US2174232A

US2174232A - Circuit breaker

Info

Publication number: US2174232A
Application number: US97949A
Authority: US
Inventors: Benjamin P Baker
Original assignee: Westinghouse Electric and Manufacturing Co
Current assignee: CBS Corp
Priority date: 1936-08-26
Filing date: 1936-08-26
Publication date: 1939-09-26
Anticipated expiration: 1956-09-26
Also published as: FR825168A; DE689829C

Description

Sept. 26, 1939. B. P. BAKER CIRCUIT BREAKER l Filed Aug. 26, 1936 2 Sheets-Sheet l |NvENToR en/am?? P. .BQ/fer.

ATTORNE WITNESSES Mw fm1 5M Sept. 26, 1939., B. P. BAKER CIRCUIT BREAKER 2 Sheets-Sheet 2 Filed Aug. 26, 195

INVENTOR 50g/Iam??? P. a/er.

WITNESSES:

Ww 5M ATToRNE Patented Sept. 26, 1939 `UNITED STATES PATENT OFFICEv 2,174,232 omcm'r BRI-:AREE

Pennsylvania Application August 276, 1936, Serial No. 97,949

19 Claims.

This invention relates to circuit breakers and particularly to operating mechanisms therefor. It is an object of my invention to provide a circuit breaker having an operating mechanism which will effect a quick make and break of the breaker contacts.

A further object of my invention is to provide a circuit breaker of the above type which is simple in construction, having a small number of parts and which may be manufactured at a low cost. l,

Another object of my invention is to provide a. circuit breaker having an operating mechanism of the snap action type which is releasable for opening the contacts on overload and trip free with respect to the operating lever.

A more specific object of my invention is to provide a circuit breaker wherein the movable contact is actuated by a spring toggle and guided 80 in its movement by a movable carrier releasably retained in operative position by a current responsive element which element is adapted to release the carrier to cause the 'separation of the contacts in response to overload or short circuit conditions.

Other objects and advantages will be m'ade apparent in the following description taken in connection with the accompanying drawings, in which Figure 1 is a vertical sectional view of the circuit breaker of my invention showing certain parts thereof in'side elevation and the contacts in the closed position,

Fig, 2 is a vertical sectional view of the circuit breaker taken at right angles to the view of Fig. 1

along the line II-II.

Fig. 3 is a vertical sectional view of the circuit breaker also taken at right angles to the view in Fig. 1 but along the line III-III,

Fig. 4 is a vertical sectional View of the circuit breaker similar to that of Fig. 1 showing the contacts in the open position,

Fig. 5 is a vertical sectional view of the circuit breaker similar to that of Fig. 1 showing the posil tion of the operating mechanism when the contacts have been opened in response to an overload or short circuit condition, and

Fig. 6 is a perspective view of the movable contact of the breaker and the actuating member upon which the contact is mounted.

Referring to the drawings, the reference numeral I designates a casing of insulating material in which the breaker contacts and the operating mechanism are mounted. The casing I is 55, adapted to ,be closed by a suitable cover 2 also pf insulating material. A stationary contact 3 is mounted upon a terminal strip 4 extending from within the casing I exteriorly thereof and is secured in place by any suitable means as shown. A movable contact 5 of elongated form iscarried by a U-shaped actuating member 6 (Fig. 6) and may be secured thereto by means of a screw 1 The contact 5 is movable endwise for the purpose of engaging the fixed contact 3 and is adapted to be guided in its movement by a guide 8 of insulating material which may be formed integral with the base of the casing I.

The movable contact 5 in its closed position is partly surrounded by a series of parallel spaced U-shaped arc extinguishing plates 9 of magnetic material which may extend at their lower extremities, into the molded base of the casing I. Each of the plates 9 is provided with a V-shaped opening I0 as shown in Fig. 3, thereby forming an aligned groove in which the arc draw-n between the contacts 3 and 5 may play. Since the fiow of current in the arc to be extinguished is in a direction at right angles to the plane of the .plates 9, there will be produced a flow of magnetic flux in the plane of the plates and across the V-shaped openings I0, thereby moving the arc into the plates and extinguishing it. Arc extinguishing structures of the type herein shown are more fully described in United States Patent No, 2,015,561, issued September 24, 1935 to O. S. 30

Jennings and assigned to the assignee of the present application.

