EP2915172B1 - Device for disconnecting an electrical supply line with a high-intensity current - Google Patents

Description

Technical area

The present invention relates to devices serving to prevent the power supply when necessary in installations using high intensity currents, and in particular relates to a device for disconnecting a high intensity current power supply line.

State of the art

In installations such as electrolysis cells which use high intensity currents greater than 1000 amperes and which can reach several tens of thousands of amperes, it is necessary to carry out regular maintenance operations. During these operations, the power supply is of course cut off, but it is mandatory to open the power supply circuit using a disconnecting device so that operators are safe during maintenance operations. .

The vast majority of disconnecting devices in use today consist of knife disconnectors. The rotary knives around an axis actuated by a suitable mechanism, provide the electrical connection by pressing with pressure on the current input contacts. The sectioning therefore consists in separating the knives from the fixed contacts by making them pivot about their axis thanks to the actuation mechanism.

Unfortunately, the cutting devices with knives are heavy and bulky, and since it is impossible to confine such a device in an enclosure, the device is not waterproof and therefore subject to rapid degradation by oxidation and deposition of dust.

There are disconnection devices comprising an enclosure containing fixed metal contacts on which a movable metal contact rests when an actuation mechanism is implemented. Although it overcomes some of the drawbacks of knife disconnecting devices, this type of disconnecting device is suitable only for a determined current intensity. It is therefore necessary to use devices whose dimensions increase with the intensity of the current passing through them. But the biggest drawback is the difficulty in removing heat due to the Joule effect in the contact resistors of the device.

The document DE1239752B describes an electrical switching device in which the contact pieces are provided with additional tightening screws so as to improve the flow of current from one connection to the other. This is made possible by U-shaped switching parts. However, the device described in this document does not concern high intensity currents.

Disclosure of the invention

The main aim of the present invention is therefore to provide a disconnecting device for high intensity electrical power supplies which has maximum conductance.

Another object of the invention is to provide a sectioning device as mentioned above which comprises effective means for dissipating the heat produced by the Joule effect in the device.

Yet another object of the invention is to provide a sectioning device as mentioned above which is easily adaptable to the value of the intensity.

• une enceinte de contact étanche comprenant au moins un premier élément conducteur de contact fixe pour établir la connexion électrique avec une entrée du courant et un second élément conducteur de contact fixe pour établir la connexion électrique avec une sortie du courant, les éléments de contact fixes étant connectés électriquement à l'extérieur de l'enceinte respectivement par deux plages de raccordement, et au moins un élément conducteur de contact mobile adapté pour venir en contact simultanément sur les premier et second éléments de contact fixes sous l'action d'un mécanisme d'actionnement qui est actionné pour supprimer le contact entre les éléments de contact fixes et l'élément de contact mobile dans le but de sectionner la ligne d'alimentation,
• au moins une première barre métallique de raccordement adaptée pour être connectée à une entrée de courant et au moins une seconde barre de raccordement adaptée pour être connectée à une sortie de courant, et
• un premier élément conducteur intermédiaire connecté d'une part à la première barre de raccordement et d'autre part au premier élément conducteur fixe et un second élément conducteur intermédiaire connecté d'une part à la seconde barre de raccordement et d'autre part au second élément conducteur fixe.

A first object of the invention is a sectioning module of an electrical supply line to direct current with an intensity greater than 1000 A including:

• a sealed contact enclosure comprising at least a first fixed contact conductor element for establishing the electrical connection with a current input and a second fixed contact conductor element for establishing the electrical connection with a current output, the fixed contact elements being electrically connected outside the enclosure respectively by two connection pads, and at least one conductive movable contact element adapted to come into contact simultaneously with the first and second fixed contact elements under the action of a mechanism d 'actuation which is actuated to remove the contact between the fixed contact elements and the movable contact element for the purpose of severing the supply line,
• at least one first metal connection bar adapted to be connected to a current input and at least one second connection bar adapted to be connected to a current output, and
• a first intermediate conductive element connected on the one hand to the first connection bar and on the other hand to the first fixed conductive element and a second intermediate conductive element connected on the one hand to the second connection bar and on the other hand to the second fixed conductor element.

