US3163735A

US3163735A - Electric circuit breaker with sealed interrupting unit

Info

Publication number: US3163735A
Application number: US206310A
Authority: US
Inventors: Richard H Miller
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1962-06-29
Filing date: 1962-06-29
Publication date: 1964-12-29
Anticipated expiration: 1981-12-29

Description

Dec. 29, 1964 Filed June 29, 1962 R. H. MILLER 3,163,735

ELECTRIC CIRCUIT BREAKER WITH SEALED INTERRUPTING UNIT 4 Sheets-Sheet 1 mmwl no? 66 mo" /02 m8 /NVENTOR.'

RICHARD H M/LLER,

ATTORNEY.

R. H. MILLER Dec. 29, 1964 ELECTRIC CIRCUIT BREAKER WITH SEALED INTERRUPTING UNIT Filed June 29, 1962 4 Sheets-Sheet 2 lNVENTOR R/cHA/w H. MILLER,

ATTORNEY.

Dec. 29, 1964 R. H. MILLER 3,153,735

ELECTRIC CIRCUIT BREAKER WITH SEALED INTERRUPTING UNIT Filed June 29, 1962 4 Sheets-Sheet 3 /N\ /ENTOR.' R/cHARo H MILLER,

ATTORNEY.

Dec. 29, 1964 R. H. MILLER 3,163,735

ELECTRIC CIRCUIT BREAKER WITH SEALED INTERRUPTING UNIT Filed June 29, 1962 4 Sheets-Sheet 4 /NVENTOR.

RICHARD H M/LLER BY W ATTORNEY.

United States Patent Ofilice t n-tented Sec. 21%, 196- 1 This invention relates to an electric circuit breaker and, more particularly, to a circuit breaker of a highly compact, exceptionally lightweight design that readily lends itself to high voltage circuit applications.

In the circuit breaker oi the present invention, circuit interruption is ellected by separating a set of contacts within interrupting unit that is disposed within a protectivehousing. The contacts are actuated by means of a linkage also disposed within the housin High voltage terminal bushings project into the housing and carry current to and from the interrupting unit.

An object of the present invention is to constructand arrange the interrupting unit, the contact-actuating linkage, and the terminal bushings in such a manner that the required electrical clearances and creepage distances for high voltages can be provided within ahousing of small volume that consumes exceptionally small amount of ground space.

The repeated operation of a circuit breaker results in the loss of contact material through wear and arc-erosion. To compensate for this loss of contact material so that adequate contact pressure can be developed despite the loss of contact material, it is customary to provide for overtravel of the contact-actuating linkage alter the contacts first engage during a closing operation. This overtravel is referred. to hereinafter as contactwvipe and the mechanism that provides for this overtravel is referred to hereinafter as a contact-wipe mechanism.

For obtaining contact-wipe in the circuit breaker of the present invention, a spring coupling is incorporated into the actuating linkage for the movable contact. This coupling permits overtravel or" the actuating linkage to occur after the contacts engage during a closing operation.

Another object of the present invention is to construct this contact-Wipe arrangement in such a manner that it is of a simple and compact design that can be used with a minimum of intermediate structure between it and the movable contact.

Another object is to construct this contact-wipe arrange ment in such a manner that it can operate smoothly and reliably during both opening and closing without the need for lengthy and precise slide bearings or guides.

Still another object is to mount the interrupter in such a manner that arc-erosion of its contacts through contactbounce produced by closing impacts is held to a nearminimum.

