US2550718A - Electric contactor and arc extinguisher therefor - Google Patents

Description

L. R. RANSON May 1, 1951 ELECTRIC CONTACTOR AND ARC EXTINGUISHER THEREFOR 2 Sheets-Sheet 1 Filed Feb. 19, 1946 1 I I l I N M p O T a H IN V EN TOR.

0 W flf j d My M 1951 L. R. RANSON 2,550,718

ELECTRIC CONTACTOR AND ARC EXTINGUISHER THEREFOR Filed Feb. 19, 1946 2 Sheets-Sheet 2 56 Li I U .57

55 //W My HTTOR/VEY Patented May 1 1951 ELECTRIC CON TACTOR AND ARC EXTINGUISHER THEREFOR Lloyd Russell ltanson, Charlotte, N. C., assignor to The Clark Controller Company, Cleveland, Ohio, a corporation of Ohio Application February-19, 1946, Serial No. 648,77 6

2 Claims. 1

This invention relates to electric contactors of the class having contacts for making and breaking electric circuits, at such potential and amperage that when the circuit is broken at the contacts a persisting arc tends to form' thereat; but

having magnetic means to quickly rupture and extinguish the arc. In prior contactors of this general class, the magnetic arc extinguishing means or magnetic arc blow-out arrangement comprises some means to produce a magnetic field disposed adjacent to the arc and directionally related to the direction of the current in the are so that the are reacts on the magnetism of the field and is rapidly propelled across it by the well recognized motor principle, and is thereby quickly elongated and ruptured.

In the contactor of the present invention the reaction between magnetism and current generally, is applied in an improved construction and utilized in an improved manner to accomplish a number of useful effects which are believed to be novel in this art.

"Generally speaking, the contactor is constructed so that when it breaks the main circuit which it controls, the are produced at the break'is subjected to two opposing magnetically produced forces, acting on the opposite sides of the arc, and squeezing it into a thin planar zone; and it is then ruptured by magnetic action; whereby arc flame is sup ressed, and the are readily and abruptly extinguished, and destructive contact of the arc with laterall adjacent parts is reduced or eliminated.

. Furthermore, the contactor has a double-break contact arrangement comprising two sets of contacts, one of the contacts of each set being supported on a movable electrically conducting bridging construction, and magnetic forces are exerted on the bridging construction, tending to move and position' it in a manner to cause the br eaks at both contact sets to occur simultane- 2 improved manner to suppress or reduce arc flame;

Double break contacts havin a construction and mode of operation, utilizing the reaction of current and magnetism, to cause the Wearing or burning away of the contacts at the two breaks, to be continuously equalized so that over a long period of use the separation of the contacts at both breaks is maintained equal, and both breaks occur simultaneously, and the arc is divided equally between them.

Generally, it is an object of the invention to provide an electric contactor of the magnetic arc extinguishing class having an improved construction and mode of operation.

Other objects will become apparent to those skilled in the art to which the invention appertains, from a reading of the following description which fully discloses the invention, taken in connection with the accompanying drawing, in which: g

Fig. 1 is a side elevational view of a contactor embodying the invention; with parts broken away and parts in section; V I

Fig. 2 is a front elevational view of the con tactor of Fig. 1;

Fig.- 3 is a top plan View of the contactor of Fig. 1;

Fig. 4 is a fragmentary side elevational view showing in elevation parts that are shown in sec-, tion or broken away in Fig. l

Fig. 5 is a sectional view from the staggered plane 5 of Fig. 1 with parts omitted;

Fig. 6 is a sectional view from the plane 6 of Fig. 1 with parts omitted: I b

Fig. 7 is a sectional View from the plane 7 of Fig. 1 with parts omitted;

Fig. 8 is a sectional view from the plane 8 0 Fig. 1 with parts omitted; Fig. 9 is a sectional view from the plane 9 of Fig. 2 with parts omitted;

Fig. 10 is a fragmentar view similar to a part of Fig. 1 but with operative parts in different positions;

Fig. 11 is a top plan view showing separately the contacts of the other figures;

Fig. 12 is a diagrammatic view illustrating an operative feature of the contactor of the other figures.

