US2623140A - Arc runner with trap for products of arcing - Google Patents

Description

Patented Dec. 23, 1952 2,623,140 anc RUNNER vvrrn rnArroa Prion-cors or AncING VPhilip L. Taylor, Abington, Mass., assigner to Allis-Chalmers Manufacturing Company, Milwaukee, Wis.

Application October 7, 1950, Serial No; 188,911 i2 claims. (o1. ccc-.1471) This invention 'relates to circuit interrupting devices and more particularly to circuit breakers of the air'` break type wherein an arc established between separable contacts is transferred along arc runners into an arc extinguishing chute.

The interruption of heavy current power arcs is often accompanied by the emission of a great deal of are products including incandescent metal particles or other inorganic substances. These particles if not confined tend to break down the dielectric strength of the surrounding air and thereby increase the time necessary to extinguish the arc, or cause failure of the circuit breaker.

In accordance with the invention Vclaimed a new and improved circuit interrupting device is provided comprising' relatively movable contacts which are actuated to initiate and elongate an arc therebetween. The arc is then transferred along a pair of spaced arc runners from the region of arc initiation to a region remote therefrom. Trap means are arranged immediately adjacent the point of arc initiation and extending along the arc runners in 'the direction of arc transfer for reducing, inhibiting or trapping the now of hot or incandescent particles emitted from the arc runners into the space therebetween. l

It is, therefore, one object of the presentinvention to provide a new and improved arc interrupting device in which the products 4of arcing are confined before they break down the dielectric strength of the air between the -arc runners.

Another object of the present invention isto provide a new and improved arcV interrupting device 4in which Ythe products ci arcing are trapped -in a pocket denning means arranged immediately adjacent the point at which the particles were emittedl i A- further object of the invention is to provide a new 'and improved electric circuit interrupting device in which Va trap means for inhibiting the free'low of the products of arcingh controls the movement of the arc along apair or" arc runners.

Objects and advantages other .than those above set forth will be apparent from the :followingl description when read in connection with the accompanying drawing, inv which: I

Fig'. 1 is' a view in cross section, of a magnetic blowout type circuit breaker employing' 'the presentwinventio'n; 'and l Fig. 2 is a'view in cross section oi` a, portion of the" embodiment illustra-ted in Fig. l taken along the line` `II;I1.

Referring more \particularlyv ite 'thev drawings by characters of reference, '.Fig.v 41 illustrates" a" magnetic blowout type of circuit breaker including as elements thereof a pair of terminal studs S and l for connecting the circuit breaker to line conductors (not shown). Although in general, circuit vbreakers of the type considered in Figs. 1 and 2 are provided with a plurality oi similar pole structures, one for each phase of a polyphase electric circuit, only one such pole structure is shown in the drawings and the circuit breaker will be described in detail as if it was of the single pole unit type.

The circuit interrupter or breaker in Fig. 1 comprises essentially means for opening the circuit to form the interrupting arc and an are extinguishing structure. Specifically, the circuit opening means comprises fixed current carrying contact 8 and tertiary contact 9, a fixed arcing contact it, and a movable contact il comprising current carrying, tertiary, and arcing contacts combined in a single structure. Arcing contact il is mounted on a lever 28 which is pvotally mounted at 2 on an extension I3 ci the circuit breaker stud 6 and is operated by means of a reciprocally movable rod i4. The operating rod i4 is suitably connected to an actuating mechansm (not shown) for operating the movable contact between closed and open circuit positions. Fig. -1 illustrates the movable contact Ii in an intermediate position. The arcing contacts are electrically connected to the lower ends of terminal studs S and i. Accordingly, when the breaker is connected in series in a power circuit and Ythe arcingy contacts are separated, an arc may forni across the gap indicated.

For the purpose of interrupting this power arc, an are extinguishing structure, such as' an arc chute i5 may be mounted so as to receive the pcvverY arc which is under the influence of the magnetic blowout means. The arc chute containing a .stackv of spaced plates of insulating 'material having inverted V-'shap'e'd slots denning an' are constricting groove preferably is disposed directlyabove the arcing contacts, as shown, when theblowout means act upward, but may be mounted in any other suitable location 'when the blowout 'means act in other directions. The switcher arcing 'contacts and the' magnetic 'blowout structure can assume any preferredforrn 'so that a 'brief description thereof will `be sui'ncient.

The magnetic blowout means comprises -a core i1, poles t8', and a coil IB which is electrically connected to the terminal stud 1 and 4toa metallic are runner l1'9s`o` that the arc current (as the arc travels 'along therunner) nows through the blowout coil in a manner well known in the art.

