US2596865A

US2596865A - Arc chute utilizing staggered u-shaped conductive members

Info

Publication number: US2596865A
Application number: US171843A
Authority: US
Inventors: Charles R Peter
Original assignee: Allis Chalmers Corp
Current assignee: Allis Chalmers Corp
Priority date: 1950-07-03
Filing date: 1950-07-03
Publication date: 1952-05-13
Anticipated expiration: 1969-05-13

Description

May 13, 1952 c. R. PETER 2,596,865

ARC CHUTE UTILIZING STAGGERED U SHAPED CONDUCTIVE MEMBERS Filed July 3, 1950 Patented May 13, 1952 ARC CHUTE UTILIZING STAGGERED U-SHAPED CONDUCTIVE MEMBERS Charles R. Peter, Wauwatosa, Wis., assigner to Allis-Chalmers Manufacturing Company, Milwaukee, Wis.

Application July 3, 1950, Serial No. 171,843

4 Claims. 1

This invention relates in general to electric switching devices and in particular to electric arc extinguishing means for such switching devices.

It is a principal object of this invention to provide an improved arc extinguishing structure in which series connected arcs are successively drawn between a plurality of arc extinguishing members.

It is an additional object of this invention to provide an are extinguishing structure in which series connected arcs are successively drawn and the series arcs are confined within a portion of the arc extinguishing structure,

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

Fig. l is a side view of a switching device embodying the present invention;

Fig. 2 is an enlarged sectional view through the arc chute of the device illustrated in Fig. 1;

Fig. 3 is a sectional view taken along line III-III of Fig. 2; and

Fig. 4 is a development View looking in the direction of arrow IV of Fig. 2.

Referring to Fig. 1, a switching device embodying the present invention comprises a pair of relatively movable current carrying contacts II, I2 between which an arc may be formed upon separation thereof. Contact II is connected through a curved conductive bar I3 to a terminal stud I4, while contact I2 is connected through a conductive member I5 and a ilexible lead IB to a terminal stud I1. Studs I4, I1 represent connections to a circuit which the device is to interrupt. y The xed contact assembly is supported on a suitable insulating base I8 through stud I4. Secured to bar I3 is a U-shaped bridging member 28 of laminated magnetic material which cooperates in a well known manner with bar I3 to form a blowout assembly for impelling the arc formed upon separation of contacts II, I2 into the arc extinguishing chute. This blowout assembly may be dispensed with if the heat generated by formation of the arc provides sufficient impelling force to blow the arc into the chute.

Contact I2 is movable into and out of engagement with contact II by movement imparted to a shaft 29. Shaft 29 is journaled in brackets 3I secured to base I8 by screws 32 and is given rotational movement by suitable actuating means (not shown) such as an electromagnet. Clockwise rotation oi shaft 29 moves contact I2y in a clockwise direction from the position shown to separate contacts II, I2 and form an arc therebetween.

As shown in Figs. 2 4, the arc chute 4I comprises a pair of spaced

side walls

42, 43 located on opposite sides of the path of movement of the arc. Chute 4I is provided with an intermediate section 44 adjacent contacts Il, I2 wherein the arc is formed and an exhaust section 45 between the top portions of

side walls

42, 43.

End members

46, 41 maintain the proper spacing between

side walls

42, 43 and serve to conne the arc within the chute 4I. The arc chute assembly is rigidly secured together by bolts 43 and nuts 49 extending through

side walls

42, 43 and

end members

46, 41.

An insulating member 5I is disposed midway between

side walls

42, 43 and extends substantially parallel to

walls

42, 43.

Recesses

52, 53 are provided in

end members

46, 41 respectively. to receive the ends of member 5I. Two pluralities of U-shaped conductive members 54a through 54f andy 55a through 55j are secured to

side walls

42, 43 and form two rows disposed in the general lengthwise direction of the arc, the row of members 54 being staggered with respect to the row of members 55. Members 54, 55 may be made of any suitable heat resistant conductor such as steel or brass. As indicated on a representative conductive member 54j in Fig. 2, each conductive member comprises a pair of spaced leg portions 56, 51 extending in the general direction of movement of the arc and a curved portion 58 joining leg portions 56, 51 in the intermediate section of the chute.