The module is characterized in that the power supply line provides a current with an intensity greater than 1000 A, at least one of the fixed contact elements or one of the movable contact elements has a silver pellet placed on the surface of the element making it possible to reduce the contact resistance between the movable contact element and the fixed contact element by half and at least one of the fixed contact elements comprises a lower layer of aluminum, an upper layer of copper comprising a silver coating and one layer foam intermediate consisting of a metal foam skeleton selected from the group consisting of iron, cobalt, nickel and their alloys covered with at least one coating of tin, indium or one of their alloys.

A second object of the invention is such a sectioning module used as a presentation model allowing the future user to know the temperature behavior of a desired sectioning device.

A third object of the invention is a disconnecting device composed of several disconnecting modules as defined above arranged in parallel so as to be able to adapt the device to the value of the intensity supplied by the electrical supply line.

Brief description of the figures

• la figure 1 représente schématiquement une enceinte de contact utilisée dans un module de sectionnement selon l'invention ;
• la figure 2 représente un mode de réalisation particulier d'un élément de contact fixe de l'enceinte ;
• la figure 3 schématiquement un module de sectionnement selon l'invention qui peut être utilisé comme maquette de présentation ;
• la figure 4 représente schématiquement un dispositif de sectionnement selon l'invention comportant une pluralité de modules de sectionnement illustrés sur la figure 3,
• les figures 5 et 6 représentent des variantes de réalisation du module de sectionnement dans lesquelles les barres de raccordement sont connectées à l'enceinte de contact par une couche de mousse constituée d'un squelette de mousse de métal tel que fer, cobalt, nickel et leurs alliages recouvert d'un revêtement d'étain, d'indium ou un de leurs alliages (ECOCONTACT).

Other aims, objects and characteristics of the invention will emerge more clearly on reading the following description given with reference to the drawings in which:

• the figure 1 schematically represents a contact enclosure used in an isolating module according to the invention;
• the figure 2 shows a particular embodiment of a fixed contact element of the enclosure;
• the figure 3 schematically a sectioning module according to the invention which can be used as a presentation model;
• the figure 4 schematically represents a sectioning device according to the invention comprising a plurality of sectioning modules illustrated on the figure 3 ,
• the figures 5 and 6 represent variant embodiments of the disconnection module in which the connection bars are connected to the contact enclosure by a layer of foam consisting of a skeleton of metal foam such as iron, cobalt, nickel and their alloys coated with a coating of tin, indium or one of their alloys (ECOCONTACT).

Detailed description of the invention

The isolating device according to the invention is essentially composed of one or more isolating modules. Each of the modules is adapted to allow the passage of a current of an intensity of approximately 3,000 A. Note that the current is mainly a direct current but that it could be an alternating current and that the intensity could be different.

The contact enclosure 10 of each disconnection module shown on the figure 1 preferably has a rectangular shape with a length of about 40 cm and a width of about 30 cm. The enclosure 10 is composed of at least one contact bridge. Each contact bridge comprises two fixed contact elements 12 and 14, preferably in aluminum, fixed by welding to 2 connection pads, preferably in aluminum, respectively the pads 16 and 18 which constitute the input and the output of the current. the enclosure respectively connected to the current input and output outside the enclosure as will be seen below.

Each contact bridge of the enclosure 10 comprises a movable contact element 20, preferably made of aluminum which is not in contact with the 2 fixed contact elements 12 and 14 when the sectioning has been operated for the course of a maintenance operation of the installation comprising the isolating device according to the invention.

When the installation is re-energized after the maintenance operation, the contact between the fixed contact elements 12 and 14 and the movable contact element 20 is effected by a downward movement of the element 20 by means of the rods 22 and 24 actuated by an actuating means 26. The top of rods 22 and 24 is blocked on the movable contact element 20 by two springs 28 and 30. A At the end of the downward movement of the element 20, the latter comes into contact with the contact elements 12 and 14 and a pressure is exerted thanks to the compression of the springs 28 and 30.