Normally the Vcurrent' is carried in the closed aces,

circuit position of the breaker by the spring biased contact 8. As the movable arcing contact II is actuated tc open circuit position, current is shunted from fixed contact il to xed contact 9, to fixed arcing Contact It. As the arc is drawn by the movable arcing contact II, the arc terminal on arcing contact II) is transferred to arc runner I9 which is usually an extension arm of the fixed arcing contact IB. As the movable arcing contact I I approaches or reaches its full opening stroke the arc terminal transfers from the movable arcing contact II to an arc runner 20 which directs the arc into the arc chute I5. One end of the blowout coil I6 is connected to the arcing contact I and the other end to tertiary contact 9. When the movable arcing contact II parts from contact 9, the flow of current is transferred from contact 9 to contact IIJ through the blowout coil I6. The movable arcing contact Il subsequently parts from contact IIJ to draw an arc. Accordingly, the blowout coil is already energized at the inception of the arc to influence the arc in a well known manner, i. e. to drive it into the arc chute I in an expanding loop. It will be apparent to one skilled in the art that the blowout field can be utilized in the most eicient manner by disposing the iron poles I3 so as to cooperate with the blowout coil in the conventional manner outside of the arc chute.

Arc runners I9 and 20 are each provided with two sections. Arc runner I9 comprises a first section 2| arranged within arc chute I5 substantially parallel to the direction of arc transfer in a zone relatively remote from the point of arc initiation, and a second section 22 conductively connected to section 2| and arranged in an acute angular relationship with respect to the direction of arc transfer and to the rst section 2| for transferring one terminal of the arc from the fixed arcing contact I0 to the rst section 2|. Arc runner 29 comprises a rst section 23 arranged within arc chute I5 and parallel with section 2| lof arc runner I9 but spaced therefrom at the opposite side of the arc chute, and a second section 24 arranged in an acute angular relationship with respect to the rst section 23 and conductively connected thereto for transferring the other terminal of the arc from the movable arcing contact I I to the first section 23.

lfrom the arc runners in the general direction of the arc path. Trap means 25, 2B may, for example, comprise two arc chute end plates each having a pair of spaced members formed integral 'therewith and -arranged to extend substantially coextensve with the arc runner sections 22, 24 and spaced therefrom in the direction of the arc path. The spaced members of trap means 25, 26 inhibit the free ow of incandescent particles from the arc runners to the space surrounding the arc as it is being elongated and introduced into the barrier structure of arc chute I5. Fig. 1 illustrates members 29, 3| of trap means 25, 26 and Fig. 2 illustrates a portion of members 30, 3| of trap means 26. As illustrated in Fig. 2 members 30, 3| may be spaced apart from each other to provide a passage between members and along the arc runners I9 and 20 for the are to travel during its movement into and through arc chute I5.

The sections of arc runners I 9 and 2|) are preferably formed by relatively wide strips of metal rather than by a pair of narrowly spaced rails. Trap means 25, 26 conne the arc roots to the center portions of the arc runners thereby resulting in a better distribution of the thermal duty of the arc runners throughout the entire width thereof.

Arc chute side walls 32, 33 are preferably provided with downward extensions forming an enclosure 34 about the Contact structure to increase the chimney effect of the arc chute.

Individual barrier plates are separated a predetermined distance from each other by suitable separators, such as, for example, fg to inch diameter round braided asbestos rope packing 35 as illustrated in Fig. 2. The packing is covered with a suitable coating of cement to protect it from the disintegrating eilects of the arc and to unite the barrier plates into a unit.

Under normal interrupting conditions an arc is initiated immediately upon separation of the arcing contacts I0 and I I. The terminal ofthe arc on xed arcing contact Il) is driven over sections 22 and 2| of arc runner I9 toward the exhaust end o arc chute I5 by the magnetic blowout means and the thermal effect of the arc. As movable arcing contact II approaches its fully open position the other terminal of the arc jumps from contact I I to arc runner 20 and particularly section 24 thereof and is also driven by the blowout means and the thermal effect of the arc along sections 24 and 23 toward the exhaust end of arc chute I5.

Upon initiation of the arc and also during its movement along the arc runners I9 and 2i! emission of arc products including incandescent metal particles or other inorganic substances occurs which heretofore were jetted into the area surrounding the elongated arc. These incandescent particles reduce the dielectric strength of the air or other gas surrounding4 the arc, thereby increasing the possibility of reignition or restriking of the arc after it was extinguished. l

The tendency of the arc to stick to the arcing contacts or arc runners is greatest at, or immediately after, the time of initial contact separation. Obviously, the velocity of are propagation is zero at the time of initial contact separation and it takes time, however little that time may be, to move the larc roots away from the points on the arcing contacts where they are initially formed. Because of the time required to accelerate the motion of the arc roots along the arc runners, the region of worst gap contamination by arc products is that immediately adjacent the point of initial separation of the con tacts. It is, therefore, important that trap means 25 be arranged at or immediately adjacent this particular point. Likewise, trap means 25 is arranged at or immediately adjacent the point of initial arcing on arc runner 24.

