupure du courant électrique par deux positions respectives; une première position de passage de courant dans laquelle le contact mobile est mis en contact avec le au moins un contact fixe et une deuxième position de coupure de courant, décalée par rapport à la position de passage de courant et dans laquelle le contact mobile est écarté du contact fixe.

For this purpose, the main object of the invention is an electrical switch disconnector of medium voltage and high voltage, by mechanical separation of the electrical contacts, the disconnector switch comprising:

• at least one fixed contact connected to an electrical conductor; and
• a movable contact in a given direction, to be able to ensure the passage and the breaking of the electric current by two respective positions; a first current-passing position in which the movable contact is brought into contact with the at least one fixed contact and a second current-breaking position, shifted by relative to the current flow position and wherein the movable contact is spaced from the fixed contact.

According to the invention, a first type of contact among the two types of movable fixed contact (s) is completed, successively and in the determined direction of movement of the movable contact (s) of a first a polyoxymethylene element and a second polytetrafluoroethylene element, so that, during a current cutting operation, the incipient electric arc is first confronted with the first polyoxymethylene element, then the second polytetrafluoroethylene element.

• les contacts fixes sont au nombre de deux et sont espacés l'un de l'autre ;
• le contact mobile est rotatif, de longueur très légèrement supérieure à la distance séparant les deux contacts fixes et est monté sur un axe de rotation situé à mi-distance des deux contacts fixes pour pouvoir assurer le passage et la coupure du courant électrique par les deux positions respectives, une première position de passage de courant dans laquelle le contact mobile étant en contact par chacune de ces extrémités avec un contact fixe et une deuxième position de coupure de courant, décalée angulairement par rapport à la première position de passage de courant et dans laquelle les extrémités du contact mobile sont écartées du contact fixe ;
• chaque premier élément en polyoxyméthylène est fixe et est une rondelle qui entoure son contact fixe correspondant ; et
• chaque second élément en polytétrafluoroéthylène est une plaque fixe, adjacente à la rondelle constituant le premier élément s'étendant en arc de cercle le long de la circonférence défini par la rotation des deux extrémités du contact mobile.

In a first envisaged embodiment of the disconnector switch according to the invention:

• the fixed contacts are two in number and are spaced apart from each other;
• the movable contact is rotatable, of a length slightly greater than the distance separating the two fixed contacts and is mounted on an axis of rotation situated halfway between the two fixed contacts in order to be able to ensure the passage and the breaking of the electric current by the two respective positions, a first current-passing position in which the movable contact is in contact with each of these ends with a fixed contact and a second current-breaking position, angularly offset with respect to the first current-passing position and in which ends of the movable contact are spaced apart from the fixed contact;
• each first polyoxymethylene element is fixed and is a washer which surrounds its corresponding fixed contact; and
• each second polytetrafluoroethylene element is a fixed plate, adjacent to the washer constituting the first element extending in an arc along the circumference defined by the rotation of the two ends of the movable contact.

• les contacts fixes sont au nombre de deux, espacés l'un de l'autre;
• le contact mobile est rotatif, de longueur très légèrement supérieure à la distance séparant les deux contacts fixes et monté pivotant sur un axe de rotation situé sur un premier des deux contacts fixes pour pouvoir assurer le passage et la coupure du courant par les deux positions respectives, la première position de passage de courant dans laquelle le contact mobile est en contact par une extrémité pivotante avec le deuxième contact fixe opposé à celui sur lequel il est monté pivotant et la deuxième position de coupure de courant, décalée angulairement par rapport à la position de passage de courant et dans laquelle l'extrémité pivotante du contact mobile est écartée du deuxième contact fixe ;
• l'élément en polyoxyméthylène est une rondelle fixe entourant le deuxième contact fixe correspondant, et
• le second élément en polytétrafluoroéthylène est une plaque fixe, adjacente à la rondelle constituant le premier élément et s'étendant en arc de cercle le long de la circonférence définie par le déplacement de l'extrémité pivotante du contact mobile.

In the second envisaged embodiment of the disconnector switch according to the invention,

• the fixed contacts are two in number, spaced apart from one another;
• the movable contact is rotatable, of length very slightly greater than the distance separating the two fixed contacts and pivotally mounted on an axis of rotation located on a first of the two fixed contacts to be able to ensure the passage and the breaking of the current by the two respective positions , the first current passage position in which the movable contact is in contact with a pivoting end with the second fixed contact opposite to that on which it is pivotally mounted and the second position of current cutoff, angularly offset with respect to the position current passing and in which the pivoting end of the movable contact is spaced apart from the second fixed contact;
• the polyoxymethylene element is a fixed washer surrounding the corresponding second fixed contact, and
• the second polytetrafluoroethylene element is a fixed, adjacent plate to the washer constituting the first element and extending in an arc along the circumference defined by the displacement of the pivoting end of the movable contact.