.lQn carrying out my invention in one form, I provide an electric circuit breaker that comprises a metallic housing and a pair of spaced-apart temrinal bushings extending through a wall of the housing. Each of the bushings comprises a conductor for carrying current between its opposite ends and means for insulating the conductor from said wall. An electric circuit interrupter comprising a sealed envelope and a pair of separable contacts located Within the envelope is provided at the inner ends of ihe terminal bushings. One end of the envelope is mounted on one of the bushings and the other end is mounted on the other of the terminal bushings. Means is provided for connecting the conductor of a first one of the bushings to the movable one of the contacts and for connecting the conductor of the other bushing to the other of the contacts. For actuating the movable contact, a rotatable op ting shaft is provided extending generally perpendicular to a once plans including the bushings. This shaft is located adjacent the wall through which the bushings extend. at a side of said first bushing opposite to ti e location or" the other bushing. Insulating means is pro vided for transmitting motion from said rotatable operating shaft to said movable contact to produce opening and closing motion of the movable contact.

In one embodiment of my invention, the rotatable operating shaft is a horizontallyextending element that is actuated by means or: an operating mechanism disposed in a location beneath the bushings and the circuit interrupter. Motion is transmitted to the rotatable operating shaft by means of a generally vertically extending rod disposed adjacent a side wall of the housing.

in accordance with another feature of this invention, the contact-wipe means is incorporated into an operating linkage for the movable contact that comprise a reciprocable driven member coupled to the movable contact and a reciprocable driving member movable along a path extending transversely to the path of movement of the driven member. The driving and driven members are interconnected by force-transmitting means that converts motion of the driving member in one direction into contact-closing motion of the driven member and converts motion of the driving member in an opposite direction into contact-opening motion of the driven member. This force-transmitting means comprises an intermediate link pivotally connected at one end to one of these members and pivotally connected with lost motion at its opposite end to the other of these members and spring means between these members bodily movable with said intermediate link for transmitting contact-closing motion of the driving member to the driven member and permitting lost motion of the driving member in a contactclosing direction relative to the driven member after the contacts engage. The force-transmitting means further comprises a stop on the intermediate link for limiting lost motion of the driving member in a contact-opening direction and for thereafter transmitting contact-opening motion of the driving member to the driven member by means of forces loading the intermediate link in tension. The driving member is loaded in compression during contact-closing and in tension during contact-opening.

For a better understanding of the invention, reference may be had to the following specification taken in con junction with the accompanying drawings, wherein:

FIG. 1 is a front view of the exterior of an electric circuit breaker embodying one form. of my invention.

FIG. 2 is an enlarged side view of the circuit breaker of FIG. 1 with a portion of the side wall broken away to show some of the internal details of the circuit breaker.

PEG. 3 is a sectional View taken along the line 3-3 of F IG. 2. The circuit breaker is shown in an open position in FIG. 3.

FIG. 4 is a detailed view of a portion of the linkage shown in FIG. 3 but illustrating the position of the parts at the end of a contact-closing stroke.

FIG. 5 is a detailed View of the mounting for one of the terminal bushings shown in FIGS. l-3.

FIG. 6 is a sectional view taken along the line ti-5 of FIG. 2.

1G. 7 is a sectional view taken along a line corresponding to 7? of FIG. 1 but illustrating amodified embodiment of the invention.

Referring now to FIGS. 1 and 2, a three-phase circuit breaker is shown therein comprising a metallic enclosure in in which the major components of all three phases or poles 12, 14, and 1d of the circut breaker are located. This enclosure 1d comprises two major portions, one of which is a box-like upper compartment 13 and the other of which is a box-like lower compartment 20 on which the upper compartment 18 is supported and fixedly mounted. The upper compartment 13 houses the interrupting components of the three poles of the circuit breaker, and the lower compartment houses a common operating mechanism 116 for these interrupting components.

The upper compartment 18 comprises a top Wall 22, which is disposed in a horizontal plane, and end walls 23 and sidewalls 24 which are disposed in vertical planes perpendicular to the top wall. Within the upper compartment 18 between adjacent poles of the circuit breaker, insulating barriers 25 are disposed to minimize the chances for an electrical breakdown between the live parts of the adjacent poles.

