US2581181A

US2581181A - Heavy-duty air circuit breaker

Info

Publication number: US2581181A
Application number: US137411A
Authority: US
Inventors: John A Favre
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1950-01-07
Filing date: 1950-01-07
Publication date: 1952-01-01
Anticipated expiration: 1969-01-01

Description

Jan. 1, 1952 Filed Jan. '7, 1950 J. A. FAVRE 2,581,181

HEAVY-DUTY AIR CIRCUIT BREAKER 2 Sl- EETS-SHEET 1 Inventor: Johrw A. Favre,

His Att or-ne Jan. 1, 1952 J. A. FAVRE HEAVY-DUTY AIR CIRCUIT BREAKER 2 SHEETSSHEET 2 Filed Jan. 7, 1950 M/Sl/L 177700 5 5 3 W M m a 0 v 7 M U Z IO I m 4 w l l0 8 J O Inventor: John A Favr-e,

9 His Attornel Patented Jan. 1, 1952 HEAVY-DUTY Am CIRCUIT BREAKER John A. Fa re, Drexel, Pa., alsignor to General Electric Company, a corporation of New York Application January 1, 1950, Serial No. 137,411-

The invention relates to circuit breakers, particularlyair circuit breakers, and the principal object is to provide an improved separately articulated compound sequential toggle actuated arcing and main contact form of heavy-duty air circuit breaker capable of closing on exceptionally large momentary load currents and having 9, ourrent-interrupting capacity of the same magnitude, for example, one hundred thousand amperes. With such large momentary currents carried during the closing and opening of the arcing and main contacts of the breaker, severe sparking and "blow-oils of a destructive and explosive character are likely to occur unless sufilcient wiping pressure as well as successive actuation of these contacts are very accurately produced in properly timed sequence. Thus insuilicient arcing contact wiping pressure at the instant the main contacts engage or disengage may result .in the relatively large current becoming highly concentrated in one or more minute conductive paths between the main contacts, thereby producing such a highconcentration of the electrical 14 Claims. (Cl. 200-153) A further object is to utilize the heavy electrodynamic forces of the main and arcing contact current loops for quickly accelerating the joint wiping movement of the separately articulated main current-carrying contacts as well as for maintaining the required contact pressure therebetween until the actual separation thereof occurs before the arcing contact pressure sequentially decreases and thereby secure as much speed and contact pressure as possible in the opening of the breaker under heavy overloads to minimize sparking and "blowoffs and reduce the possibilities of "restriking in interrupting currents of large magnitude.

Another object is to provide an improved compound sequential toggle linkage operable in closing the breaker to quickly eil'ect wiping joint movement of the separatlyarticulated arcing contacts against normal spring ,4318881116 and maintain substantially uniform thenbrmal spring energy that immediate volatilization of the main contact material occurs with explosive blow-off force. Similar results are likely to occur in case of an untimely or premature decrease in the main contact wiping pressure before the actual separation thereof occurs or in case the separating speed thereof is insufficient to prevent restrike upon a rapid sequential separation of the arcing contacts.

Hence, a particular object is to provide an improved positive sequential timing form of separately articulated heavy-duty arcing and main contact compound toggle wiping and actuating linkage capable of establishing and maintaining -the required values of wiping pressure therebetween in proper relation with their sequential closing and opening at the critical times necessary-to overcome the severe sparking and destructive blowofls to which these contacts ordinarily are subjected in such heavy-duty service. Another object is to provide an improved com'- pound sequential toggle wiping and actuating linkage for the separately articulated contacts that will substantially counterbalance or neutralize the heavy electrodynamic forces of the arcing and main contact loops so as to reduce the reaction thereof on the closing mechanism when the breaker is closed on a heavy fault. This materially facilitates a successful closing operation against the normal contact wiping sprin forces by means of a stored energy device or other operator having a limited maximum closing power.

pressure therebetween both during the sequential closing wiping engagement of the main current-carrying contacts against normal spring pressure as well as during the reverse joint wiping movement of the main contacts until after the accelerated separation thereof occurs in the opening of the breaker. In this way separate and successive wipin engagement and disengagement of the arcing and main contacts is positively .,obtained in reverse sequence.

