US2936351A - Automatic resetting mechanism - Google Patents

Description

E. T. PLATZ AUTOMATIC RESETTING MECHANISM May 1o, 1960 4 Sheets-Sheet 1 Filed April 16, 1958 imlmwl Y lm. .MUINNI -N IUIHNI May 10, 1960 E. T. PLATZ AUTOMATIC RESETTING MECHANISM 4 lSheets-Shear. 2

Filed April 16, 1958 INVENTOR. fl [fl/00D T. /ZTZ 'Wdlnlnmmll May 10, 1960 E. T. PLATZ AUTOMATIC- RESETTING MECHANISM Filed April 16, 1958 4 Sheets-Sheet 3 INVENTO ,EU/V700 7.' PEZ/ifa May l0, 1960 E. T. PLATZ 2,936,351

AUTOMATIC RESETTING MECHANISM Filed April 1e, 1958 @sheets-sheet 4 I Q lh H 47am/M United States Patent O l AUTOMATIC RESETTING MECHANISM Elwood T. Platz, Detroit, Mich., assigner to r-'r-E Circuit Breaker Company, Philadelphia, Pa., a corporation of Pennsylvania Application April 16, 1958, Serial No. 728,973

6 Claims. (Cl. 200-70) p My invention relates to a novel operating mechanism for circuit breakers, and more specifically relates to a toggle operating mechanism for automatically resetting circuit breakers in which the frictional forces tending to oppose the automatic resetting motion are reduced.

Toggle operating mechanisms for circuit breakers generally comprise a pivotally mounted yoke which carries one end of an operating spring with the other end of lthe operating spring operatively connected to 'the inovable contact. One such device is described in copending application Serial No. 426,223, tiled April 28, 1954, in the name of John A.y Herrmann et al. and assigned to the assignee of the instant invention. Y

When the movable contact of the above noted type mechanism is moved to the open position by the operating spring, its motion is stopped by some externally positioned stop means. connection is formed from the stopmeans through the contact arm to the 'operating spring and the portion of the yoke to which the operating spring is fastened?. Hence, the yoke will be forcedj into its pivotal mounting by the operating spring to thereby cause an appreciable frictional force which opposes -rotation of the yoke about its pivot. f vIn an automatically Vresetting mechanism, the yoke Iis moved to its reset position primarily because of the in- 2,936,351 Patented May 1o, 1960 "ice 2 a novel toggle operating mechanism for automatically resetting circuit breakers in which the force Vof the toggle springs are isolated from the bearing of the toggle operating link. A

These and other objects of my invention will become apparent from the following description when taken in conjunction with the drawings in which- Figure 1 shows a top View of a multiphase circuit breaker equipped with my novel indicating structure with the top of the circuit breaker removed. Y

Figure 2 shows a side view of the operating toggle mechanism for the circuit breaker of Figure 1 when in the o position.

Figure 2a shows a side cross-sectional view of the operating yoke of Figure 2.

Figure 2b shows a perspective view of the operatin yoke of Figure 2a..

Figure 3 is similar to Figure 1, and shows vthe multiphase circuit breaker with its cover and operatingfhandle in place. Y Y

Figure 4 shows a side view of one phase of the circuit breaker of Figure 1, and particularly illustrates the current path therethrough.

Figure 4a1 shows ra side cross-sectional View through one phase of the breaker of Figure l when in the on position. Y

Therefore, a force transmitting Y ertia imparted to the yoke after an initial collapse of This condition becomes more severe when the size of "the operatingA springs kare increased for circuit breakers having larger ratings, increased contact speed, or higher contact pressure.

" The essence of my invention is to substantiallyv elim- VFigure 5 shows an enlarged side cross-sectional view of the toggle mechanism of Figure 2in the o or reset position. Y e

Figure 6 is similar to Figure S where the toggle mechanism is in the on position. Y

Referring now to the figures, Figures l, 2, 201, 2b, 3, 4 and 4a set forth one type of circuit breaker Vto which my novel invention could be applied. It is to be noted that while the following description of my novel invention is made in conjunction with thespecifc circuit breaker of Figures 1 through 4, that any type circuit breaker which could be of either the single pole, or multi-pole type could be modified in -accordance with the invention.