An important characteristic of the invention is to obtain an isolating device which has the lowest possible resistance so as to obtain the smallest possible heat dissipation by Joule effect and therefore the smallest possible temperature rise.

A first means to obtain this result is to fix, preferably by high temperature brazing, silver pellets 32 and 34, for example of circular shape, on the contact surface of the movable contact element 20 which comes into contact with it. contact with the fixed contact elements 12 and 14. In fact, the fixed and movable contact elements being made of aluminum, the contact resistance between the fixed contact element and the movable contact element would be relatively high. With the presence of the silver pellets 32 and 34 whose conductivity is high, this resistance is reduced by half or, in other words, the conductance is doubled.

It should be noted that it is judicious to have in the contact enclosure 10 two contact bridges and therefore a second movable contact element 36 symmetrical to the movable contact element 20, as illustrated in FIG. figure 1 . The element 36 is brought into contact with the fixed contact elements 12 and 14 by means of rods 38 and 40 and springs 42 and 44 actuated by the same operating mechanism 26. In the same way as above, the element of movable contact 36 comprises silver pellets 46 and 48 to decrease the contact resistance with the fixed contact elements 12 and 14.

Note that the contact enclosure which has just been described present, for each of the contact elements mobile 20 and 36, a resistance of about 10µΩ, which corresponds to a power of about 90 W for a current of intensity equal to about 3,000 A.

According to a variant of the invention and still with the aim of limiting the rise in temperature by producing the least possible heat dissipation by the Joule effect, each of the fixed conductive elements 12 and 14 can be produced as illustrated in FIG. figure 2 .

As can be seen in this figure, the conductive fixed contact element 14, which is fixed to the connection pad 18, comprises a lower layer 50, an upper layer 52 and an intermediate layer 54.

Like the connection pad 18 to which it is fixed, for example by welding, the lower layer 50 is made of aluminum.

The upper layer 52 is interchangeable and is fixed to the lower layer by a bolt 56. The upper layer 52 is preferably made of copper so as to deposit a coating of silver by electrolysis on its upper surface, which would not be possible. if this layer was aluminum like the bottom layer. Thus, the electrical connection between the movable element 20 and the fixed element 14 is made by direct contact between the silver pad 34 and the silver coating of the upper layer 52, which makes it possible to reduce the contact resistance. A half.

The intermediate layer clamped between the lower layer 50 and the upper layer 52 by the bolt 56 is preferably a layer of ECOOCONTACT (registered trademark) foam consisting of a metal foam backbone selected from the group consisting of iron, cobalt, nickel. and their alloys covered with at least one coating of tin, indium or one of their alloys described in the French patent 1002988 . Due to the alveolar structure of this layer, its surface has a multitude of points contact Thanks to these points, the intermediate layer 54 has numerous contacts with the lower and upper layers, which makes it possible to obtain a high conductivity and therefore a low resistance. It can be seen that, as previously with the silver pellets, the resistance between the fixed contact element and the movable contact element is halved.

Note that the fixed contact conductor element 12 connected to the connection pad 16 also comprises, in its upper part, a structure identical to the three-layer structure illustrated on figure 2 . In the preferred embodiment illustrated in figure 1 , an identical three-layered structure, symmetrical to that illustrated on figure 2 , is also located at the lower parts of each of the fixed contact elements 12 and 14.

Also note that the three-layer structure shown on figure 2 can be used on either side of the lower parts of the fixed contact element 20 coming into contact with the fixed contact elements 12 and 14, but also in place of the silver disc 32, 34.

Although, as far as possible, the contact enclosure which has just been described is sealed, there may still be deposits of dust on the elements which it contains. Such deposits, for example on silver pellets, lead to degradation of the contacts which results in an increase in electrical resistance. In addition, during disconnection, an electric arc may occur caused by residual current due to battery power.

For the reasons which have just been mentioned, a preferred embodiment consists in filling the chamber with a perfect seal with an inert gas instead of air. Such a gas can be a neutral gas such as helium or neon, or else nitrogen, and preferably sulfur hexafluoride (SF ₆ ).

