FR2991496A1 - Switchgear e.g. circuit breaker, has contact unit, where specific number of contact points is provided between contact unit and conducting units, and one of two conducting units is ready to move with regard to contact unit during operation - Google Patents

Abstract

The switchgear (10) has two electrically conducting units e.g. electrode (1) or cylindrical conducting bar (2), that are ready to move with regard to each other during operation. An electrical contact unit (3) is ready to connect the two electrically conducting units electrically. The contact unit is received in a set of grooves (V, V') placed in one of the two conducting units. Number of contact points (P) between the contact unit and the conducting units is equal to or higher than 4. One of the two conducting units is ready to move with regard to the contact unit during operation. The grooves are provided in the form of half-hexagon, half-octagon or half-decagon.

Description

TECHNICAL FIELD The present invention relates to the field of electrical contact members for high-voltage electrical equipment, and in particular for gas-insulated switchgear (GIS) substations, isolated substations. to the air (or AIS for "Air Insulated Switchgear" in English), the gas-insulated circuit breakers (for example of the type GCB for "Generator Circuit Breaker" in English) and / or air-insulated circuit breakers (for example DT type for "Dead Tank" in English).

The invention relates more particularly to high voltage electrical equipment comprising two electrically conductive members and an electrical contact member, adapted to electrically connect the two electrically conductive members. STATE OF THE PRIOR ART High voltage means a voltage greater than about 1000 Volts. The invention finds particular application in two main types of electrical equipment. It is first of all a mobile-type apparatus, namely in particular an electrical switchgear. In this context, we will include circuit breakers, disconnectors, contactors or load switches. In known manner, such an apparatus of the mobile type comprises a contact assembly, which is provided with two respectively fixed and movable members. The movable member can thus be moved, relative to the fixed member, between a contact position and a separate position or cutoff. Each member is provided, first of all, with a respective arc contact element. In addition, these bodies, respectively fixed and movable, are provided with permanent contact members, which provide electrical continuity, especially in the closed position. These permanent contact members, of fixed or mobile type, constitute electrical contact members within the meaning of the invention. The invention also finds its application in electrical equipment, of generally static type. In this spirit, it is in particular a set of busbars. In this arrangement, the electrical continuity between two adjacent bars, which are generally immobile with respect to each other, is achieved by a connecting piece which surrounds the ends opposite these conductive bars. In service, in particular under the effect of functional clearances, thermal expansion induced by current flow or vibrations, these two bars are subjected to slight relative displacements, so that it is difficult to fix them. the aforementioned connecting piece.

We therefore use an electrical contact member, also covered by the invention. This is interposed between walls facing the connecting piece and a corresponding conductive bar.

In summary, the present invention relates to a high-voltage electrical apparatus comprising two electrically conductive members (or conductive members) adapted to be electrically connected in series by an electrical contact member. The two conductive members are likely to move relative to each other because of either the nature of the electrical equipment, or the operating contingencies of this equipment. Electrical contact elements have a major role in electrical equipment. They must ensure the passage of electrical current between the conductive members without leading to excessive heating at the connections which is harmful to the electrical contact members and increases losses by Joule effect. Also, the electrical contact members are usually made of conductive materials, such as copper or aluminum, for example. In addition, in order to guarantee a better resistance to the point (s) of contact, the electrical contact members are often protected against corrosion (oxidation type) by a coating layer of a noble metal, such as gold or silver for example, generally having a thickness of between 3 and 40 pm.

