FR2798515A1 - ALUMINUM CONNECTION CLIP FOR ELECTRICAL EQUIPMENT, PARTICULARLY A FUSE - Google Patents

Abstract

A connection clamp comprises two contact elements 14, 16 formed by aluminum bars, each comprising: - a convex contact surface 22 arranged in the internal median part between the fixing base 36 at the rear part, and a stud 26, 27 projecting playing the role of a spark gap, - a yoke 28 of insulating material covering the front part above the stud 26, 27 to form a sudden engagement member at the entry of the clamp 10, - and 30 heat dissipation fins distributed on the outer surface opposite the pad. Application: fuse connection with knife-shaped terminal.

Description

i

  ALUMINUM CONNECTION PLIERS FOR APPARATUS

ELECTRIC, ESPECIALLY A FUSE

  Technical Field of the Invention The invention relates to a connection clamp for an electrical equipment terminal, comprising: - at least two symmetrical contact elements intended to be plugged into said terminal, and having main contacts for the passage of the nominal current, and arcing contacts acting as a spark gap clamp,

  - And elastic means to ensure contact pressure on the terminal.

  STATE OF THE ART The clamps commonly used for the connection of high-caliber fuses, in particular for intensities of the order of 400 A, are produced from a copper sheet, cut and folded to form a first clamp provided with main contacts for the passage of the nominal current, and a second clamp provided with arcing contacts. The two clamps are joined to a common U-shaped base, and the contact pressure is ensured by circular springs in the shape of a circlip acting on the elastic branches of the first clamp. The cost of manufacturing such pliers is relatively

  high, and the heat absorption due to the passage of the current remains very limited.

  OBJECT OF THE INVENTION The object of the invention consists in making a connection clamp for an electrical apparatus of high ratings, benefiting from optimum heat dissipation, and cost

reduced manufacturing.

  The connection clamp according to the invention is characterized in that the two contact elements are constituted by aluminum bars, each comprising: - a convex contact surface disposed in the internal middle part between the mounting base to the part rear, and a protruding stud playing the role of spark gap, - a screed of insulating material covering the anterior part above the stud to form a snap engagement member at the entrance of the clamp, - and dissipation fins thermal distributed on the external surface opposite the stud. According to a preferred embodiment, the internal face of the yoke is inclined relative to the longitudinal direction so as to constitute a convergent with the yoke of the other contact element. Each contact element has a rectangular section, and comprises on the external surface a groove located between the fins and the fixing base for anchoring a double spring. The contact surface is advantageously provided with grooves to promote electrical contact with the knife-shaped terminal. One of the pads is made of copper or a copper alloy, while the other pad is made of insulating material, so as to transfer the arc zone to the first pad playing the role of arcing contact. According to a characteristic of the invention, the fixing base of each contact element is curved relative to the flat range of the starting conductor to allow spacing and reconciliation movements during the racking-in and

terminal removal.

  According to another characteristic of the invention, the two contact elements are provided with stops arranged under the contact surfaces and coming into engagement with each other

  to delimit a first transverse interval between the studs.

  Depending on the size and the temperature rise tolerated, each contact element is divided into at least two adjacent parts separated from each other by a second interval extending perpendicular to the first interval so as to constitute a clamp.

multiple contacts.

Brief description of the drawings

  Other advantages and characteristics will emerge more clearly from the description which follows.

  follow of an embodiment of the invention, given by way of nonlimiting example and shown in the accompanying drawings in which: - Figure 1 is a schematic perspective view of a connection clamp according to the invention; - Figure 2 shows an exploded perspective view of a clamp and starting conductor assembly before racking in the fuse; - Figure 3 is an identical view to Figure 2 after plugging in the fuse; - Figure 4 shows an elevational view of the clamp according to Figure 1; - Figure 5 shows a perspective view of another clamp with multiple contacts;

  - Figure 6 is a side view of Figure 5.

  Description of a preferred embodiment

  With reference to FIGS. 1 to 4, a connection clamp 10 of a high-caliber fuse 12, is composed of two elongated contact elements 14, 16, arranged opposite one another in symmetry with respect to the plane longitudinal median. The posterior ends of the two contact elements 14, 16 are secured to an attachment pad 18 of a

starting conductor 20.

  The contact elements 14, 16 have identical structures constituted by aluminum bars, advantageously produced by spinning, and subject to a

  nickel or silver based surface treatment.

  Each contact element 14, 16 of rectangular section, has a substantially convex and grooved contact surface 22, disposed in the internal middle part between a stop 24, 25 and a stud 26, 27, the latter constituting a spark gap for the element contact 14 on the left, and a spark gap for the contact element 16 on the right. The anterior end part above the stud 16, is capped by a yoke 28 made of insulating material, for example based on polyamide, serving as a snap-fastening member at the entrance to the connection clamp. The internal faces of the two yokes 28 are inclined relative to the

  longitudinal direction so as to constitute a convergent at the entry of the clamp 10.

  The grooves on the contact surface 22 promote electrical contact, and reduce the insertion and extraction effort of the knife-shaped terminal 29 of the fuse 12. The convex shape of the two contact surfaces 22 makes it possible to absorb any defect

  of alignment of the terminal 29 with respect to the clamp 10.

  The external lateral face of each contact element 14, 16 is provided with a series of heat dissipation fins, extending opposite the stud 26, 27 between the yoke 28 and a groove 32 in which are housed end to end the ends of two ends of contact pressure springs 34. Each spring has a U shape extended by two end tabs bent at right angles. The presence of this double spring guarantees a distribution

  uniform contact pressure of the clamp 10 on the terminal 29 in the inserted position.

