US2623139A

US2623139A - Arc chute with trap for products of arcing

Info

Publication number: US2623139A
Application number: US177938A
Authority: US
Inventors: Donald E Weston
Original assignee: Allis Chalmers Corp
Current assignee: Allis Chalmers Corp
Priority date: 1950-08-05
Filing date: 1950-08-05
Publication date: 1952-12-23
Anticipated expiration: 1969-12-23
Also published as: GB692752A

Description

DeC- 23 1952 D. E. wEsToN ARC CHUTE WITH TRAP FOR PRODUCTS oF ARCINQ Filed Aug. 5, 195o /Arfvrrndrdva the zione of arc initiation.

Patented Dec. 23, 1952 ARO CHUTE WITH TRAP FOR PRODUCTS OF ARCING Donald E. Weston, Wauwatosa, Wis., assignor to Allis-Chalmers Manufacturing Company, Milwaukee, Wis.

Application August 5, 1950, Serial No. 177,938

8 Claims.

, This invention relates to circuit interruptingv devices and more particularly to -circuit breakers a magnetic blowout coil or an air blast, into an arc chute which is arranged to quench the arc by lengthening it, cooling it, or a combination of both.

The interruption of large 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 conned, 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 claimed a new andimproved circuit interrupting device is provided comprising relatively movable contacts which are actuated to initiate and elongate Aan arc therebetween. The arc as it is elongated is transferred from the zone of arc initiation to an arc chute zone suitable for arc extinguish- -m'ent. The arc chute is arranged to receive the arc at one end thereof and exhaust the hot gases at the other end thereof. A perforated insulating plate is arranged at least partly within the arc receiving end of thel arc chute adjacent the zone of-arc initiation to provide with an element of-the arc chute a passage communicating with a zone or region in the arc chute remote from The perforated insulating plate intercepts the products of arcing issuing from the zone of arc initiation, cools and deionizes the air carrying the products of arcing, and vents it to :another zone of the arc chute through the passage formed by the perforated insulating plate and the element of the arc chute.

It is, therefore, one object of the present invention to provide a new and improved arc inter- -rupting device in which the products of arcing are isolated from the arc stream to rapidly restore the dielectric strength of the air surrounding the arcing contacts.

Another object of the present invention is to provide a new and improved arc interrupting device in which the products of arcing are trapped immediately adjacent the region of arc initiation.

A further object of the present invention is to trap the metal vapors near the region of arc initiation, cool and deionize the surrounding air, and vent it back into the air stream at a point downstream of the region of arc initiation.

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

Fig. 1 is a view in vertical cross section of a magnetic blowout type circuit breaker employing the present invention;

Fig. 2 is an enlarged view in horizontal cross section of a portion of the embodiment illustrated in Fig. 1 taken along the line II-II;

Fig. 3 is a view in vertical cross section taken along the line III- III in Fig. 2; and;

Fig. e is a view in transverse cross section taken along the line IV-IV in Fig. 3.

Referring more particularly to the drawings by characters of reference, Fig. 1 illustrates a magnetic blowout type of circuit breaker including as elements thereof a pair of terminal studs 6 and l for connecting the circuit breaker to line conductors (not shown). Although in general, circuit breakers of the type considered in Figs. 1 to 4 are provided with a plurality of similar pole structures, one for each phase of a polypliase 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 type.

The circuit interrupter or breaker in Fig. 1 comprises essentially means for opening the circuit to form the interrupting arc and an arc extinguishing structure. Specifically, the circuit opening means comprises a fixed current carrying contact 8, a tertiary contact 9, a fixed arcing contact IU, and a movable arcing contact II. Arcing contact I I is mounted on a lever 28 which is pivctally mounted at I2 on an extension I3 of 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 mechanism (not shown) for operating the movable contact between closed and open circuit positions. Fig. 1 illustrates the movable contact il in closed position. The arcing contacts are electrically -connected to the lower ends of terminal studs 6 and '1. Accordingly, when the reaker is connected in series in a power circuit and the arcing contacts are separated, an arc may be initiated across the gap formed between the contacts. y

For the purpose of interrupting this power arc, an arc extinguishing structure, such as an arc chute it, may be mounted so as to receive the power are which is under the influence of the magnetic blowout means. The arc chute preferably is disposcd directly about and above the arcing contacts, as shown, when the blowout means act upward, but may be mounted in any other suitable location when the blowout means act in other directions. The switch or arcing contacts and the magnetic blowout structure can assume any preferred form so that a brief description thereof will be sumcient. The magnetic blowout may comprise a core Il, poles I8, and a coil It which is electrically connected to the terminal stud 'I and to a metallic are runner I3 so that the arc current (as the arc travels along the runner) flows through ther blowout coil in a manner well known in the art.