Thus, the resistance and therefore the electrical resistivity are important parameters and it is sought to obtain electrical contact members having the lowest possible electrical resistance, of the order of a few micro-ohms. On the other hand, for the aforementioned electrical equipment applications, a spring type electrical contact member (hereinafter referred to as a "spring member") is used among other types. Such a spring member is formed by a wire, for example copper and covered with a layer of silver, folded on itself so as to form a succession of turns. European patent application EP 0 890 758 describes an exemplary spring member. The spring member may be assembled between a groove, for example of rectangular or V-shaped section, formed in one of the two conductive members, for example an electrode, and the other conductive member, for example a conducting bar. cylindrical. The spring member moves in a state of compression between the electrode and the conductive bar. The movement of the conductive bar causes a relative sliding between the spring member and the bar which is a source of mechanical wear. In addition, even in the absence of movement of the bar, the passage of the nominal current can cause thermal expansions causing a slip of a few millimeters. The contact force (of support) of the spring member is therefore also an important parameter. Consequently, such an electrical contact member must make it possible to obtain the lowest electrical resistance possible, but also a contact force obtained by compression, which generates only a small amount of mechanical wear, during the mechanical operations of the devices. pieces for example. Such parameters, electrical resistance and contact force, are particularly influenced by the position of the electrical contact member between the conductive members. Various prior art configurations of positioning an electrical contact member relative to the conductive members are known from the prior art. The US patent application US 2003/0094812 aims to allow a reduction of the insertion force with respect to the disconnection force, and describes an electrode provided with a first groove and a conductive bar with a second groove. , of different shape from the first, between which an electrical contact member is locked in position. This blocking, in particular the blocking of the electrical contact member in the conductive bar, does not allow a relative movement of the bar and the electrical contact member, so that this solution is not suitable for the applications described above, and in particular to applications of the electrical switchgear type. The US patent application US 2004/0245686 aims to control the insertion force and the disconnection force by the deformation of an electrical contact member placed between a first V-shaped groove (in section) of a electrode and a second U-shaped groove (in section) of a connection bar. The electrical contact member is also locked in position between these two grooves, and in particular in the conductor bar, so that this solution is not suitable for the applications described above, in particular for applications of the electrical switchgear type.

The US patent application US 2004/0175229 describes several variant shapes for a first groove of an electrode and a second groove of a conductive bar, between which is placed an electrical contact member. The variety of forms aims to control the insertion and disconnection efforts. This solution does not make it possible to obtain a reduction in the satisfactory electrical resistance.

DISCLOSURE OF THE INVENTION There is a need for providing electrical equipment having an electrical contact member which satisfactorily lends itself to high voltage matching.

There is also a need to provide an electrical apparatus comprising an electrical contact member having a low electrical resistance and an optimum contact force. The object of the invention is to at least partially remedy the needs mentioned above and the drawbacks relating to the embodiments of the prior art. To enable an electrical contact member to have the lowest electrical resistance possible, it is desirable to increase the number of contact points through which the electric current flows, in particular to facilitate the passage of current during the reduction of section. , that is to say the number of contact points between the electrical contact member and the conductive members.

Furthermore, for a spring member having two contact points with for example a first conductive member provided with a V-shaped groove and a single contact point with for example a second conductive member in the form of a cylindrical conductor bar, or a total of three points of contact, the compression force exerted by the conductive bar on the electrical contact member via a single point of contact is distributed by the electrical contact member to the first conductive member via the two points of contact In order to increase the contact force, it is also desirable to increase the number of points of contact between the electrical contact member and the conductive members.

The invention thus has, according to one of its aspects, a high-voltage electrical apparatus comprising two electrically conductive members, able to move relative to each other in use, and an electrical contact member. , capable of electrically connecting the two electrically conductive members, the electrical contact member being received in at least one groove in at least one of the two electrically conductive members, characterized in that the number of contact points between the electrical contact and the two electrically conductive members is greater than or equal to 4, and in that at least one of the two electrically conductive members is adapted to move, in use, relative to the electrical contact member.

By "able to move" is meant that a relative movement is allowed between at least one of the two electrically conductive members and the electrical contact member, the electrical contact member not being particularly blocked in a groove of said at least one of the two electrically conductive members. This relative movement can occur in service, especially outside the insertion or disconnection operations of the two electrically conductive members. This relative movement may for example allow the engagement or disengagement of the electrical contact member relative to a groove of said at least one of the two electrically conductive members. In particular, the apparatus may be in this case an electrical switchgear.

Thanks to the invention, it is possible to increase the number of points of contact between the electrical contact member and the electrically conductive members, in particular by a modification of the shape of the electrically conductive members, in particular the grooves receiving the electrical contact member. The increase in the number of contact points may thus make it possible to obtain the lowest possible electrical resistance of the electrical contact member and an increase in the contact force of the electrical contact member which makes it optimal.

The electrical equipment according to the invention may further comprise one or more of the following characteristics taken separately or in any possible technical combination.