Another object is to provide an improved double latch type of trip-free power-amplifying circuit breaker operating toggle mechanism having a latched-in centrally fulcrumed closing toggle lever biased open and provided with a releasable fulcrum lever having a separate latch controlled by a sensitive overload current-responsive means so as to operate in conjunction with the heavy electrodynamic force of both the main and arcing contact electrodynamic loops to effect the rapid opening of the breaker. Further objects and advantages of the invention will appear in the following description of the accompanying drawing in which Fig. 1 shows the improved separately articulated arcing and main contact structure of the heavy-duty circuit breaker in the closed position provided with the improved compound sequential toggle wiping and actuating linkage of the present invention and Fig. 2 shows the relative positions of the parts in the open position of the circuit breaker.

As shown, the circuit breaker indicated generally by the reference character 9 is provided with an upper suitably insulated current-conducin'g terminal stud I 0 having a main contact ll pins l2 and l8are held in current-conducting relation with their respective bearing notches by means of the holding bar 2|! that is secured to the conductor stud i by screw 2|. The articulated main contact II is provided with a wiping biasing spring '23 .for biasing the main contact I I in. one direction to the position wherein stop 24 engages with an insulating shoulder 25. Similarly the arcing contact l5'is provided with alink 58 also is provided at the other end thereof with a separate compression toggle link connection with the arcing contact 45 comprising the shorter link 55 that is connected at one end to the tension link 58 by means of the oflset pin 55 and the other end to the arcing contact 45 by means of pin 51 so as to be moved in the proper sequence toward and away from force amplifying alignment with the tension link .58 in'closing and opening. the circuit breaker. The main tension link 50 is shown provided with an inside-ting I crossarm 68 that may serve to interconnect the wiping biasing spring 21 operating on the pin 28 to bias in the same direction-the tail 29 of contact I into engagement with the insulating stop 7 88. If desired, suitable flexible braid 3| may be provided for avoiding pitting of the main con- .tact bearing pin l2 during heavy faults and a similar flexible braid 82 may be provided for. the arcing-contact bearing pin I|i for the same purpose. a

-'The circuit breaker 9 likewise is provided-with a second suitably insulated current-conducting terminal stud 83 that is electrically connected to one end-of the single turn magnetizing coil '34 for {the overload tripping device 35 which may be of .any usual type; The other-end of coil 34 is con- -nected to the current-conductor 36 on which is pivotally mounted the second separately articu- 'lated main contact 31 by means of the conducting pivot pin 38 which is held inconducting engagement with the'bearing notch 39 by means of --a conducting bar 4|! that is secured to the conductor 35 by means of the screwjl In this way the two main contacts and 31 are separately articulated for joint wiping movement in abutting engagement in one direction to compress the biasing spring 28 with the facings 42 of special contact material interposed therebetween. The second separately articulated arcing contact 45 is mechanically and electrically connected directly to the-main contact 31 by means of pivot pin 4-6 and is thus supported forjoint movement with the separately articulated arcing contact |5 in abutting-wiping engagement in the same direction to compress the biasing spring 21 with the facings 41 of special contact material interposed therebetween. Thus, the arcing contacts l5 and 45 are jointly movable in the same direction as the main contacts H and 31; Any suitable form of arc quencher or chute, 'not shown', may be provided for extinguishingthe are between the arcing contacts l5 and 45.

inorder to accurately produce the properly timed sequential engagement and disengagement of the separately articulated pairs of arcing conitacts l5 and 45 and maincontacts' ll and3l with sufficient wiping contact pressure therebetween, an improved form of compound sequential toggle linkage indicated generally by the reference character 48 is provided. This linkage 48 comprises a main tension link 5|! 'journaled at one end on the fLked pivot pin 5| to swing the other end thereof in a direction transverse the direction of joint movement of the contacts and having a compression toggle link 52'connected to'the other end thereof by means of the pin 53 with the other end-or the link 52 connected to the main contact 81 by means of pin 54 so as to be moved toward and awayvfrom force amplifying alignment with the tension link 58 in closing and opening'the circuit breaker. The main tension =and-toggle links of each pole substantially the same as shown in the drawing.