• le contact fixe est unique et tubulaire, de diamètre extérieur déterminé ;
• le contact mobile est également tubulaire et de diamètre intérieur très légèrement inférieur au diamètre extérieur déterminé du contact fixe et lui est coaxial en se déplaçant longitudinalement le long de l'axe de révolution définissant les formes tubulaires ;
• le premier élément en polyoxyméthylène et le deuxième élément en polytétrafluoroéthylène sont des pièces de forme de révolution, coaxiaux avec les contacts fixe et mobile et de diamètre intérieur légèrement supérieur au diamètre extérieur déterminé du contact fixe.

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

• the fixed contact is unique and tubular, of determined external diameter;
• the movable contact is also tubular and of internal diameter very slightly smaller than the determined external diameter of the fixed contact and is coaxial with it while moving longitudinally along the axis of revolution defining the tubular shapes;
• the first polyoxymethylene element and the second polytetrafluoroethylene element are revolution-shaped parts, coaxial with the fixed and movable contacts and of inner diameter slightly greater than the determined outside diameter of the fixed contact.

In this case, it is envisaged to position the first polyoxymethylene element and the second polytetrafluoroethylene element on the moving contact.

Preferably, the polyoxymethylene is of the homopolymer type.

Preferably, the polytetrafluoroethylene (PTFE) is chosen from the group of PTFE loaded with SiO ₂ , PTFE loaded with CaF ₂ and PTFE loaded with MoS ₂ .

List of Figures

• figure 1, un schéma représentatif d'une première réalisation de l'invention ;
• figure 2, une vue d'un détail de cette première réalisation selon l'invention ;
• figure 3, une vue cavalière de cette première réalisation, sur trois phases de courant différentes ;
• figure 4, en coupe industrielle, l'ensemble d'une installation utilisant l'invention sur les trois phases différentes de courant, correspondant à la figure 3 ;
• la figure 5, un schéma représentatif d'une deuxième réalisation de l'invention ; et
• figure 6, en demi-coupe, le principe d'une troisième réalisation de l'invention.

The invention and its various technical features will be better understood on reading the following description, accompanied by several figures respectively representing:

• figure 1 , a representative diagram of a first embodiment of the invention;
• figure 2 a view of a detail of this first embodiment according to the invention;
• figure 3 , a cavalier view of this first embodiment, on three different current phases;
• figure 4 , in industrial section, the assembly of an installation using the invention on the three different phases of current, corresponding to the figure 3 ;
• the figure 5 a representative diagram of a second embodiment of the invention; and
• figure 6 , in half-section, the principle of a third embodiment of the invention.

Detailed description of two embodiments of the invention

With reference to the figure 1 , there is mainly an insulating enclosure 14 on the edge of which are diametrically opposed, two fixed contacts 1 and inside which is pivotally mounted about an axis A concentrically to the casing 14, a moving contact 2. This is in the form of a rod whose length is slightly less than the inside diameter of the insulating envelope 14, and whose ends 21 can come into contact simultaneously on the ends 17 of the contacts 1 opening inside. the insulating envelope 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 shown schematically by a second arrow 13 out of the other fixed contact 1, diametrically opposite the first.

The invention provides to place, around the end 17 of each fixed contact 1, a first polyoxymethylene element, preferably homopolymer, in the form of a washer of polyoxymethylene 11, called POM washer. These POM washers 11 are placed at the inner wall of the insulating envelope 14, so that the end 17 of each fixed contact can open into the insulating envelope 14. The assembly is complete on the inner wall of the insulating jacket 14 of two second polytetrafluoroethylene elements in the form of two polytetrafluoroethylene (PTFE) protective strips 15, each of which is in the form of an arcuate strip. , pressed against the inner surface of the insulating casing 14, a first end substantially 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 protective strips 15 are diametrically opposed and have a shape that 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 with SiO ₂ , or loaded with CaF ₂ or charged with MoS will be chosen. ₂ .

It will thus be understood that a rotation of one or two tens of degrees of the moving contact 2 about its axis of rotation A makes it possible to pass from a first current-passing position, in which these ends 21 are in contact with a end 17 of a fixed contact 1, at a second current-breaking position, after rotation of the movable contact 2, when the ends 21 of the movable contact 2 are remote from the ends 17 of the two fixed contacts 1.