The actuating mechanism for operating the member 6 is mounted in a U-shaped frame II which may be secured in the base of the casing 3 I by means of screws I2, as illustrated in Figs. 1 and 2. Mounted upon a transversely, extending 'pin I3 is a cradle or carrier I4 which is adapted to pivot about the pin I3 and is normally maintained in operative position by means of an integral latch I5 adapted to engage the upper surface of a wedge shaped catch I6. The wedge shaped member I6 is secured by means of a screw I1 to the lower end of a bimetallic current responsive element I8. The current responsive element I8 is secured by a screw I9 to the other terminal bracket 20 of the breaker, which bracket p extends exteriorly of the casing I and may be supported in any suitable manner. Electrical connection between the current ment I8 and the Contact 5 is had through a ilexible shunt 2|, one terminal of `which may be engaged by the screw I'I, whereas the other terminal may be clamped between the contact 5 11nd the lsupport member 6,

responsive ele- 50 An operating lever 23 of insulating material is pivotally mounted between the two parallel frame members II I upon a pin 24 extending through the frame members and having its ends slightly burred for retaining it in position. The lowerend of the operating lever 23 is provided with a longitudinally extending slot 25 and a pivotal pin 2li extending transversely of the slot and irictionally retained in operative position. A connecting link 21 having one of its ends slotted at 2t is adapted to have sliding engagement with the pin 23 in the lever 23. The other end of the link 2l( has a forked projection 23 in which is journalled a roller 3U upon a pin 3i." The roller 3@ is adapted to. engage an elongated lJ-shaped notch or track provided in the carrier i4. The engagement oi the roller 3@ with the track 32 is maintained by means of a coil spring 33 engaging the forked member 23 at one end and a washer 34! at the other, which washer,`in turn, engages the rounded end of operating lever 23.

The pin 3i extends beyond the forked member 23 so as to provide a pivotal connection for the end of lJ-shaped actuating member lt will thus be seen that as the roller 3b is moved along the track the contact member al will be moved into or out of engagement with the xed contact 3. The forked member 2t) preferably extends downwardly beyond the roller 3b so as to prevent lateral displacement of the roller from the track 32.

In order to hold the movable contact 5 more rmly in engagement with the contact 3, the track 32 is provided with a depression or recess 36 in which the roller 33 may be seated. Although the contact 3 is said to be xed, it is to be understood that it is xed only in the sense that it is not directly movable by the breaker operating mechanism to eiect an opening of the contacts, but is in fact slightly movable with respect to the breaker casing Il.

To eiect the desired resiliency of the fixed contact mounting, the terminal strip 4 may be constructed of phosphor bronze or other suitable resilient material whichwill allow the contact 3 mounted on one end thereof to be seated more iirmly with respect to the movable contact 5 and which will also compensate for wear between the respective contacts caused by ordinary usage of the breaker.

Further features of the operating mechanism will be more fully understood inconnection with a description of the operation thereof. With the mechanism in the position as shown in Fig. l, that is, with the contacts 3 and 5 in the closed position, the operating lever 23 will be rocked or moved to the-left in order to eiect opening of the breaker contacts. As was pointed out above, the roller 30 is preferably seated in a recess 36 for the purpose of obtaining a higher contact pressure, which makes it necessary to provide means for assisting the coil spring 33 in moving the roller 30 from its seat to the opposite end of the track 32. This means consists of a projection 31 provided on the carrier I dradapted to engage the forked member 29 of the link 21 as thev operating lever 23 is moved to the left. Upon continued movement of the lever 23, the spring 33 will be compressed and the --upper end of" the link 21 will be moved to the right, thus causing the link 21 to pivot about the projection 31 and to force is provided a positive means for initially separating the contacts which may have become welded to each other to a more or less degree dile t0 the roller 30 from its seat 36. Thus there arranca heavy currents or to sparking action which may occur just prior to the seating of the contacts during the closing operation.