The embodiment of the invention illustrated in the drawing as will appear from an inspection of the Various figures particularly Figs. 1' to 4, 9, 10, and 11 comprises a pair of stationary contacts I and 2; a bridgin element 3 comprising contact portions or contacts 4 and 5 thereon,

constituting movable contacts movable toward and from the'stationary contacts I and 2 to engage and disengage them; and a magnetic arm 6 upon which the movable contacts are supported. An electromagnet is provided for operating the arm 6 and comprises a steel element I bolted to an insulating panel 8 (constituting a main base upon which the parts of the contactor generally are mounted). The element 1 has a groove 9 therein. A horizontally extendin steel piece 10. is seated at one end in the groove 9, and a bolt ll projected through the panel 8 and through the steel piece 7 and screwed into the steel piece I mounts these pieces together, andupon the. panel. An operating winding i2 surrounds a steel core l3 riveted as at [3A to the steel piece 1 at one end, and at the other end having a mag;- netic pole face I 4. The arm 6 has legs l5l5 straddling the steel piece I0 and pivoted upon the latter by a pivot pin I6, the axis of the pivot being to the left (as viewed in. Fig. 1. of the center of gravity of the arm 6 whereby the; arm moves by gravity to the open-contact position illustrated; and its open contact position is adjustable. by means of. a stud I! screwed vertically through the steel piece. l0. and engaging. ashoul der [8. on the arm 6, The arm, 3 has a pole fac i9 opposite the pole face 1 4 of the magnet, pro: viding a working air gap 23, therebetween.

Upon energizing the winding t2, magnetism. in the working air gap 20 rocks: the arm 6 counterclockwise as viewed in Fig. 1 to engage the contacts l 4 and 25 and upon de-energizing it the arm 6 returns to its said normal position.

The stationary contacts I and-2 are detachabl-y and renewably secured upon the ends of posts 2| and: 22: preferably parallel and transversely spaced apart; the post 2| being mounted upon the panel 8 by a stud- 23 and nut- 24:, and the stud- 23' extending beyond the nut 24' and having another nut 25 thereon, by which an electric circuit to lee-controlled may be connected tothe stud- 23 and thereiore to the contact 1:.

. The postal? is mounted upon the panel 8 by a bolt 26. Electric circuit connection tothe post 22 and therefore to the contact 2 is made throughan arc blow-out magnetic winding 2-1- to be more fully described, one end of the winding being connected to the post 22 by a bolt 28, and the other end of the winding being connected t'o a bolt 29 passing through the panel 8* and having a clamping nut 30 thereon and the boltextending beyond the nut 30 and having another nut 3|- thereon for making electrical connection In the particular embodiment illustrated in thedrawing, the two movable contacts 4, and 5 are each a part of and integral'with a one piece bridging element 3, the movable contacts 4' and 5 thus constitutin portions of the one piece bridging element; but it will be understood that the contacts 4'- and 5 canbe separatelymadehand attached to a bridging element or bridging constructionof other forms.

"The bridging element 3 with its movable con tacts 4 and 5 is mounted loosely on the arm 6 in afmanner to maintain the contacts 4 and 5 in alignment with and confronting respectively the stationary contacts I and 2, but permitting what; may be called generally a pivoting movement' around a generally vertical axis between the contacts 4 and 5; and while this pivotal movement may be variously provided for, that provided" in the particular construction illus trated'i's as follows.

A contact carrier 32 formed by bending a strip of metal into generally U-form has one leg 33, the upper leg as viewed in Figs. 1 and 10, attached by a screw 34 to the upper end of the arm 6; the closed end 35 of the U extends over the inner part of the bridging element 3 intermediat'e its ends; and the lower leg 36 of the carrier, being substantially parallel to the leg 33, is secured to the arm 6 by a bolt 31. On its upper side, the bridging element 3 has a notch 38 therein, Figs- 1 7, 9, and 10, upwardly open, and its sides embrace the leg 33 of the carrier with clearance. A protuberance 39 is provided on the back; side of the bridging element 3 substantially i at its middle,- and a protuberance 40 is provided on the'arm 6, and a compression spring 4| is telescoped over the protuberances at its ends, and, in the open contact position, resiliently holds the bridging element 3 against the closed end 35 of the carrier.

As shown in. Fig. 1, in the contact. open position, the spring Ail has an angular or upward component of thrust on the bridging element 3.; which, each time that the arm 6 moves to. open contact position, pushes the notch 38v of the; bridging element into. the: corner between the leg 33 and the closed end 35 of the carrier. which repeatedly positions or aligns the contacts: 4.a nd 5 with the stationary contacts I and; 2. The. bridging element 3, however, is at all times free to rock about the, closed end- 35 ofthe. carrier; in a manner and for a purpose to be more-.iu-ll-ydescribed, and reference may be had to Fig. 8- wherein a normal position for the. bridging eleav ment 3 is shown in solid line, and wherein. at. 3A and 3B, in broken line, it is shown in pivotally rocked positions.