Polyoxymethylene POM is a gas generating material. However, at the beginning of rotation of the movable contact 2, from the first current passage position, an electric arc is generated between the ends 17 of the fixed contacts 1 and the ends 21 of the movable contact 2. Each washer of POM 11 surrounding each end 17 of fixed contact 1, the electric arc thus sublimates a portion of the washer POM 11, causing a partial sublimation of the POM washer and thus releasing an electrophilic gas "CH ₂ O formaldehyde". In other words, under the effect of the heat related to the electric arc, there is a transition from the solid state to the gaseous state of the surface of POM in contact with the electric arc. The gas generated by this chemical transformation is a decomposition gas of POM when it is altered by high temperature. The gas thus generated will interfere with the plasmas of the electric arc, cool it and participate in its extension by its properties. Other materials such as polypropylene, polystyrene, polyethylenes and polymethyl methacrylate etc ... produce "formaldehyde" under the effect of heat.

The role of the protection plates 15 makes it possible to continue this phenomenon to achieve the rapid and complete removal of the two electric arcs between the ends 17 of the fixed contacts and the ends 21 of the movable contact.

Tests under CO ₂ gas showed the notorious efficiency of more than 50% compared to the amperage of the electric current, the presence of POM 11 washers allowing to cut electrical currents of the order of 630 amperes, under 12 kV compared to 400 amperes, at 12 kV, without presence of POM.

In SF ₆ gas tests, improvements were also noted in the cut-off time.

On the figure 2 , is mainly represented the PTFE protective strip 15, associated with the POM washer 11, which itself surrounds the end 17 of a fixed contact 1. There is a fixing lug 18 projecting from the inside of the the insulating jacket and which enters a hole 19 of the PTFE protective strip 15.

The figure 3 shows the assembly of a disconnector switch, according to the invention, according to the technology described above, applied to three electrical phases, for example three three-phase power lines. It distinguishes mainly the insulating casing 14 on the inner wall of which are three PTFE protective strips 15, each fixed by a tongue 18. Inside these insulating casings half-casings 14, is mounted rotating the axis of rotation A, which carries the movable contacts 2, which is distinguished by an end 17. This rotating shaft A also carries protective elements 19 of the movable contacts 2. It is thus understood that, after a rotation of a ten degrees of rotation shaft A, the ends 17 of the movable contact 2 travel in a circular arc along each a PTFE protective strip 15.

The figure 4 shows such a device in the form of an industrial drawing type cut with many details. It will suffice to distinguish the sealed envelope 14 inside which is mounted the rotation shaft A. There are three pairs of fixed contacts 1 protruding inside the cavity of the insulating enclosure 14 by 17. They are each surrounded by a POM washer 11 and are in contact with current arrivals 21. The PTFE protective strips 15 are suggested in finer lines behind the moving contact 2, which are realized here. by a double plate surrounding by its end 21, the end 17 of a movable contact 1.

With reference to the figure 5 a second embodiment of the invention, which can be described as pivoting, is comparable to the first embodiment. It comprises, like it, two fixed contacts 50 and 57, opposite or emitted face to face, but being separated by a determined distance. A POM washer 51, placed around the contact end of a second contact 50 is also used, similarly to the first embodiment, a curved PTFE protective strip 55 is placed adjacent to the POM washer 51. The diameter of this protective strip 55 is equal to the length of a movable contact 52, itself pivotally mounted about an axis of rotation 5A, placed on or in contact with a first fixed contact 57. Thus, the contact mobile 52, by pivoting, can separate from the end of the second contact 50, its distal end along the inner wall of the protective strip 55.

The figure 6 represents a third embodiment of the invention which will be described as longitudinal while the first may be described as circular or tubular.

It distinguishes a fixed contact 31 which has the tubular shape of longitudinal axis B. Along the latter, is still, according to a revolution design, a movable assembly 40 comprising, inter alia, a movable contact 42 partially surrounded, at least on the side where the fixed contact 31 is located, a POM sleeve 41. Between the fixed contact 31 and the POM 41 sleeve is a PTFE strip 45 whose inner diameter corresponds to the inside diameter furthermore, it will be noted that the outer diameter of the fixed contact 31 is very slightly less than the inside diameter of the PTFE protective strip 45 and that of the POM sleeve 41. On the other hand, 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 to the fixed contact 31. The mobile assembly 40 can be assembled by means of a casing 43 or holding plate 44.

It will be understood that after a relative translation of the movable assembly 40 with respect to the fixed contact 31, that the movable contact 42 will move away from one end 32 of the fixed contact 31, that the POM sleeve 41 will produce an effect of partial sublimation in contact with the electric arc and that the PTFE protective strip will contribute to the complete extinction of the latter, during the extension of the relative spacing movement.

