US3127490A

US3127490A - Extinguishing device for electrical arcs

Info

Publication number: US3127490A
Application number: US121432A
Authority: US
Inventors: Latour Andre
Original assignee: Merlin Gerin SA
Current assignee: Merlin Gerin SA
Priority date: 1960-07-01
Filing date: 1961-07-03
Publication date: 1964-03-31
Anticipated expiration: 1981-03-31
Also published as: DE1139176B; GB939710A; FR1269356A; CH370138A; BE605410A

Description

United States Patent Ofiice 3,127,490 Patented Mar; 31, '1964 3,127,490 EXTINGUISHING DEVICE FOR ELECTRICAL ARCS Andr Latour, Grenoble, France, assignor to Etablissemeats Merlin & Gerin, S.A., Grenoble, France Filed July 3, 1961, Ser. No. 121,432 Claims priority, application France July 1, 1960 4 Claims. (Cl. 200144) This invention relates to extinguishing devices for electrical arcs drawn between separable contact members located in an arc formation chamber of an electrical circuit breaker, and more particularly to extinguishing devices of this type having an arc extinguishing chamber which comprises a set of at least two parallel plates of insulating material spaced apart from one another and disposed transversely of the direction of separation of the contacts in the initial direction of the arc.

The spaced parallel plates of insulating material define narrow arc separating or extinguishing chambers and are provided with conductive members to form branches which are generally V- or U-shaped and whose legs or wings embrace or straddle the individual insulating plates. Conductive members of this general type and configuration are disclosed in my U.S. Patent No. 2,707,739. The web portion of the V- or U-shaped conductive member straddles the side or edge of an insulating plate while the legs or wings of the conductive member extend along the faces of the insulating plates in a substantially parallel arrangement. The opposed parallel wings of each conductive member are slightly offset or diverging relative to each other. The insulating plates are provided with marginal spacing members or ribs by means of which individual plates may be stacked together to form a set. These marginal ribs provide also a proper spacing of the plates to accommodate the conductive elements in the spaces between adjacent plates and also define indlvidual chambers into which the initial are or are portions are drawn. The are travels along the inner edges of the V-shaped conductive members and is caused to form peripherally expanding loops in the spaces between the lates.

p It is known that during the development or expansion of the arcs an arcing over is occasionally produced between neighboring electrodes or conductive members, particularly when the voltage of the arc reaches a certain magnitude. In known arrangements of this type these arcing phenomena take place at the base or the web portion of the conductive member which interconnects the two legs or wings of each conductive member. As the web portions of the conductive members engage the lower edge of the insulating plates, this arcing occurs therefore almost outside the arc extinguishing chambers.

According to the invention the conductive members are connected to the insulating plates at two different horizontal levels and in a set of a plurality of consecutively stacked insulating plates. A plate having a conductive member disposed at a different level is always interposed between two plates carrying a conductive member at the same level.

According to an additional feature of the present invention the conductive members which in the embodiment shown and described herein are connected at the lower edge of the insulating plate or which form the lower level conductive members have such a form that the point at which the electrical rigidity between two successive conductive members is at a minimum, is not located at the base of the insulating plates but on the inside of the extinguishing chambers. The path of the current which passes through the conductive members at the time the arcing over takes place assures, due to the formation of spiral convolutions, an electrodynamic effect which is already intense and which is favorable for driving the initial are or are portions upwardly into the arc extinguishing chambers. It is therefore an object of the present invention to provide an arc extinguishing device in which the arcing over occuring between adjacent conductive members is moved upwardly into the interior of the extinguishing ci ambers.

It is another object of the present invention to provide an arc extinguishing device in which the conductive members connected to the insulating plates are arranged to produce an electrodynamic effect on the arcing over between adjacent conductive members and thereby drive the initial arcs eifectively upward into the extinguishing chambers where they are extended and extinguished in a quick and efficient manner.