Since the poles of the circuit breaker are substantially identical only one will be described in detail. This will be done with reference to FIG. 3, which is a sectional view along the line 33 of FIG. 2. This pole of FIG. 3 comprises a sealed interrupting unit 30 which is preferably a vacuum-type circuit interrupter. The internal details of this circuit interrupter 30 form no part of the present invention and are therefore shown in schematic form only. For a more specific showing of an interrupter suitable for use in the disclosed circuit breaker, reference may be had to U.S. Patent No. 2, 892, 9l1-Crouch and U.S. Patent No. 2,949,520-Schneider, both assigned to the assignee of the present invention. Generally speaking, the circuit interrupter 30 comprises an evacuated and sealed envelope 32 in which a pair of separable butt-

type contacts

34 and 36 are mounted. The contacts have been suitably processed to free them of sorbed gases and contaminants that decompose in the presence of an arc to produce permanent gases. The envelope 32 comprises a tubular housing 37 of insulating material and a pair of

metallic end caps

38 and 39 closing oii the ends of the tubular housing. The end caps 38 and 39 are joined to the housing 37 by means of suitable seals 4-1 forming vacuum-tight connections between the end caps and the tubular housing. The left-hand contact 34 is a stationary contact that is supported on the inner end of a conductive rod 4t). This conductive rod 4% projects in sealed relationship through the left-hand end of the envelope 32 and is rigidly attached to the end cap 38 as by welding.

The other contact 36 of the circuit interrupter is a movable contact brazed to the inner end of a conductive actuating rod 45, referred to hereinafter as the contact rod. This contact rod 4-6 is mounted for substantially straight line movement along it longitudinal axis and projects through an opening in the right-hand end cap 39. A flexible metallic bellows 48 is interposed between the left-hand end cap 39 and the movable contact rod 46 to provide a seal about the contact rod that allows for longitudinal movement thereof without impairing the vacuum inside the envelope 32. As shown in FIG. 3, the bellows 48 is secured at its respective opposite ends to the contact rod 46 and the end cap 39 by means of suitable sealed joints.

Opening of the circuit interrupter 39 is effected by applying a force to the contact rod 46 to drive the movable contact 36 to the right out of engagement with the other contact 34-. This moves contact 36 from its dotted line position to its solid line position of FIG. 3. Initial separation of the contacts establishes a circuit-interrupting are between the contacts, and this are persists until about the time a natural current zero is reached. The are will then vanish and be prevented from re-igniting by the high dielectric strength of the vacuum, thus completing the circuit interrupting operation. Closing of the interrupter is effected by driving the right hand contact 36 from its solid line open position of FIG. 3 in a leftward direction into engagement with the other contact, thus reestablishing the power circuit through the interrupter.

The actuating means for effecting opening and closing movement of the contact rod .6 will soon be described in detail, but first a description will be given of the structtu'e that is relied upon for supporting the interrupter 3t and for carrying current to and from its contact-supporting rods 40 and .46. This latter structure comprises a pair of conventional high voltage terminal bushings 49 projecting through the top wall 22 of the upper compartment 18 in lateraliy spaced-apart relationship. Each of these bushings 49 comprises a tubular porcelain shell 50 and a conductive stud 51 extending through the porcelain shell along its longitudinal axis. The stud and the shell of each bushing are rigidly fixed to each other by means of nuts 52 threaded into opposite ends of the stud. When these nuts 52 are suitably tightened they clamp the porcelain shell in compression and hold the conductive stud 51 in a fixed position therein. The nuts 52 carry suitable bosses 53 projecting into the bore of the porcelain shell 50 to insure against radial movement of the stud 51 relative to the shell 50.

The interrupting units 3% is supported between the spaced-apart terminal bushings at the lower end thereof. To this end, a first adaptor 55 is suitably clamped at one end to the conductive stud of the left-hand bushing 49 and at its other end to the contact supporting rod 40. This adaptor 55 is of a conductive material and serves not only to support the left-hand end of the interrupter on the adjacent stud 51 but also to carry current between the rod 4% and the adjacent conductive stud 51.