Normally the current is carried in the closed circuit position of the breaker by the spring biased contact 8. As the movable arcing Contact I I is actuated to open circuit position, current is shunted from xed contact 8 first to fixed contact 3 and afterwards to fixed arcing contact Ill. As the arc is drawn by the movable arcing contact II, the arc terminal of arcing contact I is transferred to arc runner I3, which is usually an extension arm of the fixed arcing contact I0. As the movable arcing contact II approaches or reaches its full opening stroke the arc terminal transfers from the movable arcing contact II to an arc runner 25 which directs the arc in the arc chute I5. The arcing contact I0 and the arc runner I9 are electrically connected in series with the blowout coil I and stud i. Accordingly, the

blowout coil is already energized at the inception :i

of the arc to influence the arc in a well known manner, i. e. to drive it in the arc chute I5 in an expanding loop. It will be apparent to one skilled in the art that the blowout field can be utilized in the most efiicient manner by disposing the iron poles I8 so as to cooperate with the blowout coil in the conventional manner outside ofthe arc chute.

In accordance with the invention a pair of insulating perforated plates 23 (clearly illustrated on an enlarged scale in Figs. 2 to 4) are arranged to extend within the arc receiving end of chute I5 to capture the incandescent particles emitted in the Zone of arc initiation. Each perforated plate 23, which may be made of a ceramic material, is spaced a suitable distance apart from a different one of a pair of insulating members 2| and 22 by spacers 3 I. Insulating members 2| and 22 in turn are secured to support

members

21 and 23, which are mounted adjacent side walls 25 and 26 defining arc chute I5. Perforated plates 23 and insulating members 2| and 22 provide a pair of passages 30. Passages 35 are provided for bypassing air largely stripped of are products around at least the zone of arc initiation. Plates 23 are arranged substantially parallel to the path of' contact movement and on opposite sides of the arcing contacts.

The majority of the perforations of plates 23 are concentrated near to the stationary arcing contact I0 for providing not only rapid venting of the arcing Zone at the time of initial contact separation but, in addition, effective deionization of the vented air by surface action of the perforations. countersunk on the side of the plate nearest the arcing contacts to further increase the total surface area exposed to the air for deionization purposes.

End sections 32 and 34 of perforated plates 23 Each perforation or hole 24 may be are spaced from arc runners I3 and 20 and arranged substantially coextensive with sections thereof for providing a predetermined path along the arc runners for the movement of the arc.

Perforated plates 23 thus provide passages 30 which are each completely open on its top, bottom and sides. Immediately above the perforated plates 23 and Within the exhaust zone of chute I5 is mounted a plurality of barrier structures 33 which further elongate and cool the arc if it is not extinguished before reaching that point.

Under normal interrupting conditions an arc is initiated immediately upon separation of the arcing contacts` I0 and II. The terminal of the arc on fixed arcing contact IU is driven over arc runner I3 toward the exhaust end of arc chute I5 by the magnetic blowout means and the thermal effect of the arc. As movable arcing contact I I nears its fully open position the other terminal of the arc jumps from Contact I to arc runner 20 and is also driven by the blowout` means and the thermal effect of the arc toward the exhaust end of arc chute I5.

Upon initiation of the arc and also during its movement along the arc runners I 9 and 20, 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 surrounding thearc, thereby increasing the possibility of electric breakdown of the circuit breaker or at least restriking of the arc after it was extinguished.

The new and improved trap passages formed by perforated plates 23 and members 2|, 22 of arc chute I5, however, reduce the freeow of the arcproducts from their source, namely the arc terminals, toward the zone or region occupied by the elongated arc. As the power current iiows through the arc, the arc productsare emitted in all directions from the areas occupied by the arc as it moves from the arcing contacts and along the arc runners. By arranging the perforated plates immediately adjacent the zone of arc'initiation in the manner described, the arc products are confined, cooled and conveyed by plates 23 into passages 3Il. In such passages thearc productsv are trapped and separated from the hot ionized air displayed by the occurrence ofthe arc. The air is cooled and deionized byplates 23 and is directed through passages 30 toward a space 35 confined between barrier structures 33, which forms a part of the exhaust zone ofthe chute. In space 35 the cooled' air is mixed by the gases surrounding the` arc to help to cool and deionize the arc zone. The dielectric strength of the gases surrounding' the contact structureis restored, thus preventing breakdown of the gap in the contact region because of reionization of the zone of arc initiation by arc products.

Although but one embodiment of the present invention has been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications 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 Patent:

l. [in electric circuit interrupter comprising a pair of relatively movable cooperating :arcing contacts, means for separating said c-ontactsto initiate 'and elongate an -arc therebetween, and an arc chute for receiving the arc at oneend secure by Letters thereof andexhausting the hot gases at the other end thereof, said arc being drawn 'by said contacts transversely of the longitudinal axis of said chute, said chute comprising means for trapping products of arcing from the ,zone of arc initiation and venting air stripped of said products of varcing to a different zone within said chute remote 4from said zone of larc initiation.