These and other objects of the invention will become apparent upon reading the specific description in connection with the accompanying drawing which forms part of the specification and which by way of example illus trates an embodiment of the invention. The embodiments disclosed in the drawing and described in the specification are to be understood to serve only to explain the invention but not to limit its scope. Other embodiments incorporating the principle underlying the invention are feasible without departing from the spirit and scope of the appended claims. In the drawings:

FIGURE 1 is a front view in elevation of an insulating plate provided with a conductive member connected with its base or web portion at a lower level along the lower edge of the insulating plate.

FIGURE 2 shows a front view in elevation of an in sulating plate modified relative to the insulating plate shown in FIG. 1 in which the base or web portion of the conductive member is located at a higher level upwardly from the lower edge of the insulating plate.

FIG. 3 shows a front view of the lower part of a subassembly of the extinguishing device of the invention comprising a set of three stacked insulating plates.

FIG. 4 shows a cross-section through the axis of the arc extinguishing device along line 4-4 of FIG. 3.

Referring now more particularly to the drawings the arc extinguishing device which consists of a set of stacked insulating plates of two types designated by numerals 1 and 2 are disposed in such a manner relative to each other within the same set that each plate of one type is located between two plates of the other type. Each of the insulating plates is provided in a known manner with a peripheral flange or rib 11 which constitutes the spacing means between successive insulating plates and which limits the extension of the loops formed by the initial arcs of the arc extinguishing operation. The spaced insulating plates define the arc extinguishing chamber into which the initial arcs are drawn and extinguished. The spacing ribs 11 are provided with a groove 12 in which a sealing member is arranged to thereby provide a tight seal between adjacent insulating plates. Vertical parallel ribs 13 are provided on the upper part of the insulating plates and define discharge or exhaust channels for the ionized gases which develop during the circuit breaking and are extinguishing operation. The upper part of the insulating plate is shown and described merely for the purpose of explanation and does not form a part of the present invention. The lower edge of insulating plate 1 is embraced or straddled by conductive member 14 which comprises two legs or

wings

15 and 16 located on opposite faces of the insulating plate. The two wings are interconnected by a web portion 17 which engages a slightly cutout section along the lower edge of the insulating plate. The conductive members 14 which are connected at the lower edge of the associated insulating plate are particularly distinctive in that each wing has an inwardly extending curvilinear recess 18.

Theinsulating plates 2 are also provided with conductive members designated by reference numeral 19 and comprising each two legs or

wings

20 and 21 located along each face of the insulating plate. The two wings are interconnected by a base or web portion 22 which engages the insulating plate at the top of a substantially triangular notch 23 formed in the insulating plate 2. The conductive members 14 and 19 extend into close proximity of the vertical ribs 13 and as the conductive members 19 start only at the top of the triangular notch in the insulating plates they are not as long as conductive members 14 which start at the lower edge of the associated insulating plates.

Referring to FIGS. 1 and 2 of they drawing it will be observed that the point of two successive conductive members located in the same extinguishingchamber at which the spacing or interval is at a minimum is located at 24 with reference to Wings 16 and 2t) and at 25 with reference to

wings

15 and 25, and at the levels'24 and 25 the dielectric resistance of the conductive members is at a minimum and it is there that the arcing over between successive conductive members takes place. The tendency to are over is sometimes increased and accelerated by the presence of ionized gases which are produced by the initial arc. The path of the lines of current in the conductive members have the form of spiral convolutions and several such lines of current interconnected by arcing over constitute a solenoid which has the efiect of urging or driving the arcs upwardly into the extinguishing chambers. The curvilinear recesses 18 provided in conductive members 14 contribute also effectively to the formation of such solenoid effects. The vertically upward displacement of the conductive members to the top of the notched portions. provide an additional upward pull on the initial arcs.

