|Publication number||US2538370 A|
|Publication date||Jan 16, 1951|
|Filing date||Feb 5, 1947|
|Priority date||Feb 5, 1947|
|Publication number||US 2538370 A, US 2538370A, US-A-2538370, US2538370 A, US2538370A|
|Original Assignee||Allis Chalmers Mfg Co|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (15), Referenced by (13), Classifications (7)|
|External Links: USPTO, USPTO Assignment, Espacenet|
Jan. 16, 1951 K. LERSTRUP MEANS FOR CONTROLLING ELECTRIC ARCS 2 Sheet-Sheet 1 Filed Feb. 5, 1947 INYENTOR ka/oX t/wp y2 ATTORNEY K. LERSTRUP MEANS FOR CONTROLLING ELECTRIC ARCS Jan. 16 1951 Filed Feb. 5, 1947 2 SheetsSheet 2 lNv ENTOR (95/01/01 i/Q/QVM BY M ATTORNEY Patented Jan. 16, 1951 UNH'EED STATES PATENT OFFICE MEANS FOR CONTROLLING ELECTRIC ARCS Karl Lerstrup, Milwaukee, -W-is., assignor to Allis- Ohalmers Manufacturing Company, Milwaukee, Wis., acorporation of Delaware Application February 5, 19517, .Serial,No.'7 26,5,8f7
This invention relates to the control of electric arcs and more particularly to the control of arcs on are runners ,and arcs formed by the opening of electric switches. The principal object of the invention is the provision of new and improved methods of and means for controlling electric arcs, and new and improved electric switches.
A more specific object is the provision of new andimproved ways of controlling an electric are so that the arc will berapidly moved and rapidly extinguished. To attain that object it is necessary that the incipient arc be caused to move in-a desired direction, and the established arc be caused to move and move rapidly in a desired .direction. Itis a further object to attain these resultswithout the use. of the usual blowout coils ormagnets and in a more efficient way.
Other objects will appear as the description of the invention proceeds.
The novel features of the invention and how the objects areattained will appear from this specification and the accompanying drawings showing several embodiments of the invention and forminga part of thisapplication, and all these novel features are intended to be pointed out in the claims.
.In the drawings:
Fig. 1 is a side elevation, partly fragmentary, of apparatus embodying the invention, this apparatus including a circuit breakerprovided with arc runners;
Fig. 2 is a side elevation, on-an enlarged scale, of a detail of the movable arcing contact usedin the embodiment of Fig. 1, showing its relationto the relatively stationary arc runners fragmentarily shown;
Fig. 3 is a bottom view of the movablearcing contact shownin Fig. 2;
Fig. 4 is a section, on an enlargedscale, taken on the line IV--IV of Fig. 2, looking in the direction of the arrows;
Fig. 5 is a fragmentary, section, on an enlarged scale, taken on the line VV ,of Fig. 1
Fig. 6 is a fragmentary view of a detailv of Fig. 1 looking through the plane VI--VI in the direction of the arrows;
Fig. '7 is a side elevation, partly schematic, of another embodiment of the invention in the form of a circuit breaker;
Fig. 8 is a view of an end of one of the arc runners of Fig. 7 t aken at right angles to Fig. 7;
"Fig. 9 is a side elevation, partly schematic, of another embodiment of the invention inthe torm of a circuit breaker;
Fig. 10 islafront elevation oft-he circuitbreake how nfi 9; and A Figs. 11, 12, 13, 14, 15 and 16 are cross-sectional views of respectively different are runners em boolying the invention.
Referring f rst to Figs. 1 through 6, the circuit breaker here shown comprises relatively stationary ,main contacts 29, 2] adapted to be bridged by a relatively movable main contact 22, the latter beingheld by ablock 23, which may be moved toward and away from the relatively stationary contacts "20, 2! b-y an operating rod or Idember 24.
Thestationary main contacts 20, 21 may be supported iromfinsulating supports 25, 26 in any suitable way, and may-be connected to conductors 21,28, respectivelyiorming part of the circuitto be controlled. The construction and arrangementofthe maincontacts 20, 2|, 22 is not material as far as the present invention is concerned.
The circuit breaker further comprises relativelyfstati onary arcing contact portions 29, -30
adapted :to be abuttingly engaged by a relatively movable arcing contact 3|, The contact 3| is heresh own as of inverted heart-shaped or generally triangular form, the triangle having an apexdisposedbetween the relatively stationary arcin contacts; 29, 36, with sides 32, 33' adapted to engage the contacts 29.30. The contacts 29, 3 U, 3;l may be made of copper or any other suitable metal and, if desired, may-be provided at-the 'places of engagement with insets -34, 35'-and 36,
gagement where the portions carry current'to and from the arc, they nake an angle of substantially less than 90 and desirably lessthan The same is'true with respect to the portions 30,-33.