In the operation of that part or the contactor thus far described, when the operating magnet l2 has moved the arm 6 counterclockwise as; viewedin Fig; 1, the contact carrier 32- and the bridging element; 3 and its contactsd an-d. 5v move. in unison with the arm through the, first part. of; the movement, and the contacts 4 and; 5 b.ecome engagedrespectively with thestationary contacts I and 2. Thereafter the arm 6 continues. to: move. until the air gap 2d of. the operating magnet. is. completely closed, andduring this latterpart of. the movement, the contacts 4,. and iii are stopped by their engagement with thestationary contacts.

t and 2 and thecontact carrier. 32..goes.on, movingv and finally reaches the position illustrated, in,

Fig. 10, the closed end 35 of the, carrierleaving the bridging element 3, and the spring 41 being put under more compression and holding, the" contacts engaged. When the arm 6 returns to the open c'onta ct position, the closedzend' 35 of. the carrier picks up the bridging element and moves the movable contacts back out of'engagement with the stationary contacts I and 2.

When the contacts are in this manner closed or engaged, current in the circuit to be controlled by the contactor may be considered as; flowing in at the stud 23', through the post 2!, through the engaged contacts land 4-, thence transversely In the absence of other provisions, it is inev-l table that one set of contacts [-3 and 2-5" Wonld openbefore the other set, and draw 'on are at" theearlier than the other, and burn or wear away one advantage and defect is eliminated by the utili- I zation of the reaction between current and magnetism which will now be described in connection with the theoretical diagrammatic figure, Fig. 12.

At 42 and 43 bridged at their lower ends as viewed in the drawing by a bridging conductor 44 making contact with the conductors 42 and 43, at 45 and 46 respectively. I The conductor 43 is shown shorter than the conductor 42, so that the conductor 44 makes anacute angle with the conductor 42, and an ob tuse angle with the conductor 43.

Electric current may be considered as flowing in the direction of the arrow 41 through the conductor 42 and turning at an acute angle into the conductor 44, and flowing therethrough, and turning at an obtuse angle into the conductor 43, and flowing therethrough and out at the di? rection of the arrow 48. I

, This flowing current produces a magnetic field around the three conductors, the lines of force of the field as viewed from above being indicated,

by the lines 49. When the current makes an acute angle turn at the contact 45, the lines of force are crowded together as at 50; and when the current turns the obtuse angle at the contact 46, the lines of force are also crowded together as at but less than at 50. Where the lines of force are crowded together as at'56 and 5| they repel each other in the effort of the field to straighten out, and this repulsion force is communicated to the conductor 44 and tends to move it and break the circuit at the contacts 45 and 46.

However, due to the greater crowding together of the linesof force at 56 than at 5|, this repulsion on the conductor 44 at the gap 45 is greater than at the gap 46; and if the conductor 44 were free to move, it would break contact at 45 earlier than at 46.

By comparing Fig. 12 with Fig. 11, it will be ob:

served that in Fig. 11 the conditions of Fig. 12

are generally present. Current flowing along the,

are represented conductors a right angle on flowing into the bridging element tion described, free to pivot on the carrier por-' tion 35 as shown in Fig. 8. Therefore if at the moment opening of the contacts starts, the direction of the current in the bridging element 3 between the contacts 4 and 5 is at right angles to the direction of current in the post 2| and contact |,-and at right angles to the-direction of the current in the contact 2 and post 22, the two propulsion forces on the contacts 4 and '5 will be equal and both sets of contacts will open simultaneously. If however, due to any cause whatever, such as inaccuracies in the original construction, or microscopic amount of wear atone set of contacts greater than at the other, the angular change of direction of the flowing current at the two sets of contacts should be unequal angles, the set of contacts at which the directional angle of the current is an acute angle will be opened first; and after a few operations. the right angle conditionof both sets of contacts will be established or restored, and thereafter maintained.

In view of the foregoing it will now be clear that this inherent and continuous equalizing ac-' tion, causing both sets of contacts to break sir multaneously and wear away equally and thereafore draw equal arcs therebetween, results from giving the bridging element 3 and its contacts 4 and 5 the said pivotal movement intermediately thereof, and from utilizing the repulsion forces produced on the bridging element by the magnetism produced by the flowing current.

The arcs thus continuously equalized, are extinguished by are extinguishing parts, proper, of the structure, and these comprise a magnetic circuit energized by the blow-out winding 21, and a pair of arcchutes, one for each set of contacts. The blow-out winding 21 is wound on an insulating spool 52, and while the winding 21 may be wound from round wire the one shown in the drawing is made from an edgewise wound strip of conductor, such as copper. The insulating spool 52 is telescoped over a magnetic core 53. A magnetic yoke 54 is provided, generally of U-forrn, the closed end 55 of the U lying upon the panel 8 and the legs53 and'51 of the U extending forwardly substantially parallel to the core 53, a bolt 53 passin through the closed end 55 of the yoke and into the core 53, mounting these elements on the panel 8.