As shown in Figures l and 3, the circuit breaker' `is of the three pole type having input line conductors 10, 12 and 14 for each respective pole and output load con ductors 16, 18 and 20 respectively for the same respective poles. Each of line conductors 10,- 12 and 14 are taken through arc chute means 22, 24 and 2'6 respectively and are terminated by a respective stationary contact such as contact 28 for the phase including line member 14 as seen in Figures 4 and 4a, where Figures 4 and 4a are Views of Figure 3 takenacross lines 4--4.

inate the above described frictional force at the yoke f* pi-vot by confining the force of the operating spring wholly within the yoke after the initial contact opening operation. That is, in the past, one end of the operating spring was operatively connected to an external mem- 'ber whereby the other end drove the yoke into relatively vhigh pressure engagement. with its pivot bearing. I 'prevent this condition by providing means within the yoke for engaging the end of the operating spring which is operativelyl connected to the movable contact arm after the Contact opening operation so that both ends of the spring are connected to the yoke and the spring is incapable of transmitting a force to the yoke bearing.

Accordingly, a primary object of my invention is to provide a novel toggle mechanism for circuit breakers.

Q ,Another object of my invention is yto decrease the' A still further object of my invention is to provide Each of the stationary contacts then cooperatefwith a respective movable contact such as movable contacts 3 0, 32 and 34 (Figure 1). f f

As best seen in Figures l, 4 and 4a, each of fthe movable contacts are connected to acommon operating bar 36 and are pivotally movable on bar 36 to be movable into and out of engagement with their cooperating stationary contact. The 'operating mechanismfor yoperating the movable contacts will be set forth hereinafter in conjunction with Figures 2, 2a, 5 and 6. u

As is best seen in Figure 4, each of movable contacts 30, 32 and 34 have a conductive pigtail such as pigtail 38 for stationary contact 34 connected thereto which leads to a stationary conductor such as conductor 40, The conductor 40 for the phase including movable contact 34 and the corresponding conductors of the other `two phases then have a bimetal element associated therewith in thermal relationship, the bimetal for the phaseV shown in Figures 4 and 4a having bimetal element 42. Clearly, the bimetal elements of each of the phases operate as the overload trip elements for that phase.v

:3,936,351 Y -y l' Y f The conductors, such as conductor 40 then continue through a magnetic structure such as magnetic structure 44 in Figures 4 and 4a which has an armature member associated therewith. This combination, as is well known in the art, and as described in copending application Serial No. 706,169, iiled December 30, 1957, operates as the instantaneous trip element for the circuit breaker, and operates responsive to short circuit currents in their respective phase.

As seen in Figure 1, each conductors 40, 46 and 48 for the highest, middle, and lowest phase or pole respectively emerge from their respective magnetic trip units and are connected to load conductors 16, 18 and 20 respectively.

Accordingly, the current path for each pole is completed, and as best seen in Figure 4 for the case of the highest pole in Figures 1 and 3, is comprised of line conductor member 14, stationary contact 28, movable contact 34, pigtail 38, conductor 40 and line conductor member 20.

'Ihe circuit breaker of Figures 1 through 4 is manually operated from a rotary operating handle 50 seen in Figure l where, as shown by plaque 52, the operating handle is rotated counter-clockwise to open the contacts and clockwise to close the contacts.

As is more fully described in copending application Serial No. 706,186, tiled December 30, 1957, and assigned to the assignee of the instant invention, the operating handle 50 is secured to operating shaft 54 of Figures 1 and 4 which is seated in any desired manner in the casing of the circuit breaker. Shaft 54, as best seen in Figures 1, 2 and 4a has an extending crank arm 56 rigidly secured thereto which has its outer end secured in a ball and socket connection to one end of member 58. The 'other end of member 58 is secured in a `Second ball and socket connection to a member (not shown) which is fastened to an operating yoke 60.