inorder to obtain a further force amplifying toggle action in closing the breaker 8, the other end of the main tension link 50 is connected by means of the operating toggle link 6| with a bell crank closing member 52 that is iournaled-intermediate its ends on the pivot pin '68 carried intermediate the ends of areleasable fulcrum lever .64 that is joumaled on a fixed bearing pinat one. end; The other end of the releasable fulcrum lever-84 is provided'with a roller 65 for engagement with the rounded end of .a trip prop. .51. This trip prop 61 is pivoted on the fixedpin." and is biased by spring 69 into engagement-with the stop 18 in a position wherein the thrustfrom the roller 86" tends to move the prop 51 a ainst the bias of the spring 68. For holdin the pm current flows through the coil 34 for the required The circuit breaker 9 is shown closed, in Fig. i, with the pair of main contacts I I and 31 in abutting wiping engagement and the shunting pair of arcing contacts l5 and 45 also in abuttim wiping engagement and the bell crank operating lever 62 is held in its closing position by the engagement of the latch with the pin 8| carried adjacent the free end of the bell crank lever 52. The'l'atch 80 is pivoted on the fixed pin 22 and'is biasedinto engagement with the pinli' by. the biasing spring 83. Suitable opening biasing springs are connected between the pivot pin 58 on the main tensionlink 50 and-a fixed supporting member 85 so asto exert a strong bias tending to rotate the main tension link 58 about its fixed pivotal supporting pin 5| and bodily move the bell crank 52 and the releasable fulcrum relatively lightresetting spring "88 'and thereby lower the pivot pin 83 suflicientlyto releaseithe pin 8| from engagement with the latch 88 thereby freeing the bell crank 82' for quick Imitation under the bias of the 0penin8-springs u; As soon as this occurs, the relatively light biasing spring 08 is then free to automatically reset the lever .4 into its position in which it is shown and thereby carry the bell crank lever 62 into its circuit breaker opening pofltion shown in Fig. 2 with the other parts of the circuit breaker mechanism also occupying their respective open positions in which they are shown.

In accordance with the present invention, when the circuit breaker lsopened by the sequential togglelinkage 48 in the manner Just described, the first contact actuation produced is the joint wiping movement of the two separately articulated main contacts II and 51. Due to the heavy overload current flow therethrough, a heavy electrodynamic force is exerted on each of these contacts tending to drive them to the left and this force performs two functions. First, it accelerates the Joint wiping movement of the two main contacts I l' and 31 until the limit of motion of the contact II is reached wherein the stop 24 engages theshoulder 25. The second function performed by the magnetic force is in augmenting the force of the biasing spring 23 in maintaining abutting wiping engagement between the contact facings 42 during the. joint wiping movement of the main contacts. This serves to minimize sparking, and blow-offs" by maintaining the required pressure between these main contacts until the quick separation thereof occurs as contact II is suddenly stopped by the engagement of pin 24 with shoulder 25.

During such accelerated joint opening wiping movement of the main contacts II and 31, the arcing contacts [5 and 45 are mechanically maintained substantially at rest and consequently a substantially uniform contact pressure is maintained therebetween by the biasing force of the wiping spring 21. Thus the breaker operating linkage 48 including the main tension link 50 and the separate

sequential toggle links

52 and 55 insures, in conjunction with the pivotal mounting of the arcing contact 45 on the main pivotally mounted contact II, that substantially no opening wiping movement of the arcing contacts can occur during the joint opening wiping movement of the main contacts as only a slight vertical sliding relative movement between the arcing contacts l5 and 45 is produced due to the compound sequential

toggle pivot pins

56, 51, 46 and 3| being maintained in substantially the same alignment as shown until after the quick separation of the main contacts H' and 31 is accomplished. Thus upon counterclockwise rotation of the main tension link 50 about its pivot pin 5| to open the breaker 9, the toggle link 52 rotates the main contact 31 about its pivot pin 35 to effect the acceleraed joint wiping movement of the main contacts 31 and H until the pivotal movement of contact II is suddenly stopped by 60 the engagement of stop 24 with the insulating shoulder 25 to produce sudden disengagement of the main contacts. During such accelerated joint wiping movement and sudden separation of the main contacts II and 31, the pivotal mounting of the arcing contact 45 on the main contact 31 by means of the conducting pin 46 and the toggle connection of the arcing contact 45 with the main tension link 50 by means of the separate toggle link 55 serves to produce only movement of the lower end of contact 45 while maintaining the upper end thereof at rest in firm wiping engagement with the arcing contact l5 until after the separation of the main contacts I l and 31 occurs. Thereupon the compound seend 93 of the bell crank 62.

