FR2575327A1 - CONTACT DEVICE FOR LIMITING ARC LENGTH IN A LEAK CURRENT CIRCUIT BREAKER - Google Patents

Abstract

CONTACT DEVICE FOR LIMITING ARC LENGTH IN LEAKAGE CURRENT CIRCUIT BREAKER. THE MOBILE ELEMENT 1 AND THE FIXED CONTACT ELEMENT 2 ARE EACH EXTENDED, BEYOND THE CONTACT PLOTS 3, 4, BY A BLADE 5, 6 WHICH, UNDER THE EFFECT OF THE BLOWING, CONDUCTS THE ARC SHAPED DURING OPENING OF THE CIRCUIT BREAKER. THE DISTANCE A BETWEEN THE ENDS OF BLADES 5, 6, IN THE OPEN POSITION, CORRESPONDS TO THE REGULATORY REQUIREMENTS CONCERNING THE MINIMUM PATH IN THE AIR. WALL 9 IS INSULATING. APPLICATION: REDUCTION OF WEAR OF PLATES 3, 4 OF A CURRENT CUTTING OR SWITCHING DEVICE.

Description

The invention relates to raising the power of cou-

  pure switches, and more particularly

  safety switches or circuit-breakers and

  by a special embodiment of the contact device. More particularly, the invention relates to a contact device intended to limit the length of the arc that may appear in a fault current circuit breaker, comprising at least one movable contact element or blade and a fixed contact element or blade, each of these blades

  being extended by a conductive blade of the bow.

  In the case of safety switches, or

  With fault-current circuit breakers, it must be taken into account that fault currents and short circuits can occur simultaneously. If a strong short-circuit current passes through the contact elements, which are just opening, the fault current circuit breaker, does so

  that this circuit breaker is not damaged depends very

its cutting power.

  In the equipment of interruption of the current

  (switches, circuit breakers, circuit breakers or even

  it is known (DE-C-2 429 983) to blow the arc away from the contact elements via horn-shaped extensions. In the case of alternating current, the arc continues to burn at the ends of this horn and it goes out as soon as the current has passed through a zero value. In such an ignition of the arc, the elements

  in contact with a low wear. Because of

  its the relatively long length of the bow, it is

  also produces a work of the corresponding magnitude arc.

  The high overpressure which then occurs forces the gases of the arc in undesired directions, which can create transverse short circuits between the poles and / or short circuits between a pole and the metal support possibly present and on which breaker or

switch is mounted.

  - In a known circuit breaker of this type (patent DE-

  C-2739632), the contact device is equipped with a blowing chamber, in which the arc is blown to reduce its gas pressure and to cool it. Such a device is, at the technical or industrial scale,

  relatively more complicated and / or expensive than the one

  both the horns or the horn of passage of the bow. Finally, it is still possible to limit the distance between the fixed and movable contact elements, without arc horn, to the minimum path prescribed in the air, which is, for example, three millimeters. This minimizes the gas evolution by the arc and the overpressure of the gases which

results.

  In the absence of a blowing effect, the arc continues

  bare to burn between the contact elements until

  the current passes through a null value, which causes

  vitally a clear wear of the contact elements.

  The aim of the invention is to increase the breaking capacity

  without the use of additional organs or devices

  such as, for example, smothering or

  ting and avoiding increased wear of the contact elements. To solve this problem, the contact device of the fault current circuit breaker is made in such a way that, on the one hand, the length of the arc between the contact elements is as short as possible and that, on the other hand, the wear on the contact elements is as small as possible. We solve this problem because

  that the two arc conduction blades of the con-

  In the open or cut position, the switch and cut-off have a mutual distance which corresponds to the minimum path in the air required according to the relevant requirements.

  (VDE: Union of German Electrotechnicians, and EEC: Com-

  International Regulatory Mission with a view to

  electrical equipment).