As the axis 26 in its movement toward the right passes the center line between the pivotal axes 24`and 3i, spring 33 will have been compressed to a maximum and will thereafter during expansion, force the roller 33 to the left-hand end oi the track 32, thereby effecting the opening of the contacts 3 and t, as shown in Fig, 4. The rocking movement of the operating lever 23 is limited by

stop pins

33 and 39 passing transversely through the parallel side members of the frame M it will be apparent that in order to close the contacts 3 and il, the operating lever 23 will be moved to the right until it engages the stop 33. in its movement toward the closed' position, the pivotal axis 2t will be moved toward the left and when this axis crosses the center line between the pivotal axes 2d and 3i, the action of spring will force the roller 33, the contact carrying member d and the contact Ei oi the right, thus causing the roller 3@ toy be seated in the recess and the contact 5 to iirrnly engage the fixed contact 3.

In the event that overload or short circuit con.- ditions occur in the circuit in which the breaker is connected, the abnormal current -flowing through the bimetallic element I8 will cause it to deect to the left, thereby allowing the latch iii to\ clear the catch I6, to release the carrier it. When thus released, the carrier i4 will be rotated counterclockwise about its pivotal axis I3 to the position shown in Fig. 5, as a result of the biasing action of thespring 33 upon the carrier. As the carrier t4 begins to rotate, the projection 31 engages the roller supporting member 23 to positively eject the rollerv 30 from its seat 33, whereupon the roller is quickly moved to the left along the track 32 to thereby open the contacts. The downward movement Vof the carrier i 4 is limited by the base of the frame II. When the carrier I4 is in the limiting or released position, the connecting link A21 and the operating lever 23 straighten out, thus causing the lever to assume a position intermediate the open and closed positions, thereby giving an indication that the breaker has been tripped due to an abnormal current condition. In order to give the operating lever 23 and the connecting link 21 greater stability while in the tripped indicating position, the lower end of lever 23 is slightly attened as shown at 4I so as to provide a seat for the spring pressed washer 34.

The carrier I 4 is also provided with an upwardly .extending projection 40. This projection is adapted to engage the lower end of the operating lever 23, so that as the lever is moved to the left or open position, after the breaker has been tripped, the carrier I4 will be rotated about its pivotal axis I3 until the operating lever 23 strikes the stop 39. The stop 39 is so positioned that it will permit suiicient movement of the operating lever 23 to return the latch member I5 of the carrier I4 into latching engagement with the catch I IBHon the bimetal I8. 'I'hus if the bimetal has cooled sufliciently from a prior overload condition, its lower end will have moved to the right sufficiently to engage the latch I5. The mechanism is then in position for reestablishing engagementof the contacts by moving the operating lever 23 to the right or the closed position. If the overload condition has been removed and normal current `is ilowing through the bimetal la, the carrier I4 win be retained in 115s latched position and the contacts will remain closed until opened either by actuating the operating lever 23 or by an overload condition in the manner just described. If, however, the overload condition still persists`upon the reclosing operation following an automatic tripping operation of the mechanism, the bimetal I8 will again release the carrier I4` It is therefore apparent that it is impossible to hold the breaker contacts closed for an appreciable length of time as long as thefoverload condition persists.

From the foregoing description, it will be apparent that I have provided a simple operating mechanism for a circuit breaker having a small number of parts which may be manufactured at a low cost. The simple design also possesses the advantage of quick make and break action of the contacts and provides the additional feature of overload release in a trip free mechanism, which features are usually found only in breaker structures of a more complicated design and' which are considerably more expensive to manufacture. It is, therefore, possible by the use of the invention disclosed herein to provide the same protection for low voltage low powered circuits as has been heretofore found practical only for circuits of higher voltage and greater power requirements.

The present invention is a further development of the invention disclosed and claimed in the copending application of H. S. Gano for Circuit breaker, Serial No. 93,807, filed August i, 1936, and assigned to the assignee of the present invention.

Although I have shown and described a cuit breaker embodying a specific operating mechanism, it is to be understood that the same is for the purpose of illustration and that changes and modications may be made by those skilled in the art without departing from the spirit and scope of the appended claims.

I claim asl my invention:

1. A circuit breaker comprising a contact carrying member movable to open and to closed circuit position, a movable support provided with a guide surface along which said contact carrying member is movable, current responsive means releasably retaining said support in operative position, an overcenter spring toggle for moving said cotnact carrying member along said guide surface to open and to closed circuit position, with a snap. action, said support when released being moved to a. released position by said spring toggle to cause said spring toggle to move said contact carrying member to, open circuit position, said support having means for restraining said contact carrying member in closed circuit position when said support is retained in operative position.