Magnetic side plates 59 and 66 are pivotally connected to thelegs 56 and 57 of the yoke by pivot bolts 6| and 62. A'core extension 63 of magnetic material has an inner end surface 64 abutting upon the end of the core-53, and extends forwardly therefrom with its lower edge 65 above the contacts, see Fig. l, and-intermediately between them. The side plates 59 and 66, it is to be particularly noted, have magnetic protuberances 66 and 61 projecting inwardly from the side plates toward the core extension 63, their inner ends as shown in Figs. 5 and 6 overlapping a part of the contacts thereunder, and as shown in Figs. 1 and 9 for the protuberance 61 in dotted line,- being approximately above the arc space between the contacts.

Referring to Fig. 5, and bearing in mind the direction of the winding 21, Figs. 1 and 11, and that the current (Fig. 11) flows in at the stud 23, through the post 2|, through the contacts I4 and 5-2, and through the post 22 and through the winding 21 and out at the stud 29, the flux produced by the blowout winding 27 may be considered as flowing from the core 53 into the yoke 54 and there dividing, part flowing through the yoke leg 56, the side plate 59, the protuberance 66, across the space between the protuberance and the core extension 63, into this extension, and back to the core 53; and the other half flowing similarly through the leg 51, side plate 6|), proassay-rt 7 tuberance- S'land to the core extension- 63- and bacl to the core 53-.

The protuberances 66 and 61 may be formed separately and securedto the side plates as by Welding. At their inner ends they are of smaller cross section than the side surfaces of the core extension '63. The magnetic flux will therefore tie-concentrated and of high density as it leaves the protuberances, and will spread out and be of row density as 'it enters the core extension 63, and is thus tapering magnetic field.

The-magnetic parts adjacent the contacts are covered with refractory material providing an arc chute for each set of contacts, and the parts of the magnetic cir'cuitand of said are chutes are all assembled rigidly together with the side plates 59"and' 60. The said are chutes and the refractory material thereof may if preferredbe molded in one piece but in the construction illustrated, they aremade from several pieces bolted together as follows; A side-plate of refractory material 68 lines the inner face of the magnetic side plate 59- and'covers; as at 5'9, theprctub'erance A simi-iar sidepl'ate Til lines the inner side of the magnetic side pl'ate 5d and covers the protuberance 61. These refractory sideplates asshown'fo'r side plate l0. Figs. 1 an'd't), see also'Flg. 6, extend downwardly below .the contacts and forwardly and rearward-1y thereof. p

" Inner refractory plates 1 I and 12 are provided on opposite sides of the core extension 63 and overlap its lower edge 65 as shown at 13, Figs. 1 and'6.

- liubular refractory elements- 14' and 15 are disposed respectively between the refractory plates 7:8 and, and i2 and Hi, and a bolt id is projected through these parts and also through the core extension and clamps these parts rigidly together. Refractory barriers Ti and 18 are provided having, at their upper ends, forwardly curvirn; portions 19: and 88, and down-- ward-1y extending barrier portions ti and 82 disposed shown in Fig. 1 behind the contacting portion of the contacts 5 and; 2. see also Figs; 6' and. 9. BoltstS and 84, Figs. 1, 5,-and 9; are proj'ec'tedthrough the side plates 59 and. 66 the refractory. plates 68-16, barriers 71-18; ref-ractory'plates ii and T2, and. throu-gh'the core extension 63 and clamp these parts together rigidly.

.The. said pivot axis of the side plates 59 and 681 provided by thepivots 5i and 52, is above the axis of the main blow-out core 53', and upon this pivot axis the entire structure described and connected to the side" plates, may be hinging or pirota'lly moved" around upwardly to'give access to the contacts, for example to the broken line position 85' of Fig.v l; and when rocked back to its normal position of Fig. 1, the inner end 64 of the-coreextension 93 abuts'u'pon and is stopped upon the end of the core 53' to support and position the blow-out magnetic circuit and the'arc chutes above described.