Another way to reduce the temperature produced by the heat dissipation is to provide a circulation of a refrigerant liquid, for example water, in a pipe (not shown) located inside each of the connection pads 16. and 18.

The isolating module according to the invention can be produced as illustrated in figure 3 . Such a module comprises an enclosure 10 described above electrically connected to the current input and output by means of contact pads 16 and 18.

The current input and output (not shown) are connected to the module by two connection bars 60 and 62 for the current input and by two bars 64 and 66 for the current output.

As illustrated in the figure, the connection bars 60 and 62 are connected to the enclosure 10 by a plurality of connection blades divided into two groups of blades 68 and 70. As already mentioned, an important characteristic of the invention is to limit as much as possible the rise in temperature due to heat dissipation by the Joule effect. For this purpose, the structure in a plurality of blades has a very large surface with the air composed by the two faces of each blade multiplied by the total number of blades. As illustrated, the blades form a Z so that they have the greatest possible flexibility and can be deformed in the two angles of the Z under the effect of temperature.

Note that a plurality of blades having the same structure as for the current input and divided into two sets 72 and 74 is used to connect the connection bars 64 and 66.

The sectioning module which has just been described with reference to figures 1 , 2 and 3 has a rectangular shape the largest dimension of which is between 0.90 m and 1.20 m and the smallest dimension between 0.40 m and 0.60 m, and has a thickness of about 3 cm. Its weight is between 20 and 30 Kg.

As mentioned previously, this module can allow a current to pass, the intensity of which is approximately 3,000 A. As in general the intensity of the current used in the installation is much greater, the disconnecting device comprises a plurality of such parallel disconnection modules.

An important object of the invention is to use the sectioning module described above as a presentation model. Indeed, the size and weight of a module being relatively small, it is easy for the manufacturer to transport only the module to present it to any potential customer or future user. The latter will thus be able, by using a current of reduced intensity, to quickly define how many modules will be required in the desired disconnection device and to know the temperature behavior of said disconnection device.

In general, a disconnection device according to the invention comprises a plurality of modules which are assembled in parallel to correspond to the intensity of the current to be disconnected. Thus, if the current has an intensity of 20 kA, it is necessary to provide eight disconnection modules in parallel. The resulting disconnecting device then comprises a single connection pad, preferably made of aluminum, for the electrical connection to the outside of all the modules.

The figure 4 represents a disconnecting device used for an intensity of about 120 kA composed of six partial disconnecting devices made up of two sets of three sub-assemblies 80, 82 and 84 of eight modules each such as the sub-assembly 80. To do this , each module, illustrated on the figure 3 , of each of the three sub-assemblies is opposite a module which is symmetrical to it and which belongs to a sub-assembly of the other assembly. Thus, the modules of sub-assembly 84 are symmetrical to the modules of sub-assembly 86.

The three subassemblies or partial disconnecting devices 80, 82 and 84 have a common actuating mechanism 88. The same is true of the three symmetrical subassemblies or partial disconnecting devices which have the same actuating mechanism 90 This mechanism is for example a mechanism for rotating a shaft which, by a set of connecting rods, causes the compression of the springs described with reference to figure 1 and allows the contacts inside the enclosure for the passage of current.

All the partial disconnection devices 80, 82 and 84 which, on the figure 4 , has only one connection pad, is connected to the current input by two connection bars 92 and 94 and by means of two sets of connection strips 96 and 98. The same connection structure (not referenced ), i.e. two bars connected to the output connection pad, is used for connection to the current output. The same structure (not referenced) as that which has just been described is symmetrical to the latter and includes all of the symmetrical partial disconnection devices of the partial disconnection devices 80, 82 and 84.

According to a variant of the invention, the sets of connecting blades serving to dissipate the heat produced by the Joule effect are replaced by the devices illustrated in the figures. figures 5 and 6 .