For supporting the right-hand end of the interrupting unit 36, another adaptor 63 is provided. This adaptor 63 has a flat portion 61 that seats against the right-hand end plate 39 of the interrupter and is suitably bolted to this end plate. Spaced-apart ears 63 integral with this fiat portion project away from the end plate 39 and extend upwardly toward the stud of the right-hand bushing 49. Between these ears 63 and attached thereto is a metallic block 62 that contains an opening for receiving the stud 51. This metallic block 62 is split at its lefthand side. A bolt 65 extends through the split portion of the block 62 and can be tightened to clamp the block firmly about the lower end of the stud 51.

For carrying current between the stud 51 of the righthand bushing and the movable contact rod 46, suitable copper braid 66 is connected at one end to a copper block 64 and at its other end to the contact rod 46. The copper block is suitably clamped to the stud 51. The connection of the braid to the contact rod 46 is through a split conductive ring 67 clamped about the contact rod. The braid is suitably welded to this ring 57. Thus current can flow from the lower end of stud 51 through copper block 64, braid 66 and split ring 67 to the contact rod 46.

Each of the terminal bushing id is supported on the top wall 22 of the upper compartment 18 by means of a radially-extending flange 7th integral with theporcelain shell 50. Disposed between this flange 7t and the top wall 22 is a resilient annulus 72 made of an elastomer such as rubber or some other similar resilient material. The resilient member 72 under the flange of the left-hand bushing contributes in an important manner to the reduction of harmful contact-boruice resulting from the impacts of closing, as will soon be described in more detail. The flange 70 is clamped against this resilient annulus 72 by means including studs 73 suitably fixed to the top wall 22 at circumferentially-spaced locations about the flange 7%. Nuts threaded on these studs can be tightened to force suitable washers '75 into engagement with the top surfaces of the flange 70 to provide some initial precompression of the resilient annulus 72.

For guiding the contact rods along an essentially straight-line path during opening and closing, a stationary slide bearing 77 is provided at a location within the bellows 48. This slide bearing 77 is mounted within a tubular metallic housing 78 that is fitted within an opening in the adaptor es and suitably fixed thereto. Additional guidance for the contact rod 46 is provided at its outer end by means of a guide link 79 thatis pivotally mounted at its upper end on a stationary pivot 84) carried by the adaptor 60. This guide link 79 is pivotally connected at its lower end to the contact 46 by means of a 0 pivot Sli. The reference line connecting the two pivots 89 and M is normally approximately perpendicular to the straight line path along which the contact rod as moves. Since the total stroke of the contact rod 46 is small relative to the length of link '79, the pivot 31 follows an essentially straight line path during an operating stroke. The gni ance afforded by the guide link 79 in combination with that afforded by the slide bearing 7'7 assures motion of the contact rod in an essentially straight-line path.

For transmitting driving forces to the contact rod as in order to drive it along the above-described straight line path, a rotatable operating shaft 92 is provided adjacent the top wall 22 of the upper compartment l This rotatable operating shaft 92 is suitably journaled in spaced-apart bearings carried by transverse plates 93 welded to the top wall 22. This operating shaft 92 is located at a side of the right hand bushing 49 opposite to the location of the other bushing 49. This location contributes to the compactness of the circuit breaker, as will soon be explained.

For transmitting contact-actuating motion from the rotatable operating shaft 92 to the contact rod 46, a crank 95 is keyed to the operating shaft 92 in a position substantially aligned with contact rod 46 in a direction lengthwise of the operating shaft 92. Pivotally connected to the outer end of this crank 95 is a link 96 in the form of an operating rod of a suitable insulating material. The lower end of this operating rod 96 is guided by means of: a guide link 9'7 pivotally connected at its lower end to the operating rod 96 at 98. This guide link 97 is pivotally supported at its other end on the previously described stationary pivot 36, which is carried by the adaptor 60.