quential toggle mechanism operates to effect joint wiping movement of the contact l5 along with the contact 45 until the tail 29 of contact 15 engages with the insulating stop 30 to thereby produce sudden separation of the arcing

contacts

15 and 45. Thereupon, the arcing contact 45 is rapidly carried to its fully open position in which it is shown by the dotted lines.

During the joint wiping movement of the arcing contacts l5 and 45, the electrodynamic forces on contact 15 are substantially counterbalanced or neutralized due to the reverse loop structure. Thus, the electrodynamic loop force set up by the current flow through contacts I 5 and 45 is opposed by the electrodynamic loop force setup by the current flow through contact i5 and the opposite portion of the current-conducting terminal stud ID on which the contact I5 is pivotally mounted by the current-conducting pin It.

Upon opening of the breaker 9, the releasable fulcrum lever 64 is automatically reset by spring 88 and likewise the prop 61 is automatically reset into engagement with the roller 66 by the spring 69 with the latch 'H', the trip finger 14 and also theprojecting finger 16 of the overload current-responsive trip mechanism 35 all returned to their initial holding'position as shown in the drawing and with the other parts of the breaker in their respective positions indicated by the dotted lines.

In order to reclose the breaker, the bell crank closing member 62 must be operated to return the pin 8| into engagement with the latch 80. Although any suitable operating means may be employed for this purpose, the improved circuit breaker 9 shown in the drawing is particularly adapted for closing operation by the improved form of stored energy mechanism 19 that is more fully described and claimed in my co-pending application, Serial No. 196,075, filed November 16, 1950. As indicated in the drawing, this improved mechanism is provided with a closing arm 90 fixed on an operating shaft 9| and carrying a roller 92 for camming engagement with the free The operating shaft 5| also has fixed thereon an actuating cam member 95 that is connected by the pivotal saddle 96 with a powerful compression spring 91 in which sufllcient energy may be stored to effect the closing of the circuit breaker. The energy is imparted to the compression spring 91 by rotating the cam member 95 to the position in which it is shown by means of the roller 98 carried on the arm 99 that is fixed to a motor-driven shaft I 00 provided with the improved powerful gear reduction and trip-'free overrunning clutch mechanism more fully described and claimed in my abovementioned co-pending application.

With sumcient closing energy stored in the powerful compression spring 51 as shown, all that is necessary for closure of the breaker is to effect rotation of the arm 99 from its dead-center position in which it is shown. Thereupon the powerful force of the compression spring 51 be- 7 end 53 of the bell crank 62 to return the pin 5| into engagement with the latch 80 and thereby effect the reclosure of the circuit breakers. The stored energy closing mechanism thereupon returns to its initial position in which it is shown wherein 'suillcient energy is again storedv in the Iii-5814181 powerful compression spring 8.1 to effect the next re'closure of the breaker.

-In case the circuit breaker 9 should be closed on a heavy fault during the operation of the stored energy closing mechanism,'trip-free action is obtained due to the release of the prop 61 thereby releasing the fulcrum lever 64 and permitting the opening of the breaker to be accomplished 'in substantially the same way as previously described except that the upturned end ll of the bell crank 62 will remain in engagement with roller 92 until the stored energy mechanism I! is returned to its'initial position which occurs immediately after the breaker is opened.

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

1. A circuit breaker having in combination, a

' pair-of separately articulated abutting main contacts jointly movable in one direction, a pair of separately articulated abutting arcing contacts jointly movable in one direction, and operating mechanism having a tension link pivotally supported at one end to swing the other end in a direction transverse the direction of joint movement of the contacts and provided at the other end with sequential compression toggle links having separate pivotal connections with one of each pair of contacts for effecting separate and successive wiping disengagement and engagement of said pairs of contacts in reverse sequence as the compression links successively move away from and toward force amplifying alignment with the tension link.

