US2788421A - Circuit breaker contact structure - Google Patents

Description

April 9, 1957 c. L. JONES 2,788,421

CIRCUIT BREAKER CONTACT STRUCTURE Filed May 12, 1953 2 Sheets-Sheet l Fig.l. 23 23 I H WITNESSESI INVENTOR {.42 7 .91367.

ATTORN Charles L. Jones.

April 9, 1957 c. L. JONES 2,788,421

CIRCUIT BREAKER CONTACT STRUCTURE Filed May 12, 1953 2 Sheets-Sheet 2 Fig.2.

w :22 67 45 :46 52 BI 65 INVENTOR Charles L. Jones.

CATTORN Charles L. Jones, Beaver, Electric Corporation, tion of Pennsylvania Application May 12, 1953, Serial No. 354,553 9 Claims. (Cl. 269-166) Pa., assignor to Westinghouse East Pittsburgh, Pa, a corpora- This invention relates to circuit breakers and more particularly to contact structures for air circuit breakers.

This application is a continuation-in-part of my copending application Serial No. 305,334, filed August 20, 1952, now abandoned, and assigned to the assignee of the instant application.

An object of the invention is to provide a circuit breaker embodying an improved contact structure of rugged construction and reliable in operation.

Another object of the invention is to provide a circuit breaker having an improved contact structure in which the moving contact is loosely mounted on the movable switch arm and is provided with means for preventing lateral tilting movement of the moving contact.

A further object of the invention is to provide a contact structure which is compact and small in size for its rather large current rating, and thereby makes possible a reduction in overall size of the circuit breaker.

Another object of the invention is to provide a multipole circuit breaker embodying an improved contact structure having simple and reliable means for aligning the moving contacts for the several poles of the breaker.

This invention is an improvement on the circuit breaker shown in Patent No. 2,546,016 or" Jerome Sandin and Ture Lindstrom, issued March 26, 1951, by which the overall size of the breaker has been reduced by one-third, with very substantial savings in cost, while at the same time retaining the maximum normal currentcarrying capacity of the breaker as high as 225 amperes at 600 volts A. C.

The invention, both as to structure and operation, together with additional objects and advantages thereof, will be best understood from the following detailed description thereof, when read in conjunction with the accompanying drawings.

In said drawings:

Fig. 1 is a top plan view, with the cover partly broken away, of a three-pole circuit breaker embodying the principles or the invention with the arc chute removed from the left-hand pole;

Fig. 2 is an elevational sectional view taken substantially along line II-II of Fig. l and looking in the direction indicated by the arrows;

Fig. 3 is an enlarged sectional view showing the contact structure for the center pole of the breaker;

Fig. 4 is a perspective view showing the contact structure for one of the outer poles of the breaker;

Fig. 5 is a sectional view taken on line V-V of Fig. 3 and looking in the direction indicated by the arrows; and

Fig. 6 is an end elevational view showing the wrapper for the flexible conductor.

Referring to Figs. 1 and 2 of the drawings, the multipole circuit breaker includes a base 11 and a cover 3.3 of molded insulating material, an operating mechanism indicated generally at 15, and a trip device indicated generally at 17. The casing formed by the base 11 and cover 13 is divided into three compartments, each of nited States Patent 0 which is adapted to receive a stationary contact 19 and a cooperating movable contact 21 which, with their corresponding terminals and connecting conductors, collectively form the three poles of the breaker. Each pole of the circuit breaker is provided with end terminals 23 disposed in suitable openings formed in the base 11 at each end thereof.

The terminals 23 are 24 which are preferably suitably secured to metal inserts loosely mounted in the end portions of the base, as in the application of L. W. Dyer and C. L. Jones, Serial No. 294,229, filed June 18, 1952, and assigned to the assignee of this application. The stationary contact 19 for each pole is rigidly secured to the inner end of a conductor 25 having its outer end suitably secured to the adjacent terminal 23. The conductor 25 is secured tothe base 11 by means of screws 27 (Fig. 1) which also secures an arc runner 29 to the conductor 25 adjacent the stationary contact 19. i

The are runner 29 comprises a folded metallic member having side portions 313 (Fig. 1) which are secured to the base 11 by the screws 27 and a sheet of insulating material 31 which is inserted between the upper and lower portions of the runner for covering the side portions 30.