What is claimed is:

1. In a device for extinguishing an electric arc drawn between separable contact members, first insulating plates having on each of two opposed faces conductive means connected to each other at the lower end of said plates and extending upwardly to a predetermined level, second insulating plates having a notched portion extending upwardly from the lower edge of said second plates, each second plate being disposed between two adjacent first plates, said first and said second plates being disposed face to face and transversely of the established arc, conductive members connected to said second insulating plates and extending upwardly from the inner end of the notched portions and spacing means between two successive insulating plates forspacing said plates relative to each other and forming an arc chute.

2. In a device for extinguishing an electric arc to be drawn between separable contact members, first insulating plates having on each of two opposed faces conductive means connected to each other at the lower end of said plates and extending upwardly to a predetermined level, second insulating plates having a notched portion extending upwardly from the lower edge thereof, each second plate being disposed between two adjacent first plates, said first and said second plates being disposed face to face and transversely of the established arc, an upwardly extending conductive member connected to said notched insulating plates at the top edge of said notched portions, spacing members between adjacent insulating plates to form a chambered space between said plates, said conductive members on said first insulating plates having a recess surrounding the base portion of the conductive member of said second insulating plates to provide a point of least dielectric resistance between the conductive means in each space between adjacent plates and located above the base portion of the conductive members of said second insulating plates to draw the are upwardly between said insulating plates.

3. A device as defined in claim 2 wherein theconductive members of said first insulating plates are longer than the conductive members of said second insulating plates so as to extend upwardly along the faces of said plates substantially even with the conductive members of said second insulating plates.

4. In an arc extinction chamber comprising a first plurality of parallel plates of insulating material disposed transversely of the direction of the initial arc to be extinguished, conductive means on each of two opposed faces of each plate connected to each other at the lower edge of said plates, said conductive means comprising branches extending upwardly from the base of the plates to which they are connected, second plates of insulating material having conductive means comprising electrically connected branches extending upwardly on the opposed faces of each second plate, each second plate being disposed between two adjacent first named plates, spacing means between two successive insulating plates forming wall means to provide a chambered space between said plates, said conductive means of said first and second plates dividing said initial are into individual portions drawn into the spaces between two successive plates to turn said portions into a position substantially parallel to said plates causing said portions to expand until extinction, the lower portions of the conducting means of each second plate being disposed a distance apart above the level of the bases of said first named plates, each pair of branches in each of said chambered spaces providing a point of minimum dielectric resistance, said second plates having a notched portion extending upwardly from the lower edge of said second plates, said branches of each of said second plates being connected to each other at the inner end of the notched portions,the apex of the notched portions confronting a point located underneath said point of minimum dielectric resistance.

References Cited in the file of this patent UNITED STATES PATENTS 2,750,476 Latour June 12, 1956 2,783,336 Latour Feb. 26, 1957 2,847,540 Pfeiffer et al Aug. 12, 1958 2,868,927 Wood Jan. 13, 1959 FOREIGN PATENTS 715,121 Great Britain Sept. 8, 1954

Claims

1. IN A DEVICE FOR EXTINGUISHING AN ELECTRIC ARC DRAWN BETWEEN SEPARABLE CONTACT MEMBERS, FIRST INSULATING PLATES HAVING ON EACH OF TWO OPPOSED FACES CONDUCTIVE MEANS CONNECTED TO EACH OTHER AT THE LOWER END OF SAID PLATES AND EXTENDING UPWARDLY TO A PREDETERMINED LEVEL, SECOND INSULATING PLATES HAVING A NOTCHED PORTION EXTENDING UPWARDLY FROM THE LOWER EDGE OF SAID SECOND PLATES, EACH SECOND PLATE BEING DISPOSED BETWEEN TWO ADJACENT FIRST PLATES, SAID FIRST AND SAID SECOND PLATES BEING DISPOSED FACE TO FACE AND TRANSVERSELY OF THE ESTABLISHED ARC, CONDUCTIVE MEMBER CONNECTED TO SAID SECOND INSULATING PLATES AND EXTENDING UPWARDLY FROM THE INNER END OF THE NOTCHED PORTIONS AND SPACING MEANS BETWEEN TWO SUCCESSIVE IN-