US2707739A - Extinguishing device for electrical arcs - Google Patents

Description

May 3, 1955 A. LATOUR EXTINGUISHING DEVICE FOR ELECTRICAL ARCS 2 Sheets-Sheet 1 Filed June 8, 1955 W H 3 5 M g R R i 0 I 2 F 2 M W Gum 3 E T 7 M. 2 W A M AI 2 I L 6 M e 7 n A Q C: a N 1 m 1 4 J 6 2 3 A V 2 o 7 Ill. 5 2 m 2 2 AH orn e y May 3, 1955 A. LATOUR EXTINGUISHING DEVICE FOR ELECTRICAL ARCS 2 Sheets-Sheet 2 Filed June 8, 1855 INVENTOR.

Andr ATQUR Aitorn e y BY Ka/Mh United States Patent 0 2,707,730 EXTINGUISHING DEVICE? FOR ELECTRICAL ARC Andr Latour, Grenoble, France Application June 8, 1953, Serial No. 360,300 4 Claims. (Cl. 200-144) The invention refers to circuit breakers of the type in which the arc is drawn between separable contact members contained in an arc formation chamber provided with means for expanding the are into and within an arc extinguishing chamber contiguous with the arc formation chamber.

More particularly, the invention relates to an are extinguishing chamber which includes a set of at least two parallel plates of insulating material, spaced apart from one another to leave a narrow space therebetween and disposed transversely of the direction of separation of the contacts or the initial direction of the arc. Conductive elements or paths are provided on the faces of the plates for drawing the are as a whole or in sections into the space or spaces between the plates and turn the are round, or the arc sections round, into a position substantially parallel to the plates. The conductive elements of the space diverge relatively to each other and terminate Within the space at intermediate points thereof. The are or its sections are thus caused to form a peripherally expanding curved path within the space or spaces.

The present invention has for its object arrangements of the conductive elements and of the insulating plates carrying them, which will allow the arc loops to expand within the spaces between juxtaposed, consecutive plates starting from their roots to nearly a closed annular form of a multiple of the length of the opening angle between the electrodes from which the loops start to develop and expand.

More particularly, the invention is thus concerned with a development of the spatial conditions of the loop chambers between adjacent insulating plates, of the configuration of the conductive elements and also of this configuration relatively to the plates, so as to make possible for the loops to expand within these chambers or spaces from their roots to curves of nearly closed annular form and of great length or arcus, and of generally circular or oblong form.

This formation of the loops within the spaces or between each pair of juxtaposed, consecutive plates to curves of great length or arcus, and of generally circular or oblong form, will result in highly favorable de-ionizing conditions of the chambers and to rapid extinction of the loop or loops Within the chamber or chambers.

In my copending U. S. patent application Ser. No. 360,299 filed on even day herewith, I have disclosed means which allow the arc loop within the space between juxtaposed, consecutive plates to expand to a nearly closed annular curve of great length or arcus. This end is achieved when the part of the space or chamber above the conductive elements is so dimensioned that when the geometrical center of this part, against which the arc develops, is joined by imaginary radii to the nearest points or lateral upmost tips of the diverging edges, these radii form an angle of an arcus of at most 1r, such as 1r/2, or preferably of -1r/4 or even less. When the roots of the loop have travelled to these points or tips, the loop may develop within the space thus to a curve 2,707,739 Patented May 3, 1955 of an arcus of at least 1r or further to a nearly closed annular curve of an arcus greater than 3/27r or equal to or greater than 7/41r, allowing the shape of the loop to be almost circular.

It is now an object of the present invention to give to the loop still more play to develop freely when, with the roots of the loop more or less stationary at the outmost ends of the electrodes, deep within the loop chamber, the loop would reach a length near the length of the perimeter of the loop chamber. In accordance with the invention the conductive elements which have free top edges for the roots of the are or of the arc sections to travel thereon during their development are additionally provided with free lateral edges which beyond the upmost lateral tips of the diverging edges extend downwards inside of the spaces. These downwardly extended lateral edges thus provide a supplementary path for the roots of the loops, when the loop approaches the lateral walls of the loop chamber and is compelled, while expanding through its electrodynamic forces, to take an oblong form and on further expansion to descend with its roots downward along these downwardly extended lateral edges. The peripheral length of the loop within the loop chamber thus is greatly extended.

When the plates are provided with marginal spacing members which, when the plates are stacked together, provide the spaces between the plates of the desired widths and confine the so formed chambers laterally, the descending edges will be arranged so as to be substantially parallel to the adjacent lateral walls of the loop chamber, sufiicient space being left between the descending paths for the roots and the adjacent lateral walls for part of the loop to lodge therein. In this manner, the roots are no longer held stationary at the extreme upper tips of the electrodes, and, simultaneously, the length of the loop is augmented by the heights or nearly the heights of the descending paths.

This feature of the invention will be advantageously realized when the conductive elements comprise two symmetric wings, each generally of sector form, with a bridge integrally connecting them and bent to straddle the lower edge of the insulating plate. The upper arcuate edges of both wings diverge relatively to each other in V-form. The radial edges of each sector are perpendicular to each other, one of these edges being extended in vertical direction, the other generally in lateral direction.