When the circuit breaker is to be closed, the shaft 92 is rotated in a clockwise direction to drive the operating rod 97 downwardly. The downward path followed by the lower end of the operating rod is an are about the pivot 36 as a center. When the circuit breaker is to be opened, the shaft 92 is rotated in a reverse or counterclockwise direction to drive the operating rod 96 upwardly along the above-described path.

For converting downward motion of the operating rod 96 into contact-closing motion of the contact rod 46 and for converting upward motion of the operating red as into contact-opening motion of the contact rod 46, force-transmitting means 1% is provided between the lower end of the operating rod and the outer end of contact rod This force-transmitting means 1% comprises an intermediate link 1162 of rod form that is pivotally connected at one end to the contact rod 46 and is pivotally connected with lost motion at its opposite end to the operating rod 96. The connection to the contact rod do is through the previously described pivot 81 carried by contact rod 46. The connection to the operating rod as is by means of the previously described pivot 93 that is carried by the operating rod 95 and is jou'rnaled in the operating rod as for rotation relative to the operating rod. This latter pivot 98 has a transversely extending hole therethrough which receives the intermediate rod to permit motion of pivot 98 relative to the intermediate rod 162 along the length of intermediate rod 1&2. Disposed between the pivot 98 and the other end of the intermediate rod 192 is a compression spring that encircles the intermediate rod This compression spring tends to urge the pivot 98 against the stop liftl fixed to the intermediate rod Since the compression spring tea is carried by the intermediate rod 1%, it will be apparent that the spring moves bodily with the intermediate rod M52 during all circuit breaker operations.

When the operating rod is driven downwardly to inires,

wardly, forcing pivot 98 to slide along the intermediate rod ltlZ, compressing the spring res and opening a space between the pivot 98 and stop res on the intermediate rod Hi2. This overtravel action during which the spring is compressed serves primarily to provide contact-wipe. More specifically, this action assures that the

contacts

34, 36 are driven firmly into engagement despite loss of contact material through Wear and arc-erosion and without blocking the contacts of the other poles from engaging should the contacts 34, 3d of pole 12 engage ahead of the contacts of the other poles. Likewise, corresponding spring couplings associated with the other poles cornpensate for contact wear and arc-erosion in these poles and permit the contacts of pole iii. to be driven into engagement should the contacts of either of these other poles engage before the contacts of pole 12. Because of the role it plays in providing contact wipe, the force-transmitting means .ltltl is referred to at various points herein asa contact-wipe mechanism.

The compression spring 1% also contributes in an important manner to the reduction of harmful contactbounce. More specifically, when the contact 36 impacts against the contact 354 during closing, there is a tendency for stationary contact Bid to bounce repetitively, first out of engagement and then into engagement with the contact 36. The spring 1% reduces the tendency for this bounce action to separate the contacts since it helps impart followup ability to the movable contact as that tends to hold the contacts in engagement during these high frequency oscillations immediately following closing. The fact that the free, or forward, end of spring lilo is located immediately adjacent the contact rod 46 and no massive parts are interposed between this free end and the contact rod contribues in an important manner to the ability of spring Hi6 to produce the abovedescribed follow-up action during these oscillations. The lower the mass interposed between the movable contact and the spring, the more effective the spring is in this respect. In the disclosed linkage, this interposed mass has been held to a near-minimum.

One of the factors responsible for this reduced mass is that the spring ltld has been incorporated directly into the mechanism for converting motion of the operating rod 96 into motion of contact rod 46. This is in distinct con trast to certain prior designs, where the wiping spring has been located in an operating rod such as and it was necessary to interpose massive cranks and other mechanism between the spring and the contact rod.