2. A circuit breaker comprising a contact carhying member movable to open and to closed circuit position, a Contact carried by said member, a movable support provided with a guide surface along which said contact carrying member is movable, electro-responsive means for releasably retaining said support in operative position, and means for moving said contact carrying member along said guide surface to open and io closed circuit position with a snap action and for moving the support when the support is released, said contact being moved during the movement of the contact carrying member along the guide surface, and said support having means contact carrying member when the support is released.

3. In a circuit breaker, a contact carrying member movable to open and to closed circuit position, a Contact carried by said member, a movable carrier provided with a guide means along which said member is movable, means for releasably retaining said carrier in operative position, and means including a spring actuated toggle for moving said contact carrying member along said guiding means to open and to closed circuit position and for moving said. carrier when released to cause movement of said member from the closed to the open circuit position, said contact being moved during the movement of said contact carrying member along the guide means.

4. A circuit breaker comprising a pivoted operating lever, a contact member movable to open and to closed circuit position, a connecting link engaging said operating lever and said contact member, a movable carrier having an elongated guide along which said contact member is movable, current responsive trip means normally releasably retaining said' carrier in operative position, and spring means engaged by said operating lever and said contact member for biasing the latter with respect to said operating lever and said guide means and for moving the 4carrier when the carrier is released by operation of said trip means to cause said contact member to be moved to the open circuit position.

5. In a circuit breaker, a circuit controlling member movable to open and to closed circuit position, a movable carrier having a guide surface along which said member is movable, electro-respons-,ive means for releasably retainng said carrier in operative position, and' a toggle including a movable operating lever and a spring for moving said circuit controlling member -along said guide surface to open and to closed circuit position, said toggle when said carrier is released causing movement of said carrier to a released position and movement of said 'circuit controlling member to open circuit position, and said carrier having a portion engageable by said operating lever for resetting the carrier to operative position upon moving said lever to open position.

6. A circuit breaker comprising a circuit controlling member movable to open and to closed circuit position, a movable support having guide means along ,which said member is movable, means releasably retaining said support in operative position, a toggle including an oscillatable operating lever for moving said circuit controlling member along said guide means to open and to closed circuit position, and means engageable with said lever when said support is released for resetting said support upon movement of said lever to open position.

7. A circuit breaker comprising a circuit controlling member movable to open and to closed circuit position,.a movable support having guide means along jwhich said member is movable, means for releasably retaining said support in operative position, an overcenter toggle including an oscillatable operating' member for moving said circuit controlling member along said guide means to open andy to closed circuit position, and means on said support engageable by said operating member when said support is in the released position for resetting the support to its Aoperative position when said operating member is moved to the open position.

8. In a circuit breaker, a circuit controlling member movable to open and to closed circuit position, a movable carrier provided with a guide track along which said member is movable, current responsive trip means for releasably retaining said carrier in operative position, means including a spring loaded toggle for moving said circuit controlling member along said guide track to open and to closed circuit position, said guide track having means for restraining said circuit controlling member in its closed circuit position, and means cooperating with said toggle for positively initiating the opening movement of said contact member when said toggle is actuated.

9. A circuit breaker comprising a frame, a carrier pivotally mounted in said frame, a current carrying bimetallic trip element for nor-` mally releasably retaining the carrier in operative position, said carrier having a guide track thereon', a contact member movable along said guide track to open and to closed circuit, position, an operating lever pivotally mounted in said frame, a connecting link having sliding engagement with said operating lever and a pivotal connection with said contact member, and a spring engaged by said lever and said contact member for moving the latter along said track to open and closed positions when the operating lever is actuated.

lita circuit breaker comprising a frame, a carrier pivotally mounted in said frame, a current carrying bimetallic trip element for normally releasably retaining the carrier in operative position, said carrier lhaving a guide track-thereon, a contact member movable along said guide track to open and to closed circuit position, an operating lever pivotally mounted in said frame, a connecting link having sliding engagement with said operating lever and a pivotal connection with said contact member, and a spring engaged by said lever and said contact member for moving the latter along said track to open and closed positions when the operating lever is actuated, said spring being adapted to move said carrier when released by said trip element and to maintain the moving contact member in engagement with the carrier to affect an opening of the breaker contacts.