Yoke 60 is pivotally supported about pivot point 62, as will be described more fully hereinafter, and forms an operating toggle linkage with link 64 (Figure 2) and springs 66 where one end of toggle link 64 is positioned in a shoulder of latching cradle 68. The toggle linkage is then connected to contact arm 33 through an intermediate link 70 which is pivotally connected at the junction between spring 66 and toggle link 64.

As best seen in Figures 1 and 3, each of the phases has an indicating cylinder 74, 76 and 78 respectively associated therewith (Figure 1) which cooperate with windows `80, 82 and 84 respectively (Figure 3) in cover 85 (Figure 4a) to present the appropriate contact indication to an observer. More specifically, each of the phase indicators can present either an of't'j on, overload or short circuit indication through their respective Windows. Furthermore, they can present conditions particular to their own respective phase. By way of example, in Figure 3, the circuit breaker has been tripped and a visual inspection clearly shows that the breaker operated automatically because of an overload on the lower phase. Further details to the operation of this structure are set forth in copending application Serial No. 706,169, iiled December 30, 1957.

The specific structure of my novel automatic resetting mechanism is seen in the oli position in Figure 5 and in the on position in Figure 6. As heretofore described, the reset mechanism includes the toggle mechanism comprised of members 60, 64 and 70 wherein the contact arms 33 (Figures 2a and 2b) are on the output of the toggle drive system while springs 66 actuate the system. As is best seen in Figures 2a and 2b, the operating yoke 60 is journaled to the frame 90 to be pivotally mounted thereby. For example, projections 71 and 73 carried by yoke 60 may project through cooperating openings in frame 90 schematically indicated in Figure 2b by dotted lines.

4 The latching mechanism for the above toggle system includes the intermediate latch member 89 which is pivotally mounted at pivot point 92 and carries an extension of latching cradle 68 within slot 94. The intermediate latch member -89 is latched by the auxiliary latch 96 which is pivotally carried at pivot point 93. Aux-v iliary latch member `96 is in turn connected to latch member 100 which as is best seen in Figure 4a cooperates with latching mechanism 109 which is operated from a common trip system which is actuated by either thermal or mechanism trip elements as has been described in copending application Serial No. 706,186, filed December 30, 1957, and assigned to the assignee of the instant application.

Trip system 102 operates on a common tripper bar 104 which is rotatable to unlatch latch member' 100 and thus allow a clockwise rotation of member 100 about pivot point 98. This will cause the auxiliary latch 96 to unlatch member 89 and thus allow cradle 68 to rotate counter-clockwise about its pivotal support 106 in support 90.

When the circuit breaker is in its off and reset position, as seen in Figure 5, a rotation of operating handle 50 will cause yoke 60 to rotate counter-clockwise about its journaled pivot 62 so that the top of spring 66 supported by yoke 60 passes across the line defined by point of engagement of link 64 and cradle 68 and the lower end of spring 66 and its attachment to link 70. This will cause the lower end of link 64 to snap to the left to thereby drive link 70 downwardly so that contact arms 33 attached at pivot 108 of link 70 are moved toward the engaged position of Figure 4a.

If, while the breaker is in the on position of Figure 5, the trip unit is operated to unlatch latch 96, the auxiliary latch member 89 will rotate counter-clockwise under the force of cradle 68 which is biased counterclockwise by the toggle springs 66 operating through llink 64. The counter-clockwise motion of cradle 68 will bring the upper point of link 64 to the left and to a position where the toggle formed by links 64 and 70 breaks to the right. With the toggle defeated, the force of opening springs 66 are exerted on contact arms 33 to move the contact arms upwardly and towards a disengaged position.

At the same time, the reactive force of contact arms 33 will operate on yoke 60 so as to initiate the rotation of yoke 60 in a counter-clockwise direction and thus initiate the resetting operation while the contacts are still moving their disengaged position. That is to say, while spring 66 contracts to draw contact arms 33 upwardly, there is an equal and opposite force exerted on the yoke at the point at which the spring 66 engages yoke 60. The component of this force is perpendicular to the line joining the pivot 62 of yoke 60 and is directed to the right, and it is this component of force which causes the motion of yoke 60 towards its reset position.