Another factor that contributes to the reduced contactbounce tendency that is present in the disclosed circuit breaker is the resilient mounting 7b, T2 of the left hand terminal bushing 49 on which the stationary contact 34 of Phil. 3 is mounted. The impact of contact-closing loads this terminal bushing 49 in bending or cantilever tending to pivot it about its resilient mounting a clockwise direction. The resilient mounting yields slightly upon initial impact between the contacts, dissipating some of the impact energy in tle form of frictional heating. This yielding action is depicted in the enlarged view of PEG. 5 by the dotted line showing of flange which is shown compressing the portion of annulus 72 at its right hand side in response to the initial closing impact. The undissipated energy is returned to the supporting structure for the stationary contact to produce reverse motion ot this structure toward its initial position. The rate at which this reverse motion is decelerated is important factor determining Whether the contacts will separate as the stationary contact is brought to rest. if this deceleration is too rapid, the movable contact will continue moving in a reverse direction after the stationary contact is halted, thereby producing contact-separation for a brief interval and resultant arcing and contact erosion. The resilient mounting of the disclosed circuit breaker is capabio of decelerating this reverse motion rather gradually and thus suppresses this tendency of the contacts to separate as the reverse motion of the stationary contact is 3 halted. If this reverse motion were terminated by engagement with a rigid stop, then there would be an abrupt termination and a much greater tendency for the contacts to separate. In the disclosed mounting, the flange 7t gradually compresses the portion 72b of the resilient annulus 72 at the left hand side of the bushing 43 during this reverse motion to produce a much more gradual deceleration. The annulus '72 should be thick enough to prevent the flange 70 from engaging the top wall 22 during this return motion, so as to reduce the chances for any abrupt termination of the above-described reverse motion.

The top wall of the circuit breaker is also made slightly yieldable to these closing impacts so as to assist the resilient mounting '72 in suppressing contact-bounce, but the magnitude of this latter contribution is relatively small compared to that of the resilient mounting 7d, 72.

The resilient mounting of the right hand bushing 49 shown in FIG. 3 is essentially the same as that of the lefthand bushing. The resilience in the mounting for the right hand bushing enables the interrupter envelope 32 to follow the slight displacements of the left hand bushing 49 without imposing damaging stresses on this envelope 32 or its end seal.

An advantage of locating the resilient mounting for the stationary contact in the disclosed location instead of between parts forming the current-carrying conductor for the stationary contact is that no flexible braids or the like are required to bridge this yieldable joint since no current is intended to be carried through the disclosed joint '70, 72.

Contact-opening is effected by driving the operating rod 96 upwardly from its closed position of RIG. 4. During initial upward motion of the operating rod as, no opening force is applied to the movable contact since the pivot 93 is merely sliding along the intermediate rod 102 Without driving the intermediate rod. This lost motion continues until the pivot 9% strikes the stop 1&8. When this occurs, an abrupt opening force is applied to the movable contact 36, and it separates at high speed from the stationary contact 34 to produce interruption of the circuit as was previously described.

It will be noted that opening forces load the intermediate link 12 and the driving rod 96 in tension. In effect, there is a pulling action applied through these parts during opening. Applying opening forces by pulling, rather than pushing, is desirable because such a pulling action requires less guidance for the parts of the collapsible joint 9%, tea since there is no tendency for buckling to occur at the joint 98, 162 during pulling. On the other hand, pushing through a collapsible joint does tend to produce buckling, and precise bearings are needed to prevent such buckling.

For rotating the operating shaft 92 in order to produce the abovedescribed opening and closing actions, a vertically-extending operating rod 115- is provided adjacent the sidewall 24 of the enclosure ill. This vertically-extending rod lit) is pivotally connected at its upper end to the outer end of a crank 112, which is keyed to the rotatable operating shaft 92. The pivotal connection between the crank 112 and operating rod 110 is designated 114. The lower end of the operating rod 116 extends into the lower compartment 20 of housing 1%, where it is suitably coupled to an operating mechanism, schematically indicated at 116 in FIGS. 2 and 3. This operating mechanism 116 can be of any suitable conventional design and will therefore not be descirbed in the present application. An example of a suitable operating mechanism is, however, disclosed and claimed in application S.N. 89,233 Frank, filed February 14, 1961, now Patent No. 3,113,121, and assigned to the assignee of the present invention.