The vertical edges serve as the descending paths for the downward travel of the loop roots whereas by means of the laterally extended edges the conductive elements may be seated on correspondingly formed ledges at the lower edges of the plates.

These and other objects and features of the invention will become apparent as the specific description of the invention proceeds in which the invention will be described with reference to the accompanying drawings which form part of this specification and which by way of example illustrate an embodiment of the invention. These drawings are to be understood explicative of the invention but not limitative of its scope. Other embodiments incorporating the principle underlying my invention are feasible without departing from the spirit and ambit of my appended claims.

In the drawings:

Fig. l is, on a reduced scale and rather diagrammiatically, a longitudinal section, partly along the middle plane, partly in front thereof, of an embodiment of a circuit breaker provided with are subdividing conductive elements with their insulating plates in accordance with the invention;

Fig. 2 is a front view and Fig. 3 is a side view of the conductive element of the invention;

Fig. 4 is a front view of an insulating plate furnished with a conductive element of the invention;

Fig. 5 is a cross section along line 55-0f Fig. 4;

Fig. 6- is an elevational section along line 66 of Fig. 4;

Fig. 7 is across section along line 7-7 of Fig. 4; and

Fig. 8 is an' exploded, partly fractional view of two consecutive insulating plates furnished with the conductiveelement of the invention.

In the circuit breaker of Fig. l, the fixed and movable contacts are respectively represented by 11 and 12; The two contacts are located inside an arc formation chamber 13,,not shownihereindetail.

In order to develop the ignited arc more rapidly than the movement of the movable contact would allow, an arcing contact 15 may be placed within the arc formation chamber of insulating material. The arcing contact may be connected to the movable contact 12'. A blow out coil 16 may also be employed which may be connected to one of the terminals 17 of the circuit breaker. The coil 16 acts upon the magnetic core 1 8 the legs 19 of which enclose the arc formation chamber.

In the upper part of the circuit breaker, above the arc formation chamber, there is arranged a set of plates 21, transversely of the contacts 11, 12 and 15, and in a space which constitutes the arc extinguishing chamber. The plates 21 are of insulating material and carry the conductive elements.

The conductive elements, as illustrated in Figs. 2 and 33,, comprise two symmetric wings 23 and 24, generally of sector form. A bridge connects the two wings and is'bent over a cut out 22 of the insulating plate 21, Figs.

4, 5, 6 and 8, so that the conductive element with its wings straddles the insulatingplate, one wing 23 thus being in front, the other 24 in' the rear of the appertaining insulating plate 21, as Figs. 4, 5, 6 and 8 illustrated.

The wings, at their inmost edges, where the arc loops start to develop, may be rectilinear as between 26 and 27 and their edges are then curved, as at 28, so that conductive elements or wings on opposite faces of each plate and thus opposite elements in each space, between juxtaposed, consecutive. plates of the set, diverge with their top edges. 23 in V-forrn relatively to each other.

In this way, the arc is drawn into the spaces between the plates, is turned round into a position parallel to the plates. Travelling along the curved edges of the wings, the arc is caused to form peripherally expanding loops, or convolutions of a helix, in the spaces between successive furnishedplates, successive positions of the loops being indicated in Fig. 4 by the broken lines a, b, c, d, e, f, and g.

The outer or lateral edges 60, 61' of the Wings beyond their upmost lateral tips A, B are extended freely downwards inside the spaces between consecutive furnished plates as also shown' between the points 29, 30, Fig. 4, at a distance from the lateral spacing members or ribs 31, 32 by means of which the plates 21 may be stacked together to a set, Fig. 1. These lateral ribs or spacing members thus provide for a proper spacing of the plates to accommodate in the spaces therebetween the conductive elements and allow the arc loops to develop and expand, curves 0, b, c, d, and e, and after full expansion within the upper part of the space to descend with the roots from the upmost tips A, B laterally along the downward extended edges 60, 61, between these edges and the lateral spacing members 31, 32 as curves 1 and g illustrate, the peripheral lengths of the loops thus being augmented;

As Fig. 4 illustrates, one wing 23 of the conductive element isin front of the insulating plate 21 and is seated with its lower edge 62' on a ledge 37 of the appertaining insulating plate 21 whereas the other wing 24, to the rear of the insulating plate 21' is seated on a ledge 4 38 of the preceding insulating plate. The radial sector edges 60 and 62, on the one hand, and 61 and 63, on the other hand, subtending the arcuate edges 28, edges 62, 63 extended in the lateral direction and edges 60, 61 in the vertical direction, thus are substantially perpendicular to each other.

The conductive element with its wings 23 and 24 from the lower edges 62, 63 of the wings is extended upwards, each wing into its space or chamber between the plates and terminating in the lower part thereof.