il. A circuit breaker comprising, a contact, a movable contact member for engaging said contact, a roller journalled in one end of said contact member, a -movable carrier, a bimetallic current carrying trip element for releasably holding said carrier in operative position, said carrier having an arcuate guide track upon which said roller is adapted to move, a pivoted operating lever, a link slidzly engaging said lever and pivotally connected to said contact member, a

spring encircling said link and engaged by said lever and the pivotal connection of said link with said contact member for biasing said contact member to either end of said guide track upon theoscillation of said lever and for moving said carrier when the latter is-released, and an arm integral with said carrier engageable with said lever for resetting the carrier to operative position upon moving said lever to the open position.

12. In a circuit breaker, a movable carrier havinga guide surface, current responsive means for releasably retaining said carrier in operative position', a'contact member supported for movement on said carrier, means including an 4overcenter toggle and a member movable on said guide surface for moving said contactmember to openand to closed circuit position Yand for moving said carrier when it is released.

13. In a circuit breaker,- a. movable contact member, a movable carrier for said contact member having a guide surface, means releasably retaining said carrier inv operative position, means including an overcenter toggle having a roller movable along said guide surface for moving said contact member to open and to closed circuit position.

14. In a circuit breaker, a movable contact member, a movable carrier for said contact member-having a guide surface, means releasably retaining said carrier in operative position, means including an overcenter toggle having a spring biased roller movable along said guide surface for moving said Contact member to open and to closed circuit position and for moving said carrier to a tripped positionvvhen the carrier is released.

15. In a circuit breaker, a movable carrier having a guide surface, means releasably retaining said carrier in operative position, a movable contact member supported for movement on said carrier, an actuating roller movable back and forth along said guide surface for moving said contact member to open and to closed circuit position, a movable operating handle pivoted intermediate its ends and an overcenter spring movable thereby for moving said roller back and forth along said guide surface to actuate said contact member, said spring biasing said carrier to a tripped position. V i6. In a circuit breaker, a movable carrier having a guide surface, means releasably retaining said carrier in operative position, a movable contact member supported for movement on said carrier, an actuating roller movable along said guide surface for moving said contact member to open and to closed circuit position, a mechanism including an operating lever pivoted substantially midway between its ends and an overcenter spring for moving said roller back and forth along said guide surface to actuate said contact member to open and to closed circuit position, said carrier when released being movable by said spring to a tripped position to cause movement of said contact member to open circuit position.

i7. In a circuit breaker, a movable carrier having a guide surface, means releasably retaining said carrier in operative position, a movable contact member supported for movement on said carrier, an operating mechanism comprising a member movable back and forth along said guide surface for moving said contact member to open and to closed circuit position, an operating handle pivoted intermediate its ends and movable to open and to closed position and an overcenter spring movable thereby for moving said member along said surface, said carrier when released being moved by said spring from said operative position to a tripped position to cause movement of said contact member to open circuit position and said operating handle to an intermediate indicating position.

18. In'a circuit breaker, a movable carrier having a guide surface, means releasably retaining said carrier in an operative position, a movable contact member supported for movement on said carrier, an overcenter spring mechanism including an operating member pivoted intermediate its ends and movable to open and to closed position and an actuating element movable thereby back and forth along said guide surface for moving said contact member and to open and to closed circuit position, said carrier when released being moved by said mechanism to cause movement of said contact member to open circuit position, said carrier having a portion engageable by said operating member for resetting the carrier upon movement of operating member to open position.

19. In a circuit breaker, a switch member movable to open and to close the circuit, a movable carrierfor said switch member, means releasably retaining said carrier in an operative position, means including an overcenter spring for moving said switch member to open and to closed circuit position and for biasing said carrier to a released position, a support engaging said switch member for guiding said switch member in a substantially straight line path during normal switching operations thereof, said` carrier when released causing said switch member to pivot and slide on said support and move to a tripped position. L

BENJAMIN P. BAKER.