An arc extinguisher 32 is'previded for each pole of the breaker and comprises a stack of slotted plates 34 of magnetic material positioned adjacent the path of movement of the movable contacts 21. The presence of these plates causes the are drawn upon separation of the contacts to be drawn into the apexes of the slots where the arc is broken up and extinguished. The provision of the piece of insulation 31 covering the side portions of the arc runner prevents the are from travelling along these side portions and striking the side of the lowest plate 34 of the arc extinguisher.

The movable contact structure are the same, for which reason only the one for the center pole will be described. Mounted in the center compartment and secured to the base 11 is a U-shaped frame 35 which supports the operating mechanism for the circuit breaker. Pivotally mounted in the frame 35 by means of a pivot pin 37 supported in the side members of the frame 35 is a channel-shaped switch member 39 of steel or like material upon which is mounted the moving contact structure.

The moving contact structure comprises a contact member 41 of a good conducting material such as copper or a cupreous alloy to which is brazed or otherwise suitably secured the moving contact 21 which, like the stationary contact 19, is of a good-conducting arcresisting material such as silver-tungsten or silvermolybdenum. The outer end of the contact member 41 is turned upwardly at 41' to form an arc runner or horn. Also secured to the contact member 41 by means of a countersunk rivet 42 and disposed on the side opposite the contact 21 is a steel support member or bracket 43, the upper portion of which is provided with a T-shaped opening 45 (Figs. 3, 4 and 5) through which extends end 47 of the switch member for the several poles the reduced and notched 39 providing a removable lost-motion connection between the switch member and the contact member. In order to prevent turning movement between the bracket 43 and the contact member 41, pointed portions 44 are struck downwardly from opposite edges of the steel bracket 43 and are pressed into the softer copper of the contact member 41 during the riveting process, making it possible to use only a single rivet and still obtain a fastening which remains secure after the hammering of many opening and closing operations.

A coil spring 49 compressed between the switch member 39 and the portion of the support member or bracket 43 which is secured to the contact member 41 provides contact pressure in the closed position of the breaker. The upper end 48 of the rivet 42 provides a spring seat for the spring 49, and a spring seat 46 is formed on the switch member 39 by the process of embossing. In the open position of the breaker, the spring 49 biases the upper end of the opening 45 in the bracket 43 against the top of the end portion 47 of the switch member 39, and also biases the right-hand end 41 (Fig. 3) of the contact member 41 downwardly against a rod 51 carried in the side portions of the channel-shaped switch mem ber 39.

In order to prevent lateral tilting movement of the contact member 41, and provide a line contact across the heel of the contacts 19 and 21, an angular bracket 57 (Figs. 3 and 4) is secured to the underside of the contact member 41 adjacent the rod 51 and has an ofl'set portion extending beneath the rod. The bracket 57 is secured to the contact member 41 by means of embossed portions 59 on the contact member extending through openings in the bracket and riveted over. The bracket 57 and the right end portion 41 of the contact member cooperate with the rod 51 to prevent lateral tilting movement of the contact member and provide a good contact across the width of the contacts 19, 21.

This construction facilitates assembly of the contact member 41 on the switch arm 39 since the bracket 57 and the tail or end 41" of the contact member together form a U-shaped slot which is slipped over the pin 51 at the same time that the wide portion of the T-slot 45 is engaged with the reduced end 47 of the switch arm 39 by a motion longitudinally of the switch arm. The slot and pin connection of the contact member 41 on the pin 51 permits pivoting of the contact member about 51 as a pivot to the extent permitted by the slot 45. The contact member 41 is of lower cost than the cast contact members formerly used in breakers of the same current rating and service, since the contact member 41 is readily punched and formed or stamped from flat copper stock with the arc-horn portion 41' bent up at one end and the tail 41" for supporting it at the other end.