  The rear part of each contact element 14, 16 is provided with a substantially curved base 36, and equipped with a tapped hole in which is screwed at least one screw 38 allowing the mounting of the contact elements 14, 16 on the track fixing 18 of the conductor 20. A compression spring 40 is interposed between the pad 18 and the head of each screw 38, so as to allow a slight movement of separation of the contact elements 14, 16 during entry or the output of the terminal 29. The coming into engagement of the respective stops 24, 25 prevents the contact elements 14, 16 from coming closer to the input of the clamp 10, and permanently maintains a transverse gap 42 between the pads 26, 27 The stud 26 constituting the spark gap on the contact element 14 on the left, is made of copper, or of a tellurium copper alloy, intended to resist welding solder. The other stud 27 constituting the counter-spark gap of the second contact element 16 is advantageously made of insulating material, for example polyamide, so as to permanently transfer the arc zone onto the stud 26, which plays the role of contact arc. It's clear that

  the stud 27 could also be conductive like the stud 26.

  The operation of the connection clamp 10 according to FIGS. 1 to 4 is as follows: In the withdrawn position of the clamp 10 illustrated in FIGS. 1 and 4, the spacing between the studs 26, 27 is less than the thickness of the terminal 29, and at the interval formed between the two contact surfaces 22. The double spring 34 and the coming into engagement of the stops 24, maintain the two contact surfaces 22 substantially parallel to one another, and perpendicular to the attachment pad 18 The studs 26, 27 remain permanently projecting

  relative to the converging of the yokes 28.

  In the plugged-in position (FIG. 3), the terminal 29 of the fuse 12 is inserted between the two contact surfaces 22, and the double spring 34 ensures a uniform distribution of the contact pressure. The mechanical reaction generated during the insertion phase of the terminal 29 causes a slight movement of separation of the contact elements 14, 16 following the

  pivoting in the opposite direction of the bases 36 on the attachment range 18 of the conductor 20.

  The current from fuse 12 is split in two in contact elements 14, 16, and the corresponding Joule effect is evacuated by fins 30 for heat dissipation. The presence of the insulating yokes 28 at the entry of the clamp 10 allows an abrupt engagement under tension, the arc occurring exclusively between the stud 26 and the terminal 29 without migration on the

  contact elements 14, 16 made of aluminum.

  When racking-out occurs, in particular for the replacement of a defective fuse, the removal of terminal 29 in the direction of arrow F (Figure 3) causes the contact surfaces 22 to come together as soon as terminal 29 leaves studs 26, 27 If the maneuver is

  operated under voltage, the arc is established only on the stud 26 serving as arcing contact.

  FIGS. 5 and 6 show a multiple contact clamp 100, in which each contact element 114, 116 is divided into two parts 114a, 114b; 116a, 116b adjacent, separated from each other by an interval 142 extending perpendicular to the interval 42. It is clear that the contact elements 114, 116 could be subdivided into three or four parts

  equal depending on the size of the switchgear, and the maximum temperature rise allowed.

Claims (10)

  1. Connection clamp for a terminal (29) of electrical equipment, comprising: - at least two contact elements (14, 16; 114, 116) symmetrical intended to be connected to said terminal, and having main contacts for the passage of the nominal current, and of the arcing contacts playing the role of spark gap, - and elastic means for ensuring a contact pressure on the terminal (29), characterized in that the two contact elements (14, 16 ; 114, 116) are constituted by aluminum bars, each comprising: - a convex contact surface (22) disposed in the internal middle part between the fixing base (36) at the rear part, and a stud (26 , 27) protruding playing the role of spark gap, - a yoke (28) of insulating material covering the anterior part above the stud (26, 27) to form a snap engagement member at the entrance of the clamp ( 10,), - and heat dissipation fins (30) distributed over the external surface rne to the opposite of the stud (26, 27).   2. Connection clamp according to claim 1, characterized in that the internal face of the yoke (28) is inclined relative to the longitudinal direction so as to   constitute a convergent with the yoke of the other contact element.   3. Connection clamp according to claim 1, characterized in that each contact element (14, 16; 114, 116) has a rectangular section, and comprises on the external surface a groove (32) located between the fins (30) and the mounting base   (36) for anchoring a double spring (34).   4. Connection clamp according to claim 1, characterized in that the contact surface (22) is provided with grooves to promote electrical contact with the knife-shaped terminal (29).   5. Connection clamp according to claim 1, characterized in that the fixing base (36) of each contact element (14, 16; 114, 116) is curved with respect to the plane area (18) of the conductor. start (20) to authorize spreading and closing movements during the racking-in and racking-out phases of the terminal (29). 6. Connection clamp according to claim 5, characterized in that the two contact elements (14, 16; 114, 116) are provided with stops (24, 25) arranged under the contact surfaces (22) and coming into engagement with each other to define a first   transverse gap (42) between the studs (26, 27).   7. Connection clamp according to claim 5 or 6, characterized in that the curved base (36) is secured to the fixing range (18) by means of screws (38) with interposition of compression springs (40) allowing a slight pivoting movement of the two contact elements (14, 16; 114, 116) during racking-in, or removal.   8. Connection clamp according to any one of the preceding claims,   characterized in that one of the studs (26) is made of copper or a copper alloy, while the other stud (27) is made of insulating material, so as to transfer the area   arcing on the first stud (26) playing the role of arcing contact.   9. Connection clamp according to claim 3, characterized in that the double spring (34) comprises two U-shaped springs each having two end tabs folded in square.   10. Connection clamp according to any one of the preceding claims,   characterized in that each contact element (114, 116) is divided into at least two adjacent parts (114a, 114b; 116a, 116b) separated from one another by a   second interval (142) extending perpendicular to the first interval (42).