To produce closing, the operating mechanism drives the vertically-extending rod 11% downwardly from the position of FIG. 3. This rotates the operating shaft 92 clockwise to produce the above-described closing. Downward motion of the operating rod lit) also compresses a circuit breaker opening spring 120, which encircles the operating rod 114 and bears at its top end against a stop 122 carried by the operating rod 116. The opening spring 129 bears at its lower end against the stationary support formed by the floor 123 of the upper compartment 13. At the end of the downward closing stroke of operating rod 110, the operating rod is held in its depressed position by a suitable latch (not shown), and thus the opening spring 129 is latched in a charged condition. Circuit breaker opening is effected by suitably releasing this latch to permit the compressed opening spring 126 to drive the operating rod 113 upwardly back into its position of FIG. 3. Opening travel is terminated by means of a suitable buifer 145 that is arranged to be impacted at the end of the opening stroke by a clevis 141 rigid with the operating rod 119. This buffer preferably comprises a stack of disked spring washers.

It will be apparent from the above description that the current-carrying circuit through the

circuit breakers

51, 62, 66, 67, 4-6, 36, 34, 40, 5'5, 51 and all metallic parts connected thereto are normally at a high voltage with respect to ground potential. This means that the forcetransmitting means ltltl at the right hand end of the interrupter 30 is at a high voltage with respect to ground. The metallic commpartment 18, on the other hand, is at ground potential and so are all metallic parts connected to the compartment 13. F or example, the rotatable operating shaft 32, the metallic cranks 35 and 112, the verticallyextending operating rod 11%), the opening spring 12%, and its protective casing 129a are all at ground potential. The high voltage parts are electrically isolated from these grounded parts by the air space about the high voltage parts and by the insulating character of the operating rod 36 that extends between the two sets of parts.

As was pointed out hereinabove, one of the important objects of the present invention is to construct and arrange the components of the circuit breaker in such a manner that the required electrical clearance and creepage distances for high voltage can be provided within an enclosure of small volume that consumes an exceptionally small amount of ground space. There are a number of difierent features that contribute toward attainment of this desired result. One of these features is that the operating mechanism 116 for the contacts is located in a position beneath the main compartment 13 of the circuit breaker rather than at the end of this compartment as in certain prior designs. As a result of this underneath location, the operating mechanism consumes no ground space beyond that already occupied by the main compartment 18.

Another feature contributing to the compactness of the disclosed circuit breaker is the location of the operating shaft 92, which interconnects poles of the circuit breaker, at one side of the circuit breaker instead of centrally thereof, as in certain prior designs. In this respect, note that the operating shaft 32 is located at a side of one of the terminal bushings 49 of each pole that is opposite to the location of the other terminal bushing, for example, on the right hand side of the right hand terminal bushing 49 of FIG. 3. This location of the operating shaft at one side of the circuit breaker enables the verticallyextending metallic operating rod to be located closely adjacent the side wall 24 of the circuit breaker without requiring complicated, space-consuming linkages for connesting the operating rod 110 to the operating shaft 102. A simple crank 112 that projects from the operating shaft N2 in a direction away from the nearest bushing 49 is all the mechanism that is needed for this coupling. The additional fact that the operating shafit 92 is a rotatable element, instead of a longitudinally-reciprocable one, also permits this coupling between @2 and 110 to be simplified so that the coupling consumes a minimum of space. Generally speaking, the smaller the space consumed by such coupling, the more distance there is available to withstand the voltages present between the live parts of the circuit breaker and the grounded metallic parts, such as Q2, 112, and 110.