In order to insure simultaneous separation and engagement of the moving contacts with the stationary contacts for all of the poles, means is provided to adjust the position of the contact member 41 for one or more poles relative to the corresponding switch member 39. This means comprises shims 52 of different thickness, one or more of which may be inserted in the opening 45 between the top of the switch member 39 and the bracket 43 and secured to the switch member 39 by means of a screw 54. In this manner, the contact member 41 for each of the poles may be adjusted so that the contacts for all the poles break and touch simultaneously on opening and closing operations, respectively.

The assembly just described with the formed copper contact member 41 having the steel bracket 43 secured thereto by the countersunk rivet 42, over the head of which is secured the arc-resisting contact 21, together with the use of the headed-over end of the rivet and the boss 46 for holding the contact pressure spring 49 in place, and the notch and slot connection between the bracket 43 and the end 47 of the contact arm, with the shims 52 for giving simultaneous make and break of the contacts, gives the advantages of most efiicient use of the parts to save materials, low assembly labor, easy removability, ruggedness to stand up during many operations, and compactness to reduce the overall size of the circuit breaker.

A flexible conductor 53 is mechanically and electrically connected at one end directly to the contact member 41 by welding or brazing. The other end of the flexible conductor 53 is provided with a metallic Wrapper 60 in order to provide a fiat surface and to facilitate punching a hole therein to receive a screw 61 by which the conductor 53, together with the conductor 55, is secur to the base 11. v

The wrapper 60 is preformed to substantially the shape shown in Fig. 6. As shown in Fig. 6 the wrapper 60 is formed with an arcuate bottom portion 62, side portions 64 and beveled or angular corner portions 66. In practice the edges of the flexible conductor are placed in the angular corners and then the side portions 64 are bent down on top of the flexible conductor as shown by dot and dash lines in Fig. 6, providing flat top and bottom portions. The end of the assembly may be brazed or soldered after which the hole is punched through both the wrapper and the conductor to receive the screw 61.

One end of the flexible conductor 53 is brazed to the contact member 41, and the other end of the flexible conductor is electrically connected to a conductor 55 which extends through the current-responsive trip device of the breaker and is finally connected to the terminal 23 at the right end of the breaker.

A metal tie bar 63 encased in an insulating tube 65 is clamped to the channel-shaped switch arm 39 by means of a clamp 67 having its ends riveted over on the underside of the switch arm. The tie bar 63 extends across all three poles of the breaker, and the switch arms 39 (Figs. 1 and 4) for the outer poles are similarly clamped thereto for unitary movement to open and closed positions. Brackets 69 (Fig. 1) disposed in the end compartments and secured by means of screws 71 to the base 11 have pivot pins 73 (see also Fig. 4) mounted therein in alignment with the pivot pin 37 (Fig. 2). The pivot pins 73 extend inwardly from the brackets 69 and pivotally support the switch members 39 for the outer poles.

The operating mechanism 15 for operating the movable contact structure to open and close the contacts for all of the poles of the breaker is supported between the side members of the U-shaped frame 35 in the center compartment of the breaker housing. The operating mechanism comprises a pair of toggle links 77 and 79 pivotally connected together by a knee pivot pin 81. The toggle link 77 is pivotally connected by means of the rod 51 to the center pole switch member 39, and the toggle link 79 is pivotally connected by means of a pivot pin 83 to a releasable cradle 85. The releasable cradle 85 is pivotally mounted on a pin 87 supported in the frame members 35, and its free end is releasably engaged by a latch 89 forming a part of the trip device 17.

The toggle 77, 79 is operated to effect opening and closing movement of the contact structure by means of a U-shaped operating lever 91 and an overcenter operating spring means 93. The legs of the operating lever 91 (only one leg being shown) are pivotally mounted on pins 95 in the side members of the frame 35. The overcenter spring means is connected under tension between the knee pivot pin 81 of the toggle 77, 79 and the bight of the U- shaped operating lever 91. An insulating operating handle 97 has side portions 99 which are attached by means of screws (not shown) to the legs of the operating lever 91. The handle 97 extends out through an opening 102 in the cover 13 and has an arcuate portion 104 integral therewith which substantially closes the handle opening 102 in all positions of the handle.

