US2450268A - Circuit breaker - Google Patents

Description

Sept. 28 1948. c. E. BAzLEY CIRQUIT BREAKER P11edAug-5o, 194s Inventor: Caf! E. B

ley. b Y His Attorney.

Patented Sept. 28, 1948 t CIRCUIT BREAKER CarlE. Bazley, Schenectady, N. Y., assigner to General Electric 'Com New York pany, a, corporation of Application August 30,v 1945, Serial No. 613,462

1 claim. l

My invention relates to circuit breakers, more l particularly to'electrom/agnetically operated circuit breakers of the type known as contactors, and has for its object a simple, reliable and low cost arc extinguisher means for directcurrent contactors.

In carrying out my invention in one form I provide an enclosure made of electrically insulating material for the switch contacts, one wall of which is mounted adjacent the station-ary contact and provided withV a curved surface for defiecting an arc formed between the contacts to obtain rapid cooling and extinguishment of the arc while at the same time offering the least possible interference with the movement of the arc and without 'elongation or compression of the arc. This curved surface, which-is preferably arc-v uate, begins at a point immediately adjacent the stationary contact surfacey and extends away from the stationary contact and in the direction of movement of the movable contact, thereby to deiiect the arc substantially at right angles. It moreover extends crosswise of the arc chute enclosure in a direction at right angles to the plane of movement of `the movable contact.

For a more complete understanding of my invention, reference should be had to the accompanying drawing, Fig. 1 of which is a front elevational vlew of a. contacter embodying my invention; Fig. 2 is a sectional view taken along the line 2--2 of Fig. 1 looking in the direction of the arrows; Fig. 3 is a plane view of the device shown in Fig. 1, while Fig. 4 is an exploded view of the parts forming the contact enclosure and the guiding means for the arc.

Referring to the drawing, I have shown my invention in one form as embodied in a two-circuitl or two-pole contactor having a separate enclosure means for each pole. 'The separate switching means and enclosure means l and 2 for the two poles are identical in construction and therefore only one will be described in detail, this one being the switch means and enclosure 2.

In the form shown, the movable contacts are pivoted and are mounted on the ends of -arms secured to an operating shaft 3 mounted at its opposite ends on bearings, one of which, 4, is shown in the drawing, the bearings being mounted on supports or pedestals secured to a supporting plate member 5 made of molded electrically insulating material, which member 5 is in turn secured to a panel support 8. The pedestal bearing support 1 for the bearing for the left-hand end of the shaft 3, as seen in Fig. 1,*is shown in Fig. 2. By means of the pedestals, the shaft is (Cl. 20o-144) 2 mounted in spaced parallel relation with the plate support 5.

As shown in Fig. 4, for the purpose of increasing the current carrying capacity of the circuit breaker and rate of cooling of the arc, two electrically connected movable contacts! and i are provided for each pole, these two contacts being mounted on the ends of flexible, electrically conducting, springarms i0 and Il which are electrically Joined together by a base connecting portion i2 arranged to be secured by suitable screws I3 to an intermediate portion of the shaft l having a square cross section. On the opposite face of the square portion of the shaft is secured by the screws Iii-a. member i4 having two relatively rigid arms which extend along the rightL-hand side or below the two switchvarms I0 and Il, as seen in the drawing, and engage the switch arms at intermediate points as indicated in Fig. 2. These rigid arms assure forcible separation of the contacts in case the contacts should become welded together.-

Also, the rigid arms create a substantial initial contact pressure by reason of the fact that the spring arms I0 and Il are biased by their own resiliency against the rigid arms. As shown in Fig. 4, the movable contacts I and 9 of each pole cooperate respectively lwith stationary contacts l5 and i6l on the ends of spaced apart U-shaped arms, the opposite ends of the arms being integrally' secured to an electrically conducting supporting member l1 which in turn is secured by screws I8 to the supporting block i.

y Also secured by the screws Il against the outer or left-hand side of the support I1 is p. rectangular positioning base or plate i9, the purpose of which willtbe described hereinafter. A

For the purpose of guiding an arc formed between the contacts so as to facilitate its cooling and extinguishment, I provide blocks 2| and 22 adjacent the outer or upper ends of fthe stationary contacts, these blocks having each an arcuate curved surface perpendicular tothe plane of movement of the movable contact as indicated by the curved surface 23 on the block 22.