  Thanks to the conductive blades of the bow, which always have the form of extensions of the elements or blades

  of contact, we obtain that the arc appearing during the

  contacts are guided, under the effect of blowing, on these arc guiding blades. Since the distance between the conductive blades of the arc corresponds to the aforementioned minimum path in the air, the arc can not necessarily be amplified until its extinction when the current passes through a zero value and therefore , its intensity can not also increase. The presence of insulating walls near the ends of the conductive blades of the arc makes it possible to obtain that this arc can not spread out. In an advantageous embodiment and to further limit the length of the arc to the minimum path in the air, this arc can be subdivided into two partial arcs. This is achieved by placing a plate of conductive arc sheet

  in order to arrange this plate between the two ends

  mites conductive blades of the arc.

  Other features of the invention stand out

  of the following more detailed description of illustrative examples

  and in no way limiting, with reference to the attached drawing in which:

  FIG. 1 schematically represents the device

  contact circuit intended in particular for a safety switch or fault current circuit breaker with a single break, and FIG. 2 shows a variant of the embodiment

  according to Figure 1 and which has an additional plate

  arc conducting sheets placed between the ends

  the conductive lamellae of the arc.

  The contact device according to the invention is

  devices known by a special form of

  realization of the two elements or blades 1 and 2 of contact.

  The moving contact element 1 must, during a cutting process, make an opening movement in the direction indicated by the arrow F. When the opening is complete, the contact element 1 has reached the position

indicated by broken line.

  The movable element 1 of contact and the fixed element 2 of contact are extended, beyond their studs 3 and

  4 contact by laminations 5 and 6 conductors of the arc.

  These blades 5 and 6 are configured so that the distance

  "A" corresponds to the cut-off or opening position of the -

  contact device, at the aforementioned minimal path in the air.

  Due to the blowing effect, the arc that occurs during a cut is moving quickly contact pads 3 and 4 on the blades 5 and 6 conducting the arc. The distance "A" thus provided in the contact device

  also imposes a limitation, at this distance, of the length

  the bow. The propagation or spreading of the arc at the ends of the arc-conducting plates 5 and 6 is limited by the presence of a wall 9 made of an insulating material. These measures make it possible, at the cost of a relatively modest complication and cost, to achieve the objects of the invention, namely to reduce the pressure of the

  gas corresponding to the arc and obtain only extreme wear

  limited contact pads 3 and 4.

  Figure 2 shows a variant of the contact device according to the invention, shown in Figure 1. It is recognized in Figure 2 the blades 5 and 7 conductors of the arc. The blade 5 corresponds to that of FIG. 1, whereas the blade 7, extending the element or blade 2, is slightly modified with respect to the blade 6 of FIG. 1, and there exist between the ends of the blades 5 and 7 a

  plate 8 of conductive arc sheet. The sum (B + C) of the dis-

  B (between one end of the contact element 1, in the open position, and the wafer 8) and C (between the end of the blade 7 and an end of the wafer 8) corresponds, in this case also , at the minimum path in the air. The mode of action and effect of this variant is the same as for the device shown in Figure 1. During the cutting process, the arc is directed contact pads 3 and 4 to the blades 5 and 7 of conduction of this arc and, in the variant according to FIG. 2, the arc is

subdivided into two partial arcs.

  It goes without saying that, without departing from the scope of the invention,

  many changes can be made

  to the contact device described and shown.

Claims (3)

  1. A contact device for limiting the length of an arc in a fault current circuit breaker comprising at least one movable contact element and a fixed contact element, each of which is extended by an arc conducting plate, characterized in that the two arc-conducting blades (5 and 6) extending the elements (1   and 2) of contact present, in open or   pure, a mutual distance (A) which corresponds to the minimum path in air according to the relevant requirements of the German Electricians Union and the International Regulatory Commission for approval Electrical Equipment.   2. Contact device according to the claim   1, characterized in that between the blades (5 and 7) conducting   arc plates is placed a plate (8) of conductive sheet   trice whose ends have, in relation to   ends of the arc-conducting blades (5 and 7),   (B and C) such that the sum (B + C) corresponds to minimum path required in the air.   3. Contact device according to one of the claims   cations 1 and 2, characterized in that the propagation and spreading of the arc are prevented at the ends of the conductive blades of this arc by the presence of a wall (9) insulating.