The number of contact points between the electrical contact member and the two electrically conductive members may be greater than or equal to 5, more preferably 6, more preferably 7 or even 8. The number of contact points between the contact member electrical and only one of the two electrically conductive members may be greater than or equal to 2, better 3, better still 4 or 5. When observed in section, said at least one groove may have substantially a half-polygon shape, in particular of a regular polygon, and have at least two points of contact with the electrical contact member. One of the electrically conductive members may be devoid of groove for receiving the electrical contact member. At least one of the conductors may comprise substantially when observed in section a form of half-hexagon, half-octagon or half-decagon, 25 or half-polygon n sides. The first and second electrically conductive members may respectively comprise first and second grooves intended to receive the electrical contact member, the first groove having substantially when observed in section a half-hexagon, half-octagon or electrically groove having half-decagon, and the second groove having substantially when observed in section a form of half-rhombus or V-shaped. As examples, the first electrically conductive member 5 may be devoid of groove for receiving the electrical contact member, and the second electrically conductive member may comprise a groove having substantially when observed in section a half-decagon shape. Alternatively, the first electrically conductive member may comprise a groove having substantially when observed in cross section a half-rhombus shape or V-shaped, and the second electrically conductive member may comprise a groove 15 having substantially when observed in section a half-decagon shape, or a half-hexagon or half-octagon shape, see half-polygon with n sides. The electrical contact member can be folded over itself in the manner of a ring. The electrical contact member may be a spring member formed of a single wire wound on itself so as to form a succession of turns. The electrical equipment may be an electrical switchgear, such as a circuit breaker, a disconnector, a contactor or a load switch. Alternatively, the electrical equipment may be a set of busbars.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood on reading the detailed description which follows, non-limiting examples of implementation thereof, as well as the examination of the figures, schematic and partial, of the accompanying drawing, in which: - Figure 1 illustrates, in section, an example of a contact zone of an electrical equipment according to the prior art, and more particularly the connection between an electrical contact member and two electrically conductive members, and - Figures 2 to 4 illustrate, in section, alternative embodiments of electrical equipment according to the invention.

In all of these figures, identical references may designate identical or similar elements. DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS According to the invention, the increase in the number of contact points between the electrical contact member and the electrically conductive members may make it possible to obtain a reduction in the electrical resistance of the electric contact.

Indeed, the electrical resistance R of a room, property of the room to slow the passage of an electric current, is related to the nature of the material that constitutes and its dimensions. It is classically calculated by the following formula: R = p x (L / S) (1), where. R is the electrical resistance in ohm (S)), p is the volume resistivity of the material in ohm-meter (Qm), L is the length traveled by the current on which the resistance is calculated in meters (m), and S is current flow section in square meter (m2). The formula (1) can allow the calculation of the electrical resistance R for volumes. At a point of contact (or point of necking) between two pieces, the contact resistance R (called the constriction resistor Rc) is calculated using mathematical formulas that take into account the geometry of the point of contact and the characteristics materials from both rooms. For the sake of simplicity and clarity, the constriction resistance Rc can be calculated using the following formula: Rc = p / (2xa) (2), where. Rc is the resistance of constriction in ohm (Q), p is the resistivity of the materials at the point of constriction in ohm-meter (S) .m), and a is the radius of the contact circle in meter (m) (the area contact is approximated by a circle). From the formula (2), we therefore find that the larger the contact area, the lower the electrical resistance at the point of contact. In addition, the surface of the contact zone 30 strongly depends on the contact force proportionally. The greater the contact force, the larger the area of the contact area. Therefore, to decrease the electrical resistance at the point of contact, it is desirable to increase the area of the contact area, and thus to increase the number of constriction areas or contact points. Such an increase in the points of contact between the electrical contact member and the conductive members may in particular be obtained by creating grooves with several slopes, in particular by creating grooves having in section a form of half-polygon with n sides. Referring to Figure 1, there is schematically illustrated, in section, an example of a contact zone of a known electrical equipment 10, and more particularly the connection between an electrical contact member 3 and two electrically conductive members 1 and 2. The electrical apparatus 10 thus comprises a first conductive member 1 in the form of an electrode and a second conductive member 2 in the form of a conductive bar. The electrical apparatus 10 further comprises an electrical contact member 3, in particular in the form of a spring member. The electrode 1 has in section a V-shaped groove 4, in particular in the form of a half-hexagon, intended to receive the spring member 3, and the conductive bar 2 is a cylindrical bar devoid of groove. As can be seen in this FIG. 1, the spring member 3 is in compression between the conductive members 1 and 2 at a single contact point P on the conducting bar 2 and at two points of contact P on the electrode 1, a total of three points of contact P.

Such a configuration may not be sufficient to allow a significant reduction in the electrical resistance of optimal contact stress conductors 1 and 2.