2. An electric circuit interrupter comprising a pair of relatively movable cooperating arcing contacts, means for separating s-aid contacts to initiate and elongate an ar-c therebetween, and an arc chute for receiving the arc at one end thereof and exhausting the hot gases at the other end thereof, said chute comprising a perforated insulating plate mounted within the arc receiving end of said chute adjacent the zone of arc initiation for dividing the arc receiving end of said chute into an arc conducting passage and la tributary passage for receiving the products of arcing, said tributary passage being arranged to trap the products of -arcing and to vent gases stripped of said products of arc-ing back into said arc conducting passage at -a point near the exhaust zone of sai-d chute.

3. 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, and an arc chute for receiving the arc at one end thereof and exhausting the hot gases at the other end thereof, said arc being drawn by said contacts transversely of the longitudinal axis of said chute, said chute comprising a perforated ceram-ic plate mounted within the arc receiving end 'of said chute near the zone of arc initiation and extending longitudinal to the direction of relative movement of said contacts for dividing the arc receiving end of said chute into an arc conducting pas- Sage Iand a tributary passage for receiving the products of arcing, said plate effectively deionizing the products of arcing and providing a means for venting through said tributary passage the gases stripped of said products of ar-cing back into said arc conducting passage at a point near the exhaust zone of said chute.

4. An electric circuit interrupter comprising a pair of relatively movable cooperating arcing contacts, means for separating said contacts to initiate and elongate an ar-c therebetween, and an `arc chute for receiving the arc at one end thereof Iand exhausting the hot gases at the other end, said chute comprising a pair of side walls and a pair of perforated ceramic plates mounted Within the arc receiving end, said plates extending on opposite sides of the path Vof contact movement and substantially parallel thereto to form between said plates an arc conducting passage, said plates forming within the said side walls of said chute la pair of auxiliary passages for bypassing at least the zone of larc initiation and merging With said arc conducting passage in the exhaust zone of said chute, the perforations of said plates being :arranged to trap, cool and convey the products of arcing from the zone of arc initiation into said auxiliary passages.

5. An electric circuit interrupter comprising a pair of relatively movable cooperating arcing lcontacts, means for separating said contacts to initiate and elogate an arc therebetween, ya pair of side walls defining an arc chute for receiving the arc at one end thereof and exhausting the hot gases at the other end, arc runners for aiding the movement of said arc in said chute, magnetic blowout means' for driving. the are in-saidchute toward the exhaust endthereof, and trap means comprising a pair of insulating perforated plates mounted to extend within said chute, said plates 'being arranged on opposite sides of the path of -.said arc conducting passing in the exhaust zone of said chute, the perforations of 'said plates being arranged to cool and convey the products of varcing from the zone of arc initiation to said lauxiliary passages, said plates comprising end sections which are arranged substantially coextensive with sections of s-aid arc runners for providing predetermined paths along said arc xrunners for movement of the arc.

6. 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, and an arc chute for receiving the arc at one end thereof and exhausting the hot gases at the other end thereof, said chute comprising means for dividing the arc receiving end of said chute into an arc conducting passage and an auxiliary passage for receiving the products of arcing, said dividing means 'being provided with a plurality of perforations near the zone of arc initiation for venting the products of arcing from said zone into said auxiliary passage, said auxiliary passage venting said gases stripped of said `arcing products back into said arc conducting passage in another zone within said chute remote from said zone of arc initiation.

7. 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, and an arc chute for receiving the arc at one end thereof and exhausting the hot gases at the other end thereof, said chute comprising a perforated insulating pla-te mounted within the arc receiving end of said chute near the zone of arc initiation and extending substantially longitudinally of the direction of relative movement of the arcing contacts for providing an arc conducting passage and an auxiliary passage bypassing at least said zone of arc initiation and merging with said arc conducting passage in the exhaust rone of said chute.

` the perforations of :said plate being arranged to trap, cool and convey the products of arcing to lsaid auxiliary passage, said auxiliary passage venting said gases stripped of said arcing products into said arc conducting passage at a point remote from the zone of arc initiation.

8. 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, a pair of :side walls defining an are chute for receiving the plates, being arranged to trap, cool and convey UNITED STATES PATENTS.

the productsA of arcing from the zone of are ini- Number Name Date tiation to said auxiliary passage, said auxiliary 1 944 403V l Chamv Jan 23 1934 passage venting said gases strippedof said arcing 234537'5 f Bennegt; Mar.; 28 1944 products into said arc conducting passage in a 5 2450727 Atwood et a1. n Feb 1,1949 zone within said chute remote from said zone of 5551993 Oppel et aL Jun 5; 1951 arcxnitiation. 2,570,610 Taylor Oct. 9, 1951 DONALD E. WESTON.

FOREIGN PATENTS REFERENCES CITED 10 Numberk Country Date The following references ae of record in the 403,068 Germany Sept. 26, 1924 le of this patent: 649,237 Germany Aug. 21,1937