The new improved trap means 25, 26 .being disposed immediately adjacent the point o f arc initiation, inhibit the free flow of the arcing. products from their source, namely the arc terminals, toward the zone occupied by the elongated arc. As the power current iiows through the arc, the arc products are emitted in all directions from the areas occupied by the arc terminals asr they move across the sections of the arc runners. By mounting the sections of trap means 25, 26 immediately adjacent the arc runners I9 and 2B in the manner described, the rate of Iiow of arc products into the space between the arc runners where there is potential danger of reignition and restriking is controlled. Reignition lusually occurs substantially along the path 'which the are `occupied previous to current zero andres'triking usually occurs in the are chute where the gap between the arc'runners is relatively short. Thus, the arc products :are coniined in the pockets formed between the arc runners and the members of trap means 25, 26 to preserve the vdielectric strength of the gases surrounding the -elongated arc to prevent reignition and res-triking.

Although but one embodiment of the present invention has been illustrated and described, it will be apparent to those skilled in the vart that various changes and modiiications may be 'made therein without departing from the spirit of the invention or from the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

l. An electric circuit interruptor comprising a pair of relatively movable cooperating arcing contacts, means for separating said contacts to initiate and elongate an arc therebetween, arc runners for transferring said arc from the region of arc initiation to a, region remote therefrom, said arc lrunners comprising a first sect-ion arranged substantially perpendicularly to the direction of relative movement of said contacts and spaced from the region of arc initiation and a second section arranged angularly with respect to said first section for transferring one terminal of said arc from the region of arc initiation to said rst section, and trap means arranged substantially coextensive with said second section for reducing the free flow of products of arcing from said second section in the general direction of the arc path.

2. An electric circuit interrupter comprising a pair of relatively movable cooperating arcing contacts, means for separating said contacts to initiate and elongate an arc therebetween, an arc runner for transferring said arc from the region of arc initiation to a region remote therefrom, said arc runner comprising a flat metallic member arranged angularly with respect to the direction of movement of the arcing contacts, and trap means comprising two fiat insulating members mounted substantially coextensive with said flat metallic member for inhibiting the free flow of products of arcing from said arc runner in the general direction of arc transfer, said insulating members separated from each other to provide a passagey for the are to travel along the arc runner between said insulating members in the direction of arc transfer.

3. An electric circuit interruptor comprising a pair of relatively movable cooperating arcing contacts, means for separating said contacts to initiate and elongate an arc therebetween, an arc chute for receiving the arc at one end thereof and exhausting the hot gases at the other end, arc runners for transferring said are from the region of arc initiation into said chute, said arc runners comprising a rst section arranged within said arc chute substantially perpendicularly to the direction of relative movement of said contacts and a second section arranged adjacent said arcing -contacts angularly with respect to said rst section for transferring one terminal of said arc from the region of arc initiation to said first section, and trap means comprising two flat insulating members mounted substantially parallel with said second section of said arc runners for inhibiting the free flow of products of arcing from said arc runners, said insulating members being .for thevarc to` travel along the arc runner between said insulating members in the direction of arc transfer.

4. An electric circuit interrupter comprising a pair of relatively movable cooperating arcing contacts, means for separating said contacts to initiate and elongate an are therebetween, an arc chute for receiving the arc at one end thereof and exhausting the hot gases at the other end, are runners for transferring said arc from the region of arc initiation into said chute, said arc runners comprising a first pair of sections mounted within said `chute and longitudinally thereof for transferring the terminals of the arc through at least a part of said chute, and a second pair of sections arranged adjacent said arcing contacts for transferring the terminals of the arc from the arcing contacts to said il'rst pair of sections, magnetic blowout means for driving the arc into said chute and toward the exhaust end thereof, and trap means comprising two pairs of flat insulating members.` each pair mounted substantially coextensive with one of said second pair of sections for collecting the products yof arcing from said arc runners, said insulating members of each pair being separated from each other to provide a passage for the arc to travel along said second pair of sections between said members in the direction of arc transfer.