2. A circuit breaker having in'combination, cooperating pairs of separately articulated abutting arcing and main contacts separately movable in wiping relation in the same direction, means nor.- mally biasing one contact of each pair for joint wiping movement with the other contact within a limited range, and operating mechanism having a tension link pivotally supported at one end to swing the other end in a direction transverse the direction of joint movement of the contacts in wiping relation and provided at the other end with sequential compression link connections with the other contacts of each pair for substantially separately operating each other contact through the wiping range of the corresponding one contact as the compression link connections move toward and away from force amplifying alignment with the tension link in closing and opening the breaker.

3. A, circuit breaker having in combination, cooperating pairs of separately articulated abutting arcing and main contacts separately movable in wiping relation inthe same direction, separate means normally biasing one contact of-each pair for joint wiping movement with the other contact, means for pivotally mounting the other of the arcing contacts on the other of the main contacts and operating mechanism including a tension link pivotally supported at one end to swing the other end in a direction transverse the direc-v tion of joint movement of the contacts in wiping relationand having at the other end thereof separate toggle link connections with the other contacts of, each pair offset for maintaining a substantially uniform wiping contact' pressure between the pair of arcing contacts before, after, and during the wiping engagement of the pair of main contacts.

4. A circuit breaker having in combination a pair of spaced apart current conductors having separately movable inner and outer arcing and inner and outer main contacts articulated in looped spaced relation therewith for'electrodynamically biasingtheinner main contactintb engagement with the outer main contact, separate means biasing each inner contact for joint wiping movement with the outer contact through a limited range, and sequential linkage mecha-- nism interconnecting the outer contacts for effecting substantially separate movement of the outer arcing and main contacts each way through the limited range of joint wiping movement with the corresponding inner contacts.

5. A circuit breaker having in combination, separately movable inner and outer main and inner and outer arcing contacts having pivotal mounting and conducting connections for electrodynamically biasing the inner main contact for joint movement in wiping engagement with the outer main contact and having the outer arcing-contact pivotally mounted on the outer maincon-- contact for joint wiping movement with the outer contact, and sequential linkage mechanism iiieluding a tension link pivotally supported at one end and provided with sequential offset compression links of different lengths at the other end for interconnecting the outer contacts to maintain'a predetermined siibstantially uniform contact pressure between the arcing contacts during the wiping engagement and disengagement of the main contacts. I

6. A circuit brea er having in combination, separately'movable butting-inner and outer main and inner and outer arcing contactshaving pivotal mounting and conducting connections in looped spaced relation for electrodyna'mically biasing the inner main contact for joint movement in abutting wiping engagement with the outer contact,separate' means normally biasing each inner contact for joint wiping movement with the abutting outer contact, stop means limiting the biased movement of each inner contact, and compound toggle operating means having a tension link pivotally supported at one end and provided at the other end with separate compression toggle links of different lengths connected with the outer contacts for separately holding the arcing andmain contacts in wiping current-conducting engagement against the biasing forces exerted thereon and for effecting sequential disengagement of the outer contacts from the inner contacts at the limits of the biased movement thereof. 7 I

7. A circuit breaker having in combination a pair of main contacts separately pivoted for Joint wiping movement in one direction, a pair of arcfing contacts separately pivoted for joint wiping movement in the same direction, one of the arcin contacts being pivotally mounted on one of the main contacts, and operating mechanism having a tension link pivotally supported atone end to swing the other end thereof in a. direction transverse the direction of joint wiping movement of the contacts and provided at the other F end thereof with separate toggle link connections of different lengths with the one arcing contact and the one main contact offset for effecting separate and successive wiping disengagement and engagement 'of said pairs of contacts in reverse sequence. A

8. A circuit breaker-having in combination, a fixed conductor having "an arcing and a main contact separately pivoted thereon in conducting relation therewith, 'a' second fixed conductor having a second main contact pivoted thereon in con 76 ducting relation therewith for abutting wiping tact, separate'means normally biasing each inner engagement with the first pivoted main contact in electrodynamic looped relation with the conductors to increase the wiping pressure between the main contacts, a second arcing contact pivotally mounted on the second main contact in conducting relation therewith for abutting wiping engagement with the first arcing contact, and operatin mechanism having a tension link pivotally supported at one end and provided at the other end with separate compression toggle link connections of difierent lengths with the second arcing and second main contacts for effecting sequential engagement and disengagement thereof with the corresponding first arcing and main contacts in reverse sequence.