It is now to be noticed that if the contact arms 33 are moved to a fully open position against some external stop member, that the force transmitted through springs 66 to the stop member would include the journal bearing 62. This may be seen in Figures 2a and 2b where there would be a connection from the top of the yoke 60 through springs 66, link 70, contact arms 33, and to the external stop. This spring force would operate to drive yoke 60 into its journaled bearing 62 to thereby create a relatively high frictional force which would oppose the free rotation of yoke 60.

In accordance with the instant invention, the yoke 60 has inwardly protruding semi-cylindrical projections 112 and 114 which may be integral with the bearings of the yoke and extending over the outwardly protruding ends ofpivot shift 108.

Accordingly, as the contact arms 33 are drawn upward- 1y during contact disengagement, the protruding ends of shaftl will seat in semi-cylindrical projections 112 'and 114 prior to the engagement ofcontact arms 33 with any external stop member. Therefore, the motion of contact arms 33 is limited by the distance that shaft 108 maydrive prior to engagement with projections 112 and 114. Once the shaft 108 seats within projections 112 and 114,-the force of operation springs 66 is completely confined within the operating yoke 60 and no additional force will now be transmitted to the journal bearings 62. By so confining the operating force of springs 66, these springs may be as powerful as required and still will not transmitany vforce opening to drive yoke 60 into journal bearings 62. y

Since the force of springs 66 is confined, the initial rotation imparted to yoke 60 will now. be suicient to allow yoke 60 to continue its clockwise rotation after the contacts'have been disengaged. Therefore, links 64 and 70 will be moved from the position of Figure 6 and toward the position ofr Figure 5 and cradle 68 and its associated intermediate latch 89 will be permitted `to return to a latching position. For this purpose, alight auxiliary spring (not shown) may be associated with latch cradle 68. Hence, the breaker will be automatically reset after its automatic operation due to automatic tripping through trip unit 102.

Similarly, a relatively light handle return spring may be wound on the lower end of the operating handle shaft to supply energy for bringing the operating yoke to its off position in the event that during automatic tripping, the operating handle is held in its on position by an operator.

In the foregoing, I have described my invention only in connection with preferred embodiments thereof. Many variations and modifications of the principles of my invention within the scope of the description herein are obvious. Accordingly, I prefer to be bound not by the specific disclosure herein but only by the appended claims.

I claim:

l. An automatic resetting mechanism for a circuit breaker; said automatic resetting mechanism comprising a yoke member operatively connected to the operating handle of said circuit :breaker and supporting a first end of an operating spring, a toggle mechanism having a first portion thereof connected to a second end of said operating spring and a second portion thereof operatively connected to the cooperating contacts of said circuit breaker; said operating spring being loaded responsive to operation of said yoke member to a closed position to move said contacts to an engaged position through said toggle mechanism, said spring moving said contacts to a disengaged Vposition responsive to breaking of said toggle mechanism; and confining means operatively connectable to said second end of said spring to directly connectV said second end of said spring through ia rigid member .to said first end of said spring when said cooperating contacts are disengaged.

2. An automatic resetting mechanism for a circuit breaker; said automatic resetting mechanism comprising a yoke member operatively connected to the operating handle of said circuit breaker and supporting a first end of an operating spring, a toggle mechanism having a first portion thereof connected to a second end of said operating spring and a second portion thereof operatively connected to the cooperating contacts of said circuit breaker; said operating spring being loaded responsive to operation of said yoke member to a closed position to move said contacts to an engaged position through said toggle mechanism, said spring moving said contacts to a disengaged position responsive to breaking of said toggle mechanism; and confining means operatively connectable to said second end of said spring to connect said second end of said spring through a'rigid member to said first end of said spring when said cooperating contacts are 6 disengaged;said confining means being rigidly supported by said yoke member, said operating'spring being completely confined within said yoke member after said cooperating contacts are disengaged. A