T-he apex of the triangular contact 3| has a split;38, and, as maybe seen in Figs. 2 and 3 the side of the triangular contact opposite the ,apex also has a, ,split s9.,.. dividing that side into two partsfllLt I butunless it is desired to increase the magnetic efiect of current flowing in the triangular contact 13!, as will appear, the split 39 may be omitted and the side portions, 4| made integral.
Th co ac 3 114% h u ort and m v in any suitable way. As here shown the composite side 4U4|-is fastened by an insulating clamp 42 to an insulating support 43 through which freely pass a pair of headed studs 44, one pair on each side of the composite side 4|l--4|. The studs 44 are fastened in the block 23 and springs 45 may be provided for biasing the support 43 to the position in which the insets 35, 36 are in engagement with the insets 34, 31. The lost motion connection provided by the studs 44 and support 43 permits the springs 45 to maintain the contact 3| in engagement with the contacts 29, 35 after the bridging member 22 has been moved out of engagement with the contacts 2|], 2|.
Desirably, a member of magnetic material 50, here shown as having two flat portions joined at is disposed within and complementary to the inside surfaces of the sides 32, 33 of the contact 3|; from the contact 3| by an insulating member 52, here shown as covering the entire inside surface of the contact 3|.
The member of magnetic material 50 may be laterally sup-ported in any suitable way, as by i an insulating block 53 shown in Fig. 4 but omitted in Figs. '1, 2 and 3 to more clearly show the otherwise hidden parts. The block 53 may be of generally triangular form complementary to the inside surface of the insulating members 52 and fastened thereto.
The block 53 has a channel 54 for receiving the magnetic member 50.
When the split 39 is used, the parts 40 and 4| may be electrically connected by an insulated conductor 55 disposed in a recess 55 in the portions 32, 33, 4|], 4| of the triangular contact 38. One bared end 5! of the conductor 55 is disposed in a hole 58 in the portion 40, radially outside of the recess 55, and the other bared end 59 of the conductor 55 is disposed in a hole 60 in the portion 4|. The ends 5I, 59 are soldered or otherwise suitably fastened and electrically connected in the respective holes 58, 59. The conductor 55 is here shown as so constructed and arranged that it makes three turns from the end 51 to the end 59. From the end 51 the conductor goes to the level of the recess 56, makes a turn in the uppermost position, as viewed in Fig. 3, then crosses to the central position, makes a turn, then crosses to the lowermost position, and makes a turn to .the end 59.
It will be apparent that a conductor making any other desired number of turns may be used. a
The portion 29 of the stationary arcing contact is here shown as integral with a generally horizontal portion I5 which may be electrically immediately connected to the contact 29 or the conductor 21, or it may be mediately connected as will appear. The portion 29 is also here shown as integral with an arc runner portion II which extends upwardly at an angle toward the left as viewed in Figs. 1 and 2.
The portion II of the arc runner is here shown as joined to a generally vertically extending portion I2 which in turn is shown as joined to an eye or loop I3 as may be seen in Fig. 6. The loop I3 is here shown as substantially circular but having a terminal end I4 spaced from the beginning of the loop. The portions 19, 29, I2 and I3 may be of circular section or other desired Disposed about the arc runner and also about The member 59 is here shown as insulated the portion 29 is magnetic material here showii as separate, longitudinally spaced sections I5, the cross-sectional form of which may be seen in Fig. 5. As here shown the sections I5 are of clip form having a body I5 extending more than 189 around the conductor in question, in Fig. 5 the arc runner portion II. The sections I5 are here shown as provided with outwardly flaring wings TI. The sections I5 may be insulated from the respective conductor portions with which they are associated by insulating material I8. Thus, the sections I5 comprise a plurality of bodies of magnetic material disposed alongside of and in laterally confronting relation to the arc runner I I, and are so arranged that the are runner II extends in either direction past the sections I5.
If desired the portion 29 and that part of the portion I0 at the right of support 25, and the arc runner portions I|, I2 may be backed by a suitably shaped insulating block I9 fastened to the support 25, as by screws 80, and may be laterally supported by insulating plates 8| fastened to the block I9 as by screws 82. The parts I9, 9| are fragmentarily shown in the left half of Fig. 1 and entirely omitted in the right half, for the sake of clarity.