Members 54, 55 abut their respective side walls along an edge extending from the bight of the U to the exhaust section of the chute. Some of the conductive members 54, 55, and preferably all of them, increase in depth in a direction perpendicular tothe direction of movement of the arc and to the lengthwise direction of the arc, i. e., away from the side walls to which they are secured and toward the insulating member 5I, from the bight of the U, and are adjacent to or abut the insulating member 5I in the exhaust section of the chute. This increase in depth of members 54, 55 forms edges 6 I, as shown in Fig, 3, upon which the varc impinges during its movement in chute 4I. As shown in the drawing, members 54, 55 may be set in recesses 62 in their

respective side walls

42, 43, and if members 54, 55 abut insulating member 5I in the exhaust section of the chute, recesses 63 may be provided in member 5I to receive the abutting ends.

The arc chute assembly is detachably mounted with respect to contacts II, I2 by any suitable known means (not shown) to provide easy removal for replacement or repair.

Upon separation of contacts II, I2, an arc is formed therebetween in the intermediate section 44 of chute 4I. The heat generated by this arc impels the arc upwardly in the chute and the blowout assembly described above furnishes additional impelling force. The are in moving upward rst impinges on conductivemember 55a between contact I I and member 55a, and as contact I2 continues to move, the arc is extended until it impinges on member 55h. At this time the arc will exist in the form of a short arc between contact I I and member 55a, another short arc between adjacent leg portions of adjacent members 55a, 55h, and another short arc between member 5519 and contact I2. Continued movement of contact I2 causes the arc to successively impinge on the succeeding

conductive members

55C, 55d, 55e, 55j, thereby successively drawing a plurality of short arcs between adjacent leg portions of adjacent conductive members 55.

As these short arcs move toward the exhaust section of the chute, the distance between adjacent leg portions of adjacent members 55 increases, thereby progressively increasing the resistance of the air gaps through which the short arcs must travel and hence reducing the magnitude of the arc current and hastening the extinction of the arc. In addition, the arc current ilowing in conductive members 55 meets a path of continually increasing resistance as the short arcs move in the chute, owing to the increasing distance in the conductive members through which the arc current must flow. This increasing resistance further progressively reduces the arc current and thereby further speeds the extinction or" the arc.

The plurality of short arcs continue to travel in chute 4I, encountering paths of progressively increasing resistance, until the arcs are extinguished in the exhaust section of the chute.

Although in the above described operation of the arc chute, it was assumed that the arc impinged on member 55a upon separation of contacts II, I2, it will be readily apparent that the arc might impinge on member 54a upon separation of the contacts and then be caused to successively impinge on members 54h, 54o, 54d, 54e, 54j, without changing the principle of operation of the arc extinguishing means.

Insulating member 5I serves to separate members 54 from members 55 and thereby confine the short arcs between either adjacent members 54 or adjacent members 55.

Members 54 are staggered with respect to members 55 to provide a maximum arc extinguishing effect regardless of the size of the arc current. When the interrupted current is of suincient magnitude, the resultant are will produce a region of conductive gas extending around insulating member 5I and in contact with both rows of members 54, 55. If members 54, 55 were aligned with each other, there would be no increase in the number of series arcs obtained in the chute with a current of this magnitude with respect to the number of arcs obtained with smaller currents. However, when members 54, 55 are staggered with respect to each other, as shown, if the arc current is of sufficient magnitude to produce an arc extending between staggered members 54, 55, around member 5I, the arc current must ow in a zigzag path between leg portion of members 54 and leg portions of members 55, thereby nearly doubling the number of series arcs with respect to the number of series arcs which would be available if members 54, `55 were aligned. Also, the staggered relation of members 54, 55 insures that there is no point throughout the length of the arc at which the arc does not encounter a U-shaped short circuiting member, 54, 55, thereby insuring that the arc impinges on a conductive member shortly after being drawn.

