EP0639841B1 - Female contact for H.T. isolator - Google Patents

Abstract

Female contact, especially for high-voltage isolator, characterised in that it comprises two interpenetrated bell shapes, a first metal bell shape produced by extrusion of a metal block followed by machining, the said first bell shape comprising metal contact fingers (2) intended to interact electrically with a male contact (8), the other bell shape comprising fingers (11) made of an insulating material, the insulating fingers (11) limiting the excursions of the contact fingers, in the radial direction and in the lateral direction, to predetermined values below the elastic deformation limit of the finger, and insulating the contact fingers from one another, as well as the contact fingers of a possible pressure spring surrounding the contact fingers, so as, when short circuit forces are present, to counteract the risk of welding of the fingers and/or burning of the spring. <IMAGE>

Description

The invention relates to a female electrical contact of the type comprising a plurality of metal fingers arranged parallel to each other according to the generators of a cylinder, in an assembly known as tulip contact. Such contact is intended to cooperate with a male contact consisting of a tube, or a rod, cylindrical coaxial in female contact and moving coaxially.

Such tulip-type female contacts are known. in particular by document FR-A-9205689 and by document DE-A-2310129. The latter describes a female contact comprising a first metal tulip provided with fingers metal contacts intended to cooperate with a male contact and separated from each other by insulating elements.

A first object of the invention is to provide a female contact in which the contact force is the same on all tulip fingers, even if the male contact penetrates axially offset.

Another object of the invention is to provide a female contact in which the deformation of fingers, due to the electrodynamic forces which are exercised on parallel fingers, either limited and does not exceed the limit of elastic deformation.

Another object of the invention is to provide a female contact in which, in the event of a short circuit, the risk of welding fingers to each other and of the pressure spring surrounding the contact fingers be removed.

All these goals are achieved by the female contact of the invention.

This female contact, in particular for high disconnector tension, comprises a first metal tulip provided with metallic contact fingers intended to cooperate with a male contact and separated from each other by insulating elements.

According to a characteristic of the invention, the contact female has a first tulip made by extrusion of a metal block followed by machining and insulating elements in the form of fingers carried by a second tulip, these fingers made of material insulation limiting movement of contact fingers in the radial direction and in the lateral direction to values predetermined values below the strain limit elastic of these contact fingers.

• la figure 1 est une vue en perspective partiellement arrachée de la tulipe métallique constituant l'un des éléments du contact femelle de l'invention,
• la figure 2 est une vue en perspective partiellement arrachée montrant notamment la tulipe isolante imbriquée dans la tulipe métallique,
• la figure 3 est une vue en coupe axiale du contact de l'invention, en coopération avec le contact mâle associé,
• la figure 4 est une vue en coupe transversale d'un contact selon l'invention, sans ressort,
• la figure 5 est une vue en coupe axiale du contact femelle de l'invention, muni d'un ressort, le contact mâle étant engagé.

The invention is now explained in detail by the description of a preferred embodiment, with reference to the appended drawing in which:

• FIG. 1 is a partially cutaway perspective view of the metal tulip constituting one of the elements of the female contact of the invention,
• FIG. 2 is a partially cut away perspective view showing in particular the insulating tulip nested in the metal tulip,
• FIG. 3 is a view in axial section of the contact of the invention, in cooperation with the associated male contact,
• FIG. 4 is a cross-sectional view of a contact according to the invention, without spring,
• Figure 5 is an axial sectional view of the female contact of the invention, provided with a spring, the male contact being engaged.

As already mentioned, the female contact of the invention comprises two tulips, one conductive, the other insulating, interpenetrated.
Figure 1 shows the conductive tulip.
It is produced by an extrusion of an aluminum block 1, completed by a machining operation.
The extrusion makes it possible to produce substantially rectangular cross-sections with rounded edges, with a large face provided with a radial edge 2A with a flat top of height Y.

The choice of height Y is determined, in conjunction with the length X of the finger, to obtain rigidity contact finger.

The edge 2A extends from the bottom of the finger over all the length of the finger except the end of the finger. On the flat part of the end of the finger is reported a pad 3 of material resistant to wear and effects of the arch, and which has an inner protuberance 3A intended to cooperate electrically with the male contact.

At the base of the block is machined a groove 4 whose depth adjusts the length X of the fingers.

The base of the block includes a threaded portion 5 allowing the fixing by screwing of a centering cone 7 for male contact 8 (see figure 3). The cone 7 is provided icebreaker lugs 7A.