Disposed within the loop I3, a magnetic core 83 is here shown, which core may have a flange 84. The loop I3 is insulated from the core 83 and flange 84 by a layer of insulating material 85. The flanged core is supported in any suitable way from the support 25.
As hereinbefore mentioned the arcing contact portion 29 and the arc runner II, including also the arc runner portions I2, 13, may be provided with a longitudinally extending recess 90. The recess 99 is clearly shown in the portion II in Fig. 5, and in the portion 30 (corresponding to the portion 29) in Fig. 4.
Referring again to the left side of Fig. 1, disposed in the recess 99 is an insulated conductor 9 i, one end 92 of which is mechanically and electrically connected to the contact 20, and extends in the recess 99 in the portion I0, 29, II, I2, I3 and emerges from the portion l3 at a place spaced somewhat from the end I4, and has its other end 93 mechanically and electrically connected to the portion I9. Instead of having the insulated conductor 9| in a slot or recess 90, it may be disposed, as in the case of conductor 9|c, Fig. 15, in a longitudinal hole 900 in a runner I I0 or analogous part. On the other hand the runner or analogous part may be of solid section and the auxiliary conductor may be disposed alongside such construction being shown in Fig; 16 where ,IId is a runner and 9|d is the insulated auxiliary conductor. The construction comprising a slot or recess is preferred.
The right side of Fig. 1 is the same as the left side hereinbefore described except of course that the conductor 9| has its end 92 connected to the contact 2|. In the left side of Fig. 1 some of the lower clips I5 have been broken away, whereas in the right side of Fig. 1 some of the upper clips I5 have been broken away to show otherwise hidden parts. If desired, the usual arc barriers (not shown) may be provided between the runners II.
The operation of the embodiment of Figs. 1 through 6 is as follows. Assume that current is flowing from the conductor 21 to the conductor 29through the contact 20, bridging member 22 and contact 2|, and that the rod 24 is moved downward thereby interrupting the path for cur-.-
5 rent through the bridging member 22. Current then continues to flow from point 92 through. conductor 95 to point 93, through portion I through portion 29 acrosscontact points 34, 35 downward through portion 32 through portion 49 to end of conductor 55, through conductor 55 to the end 53 thereof, thence through portion 4|, then upwardly through portion 33 to contact point 33 across to point 3's downward through portion 3i through portion Til, and from terminal 93 through conductor 9I to terminal 92 and conductor 28.
By reason of the acute angle made by the parts of the portions 29 and 32 just below the contact points 3 3, 35, that is, on the arc-trailing side of these points, and the fact that the current flow is in opposite directions in these parts, an intense magnetomotive force is provided inthe space defined by that angle. This magnetomotive force is multiplied, in the embodiment of Fig. "1, by the conductor 9i, the current in which it is collateral to and in the same direction as that in the portion 29, and is further multiplied by the conductor 55, the current in which it is collateral to and in the same direction as in the portion 32. The magnetic flux produced by the magnetomotive force is multiplied by the provision of the magnetic members '55 and the magnetic member Ell, which members greatly reduce the magnetic reluctance of the flux path around the portion 29 (and the conductor iii if present) and similarly greatly reduce the reluctance of the flux path around the portion 92 (and the conductor 55 if present). What has been stated applies as well to the similar parts on the right side of Fig. 1.
Accordingly, when the contact 35 is moved downwarc, disengaging the contact points 35, 36 from the points 3 3, 3?, the incipient arcs formed at the places of disengagement are being powerfully acted on by the magnetic fluxes hereinbefore referred to whereby the arcs are caused to move upward, the leithand are continuing upward with its terminals on the lefthand runner it and the portion 32 respectively, and the righthand' arc continuing upward with its terminals on the portion 33 and th righthand runner 7! respectively.
The right and lefthand arcs move upward rapidly and leave the portions 32, 33, uniting at the middle into a single are extending from the lefthand runner i l to the righthand runner 'i i. This single arc, and especially the foot points or terminals thereof, is powerfully acted on by the magnetic flux produced by the current in the arc runners H at the trailing side of the arc erminals, causing the arc to move rapidly up-. ward. If the arc has not been extinguished by the time its terminals reach the loops I3, the terminals will be caused, by the magnetic flux produced by the current in the loops at the trailing side of the arc terminals, to move along the loops. When the arc terminals reach the ends l4, the terminals will jump to the beginnings of the loops l3 and again run around the loops until the arc is extinguished. It will be apparent that the arc terminals will, accordingly, not remain at one point, and severe burning of the arc runners and especially the ends of the arc runners is prevented.