Theoperation' of the magnetic arc extinguishirig arrangement as described" above involves a triple application of the reaction of current and magnetism as follows:

The contacts in the drawing are shown in Figs. 1, 5; 9, and 11 in the open position, and for purposes of description it maybe assumed that when arcs are drawn between the contacts l-A and the contacts 25, the current in the arcs flows from the contact I to the contact 4 and from the contact 5 to the contact 2. By reason of the disposition of the'parts as" described, the current in these two arcs is in opposite directions and in 8 two adjacent parallel paths; and therefore, by the wenknown law, the arcs repel each other apart laterally;

These arcs while continuing to be mutually re p'e'lled rise the arc chutes above described due to thermal action and the repulsion forces push them respectively in the directions toward the re fract'ory plates; 68 and It. Asthe arcs rise they enter the said magneticfields and due tothe tapering density of the fields, and the density bein'glessand less proceeding" from the protuber ance's 6G and 61 toward the core extension 63, the reaction of the current in the arcs on these tapering fields exerts forces on-them-inthedirec tion topushthem both upwardly and toward the refractory side plates H and 72; that is to say, theseforces" have a component which is away rr'omthe protuber'ances and toward the core ex: tension 63.

Each arc is therefore subjected to two opposite forces by magnetic action, and taking the center line of Fig. 5 as a reference line, oneforce; the mutually repelling force, pushes the arcs away from the" center line; and the other force,- the force of the tapering field, pushes-the arc toward the tes er: line; and the two forces squee'ze the arc into a thin planar zone between the refractory side walls of the corresponding chutes.

(These thin planar arcs also concurrently" reacton' the magnetic fields to accelerate their upward movement and they become elongated thereby and are finally ruptured.

It has been found that the arc, squeezed into thin" planar form in this manner, accompanied concurrently by the propulsion of the' a'rc up ward-1y through the arc chute and across the ma netic field therein, is ruptured and goes out-very quickly, and before any considerable flame is propagated; and the are being confined" more media-1 portion of each arc chute is kept out of destructive contact with the refractory material of th-e'chute;

The ease or efiicienc'y with which the arc" extin'gui'she'd in" the manner above described is evidenced by the emitted sound.

nary arc'exti nguisher in which the arc can spread In the" ordiout and produce flame, the sound is a ragged; tearing; explosive sound. The extinguishing of the 'ar'c by the present structureis accompanied by merely a sharpabrupt craclrof sound. Because the arc is extinguished so quickly and" abruptly; a given amperage of" current" can be broken with less opening space between the con tacts tharr by prior devices, and accordingly the magnetic ci'rcuitfor operating the a'rnf' 61' and the winding l2 for energizing it, can be smaller and-more economical than in prior constructions;

The principles of the contactor will function equally wellwith alternating current or with" di meet current, although in the case ofalterna'ting current some of the parts of the magnetic ci'r-' Gui-t would be laminated as" is well understood by" those skilled inthe art.

While it is preferable to provide a magnetic core'dflenergized magnetically by a winding'such as 21;; a permanent magnet may be employed instead, and it is believed unnecessary to illustrate extension with the end of the core 53, there is no liability that they will be vibrated or dislodged from operative positions at the time of functioning because at that time the core extension adheres to the end of the core 53 by magnetic attraction.

Due to the proximity of the contact carrier 32 to the magnetic parts of the blowout magnetic circuit, it is preferable to make the carrier from a strip of non-magnetic material, but this is not 1 above the arcs respectively to rupture the arcs,

comprising magnetic plate like side elements and an intermediate plate like element disposed and energized to produce said magnetic fields between the intermediate element and the side elements respectively; protuberances on the side elements projecting toward the intermediate ele ment, disposed to cause the magnetic flux in the fields to be distributed so as to exert forces on the arcs before rupturing tending to move them in directions toward each other; the two forces on each arc, thus occurring, acting concurrently and reducing the transverse dimensions of the propeller arc therebetween before rupturing.

2. In a contactor, contacts operable to break an electric circuit at two spaced points and disposed to draw two arcs in parallel whereby magnetic forces develop therebetween tending to move them apart; means to propelthe arcs upwardly to rupture them comprising members of magnetic material disposed in spaced relation transversely of the arcs to provide, when magnetically energized, two magnetic fields, one for each arc; winding means for energizing the magnetic members; protuberances of magnetic material, one for each arc, projecting respectively transversely into the fields and disposed to be energized by flux in the magnetic members, and

- to distribute the flux in the fields so as to exert forces on the arcs tending to move them in directions toward each other; the two forces on each are, thus occurring, acting concurrently and reducing the transverse dimensions of the propelled arc.

LLOYD RUSSELL RAN SON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 762,644 Leonard June 14, 1904 1,002,595 McElroy Sept. 5, 1911 1,364,389 Lindquist et a1. Jan. 4, 1921 2,255,886 Hudson Sept. 16, 1941 2,289,086 Van Valkenburg July 7, 1942 2,356,039 Ellis et a1 Aug. 15, 1944 2,411.893 Peters Dec. 3, 1946

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