In the closed position of the circuit breaker, the toggle 77, 79 is slightly overset, thus locking the movable contact structure in closed position against magnetic blowofi action in response to short-circuit currents. The overset position of the toggle 77, 79 is determined by the engagement of an arcuate surface 103 (Fig. 3) on the toggle link 77 with a projection 105 on the cradle 85 adjacent the pivot pin 87. The movement of the operating lever 91 to the closed position is limited by engagement thereof with inwardly formed ears 107 (only one being shown) on the frame member 35.

The circuit breaker is opened by movement of the operating handle 97 in a counterclockwise direction from the position in which it is shown in Fig. 2. This movement carries the line of action of the overcenter spring 93 over to the left of the pivot pin 83, whereupon the force of the spring 93 causes collapse of the toggle 77, 79 and causes simultaneous opening movement of the movable contact structure to open the contacts of all of the poles with a snap action. The opening movement of the movable contact structure is limited by engagement of a depressed portion 106 of the switch arm 39 for the center pole with the pivoted end of the releasable cradle 85.

In the closed position of the contacts 19, 21 the movable contact 21 is at a slight angle with respect to the stationary contact 19 so that the contacts are in engagement at a line across the width of the contacts at a point adjacent the heel of the movable contact as shown in Fig. 3. As the switch member 39 moves in opening direction the contact member 41 pivots about the pin 51 until the switch member 39 engages the upper end of the slot 45 in the bracket 43. During this movement the pin 51 moves upwardly and the spring 49 causes the contact member 41 to pivot about the pin 51. This causes the movable contact to rock forward on the stationary contact 19 so that the contacts separate at their tips adjacent the arc runner 29 and the arc horn 41. The reverse movement occurs when the contacts are closed, that is, the contacts touch at their tips and the movable contact rocks back to the closed position in which it is shown in Fig. 3.

The movable contact structure is operated to the closed position by clockwise movement of the operating handle 97 and the operating lever 91 back to the position shown in Fig. 2. This movement of the operating lever 91 carries the line of action of the spring 93 overcenter to the right of the pivot pin 83, whereupon the force of the overcenter spring 93 straightens the toggle 77, 79 and moves the switch members 39 for all of the poles to the closed position to close the contacts with a snap action.

The circuit breaker is opened automatically in response to overload currents occurring in the circuit of any pole of the breaker, by operation of the trip device 17. The trip device may be of any suitable type, preferably of the type disclosed in Patent No. 2,586,326, issued February 19, 1952, to G. G. Grissinger and Jerome Sandin, and assigned to the assignee of the instant application. Such trip devices are provided with thermally-responsive means operable to release the latch 89 after a time delay in response to overload currents below a predetermined value, and are also provided with electromagnetic means operable to instantaneously release the latch 89 in response to overload currents above the predetermined value, or in response to short-circuit currents.

When the latch 89 is released by the trip device 17 in response to an overload current, it frees the cradle 85 and permits the spring means 93 to rotate the cradle in a counterclockwise direction about its pivot 87, thus causing collapse of the toggle 77, 79 and movement of the movable contact structure to open position to thereby open the contacts for all of the poles of the breaker. The contacts cannot be closed following an automatic opening operation until the cradle 85 has been reset and relatched. This is accomplished by moving the operating handle 97 as far as it will go in opening direction during which movement a projection 109 on the operating lever 91 engages a shoulder 110 on the cradle and moves the latter clockwise to reengage the free end thereof with the latch 89. After the cradle 85 has been reset and relatched, the contacts may be closed by counterclockwise movement of the operating handle 97 in the manner previously described.