The various parts of magnetic material hereinbefore described serve not only to reduce magnetic reluctance but to aid in dissipation of heat produced by the arc. Sectionalizing that part of, the magnetic material comprised in the clips I5 prevents current from following the magnetic material if the arc should burn to one of the clips.
Referring now to the embodiment of Figs. '7 and 8, there is here shown a switch comprising a movable member 94 swingable about a pivot 95. The movable member 94 is shown in closed position in which it engages a conducting portion 29a continuing upwardly as an arc runner Ila. It will be noted that the angle defined between the contact 94 and portion 29a is an acute angle as hereinbeiore described with reference to the portion 29 and the contact portion 32 of Fig. 1. The movable member94 is connected by a conductor 96 to the circuit conductor 28a, and when the movable member 94 is moved to the dotted line position an arc is first drawn between the portion 29a and the member 94, the righthand terminal of the arc being then transferred to the righthand runner I la. The are then rises along the runners Na and if not sooner extinguished continues on the loops 13a until extinguished.
In Figs. 7 and 8 parts corresponding to similar parts in Fig. I bear the same reference numerals with the sufi-lx a, but in Figs. 7 and 8 the conducting parts are of solid section and no auxiliary conductors, such as 55 and 9| of Fig. 1, are provided. Also no magnetic material constructed and arranged for reducing magnetic reluctance is provided. A construction of the type shown in Figs. 7 and 8 may be employed where the operating requirements are met thereby.
Figs. 9 and 10 show a switch comprising a stationary main contact 9! with which a movable main contact 93 is cooperable. The movable contact 9B is shown as carried by a member 99 pivoted at N19 to a terminal IN. The contact 91 and terminal HlI may be carried in any suitable way by. an insulating support I02. The member 99 carries an arcing contact I03 engageable with a relatively stationary arcing contact portion 29b. Here too "the angle defined between the portion 29b and the contact W3 is an acute angle. Above the point of engagement the contact I93 may be provided with an outwardly bent portion i594 of any desired length. The contact I03 may be made flexible, constructed and arranged in any way so that it will leave engagement with the contact portion 291) after the main contacts 91, 98 are opened.
The portion 29b is continued upwardly as an arc runner lib which as here shown is terminating in a vertical portion 12b but unlike these similar parts in Figs. 1 and '7, no loop is provided at the end of the portion 12?). In the embodiment shown in Fig. 9, the portions 19b, 29b, 1 I11 and 12b are provided with longitudinal recesses in which, as in the embodiment of Fig. '1, a conductor 9Ib is disposed, this conductor having the end emerging from the recess in the portion 191) connected to the contact 9? and the other end connected to the portion 19b. The effect is the same as described in connection with Fig. 1.
Fig. 11 shows a cross-section of an are runner I05 which is held by insulating enamel I96 or other suitable material in a longitudinal groove or recess in a magnetic member I 01 of any desired suitable cross-section. The are runner lilimay, if desired, be made of such small cross-section that it would be inadequate to withstand the heat of the arc and/or not mechanically stiff enough to be desirably self-sustaining. When so designed, the arc runner I may carry an arc current capable of generating a quantity of heat in the arc runner greater than the heat required for fusing the arc runner. However, since the runner 105 is mechanically supported by and in heat transfer relation to the magnetic member lOl, it need not be selfsustaining and the heat of the arc will be dissipated and, both because of its small diameter and because the member 101 is magnetic the reluctance of the path around the runner will be of low value. Insulating enamel IllBa may also be applied to the front surface of the member I01.
In general, irrespective of the particular embodiment of Fig. 11, it is advantageous to make the cross-section of-the arc runner as small as possible because the magnetic flux path around the runner is decreased. Also, the mechanical force of the magnetic field produced by current in the runner and acting on the are is proportional to the square of the current, and the force at the surface of the runner, which is of greatest importance, is inversely proportional to the length of the shortest magnetic path around the runner, Thus it is advantageous to use an arc runner of as small, circular cross-section as possible, and, in addition, to increase the permeability of the fiuX path around the runner. Whether or not the magnetic material used to increase the permeability of the flux path functions to dissipate heat from the runner, it can be constructed and arranged to stiffen and mechanically strengthen the runner.
Fig. 12 shows a cross-section of an arc runner I08 disposed in a longitudinal groove or recess in a member H19 of magnetic material. A member- I it of self-sustaining insulating material may be interposed between the runner 498 and the surface of the groove, the member his and. i lating material liil being cemented together in any suitable way. The member ill] may be pro vided with outwardly flaring wings iii to pro tect the member H19 from the arc.