The part of the space above the conductive element or the part of this space left free for the development and expansion of the loop, as described in my aforesaid U. S. patent application, may be so dimensioned that the imaginary radii from the geometric center C of this part, that is of the part 33, 34, 35 and 36, to the lateral tips A, B of the diverging elements or wings 23, 24 form an angle less than 1r/2, in the instance illustrated about 1r/4, or even a still smaller angle. Accordingly, when the roots of the loops have travelled to the tips A, B, the loops may develop within the space to a nearly closed annular form of an arcus greater than 3'/21r, as the curves 1 and g indicate.

In order to hold the transverse dimensions of the loop chamber in certain limits, the distance between the lateral spacing members or walls 31, 32 will be made narrower than the width a freely expanding loop would occupy so that the loop is compelled to take an oblong form along the lateral walls of the chamber, as likewise indicated by'the curves f and g;

The heights of the spacing members, as a rule, will be substantially equal to the thickness of the conductive element, as Figs. 1, 3 and 6 illustrate. The plates, when stacked together, will thus hold the conductive element on the foot ledges 37, 38 against displacement.

In order to produce an intimate contact between loop and plate, the clearance between adjacent plates may be reduced. enhance the cooling efiect of the insulating plates, a portion 39 of the space for developing and expanding the arc, Figs. 4, 6, 7, may be raised above the remaining surface of the plate 21, thus leaving a narrow clearance 40 between boss 39 and the consecutive plate 21.

To a similar purpose the plates may be provided at their top part with a flame-arrester 41 of insulating material. This flame-arrester is extended between the lateral spacing members 31, 32 and may be held in position by supplemental, intermediate spacing members 42,- 43.

This flame-arrester is of a thickness so as to leave narrow clearances 44, 45 between arrester plate 41 and the appertaining plate 21 and between arrester plate and the juxtaposed, consecutive insulating plate, respectively. The are, if not priorly extinguished, will be attenuated and effectively cooled and will thus be finally extinguished and prevented from issuing as a flame fromthe top of the set of the plates.

In order to make possible a further extension of the length of the loop' within the loop chamber, the plates may be provided with obstacles, such as lateral, internally projecting points 48 at one or both of the lateral walls 31 or 32, points 49 at the internal ends of the spacing members 42, 43, which points compel the arc loops to take a meandrous path, as illustrated by curve g.

I claim:

1. In a device for extinguishing an electric arc to be drawn. between separable contact members, a set of at least two plates of insulating material disposed transversely of the direction of separation of said contact members, wall members of insulating material closinglaterally the spaces between adjacent ones of said insulating plates, said plates having upon their faces conductive elements straddling the lower edges thereof, said conductive elements having, deep within the spaces between said plates, free top edges for the roots of the arc to travel thereon, conductive elements on opposite In order thus to attenuate the loop and e, rowan faces of each plate and opposite elements in each space between juxtaposed consecutive plates being disposed so as to diverge with their top edges in \.-form relatively to each other; thereby to draw the are into the spaces between said plates, turn it round into a position substantially parallel to said plates to form peripherally expanding loops within said spaces; the lateral edges of said elements beyond the upmost lateral tips of said diverging edges being extended freely downwards inside each of said spaces, spaced a distance apart from said lateral wall members and generally following the downward direction of the same; thereby to allow the roots of the loops to descend from said upmost tips laterally downward along said downward extended edges and augment the peripheral length of the loop.

2. In a device for extinguishing an electric arc to be drawn between separable contact members, a set of at least two plates of insulating material disposed trans versely of the direction of separation of said contact members, wall members of insulating material for closing laterally the spaces between adjacent ones of said insulating plates; said plates having upon the lower part of their faces conductive elements comprising two wings of generally sector form, the lateral edges of said wings spaced a distance apart from said lateral wall members and generally following the downward direction of the same, a bridge connecting said Wings and bent to straddle the lower edge of the plate, the arcuate edges of each pair of opposite sectors on the opposite faces of each plate and of opposite elements in each space between juxtaposed, consecutive plates diverging relatively to each other in V-form; thereby to draw the are into the spaces between said plates, turn it round into a position substantially parallel to said plates and cause the arc to form peripherally expanding oblong loops within said spaces.

3. A device as set forth in claim 2 wherein the radial edges of each sector which subtend the arcuate edge thereof are substantially perpendicular to each other, one of said radial edges of each sector being extended generally in a lateral direction, the other in the vertical direction, each of said plates being provided at its base with a laterally extended ledge for seating thereon, by means of said laterally extended sector edge, one wing of the conductive element appertaining to said plate and the opposite wing appertaining to the conductive element of the juxtaposed consecutive plate.

4. A device as set forth in claim 2 wherein said plates are provided with marginal spacing members, forming lateral walls thereon, thereby to stack the plates of said set together and provide between juxtaposed consecutive plates spaces for the development and expansion of the loops therebetween; and wherein one of said lateral edges of said sector is extended vertically downwards parallel to and spaced a distance apart from the lateral wall at the side of the sector; the distance between said lateral walls being narrow so as to compel the arc to take within said space an oblong form and further to compel the roots of the loops to descend along said vertical sector edge into the space between edge and wall thereby to augment the length of the loop within said space.

References Cited in the tile of this patent UNITED STATES PATENTS Switzerland Nov. 1, 1948

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