3. An automatic resetting mechanism for la circuit breaker; said automatic resetting mechanism comprising a yoke member operatively connected to the operating handle of said circuit breaker and supporting a first end of an operating spring, a toggle mechanism having a first portion thereof connected to a second end of said operating spring and a second portion thereof operatively connected to the cooperating contacts of said circuit breaker; said operating spring being loaded responsive to operation of said yoke member to a closed position to move said contacts to an engaged position through said toggle mechanism, said spring moving said contacts to a disengaged position responsive to breaking of said toggle mechanism; and conning means operatively Vconnectable to said second end of said spring to connect said second end of said spring through a rigid member to saidv first end of said spring when said cooperating contacts are disengaged; said confining means being rigidly supported by said yoke member, said operating spring being completely confined within said yoke member after said cooperating contacts are disengaged; said yoke being thereafter free to move independently of the force of said spring.

4. An automatic resetting mechanism for a circuit breaker; said automatic resetting mechanism including a pivotally mounted yoke member, an operating spring, a toggle mechanism and a latch means; said pivot-ally mounted yoke member having one end of said operating spring attached thereto, said toggle mechanism forming an operative connection between the other end of said operating spring and a movable contact of said circuit breaker, said latch means being operative to latch said toggle mechanism in a latched position, said yoke member operating through said operating spring being operative to drive said movable contact to an engaged position and load said operating spring when said toggle mechanism is latched and said yoke member is moved to a closed position; said latch member being defeatable responsive to predetermined conditions toV allow said toggle to break, said movable contact being moved to a disengaged position by said operating spring when said toggle breaks; and

V confining means operatively connectable to said end of said spring connected to said toggle mechanism when said movable contact moves to said disengaged position to rigidly connect each of said ends of said operating spring and preventing the force of said operating spring from being applied to the pivot point of said pivotally mounted yoke member.

5. An automatic resetting mechanism for a circuit breaker; said automatic resetting mechanism including a pivotally mounted yoke member, an operating spring, a toggle mechanism and a latch means; said pivotally mounted yoke member having one end of said operating spring attached thereto, said toggle mechanism forming an operative connection between the other end of said operating spring and a movable contact of said circuit breaker, said latch means being operative to latch said toggle mechanism in a latched position, said yoke member operating through said operating spring being operative to drive said movable contact to an engaged position and load said operating spring when said toggle mechanism is latched and said yoke member is moved to a closed position; said latch member being defeatable responsive to predetermined conditions to allow said toggle to break, said movable contact being moved to a disengaged position by said operating spring when said toggle breaks; and confining means operatively connectable to said end of said spring connected to said toggle mechanism when said movable contact moves to said disengaged position to rigidly connect each of said ends of said operating spring and preventing the force of said operating v spring attached thereto, said toggle mechanism forming an operative connection between the other end .of said operating spring and a movable contact of said circuit breaker, said latch means being operative to latch said toggle mechanism in a latched position, said yoke member operating through said 'operating spring being operative to drive said movable contact to an engaged position and load said operating spring when said toggle mechanism is latched and said yoke member is moved to a closed position; said latch member being defeatable responsive to predetermined conditions to allow said toggle to break, said movable contact being moved to a disengaged position by said operating spring when said toggle breaks; and coniining means operatively connectable to said 4encl of. said spring connected to Vsaid toggle mechanism when said movable contact'moves to said disengaged position to rigidly connect each of ,said ends-of said operating spring and preventing the force of said operating spring from being applied to the pivot point ,of said pivotally mounted yoke member; said coniining means being supported within said yoke member; said operating yoke being relatively free to rotate to an open and reset position after unlatching of said latching means independently of friction at said pivot point normally caused by said operating spring.

References Cited in the tile of this patent `UNITED STATES PATENTS 1,786,798 Von Hoorn Dec. 30, 1930 1,815,561 Getchell July 21, 1931 1,952,039 Frank Mar. 20, 1934 1,985,023 Dorfman Dec. 18, 1934 2,357,210 Leonard Aug. 29, 1944 2,829,219 Christensen Apr. 1, 1958 2,830,154 Herrmann et al Apr. 8, 1958

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