Although but two embodiments of the invention have been shown and described, it will be apparent to those skilled in the art that various 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 secure by Letters Patent:

l. Means for extinguishing an electric arc movable in a predetermined general direction comprising an arc chute provided with a pair of spaced side walls located on opposite sides of the path of movement of said arc and having an intermediate section wherein said arc is formed and an exhaust section, an insulating member disposed between said side walls in said exhaust section and extending parallel to said side walls, and a plurality of U-shaped conductive members on which different portions of said arc successively impinge, said members being secured to said side walls and forming two rows disposed in the general lengthwise direction of said arc, the members of one of said rows being staggered in said lengthwise direction with respect to the members of the other of said rows, each said conductive member comprising a pair of spaced leg portions extending in the general direction of movement of said arc and having a curved portion joining said leg portions in said intermediate section to form a U, the said conductive members secured to one of said walls abutting said one wall in said intermediate section and increasing in depth from the bight of said U in a direction toward said insulating member and abutting said insulating member in the exhaust section of said chute.

2. Means for extinguishing an electric arc movable in a predetermined general direction comprising an arc chute provided with a pair of spaced side walls located on opposite sides of the path of movement of said arc and having an intermediate section wherein said arc is formed and an exhaust section, an insulating member disposed between said side walls in said exhaust section and extending parallel to said side walls, and a plurality of U-shaped conductive members on which different portions of said arc successively impinge, said members being secured to said side walls and forming two rows disposed in the general lengthwise direction of said arc, the members of one of said rows being staggered in said lengthwise direction with respect to the members of the other of said rows, each said conductive member comprising a pair of spaced leg portions extending in the general direction of movement of said arc and having a curved portion joining said leg portions in said intermediate section to form a U, the said conductive members secured to one of said walls abutting said one wall in said intermediate section and increasing in depth from the bight of said U in a direction toward said insulating member.

3. Means for extinguishing an electric arc movable in a predetermined general direction comprising an arc chute provided with a pair of spaced side walls located on opposite sides of the path of movement of said arc and having an intermediate section wherein said arc is formed and an exhaust section, an insulating member disposed between said side walls in said exhaust section and extending parallel to said side walls, and a plurality of U-shaped conductive members on which different portions of said arc successively impinge, said members 'being secured to said side walls and forming two rows disposed in the general lengthwise direction of said arc, the members of one of said rows being staggered in said lengthwise direction with respect to the members of the other of said rows, each said conductive member comprising a pair of spaced leg portions extending in the general direction of movement of said arc and having a curved portion joining said leg portions in said intermediate section to form a U, each said conductive member abutting one of said side walls in said intermediate section and increasing in depth from the bight of said U in a direction toward said insulating member and abutting said insulating member in the exhaust section of said chute.

4. Means for extinguishing an electric arc movable in a predetermined general direction comprising an arc chute provided with a pair of spaced side walls located on opposite sides of the path of movement of said arc and having an intermediate section wherein said arc is formed and an exhaust section, an insulating member disposed midway between said side walls in said exhaust section and extending parallel to said side walls, and a plurality of U-shaped conductive members on which different portions of said arc successively impinge, said members being secured to said side walls and forming two rows disposed in the general lengthwise direction of said arc, the members of one of said rows 'being staggered in said lengthwise direction with respect to the members of the other of said rows, each said conductive member comprising a pair of spaced leg portions extending in the general direction of movement of said arc and having a curved portion joining said leg portions in said intermediate section to form a U, each said conductive member abutting one of said side walls in said intermediate section and increasing in depth from the bight of said U in a direction toward said insulating member and abutting said insulating member in the exhaust section of said chute.

CHARLES R. PETER.

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

UNITED STATES PATENTS Number Name Date 2,353,729 Jensen July 18, 1944 2,356,040 Ellis et al. l Aug. 15, 1944 2,408,352 'Iitus Sept. 24, 1946 2,446,027 Scott, Jr July 27, 1948