9. A circuit breaker having in combination, a first movable main contact having a separately movable arcing contact, and each having biasing means for eflecting separate wiping movement thereof in a limited range extending in the same direction, a second main contact pivotally mounted adjacent one end for joint wiping movement with the first main contact, a second arcing contact having one end thereof pivotally mounted intermediate the ends of the second main contact for joint wiping movement with the first arcing contact, and operating mechanism including a tension link pivotally mounted adjacent one end to swing the other end thereof in a directiontransverse the direction of the limited ranges and havin separate compression toggle links of different lengths offset for interconnecting the other end thereof with the second main contact and the second arcing contact to effect separate and successive wiping engagement and disengagement thereof with the corresponding first contacts in reverse sequence as the compression links successively move toward and away from force amplifying alignment with the tension link in closing and opening the circuit breaker.

10. A circuit breaker having in combination, a pair of main contacts separately pivoted in alignment for Joint wiping movement in one direction, a pair of arcing contacts separately pivoted in alignment for joint wiping movement in the same direction, one of the arcing contacts being pivotally mounted on one of the main contacts, a pivotally mounted tension link having one end movable in a direction transverse the direction of joint wiping movement of the contacts and having separate compression toggle links of different lengths connected between the one end thereof and the one arcing contact and the one main contact for effecting separate and successive wiping disengagement and engagement of said pairs of contacts in reverse sequence upon predeterr-ined reverse angular moverrents of they tension link in said transverse direction, and means including a toggle mechanism for effecting said predetermined reverse angular movement of the tension link in said transverse direction to close and open the breaker. v

11. A circuit breaker having in combination, a centrally fulcrumed closing lever provided with a releasable fulcrum lever pivoted at one end and having overload current-responsive releasable holding means engaging the other end thereof, a contact mechanism operatively connected with one end of the operating lever to close the contacts upon movement of the closing lever from one position to another position and provided with biasing means for opening the contacts upon response of the current-responsive holding means 10 to release the fullcrum lever, and a latch engageable with the other end of the closing lever for holding the closing lever in said other position against the opening bias of the contact mechanism.

12. A circuit breaker having in combination, a centrally fulcrumed main operating lever provided with a releasable fulcrum lever pivoted at one end and having overload current-responsive releasable holding means engaging the other end thereof, a sequential arcing and main contact toggle mechanism having a toggle link connection with one end of the main operating lever to close the contacts sequentially upon movement of the main operating lever from one position to another position and provided with a biasing spring for opening the contacts sequentially upon response of the current-responsive holding means to release the fulcrum lever, and a latch engageable with the other end of the main operating lever for holding the main operating lever in said other position against the bias of the spring.

13. A circuit breaker having in combination, an operating bell crank provided with a releasable fulcrum lever pivoted at one end and having overload current-responsive releasable holding means engaging the other end thereof, switching means having separate toggle operated main and arcing contacts provided with a common tension link having an intermediate toggle link connection with one end of the bell crank to close the contacts upon movement of the bell crank from one position to another position and provided with biasing means for opening the contacts upon response of the currentresponsive holding means to release the fulcrum lever, a latch engageable with the other end of the bell crank for holding the crank in said other position and closing mechanism having a member engageable with the other end of the bell crank to effect movement thereof from the one position to the other position.

14. A circuit breaker having in combination, an operating bell crank provided with a releasable fulcrum lever pivoted at one end and having overload current-responsive releasable holding means provided with a movable prop for engaging the other end thereof when the current is below a predetermined value, switching means having sequential toggle operating main and arcing contacts operatively connected with one end of the bell crank to be closed upon movement of the bell crank from one position to another position and provided with biasing means for opening the contacts upon response of the current-responsive holding means to release the prop from the other end of the fulcrum lever, a latch engageable with the other end of the bell crank for holding the crank in said other position and releasable upon the resulting movement of the bell crank upon release of the prop, and means biasing the fulcrum lever to return into engagement with the prop after the contacts are opened.

JOHN A. FAVRE.

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

UNITED STATES PATENTS Loguin Oct. 27, 1914