With reference to FIGS. 2 to 4, diagrammatically, in section, variants there is illustrated embodiment of the spring member 3 and one of the two electrical equipment members 10 according to the invention. In the example of FIG. 2, the electrode 1 comprises a groove having a cross-section of a shape of 15 V, or else a shape of half-hexagon, whereas the conducting bar 2 comprises a groove V 'in the form of a V-notch, or a half-diamond shape. The electrical apparatus 10 of FIG. 2 has four contact points P between the spring member 3 and the electrode 1 and the conductive bar 2. With respect to the electrical equipment 10 according to the prior art of FIG. it may be possible to reduce by two the constriction resistance on the conductive bar 2. FIG. 3 differs from FIG. 1 in that the electrode 1 comprises a groove V having in section a shape with multiple slopes, in particular a half-decagon shape. Compared with the electrical apparatus 10 of FIG. 1 according to the prior art, the electrical equipment 10 of FIG. 3 has five contact points P between the spring member 3 and the electrode 1 and the conductive bar 2, and may make it possible to reduce the constriction resistance on the electrode 1 with four contact points P. Finally, in the example of FIG. 4, the electrode 1 comprises a groove V similar to that of the electrode 1 of the 3, and the conductive bar 2 has a groove V 'similar to that of the conductive bar 2 of Figure 2. The electrical equipment 10 partially shown in Figure 4 thus has six contact points P between the spring member 3 and the electrode 1 and the conductive bar 2. Compared to the electrical equipment 10 of FIG. 1, it can make it possible to reduce the constriction resistance on the electrode 1 with four contact points P and on the conducting bar 2 with two points of In the set of examples described above, the conductive member 2 in the form of a conducting bar is able to move, in use, relative to the electrical contact member 3. In particular, the groove V ' of the conductive member 2 is arranged to allow such a displacement. More specifically, the shape of the groove V 'of the conductive member 2 is adapted to a displacement, in use, of the electrical contact member 3 relative to this conductive member 2. The electrical contact member 3 is in particular not blocked in the conductive member 2.

Of course, the invention is not limited to the embodiments which have just been described.

Various modifications may be made by the skilled person. The expression "having one" shall be understood as being synonymous with "having at least one", unless the opposite is specified.

Claims (10)

REVENDICATIONS1. High-voltage electrical equipment (10) comprising two electrically conductive members (1, 2) able to move relative to one another in use, and an electrical contact member (3) able to electrically connect the two electrically conductive members (1,2), the electrical contact member (3) being received in at least one groove (V, V ') formed in at least one of the two electrically conductive members (1,2), characterized in that the number of contact points (P) between the electrical contact member (3) and the two electrically conductive members (1,2) is greater than or equal to 4, and in that at least one of the two members electrically conductive (1,2) is able to move, in use, relative to the electrical contact member (3). 2. Electrical apparatus (10) according to claim 1, characterized in that, when observed in section, said at least one groove (V, V ') has substantially a shape of half-polygon, in particular of a regular polygon, and has at least two points of contact (P) with the electrical contact member (3). 3. Electrical apparatus (10) according to claim 1 or 2, characterized in that one (2) of the electrically conductive members is devoid of groove for receiving the electrical contact member (3). 4. Electrical equipment (10) according to one of the preceding claims, characterized in that at least one of the electrically conductive members (1,2) comprises a groove (V, V ') having substantially when observed in section a shape half-hexagon, half-octagon or half-decagon. 5. Electrical apparatus (10) according to any one of the preceding claims, except claim 3, characterized in that the first (1) and second (2) electrically conductive members respectively comprise first (V) and second (V) ') grooves intended to receive the electrical contact member (3), the first groove (V) having substantially when observed in section a form of half-hexagon, half-octagon or half-decagon, and the second groove ( V ') having substantially when observed in section a form of half-rhombus or V-shaped. Electrical apparatus (10) according to one of the preceding claims, characterized in that the number of contact points (P) between the electrical contact member (3) and the two electrically conductive members (1,2) ) is greater than or equal to 5. Electrical apparatus (10) according to one of the preceding claims, characterized in that the number of contact points (P) between the electric contact member (3) and the two electrically conductive members (1,2). is greater than or equal to 6. 8. Electrical apparatus (10) according to any one of the preceding claims, characterized in that the electrical contact member (3) is a spring member, formed of a single wire wound on itself so as to form a succession of turns. 9. Electrical equipment (10) according to any one of the preceding claims, characterized in that it is an electrical switchgear, including a circuit breaker, a disconnector, a contactor or a load switch. Electrical equipment (10) according to any one of claims 1 to 8, characterized in that it is a busbar.