On the figure 5 , the connection bar is fixed directly to the connection area 16 (or 18) by bolts 102. Between the connection bar 100 and the connection area is a layer 104 of ECOCONTACT foam (registered trademark) consisting of a skeleton foam of metal selected from the group consisting of iron, cobalt, nickel and their alloys covered with at least one coating of tin, indium or one of their alloys. As mentioned above, the surface of the layer has a multitude of contact points. Thanks to these points, the layer 104 has numerous contacts with the connection bar 100 on the one hand and with the connection pad 16 on the other hand, which makes it possible to obtain a high conductivity and therefore a low resistance.

On the figure 6 , the connection bar 106 is connected to the connection area 16 by means of an intermediate bar 110 to which it is welded. The intermediate bar 110 is fixed to the connection area 16 by means of bolts 112 and 114. Between the bar 110 and the connection area, there is a layer of ECOCONTACT foam as in the embodiment of the figure 5 .

Claims (10)

1. A disconnecting module of a power supply line adapted to have the lowest possible resistance so as to obtain as little heat dissipation by Joule effect as possible, comprising:

   - a tight contact casing (10) comprising at least a first fixed-contact conductive element (12) to establish the electrical connection with a current input and a second fixed-contact conductive element (14) to establish the electrical connection with a current output, said fixed-contact elements being electrically connected on the outside of the casing by two connection terminals (16, 18) respectively, and at least one mobile-contact conductive element (20 or 36) adapted to come in contact simultaneously on said first and second fixed-contact elements under the action of an actuating mechanism (26), said mechanism being actuated so as to interrupt the contact between said fixed-contact elements and said mobile-contact element with the aim of disconnecting said supply line,

   - at least a first metal connection bar adapted to be connected to a current input and at least a second connection bar adapted to be connected to a current output, and

   - a first intermediate conductive element connected firstly to said first connection bar and secondly to said first fixed conductive element and a second intermediate conductive element connected firstly to said second connection bar and secondly to said second fixed conductive element;

   said module being characterised in that:

   - said electrical supply line supplies a current of an intensity higher than 1000 A,

   - at least one of said fixed-contact elements (12, 14) or one of said mobile-contact elements (20 or 26) comprises a silver pellet placed on the surface of said element, allowing the contact resistance between the mobile-contact element and the fixed-contact element to be reduced by half,

   - at least one of said fixed-contact elements (12 or 14) comprises a lower layer made of aluminium (50), an upper layer made of copper having a silver coating (52) and an intermediate layer (54) of foam comprising a metal foam skeleton selected from the group consisting of iron, cobalt, nickel and alloys thereof coated with at least a coating of tin, indium or one of their alloys.
2. The disconnecting module according to claim 1, wherein a silver pellet is fixed on the surface of each of said mobile-contact elements (20, 26) coming into contact with each of said fixed-contact elements (12, 14).
3. The disconnecting module according to claim 1 or 2, wherein said tight contact casing (10) is filled with an inert gas instead of air.
4. The disconnecting module according to claim 3, wherein said gas is a neutral gas such as helium, neon or nitrogen, and preferably sulphur hexafluoride (SF6).
5. The disconnecting module according to any one of claims 1 to 4, used as a presentation model wherein said electric supply line supplies a current of reduced intensity allowing the future user to know the behaviour according to the temperature of a disconnecting device.
6. The disconnecting module according to any one of claims 1 to 4, wherein said first intermediate conductive element and said second intermediate conductive element are both comprised of at least one group of connection blades (68, 70 and 72, 74).
7. The disconnecting module according to claim 6, wherein said connection blades (68, 70 and 72, 74) form a Z so that they have the greatest possible flexibility and can be deformed in both corners of the Z under the effect of temperature.
8. The disconnecting module according to any one of claims 1 to 4, wherein said first intermediate conductive element and said second intermediate conductive element comprise a layer (104, 108) of foam comprising a metal foam skeleton selected from the group consisting of iron, cobalt, nickel and alloys thereof covered with a least a coating of tin, indium or one of their alloys.
9. The disconnecting module according to any one of claims 1 to 8, wherein the current supplied by said electric supply line is direct current.
10. A disconnecting device comprising a plurality of disconnecting modules according to any one of claims 1 to 9 arranged in parallel between the current input and the current output.

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