Claims (7)

1. A medium and high voltage disconnector interrupter for interruption by mechanical separation of switch contacts, the interrupter comprising:

   • at least one fixed contact (1, 31) connected to a conductor (21); and

   • a moving contact (2, 42) moveable in a predetermined direction so as to be able to allow the current to flow and be broken in two positions, which are, respectively, a first position, being a current flow position, in which the moving contact (2, 42) is in contact with at least one fixed contact (1, 31), and a second position, being a current break position, which is offset relative to the current flow position, and in which the moving contact (2, 42) is spaced away from the fixed contact (1, 31);

   • characterized in that a first type of contact, selected from the two types consisting of fixed contacts and moving contacts, is made, in succession and in the said predetermined direction of displacement from the moving contact or contacts, with a first element (11, 41) made of polyoxymethylene (POM) and a second element (15, 45) made of polytetrafluorethylene (PTFE), so that in a current breaking operation, the nascent arc first meets the polyoxymethylene (POM) first element (11,41), and then the polytetrafluorethylene (PTFE) second element (15, 45).
2. A medium and high voltage disconnector interrupter according to claim 1, characterized in that:

   • there are two said fixed contacts (1), and they are spaced apart;

   • the moving contact (2) is a rotary contact, the length of which is slightly greater than the distance by which the two fixed contacts (1) are separated, the moving contact being rotatably mounted on an axis of rotation (A) situated halfway between the two fixed contacts (1), so as to be able to allow the current to flow and be broken in the said two respective positions, namely the first, current flow, position in which the moving contact (2) is in contact with a fixed contact (1) through each of its ends (21), and the second, current break, position, which is offset angularly relative to the current flow position and in which the ends (21) of the moving contact are spaced away from the fixed contact (1);

   • each polyoxymethylene (POM) first element (11) is a fixed ring surrounding its corresponding fixed contact; and

   • each polytetrafluorethylene (PTFE) second element (15) is a fixed strip or plate, adjacent to the ring (11) that constitutes the said first element and extending in a circular arc along the circumference defined by the rotation of the two ends of the moving contact (2).
3. A medium and high voltage disconnector interrupter according to claim 1, characterized in that:

   • there are two said fixed contacts (50, 57), and they are spaced apart;

   • the moving contact (52) is pivoted, and has a length slightly greater than the distance by which the two fixed contacts (50, 57) are separated, the moving contact being mounted for pivoting movement on an axis of rotation situated on a first one (57) of the two fine contacts, so as to be able to allow the current to flow and be broken in the said two respective positions, namely the first, current flow, position in which the moving contact (52) is in contact through a swinging end thereof with the second one (50) of the two fixed contacts, opposite to the fixed contact on which the moving contact is pivotally mounted, and the second, current break, position, which is offset angularly relative to the current flow position and in which the said swinging end of the moving contact (52) is spaced away from the second fixed contact (50);

   • the polyoxymethylene (POM) element is a fixed ring (51) surrounding the corresponding second fixed contact (50); and

   • the polytetrafluorethylene (PTFE) second element is a fixed strip or plate (55) adjacent to the ring that constitutes the said first element and extending in a circular arc along the circumference defined by the displacement of the said swinging end of the moving contact (52).
4. A medium and high voltage disconnector interrupter according to claim 1, characterized in that:

   • there is a single said fixed contact (31), which is of tubular form with a predetermined outside diameter;

   • the moving contact (42) is also of tubular form, and has an inside diameter that is very slightly smaller than the predetermined outside diameter of the fixed contact (31), with which the moving contact is coaxial, the moving contact being displaceable longitudinally along the axis of revolution (B) that defines the said tubular formes; and

   • the polyoxymethylene (POM) first element (41) and the polytetrafluorethylene (PTFE) second element (45) are each in the form of a body of revolution, with both of the said elements being coaxial with the fixed and moving contacts and having an inside diameter slightly greater than the predetermined outside diameter of the fixed contact (31).
5. A disconnector interrupter according to claim 4, characterized in that the polyoxymethylene (POM) first element (41) and the polytetrafluorethylene (PTFE) second element, that is to say the protective band (45), are fixed to the moving contact (42).
6. A disconnector interrupter according to claim 5, characterized in that the polyoxymethylene (POM) material used is of a homopolymeric type.
7. A disconnected interrupter according to claim 5, characterized in that the polytetrafluorethylene (PTFE) material is of the type of materials that are part of the group consisting of natural polytetrafluorethylenes (PTFE), polytetrafluorethylenes (PTFE) reinforced with SiO₂, polytetrafluorethylenes (PTFE) reinforced with
   CaF₂, and polytetrafluorethylenes (PTFE) reinforced with MoS₂.

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