Preferably, as shown in Fig. 4. the two blocks 2i and 22 are secured on opposite sides of a. partition wall member 24 which is removably inserted between the contacts of each pair, the partition Wall 24 and the blocks 2l and 22 being molded integrally from a heat refractory electrically insulating material having good heat conductivity.

preferably an inorganic compound, such as 'a 'coldJ molded mixture of asbestos and Portland cement. As shown in Fig. 2, the plate 24 is inserted from,

left to rightl between the arms I3 and ll and between the corresponding two arms supporting the stationary contacts, thereby to isolate from each other the two arcs formed upon separation of the two pairs of contacts. The right-hand edge of the plate 24 extends into a groove provided for it in the block l. while a portion at the top of the right-hand edge is cut away flush with the righthand wallsof the members 2i and 22 which engage the member I9. The plate i3 serves accurately to position the blocks 2| and 22 so that the arcuate arc deflected surfaces 23 are immediately adjacent the upper ends or extremities of the stationary contacts. A molded cover member 2l nts over the two pairs of contacts for each pole and the shaft 3 onto the plate fthus forming two arc chambers separated by the partition wall 2l. The cover, as well as the plate 3, is made from the heat refractory electrically insulating material referred to above. Grooves 23 and 21 are formed in the inner walls of the cover to receive the lefthand and top edges of the plate 24, thereby to secure the plate in position, while the lower end of the plate terminates above the shaft 3.

It will be observed that the arcuate curved surface 23 on the block 22 forming part of the wall of the arc chamber begins at its right-hand or lower end, as seen in Fig. 2. at a point adjacent the upper or outer end of the stationary contact I3, but somewhat below or to the right of its contact face to reduce burning of the block 22 by the arc. The arcuate surface extends upward away from the upper end of the contact i3 and toward the left-hand in the direction oi' the movement of the movable contact. Also, the curved surface 23 extends transversely at right angles with the plane of movement of the contact 3, across the arc chamber space between the plate 24 and the adjacent side wall of the cover 23. The surface 23 is at all points arcuate in s ome plane parallel with the plane of movement of the movable contact 3. Its radius of cunvature in a typical contactor, as shown in the drawing. was substantially equal to the length of the contact 3 or I4.

Preferably the cover member 23 is provided with an elongated aperture 23 for the escape of air and other gases heated or formed by the are. This opening 23 is provided with a munie 23 extending over it consisting of three substantially semi-cylindrical plates secured together at their ends by end plates. These members are each provided with one or more rows of apertures extending lengthwise of the opening 23, -the apertures in the respective members, however, being in staggered relation with each other.

For the operation of the contactor I have shown shockproof electromagnetic operating means such as described and claimed in copending applicaton of Chester I. Hall filed October 22, 1945, Serial No. 623,650, assigned to the same assignee asthis application.

' This mechanism comprises a rectangular magnet frame 33 provided with a coil 3| and a plunger armature 32. On the lower end of the armature is a -r'ack 33 which engages with a pinion 34 o'n a shaft 33. Also secured to the shaft 3l is a crank 33, the end of which is connected by a link 31 -to the lower end of a pivoted operating arm 33. A second weight counterbalancing rack 33. provided with guides for slidable movement, is connected to the pinion 34 whereby the operating parts and armature are balanced about the axis of the shaft 3l. The upper end of the operating lever- 33, which lever is mounted on a pivot 43, is connected by a link 4| toa crank arm 42 secured on the left-hand end of the shaft 3. As shown. a second crank arm 43 is provided' which is secured on the end of the operating shaft for the mechanism I, this shaft being in alignment with the shaft 3. The crank arms 42 and 4-3 are made of electrically insulating material and the link 4I is positioned between them and secured to them by a pivot pin.