At the base of block 1, the extrusion made it possible to define, between each of the fingers, spaces 10 between which a tulip made of insulating material, produced by extrusion followed by machining or molding, and comprising a plurality of fingers 11 joined by bridges 12 to a portion cylindrical 13. The insulating material can be chosen by example among the products known under the brands Teflon or GSM nylatron, the latter being a type 6 nylon with high resistance with a charge of molybdenum disulphide of which one of the characteristics is not to maintain the combustion.

The fingers 11 have a section which is substantially rectangular with rounded edges. The insulating fingers 11 have the same length as the metal fingers 2. The portion cylindrical 13 stops substantially at the thread 5. Between the end of the cylindrical portion 13 and the end fingers 11, bridges 12 define edges 11A to flat top.

The female contact, which has just been described, solves the technical problems stated in the preamble to the present brief.

Limitation of movement in the event of a short circuit radial of the contact fingers 2, to a value less than their elastic limit, thanks to the presence of the fingers insulators 11, prevents plastic deformation of the fingers. The insulating fingers avoid contact with metal fingers with an outer metal casing and therefore their possible burning by bypass currents destructive.

The lateral displacement of the contact fingers 2, due electromagnetic forces exerted on parallel conductors, is limited by the presence of nested insulating fingers 11, which avoids the risk permanent deformation by exceeding the limit elastic.

The presence of the insulating tulip ensures a substantially equal contact between the male contact and each pads 3, even if male contact occurs axially offset.

Insulating fingers not only limit bending metallic fingers but they keep them isolated the each other, which avoids welding problems between two parallel fingers deformed by the effect of a short circuit (effect of bringing together parallel currents, these effects being sensitive from around 80kA 1 sec. and 216 kA asymmetric peak 10 cycles).

Note that burning or welding of fingers occur when the shock of the short circuit move your fingers, which increases contact resistance at the transfer point and tends to cause an elevation of temperature up to the melting point of copper.

The female contact can be fitted with a spring circular 15 to increase the contact pressure of the metallic tulip. The use of such a spring for the purpose above is a technique well known to those skilled in the art; however, the springs directly in contact with the metal fingers may experience a bypass current due to dynamic or thermal shocks during short-circuits, when one or more fingers are no longer in frank contact with male contact.

According to the present invention, the spring 15 is arranged around the insulating tulip, which avoids any galvanic contact between the spring and the contact fingers metallic, the spring pressure force being transmitted through the insulating tulip. Maintaining the spring is provided by a groove machined in all insulating fingers 11.

The invention finds application in the equipment of high voltage disconnectors in which the movable hammer moves axially at the end of the closing operation.

Claims (7)

1. A female contact, in particular for a high tension section switch, including a metal first thimble provided with metal contact fingers (2) designed to cooperate with a male contact (8) and separated from one another by insulating elements, the female contact being characterized in that it includes a first thimble made by extruding a block of metal and then machining it, and insulating elements constituted in the form of fingers (11) carried by a second thimble, said fingers made of insulating material limiting the displacement of the metal contact fingers in a radial direction and in a lateral direction to predetermined values that are less than the elastic limit of deformation of the metal contact fingers, and serving in particular to prevent contact between the metal contact fingers.
2. A female contact according to claim 1, characterized in that the contact fingers of the metal thimble have a section in the form of a rectangle with rounded edges, and possess a ridge (2A) extending over at least a fraction of the length of the finger.
3. A female contact according to claim 1 or 2, characterized in that the insulating material fingers of the second thimble are of the same length as the metal contact fingers.
4. A female contact according to any one of claims 1 to 3, characterized in that the insulating material fingers (11) of the second thimble are of a section that is substantially rectangular with rounded edges and each possesses a ridge (11A) projecting from one of the large faces of the rectangle.
5. A female contact according to any one of claims 1 to 4, characterized in that the length of the contact fingers is adjusted by machining a groove (4) in the extruded metal block.
6. A female contact according to any one of claims 1 to 5, characterized in that the block includes a cylindrical thread (5) designed to have a centering cone (7) provided with ice-breaking spurs (7A) screwed thereon to receive the male contact (8), said cone serving to limit the total deflection of said interleaved thimbles when assembled together.
7. A female contact according to any one of claims 1 to 6, characterized in that it includes a spring (15) surrounding the insulating fingers and acting through them to impart contact pressure to the metal fingers (2) without electrical continuity being established between the spring and the metal contact fingers.

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