It will thus be seen that the invention provides a circuit breaker having an improved compact and low-cost contact structure in which the moving contact carrying member is loosely'mounted on the movable switch member but is prevented from tilting sidewise. Spring means is disposed between the switch member and the moving contact member to provide contact pressure in the closed position of the breaker, and simple, reliable aligning means is provided to align the moving contact members of the several poles so that the contacts for all of the poles make and break simultaneously.

Having described the invention in accordance with the requirements of the patent statutes, it is to be understood that various changes and modifications may be made in the structural details thereof without departing from some of the essential features of the invention.

I claim as my invention:

1. In a circuit breaker, stationary and movable contacts, a pivoted switch member having side portions and a. end portion, operating means operatively related to said switch member for moving said switch member to open and close said contacts, a movable contact member having said movable contact mounted thereon adjacent one end, a member rigidly secured to said contact member and having an opening therein for receiving the reduced end of said switch member to thereby support said one end of said contact member for limited movement relative to said switch member, a support member disposed between the side portions of said switch member for supporting the other end of said contact member, a bracket secured to the other end of said contact member, and having a portion disposed on the side of said support member opposite said contact member, said contact member and said bracket cooperating with said support member to maintain said contact member and said movable contact in alignment with said stationary contact, and spring means disposed between said switch member and said contact member for providing contact pressure in the closed position of said breaker.

2. In a circuit breaker, stationary and movable contacts, a movable switch member having side portions and an end portion, means operatively related to said switch member for moving said switch member to open and closed positions to open and close said contacts, a contact member supporting said movable contact, a part riveted to said contact member and having an opening therein for receiving the end of said switch member, said part having portions thereon for penetrating said contact member to prevent said part from turning relative to said contact member, a pin supported between the side portions of said switch member, an angular member secured to said contact member adjacent the other end thereof, said contact member and a portion of said angular member being disposed on opposite sides of said pin to support said contact member for limited pivotal movement while preventing lateral tilting movement of said contact member, and a coil spring compressed between said switch member and said contact member for providing contact pressure when said contacts are closed.

3. In a multi-pole circuit breaker having a housing divided into three compartments, stationary and movable contacts in each compartment, a movable switch member in each compartment, means interconnecting said switch members adjacent one end thereof for unitary movement to open and closed positions, operating means in one of said compartments connected to move said switch members to open and closed positions, a contact member in each compartment, a support member rigidly secured to each of said contact members and having an opening therein fitting over the other end of the associated switch member for supporting one end of said contact member on its associated switch member for limited movement relative thereto, a pin mounted on each of said switch members for supporting the other end of the corresponding contact member, a bracket on each of said contact members, each of said brackets having a portion disposed on the side of said pin opposite said contact members, said contact members and said brackets cooperating with said pins to prevent lateral tilting movement of said contact members, spring means between each of said switch members and its associated contact members for providing contact pressure, and

adjusting means comprising one or more members insertable in one or more of said openings between said switch members and said support members for adjusting one or more of said contact members relative to the associated switch members so that all of said movable contacts engage and disengage their associated stationary contacts substantially simultaneously.

4. In a circuit breaker, stationary contact means, a movable switch member, movable contact means mounted on said switch member, said switch member being movable to open and closed positions to open and close said contact means, operating means disposed to move said switch member to open and closed positions, means for attaching one end of said movable contact means to said switch member for limited movement relative thereto comprising a bracket mounted on said contact means and having an opening therein through which one end of said movable switch member extends, means for determining the movement of said movable contact means relative to said switch member comprising a member insertable in said opening between said switch member and said bracket, means for supporting the other end of said movable contact means on said switch member for pivotal movement relative thereto comprising a support on said switch member, and a member mounted on said movable contact means having a portion engaging the side of said support opposite said contact means.