In the closing of the switch when the coil 3l is energized, the plunger armature 32 is moved from its deenergized position shown in Fig. 2 to its raised position whereby the crank 33 is turned clockwise substantially 180 degrees to its opposite dead center position with respect to the link 31. This movement of the crank 34 turns the arm 33 clockwise about its pifvot 4I whereby the link 4l is moved to turn the operating shaft 3 on which the movable contacts are mounted, whereby the switch is closed. The turning movement of the shaft 3 is somewhat greater than just necessary to produce engagement between the contacts whereby after engagement of the contacts the spring contact arms I3 and Il are bent and the movable contacts thereby caused to roll downward on the stationary contacts whereby the circuit is maintained closed through different engaging portions of the contacts than the portions through which the circuit is rst closed. It will be noted that the stationary and movable contacts are of curved cross-sectional configuration with upper portions of their engaging surfaces extending toward each other. Thus the contacts first engage each other at their upper tips during the closing of the switch. Thereafter, the mov- I able contacts roll downward on the stationary contacts as the spring arm i I is stressed to give a wiping action. During the opening of the switch upon deenergization of the coll 3|, which is effected by the spring 44 connected to the rack 33, the reverse action takes place, so that the contacts are always separated at their upper extremities.

Upon separation of the fixed and movable contacts any arc between them is drawn at the extreme upper ends of the contact surfaces. The configuration of the contacts and the resilient mounting of the movable contacts ensures an upward rolling disengagement such that the contacts tlnally separate at their upper extremities. Als soon as the arc elongates, it flows naturally and freely onto the curved defiecting surface 23 of the associated block 2i and 22, by reason of the close proximity of the deflecting surface to the upper extremity of the tip of the stationary contact. The surface 23 turns ordefiects the arc and causes the arc to take a path substantially at right angles toits initial path. This defiecting or guiding action of the curved surface brings the arc into intimate thermal relation with the block 22, whereby the heat of the arc is transmitted very rapidly to the block-22 and also to the side walls formed by the partition member 24 and the cover member 25. This resuits in a very rapid cooling and extinguishment of the arc. At the same time, curved surface 23 cuers the least possible interference with the movement of the arc and provides for a free movement of the arc ,with a minimum of turbulence of the gasses surrounding the contacts.

By reason of the'fact that the crank 33 is in a dead center position in the open and closed positions of its switch, the crank serves to secure the mechanism against false operation as a result of the heavy shock. Moreover, the weight-balancing rack 39 further makes the moving parts free from the effects of shocks.

As shown, the electrically conducting support Il projects upward outside the cover 21 and serves as an electric connection for connecting the circuit breaker in an electric circuit. A second electric connection for the movable contact is provided by means of a exible electric conductor I5 having one end electrically connected to the base connecting portion I2, as by means of the screws i3 and its other end extending through a' notch 46 at the lower edge of the cover 25 and connected to the connector screw I1.

While I have shown a particular embodiment of my invention it will be understood of'course that I do not wish to be limited thereto since many modifications may be made and I therefore contemplate by the appended claim to cover any such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

A circuit breaker comprising a supporting member made of electrically insulating material, a pair of fixed contact members electrically connected together and mounted upon said supporting member in a spaced relation, a pair of movable contact members electrically connected together and pivotally mounted in spaced relation for cooperation with said iixed contact members respectively, said `movable contact members being supported upon resilient cantilever spring fingers and said xed and movable contact members having engaging surfaces curved to provide rolling engagement and reverse rolling disengagement of said ilxed and movable contact membersiand to effect iinal disengagement of said contact members always at a predetermined extremity thereof, a partition wall of electrically insulating material positioned between the cooperating pairs of iixed and movable contact members; a pair of arc deilecting members of electrically insulating material supported on opposite sides oi' said partition wall and each having a concave arcuate surface extending from said extremity of the associated ilxed contact member away from said iixed contact member and inthe direction of movement of said movable contact members, and a cover made of electrically insulating material mounted upon said `supporting member and enclosing said contact members and said partition wall thereby to form separate arc extinguishing enclosures for said pairsfof cooperatingcontact members.

CARL E. BAZLEY.

REFERENCES CITED The following references are of record in the ille of this patent: I l

UNITED STATES PATENTS Number Name A Date 1,022,049 Reisbach Apr. 2, 1912 1,244,224 McRae, et a1 Oct. 23, 1917 1,503,981 CarichoiI Aug. 5, 1924 2,249,499 Seaman July 15, 1941 2,291,466 Goldberg July 28, 1942 2,318,488 Hunter, et al May 4, 1943

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