5. An electric circuit interrupter comprising a pair of relatively movable cooperating arcing contacts, means for separating said contacts to initiate and elongate an arc therebetween, an arc chute comprising a pair of side Walls mounted for receiving the arc at one end thereof and exhausting the hot gases at the other end, arc runners for transferring said arc from the region of arc initiation into said chute, said arc runners comprising a first pair of sections mounted within said chute longitudinally thereof for transferring the terminals of the arc through at least a part of said chute, and a second pair of sections arranged adjacent said arcing contacts fortransfering the terminals of the arc from the arcing contacts to said first pair of sections, magnetic blowout means for driving the arc into said chute and toward the exhaust end thereof, and trap means comprising two pairs of flat insulating members attached to the said side walls of said arc chute, the insulating members of each pair being spaced apart from and mounted substantially coextensive with one of said second pair of sections for collecting the products of arcing from said arc runners, said insulating members of each pair being separated from each other to provide a passage for the arc to travel along said second pair of sections between said members in the direction of arc transfer.

6. An electric circuit interrupter comprising a pair of relatively movable cooperating contacts, means for separating said contacts todraw an arc therebetween, means including a pair of spaced are runners for transferring said arc from the region of initial contact separation to a region remote therefrom, and trap means arranged immediately adjacent the point of initial contact separation and extending along said pair of arc runners in the direction of are transfer for reducing the flow of products of arcing into the space between said arc runners.

I. An electric circuit interrupter comprising a pair of relatively movable cooperating arcing contacts, means for separating said contacts to initiate and elongate an arc therebetween, an

arcchute for receiving the arc at one end thereof and exhausting the hot gases at the other end, spaced insulating barriers mounted within said chute to extend transversely of the arc, one end .of said barriers being disposed adjacent the zone of arc initiation, an arc runner for transferring said arc from the region of arc initiation into said arc chute, said arc runner comprising a first section arranged relatively remote from the point of arc initiation and a second section arranged relatively close to the point of arc initiation, and 4trap means for reducing the free iiow of arc products in the direction of arc transfer comprising two fiat insulating members mounted substantially coextensive with said second section and two further fiat insulating members forming a part of one of said barriers and extending adjacent to and substantially coextensive with said first section.

8. An electric circuit interrupter comprising a pair of relatively movable cooperating contacts, means for separating said contacts to draw an arc therebetween, means including a pair of spaced arc runners for transferring said arc from the point of initial contact separation to a region being arranged adjacent the point of initial contact separation and coextensive with at least a portion of one of said pair of arc runners.

9. An electric circuit interrupter comprising a pair of relatively movable cooperating contacts, means Ifor separating said contacts to draw an arc therebetween, means including a pair of spaced arc runners for transferring said arc from the point 0f initial contact separation to a region remote therefrom, and means for reducing the flow of conductive products of arcing from said pair of contacts and said pair of arc runners into the space between said pair of contacts and said pair of arc runners, said iiow reducing means extending substantially from the point of initial contact separation to the points on said pair of arc runners forming the ultimate terminals of the arc.

10. An electric circuit interrupter comprising a pair of relatively movable cooperating contacts, means for separating said contacts to draw an arc therebetween, an insulating structure for lengthening and cooling said arc to cause extinction thereof, arc propelling means for transferring said arc from the point of initial contact separation into said insulating structure, said arc propelling means including means for producing a transverse magnetic field and a pair of spaced arc runners on opposite sides of said insulating structure, and means for reducing the flow of conductive products of arcing from said pair of contacts and said pair of arc runners into the space between said pair of contacts and, said pair of arc runners, said flow reducing means being coextensive with at least a portion of each of said pair of arc runners situated relatively close to said point of initial contact separation. A

11. An electric circuit interrupter comprising a pair of relatively movable cooperating contacts to draw an arc therebetween, a stack of spaced plates of insulating material having inverted V- shaped slots defining an are constricting groove, means including a pair of spaced are runners for f transferring said arc from the point of initial contact separation into said groove, each of said pair of arc runners comprising a slantingportion arranged relatively close to the open end of said groove and a portion substantially parallel to the piane of one of the end plates of said stack and arranged relatively close to the closedend of said groove, and means for trappingA and deionizing conductive products of arcing generated at the surface of said pair of contacts and at the surface of said pair of arc runners toireduce the quantity of said products entering the space between said pair of contacts and said pair of arc runners, said trapping means being arranged immediately adjacent said point of initial contact separation and coextensive with at least said slanting portion of each of said pair of arcrunners.

12. An electric circuit interrupter comprising a pair of relatively movable cooperating contacts,

d means for separatingr said contacts to draw an into the space between said arc runners.

PHILIP L. TAYLOR.

REFERENCES CITED Thefollowing references are of record in the iile of this patent:

` UNITED STATES PATENTS Number Name Date 1,944,403 Clerc 1 Jan. 23, 1934 `2,276,859 Nau Mar. 17, 1942 2,345,375 Bennett Mar. 28, 1944 2,436,189 Buehne Feb. 1'7, 1948 2,555,993 Opel et al June 5, 1951

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