5. In a circuit breaker, stationary contact means, a movable switch member, a movable contact carrying member mounted on said switch member and having a movable contact thereon, said switch member being movable to open and closed positions to open and close said contacts, operating means operatively related to said switch member for moving said switch member to open and closed positions, means for attaching one end of said movable contact carrying member to said switch member for limited movement relative thereto comprising a bracket mounted on said movable contact carrying member and having an opening therein through which one end of said movable switch member extends, means for supporting the other end of said movable contact carrying member on said switch member for pivotal movement relative thereto comprising a support on said switch member engaged by the other end of said movable contact member, and a member mounted on said movable contact carrying member having a portion engaging the side of said support opposite said movable contact carrying member to prevent excess movement of said contact carrying member relative to said support.

6. In a circuit breaker, stationary contact means, a movable switch member, a movable contact carrying member mounted on said switch member and having a movable contact thereon, said switch member being movable to open and closed positions to open and close said contacts, operating means connected to move said switch member to open and closed positions, means for attaching one end of said movable contact carrying member to said switch member comprising a bracket mounted on said movable contact carrying member and having a lost motion connection with said switch member, spring means between said switch member and said bracket for providing contact pressure in the closed position of said switch member, means pivotally supporting the other end of said movable contact carrying member on said switch member comprising a pin on said switch member supporting said other end of said movable contact carrying member, and a member secured to said movable contact carrying member and having a portion disposed on the side of said pin opposite said movable contact carrying member to prevent excess movement of said contact carrying member relative to said pin. 7 7. In a circuit breaker, a pivotally mounted switch arm, a movable contact carrying member of good conducting material mounted under said switch arm and extending substantially parallel thereto, said movable contact carrying member comprising a stamping of flat stock formed with an integral arc-horn portion extending outwardly at one end, a bracket fastened to the upper side of said movable contact carrying member adjacent said arc horn portion and having an opening therein through which the end of said switch arm extends to form a lost-motion connection, a contact of arc-resisting contact material mounted on the lower side of said movable contact carrying member opposite said bracket, a contact pressure spring between the switch arm and said movable contact carrying member, and a tail portion at the other end of said movable contact carrying member supported on a portion on said switch arm.

8. In a circuit breaker, a pivotally mounted switch arm, a contact carrying member of good conducting material mounted under said switch arm, said contact carrying member comprising a stamping of flat stock formed with an arc-horn portion extending outwardly at one end, a bracket fastened to the upper side of said contact carrying member adjacent said are horn portion by means of a rivet having a head countersunk at the lower side of the contact carrying member and having its other end riveted over at the upper side of said bracket, and said bracket engaging said switch arm with a lost-motion connection, a contact of arc-resisting contact material positioned on the lower side of said contact carrying member opposite said bracket and over the countersunk head of said rivet, a contact pressure spring between the switch arm and the bracket held in place at one end by a downwardly extending projection on the switch arm and at the other end by the end of the rivet at the upper side of the bracket, and means on said switch arm supporting the other end of said contact carrying member.

9. In a circuit breaker, a pivotally mounted switch arm, a contact carrying member of good conducting material mounted under said switch arm, said contact carrying member comprising a stamping of fiat stock formed with an arc-horn portion extending outwardly at one end, a bracket fastened to the upper side of said contact carrying member adjacent said are horn portion and engaging said switch arm with a lost-motion connection, a contact of arc-resisting contact material positioned on the lower side of said contact carrying member opposite said bracket, a contact pressure spring between the switch arm and contact carrying member, a tail portion at the other end of said contact carrying member engaging a portion on said switch arm, an integral projection embossed through the contact carrying member adjacent its tail portion, and an element secured to said tail portion on said integral projection and also engaging said portion on the switch arm on the opposite side from said contact carrying member.

References Cited in the file of this patent UNITED STATES PATENTS 1,724,840 Jones et al. Aug. 13, 1929 1,762,604 Ainsworth June 10, 1930 1,779,659 Carichofl Oct. 28, 1930 2,047,739 Lingal July 14, 1936 2,165,511 Sandin July 11, 1939 2,288,270 Dorfman et al June 30, 1942 2,459,588 Sandin et a1. Jan. 18, 1949 2,546,016 Sandin et al. Mar. 20, 1951

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