Fig. 13 shows a cross-section of an arc runner H2 of flat cross-sectional form which may provide a desirably large cross-sectional area. Disposed about the runner I 12 is a clip l 63 of magnetic material conforming to the outline of the runner for most of its circumference and having outwardly flaring wings H t. A layer of insulating material H covering the inside surface of the clip H3, H4 is provided. This combination provides a runner 12 of desired larger crosssectional area and at the same time a flux path around the runner having a low reluctance.
Fig. 14 shows a cross-section of a runner it of generally circular cross-section having a longitudinally extending lateral extension or rib ii! here shown as of generally rectangular crosssectional outline. Disposed about the runner i it, I ll is a clip i it? of magnetic material conforming generally to the outline of the runner for most of its circumference and having outwardly flaring wings H9. The runner may be of suificient cross-sectional area to provide for cooling and due to this factor and/or due to the presence of the rib Hl is of sufficient mechanical strength and stiffness without the clip M3, the latter serving, however, to reduce the magnetic reluctance of the flux path around the runner. Self-sustaining insulating material I23 protects the surface of the wings 1 i9 and is interposed between the clip proper H3 and the runner H6.
From the foregoing it will be apparent to those skilled in the art that the illustrated embodiments of the invention provide new and improved methods of and means for controlling electric .arcs and new and improved electric sw tch and accordingly accomplish the objects of the invention. On the other hand, it will also be obvious to those skilled in the art that the illustrated embodiments of the invention may be variously changed and modified, or features thereof, singly or collectively, embodied in other combinations than those illustrated, without departing from the spirit of the invention, or sacrificing all of the advantages thereof, and that accordingly the disclosure herein is illustrative only, and the invention is not limited thereto.
It is claimed and desired to secure by Letters Patent:
1. An arc runner comprising, a continuous conductor means forming a path for a movable terminal of an electric arc and means for reducing the magnetic reluctance of the flux path around said conductor means with respect to magnetic flux generated by current flow in said conductor means, said reluctance reducing means including a plurality of bodies of magnetic material disposed opposite the terminal of the are alongside of and in laterally confronting relation to said conductor means, said conductor means extending past said magnetic bodies, the adjacent said bodies being spaced from each other longitudinally with respect to said conductor means for substantially restricting said are to said conductor means during movement of said are terminal.
a. An electric switch, comprising: arcing contacts engageable at a given place of contact and relatively movable away from each other to strike an electric are at said. place; means for increasing the magnetomotive force acting on the are at the trailing side thereof; at least one of said contacts forming an arc runner for a movaole terminal of an electric arc, said runner including means for continuously shifting the arc to shut the spot of junction between the arc and said are shifting means while the arc exists, said are shifting means comprising a substantially circular conducting loop at the end of said runner; and means for reducing the magnetic reluctance of the flux path around said runner with respect to magnetic flux generated by current flow in said runner.
3. An electric switch, comprising: arcing contacts engageable at a given place of contact and relatively movable away from each other to strike an electric are at said place; means for increasing the magnetomotive force acting on the are at the trailing ide thereof; at least one of said contacts forming an arc runner for a movable terminal of an electric arc, said runner including means for continuously shifting the arc to shift the spot of junction between the are and said are shifting means while the are exists, said are shifting mean comprising a substantially circular conducting loop at the end of said runner; and means for reducing the magnetic reluctance of the flux path around said runner with respect to magnetic flux generated by current how in said runner, said reluctance reducing means including a plurality of bodies of magnetic material disposed opposite the terminal of the arc alongside of and in laterally confronting relation to said runner, said runner extending past said magnetic bodies, the adjacent said bodies being spaced from each other longitudinally with respect to said runner for substantially restricting said are to said runner during movement of said are terminal.
4. Electric arc extinguishing means, comprising: means for lengthening the are including an 9 arc runner providing a path along which the arc can move toward the 'end of the runner as the arc is lengthened, said runner having an end comprising a substantially circular conducting loop for supplying a magnetic field to continually shift the spot of junction between the arc and said 100p while the arc exists; and magnetic means positioned within said loop for strengthening said magnetic field.
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS Number Name Date 701,577 Klein June 3, 1902 Number Number 15 71,393 114,061 368,645 514,100
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|U.S. Classification||218/40, 218/36, 218/148|
|International Classification||H01H9/30, H01H9/44|