Another related feature that contributes to the use of a minimum of ground space is the rectangular cross section of the main compartment 18 as viewed in FIG. 3. This rectangular cross section makes available corner at the upper right hand edge of the compartment 13 that is ideal for the location of the operating shaft 92 and the coupling 11%, lid between the operating shaft 92 and the operating rod 1Z0. In this regard, this corner location is a near maximum distance from the live parts at the bottom of the terminal bushings and thus can accomn'iodate grounded parts such as shaft M and crank 112 without detracting from the otherwise available electrical clearance distances. The relatively large distance that is available between this upper corner location and the live parts at the bottom or the terminal bushings enables me to use an insulating operating rod 96 of electrically adequate length to interconnect these regions of widely diverse voltages despite the small dimensions of compartment 18.

By locating the operating shaft 92 at the right hand side of: the right hand terminal bushing 49 of FIG. 3, I can interconnect the movable contact rod 46 and the operating shaft 92 with a simple linkage that has its parts aligned with the contact rod in a direction lengthwise of the circuit breaker, i.e., in a direction normal to the phase barriers 25. if the operating shaft H was located between the bushings or at the left hand side of the left hand bushing 49, then a. considerably more complicated linkage would have been needed in order to connect the operating shaft and the contact shaft 46 without interference from the bushings or the envelope 32 of the in terrupter. This more complicated linkage would tend to require more room lengthwise of the breaker, thus undesirably increasing this dimension of the breaker.

it is to be noted that the contact-wipe means W2, we is built into the means for converting reciprocating motion of the insulating operating rod 96 into opening and closing motion of the contact rod 46. This contributes to the compactness of the contact-wipe mechanism and thus makes available more electrical clearance between the live parts adjacent the interrupter 30 and the adjacent metallic side wall 24. The compactness of the contactwipe means 102, 1% also enables me to locate this means entirely below the bottom of the porcelain shell 50 of the terminal bushing 49, thus minimizing any interference with the electric field distribution along this portion of the shell.

Another feature contributing to the high degree of comactness is the location of the operating rod 110 in a plane approximately midway between adjacent poles of the circuit breaker. For example, refer to FIG. 6 which is a sectional view taken along the line 6-6 of FIG. 2. The operating rod 110 is shown located in the plane of the phase-isolating barrier 25 which is disposed midway between the poles of the circuit breaker. Assume now that an arc of a reference circle is swung from a center defined by the live part of each pole closest to the side wall 254, as shown in dotted lines at 13% and 131. The radius of this are is the minimum safe clearance distance for the voltages involved. It will be seen that within the compartment ill the largest space outside the line defined by these arcs llEii, is located in the mid-plane between the poles. I have utilized this space to accommodate metallic operating rod lit), the opening spring 1% and the metallic protective housing 12% about the opening spring and operating rod 110. By relying upon. this particular location, I can incorponate these latter parts (it'd, 128, 12%) without reducingthe electrical clearances otherwise available. The housing 12% serves also as an electrostatic shield for the sharp corner on the operating rod 110 and the sering 120.

The location of the interrupting unit 3?: at the ends of to the contact spring 1%.

'e second and th rd systems to be brought essentially the terminal bushings 4-9 is advantageous in that the various external components of the interrupter 30 are freely exposed to the surrounding air so that heat can readily be dissipated therefrom. The horizontal disposition of the interrupter is advantageous as compared to a vertical disposition in that a compartment id of reduced height can without sacrificing electrical clearance distances. The horizontal disposition of the interrupter between the lower ends of the terminal bushings is another factor adapting the circuit breaker for operation with the simple, compact linkage described hereinabove.

in the disclosed circuit breaker, there is no problem that the insulating properties of the creepage paths along solid insulation or of the air within compartment 18 will e impaired by arcing products resulting from interrupter operation. This follows from the fact that the interrupter is a sealed device in which the arcing products are t tally confined. Thus, these arcing products cannot escaoe irto regions external to the interrupter to impair the bio insulation.

Sin e the fluid within the compartment 18 outside the sealed envelope performs no arc-extinguishing function, it may air, rather than the oil that is used in conventional tank-type breakers. This substantially lightens the breaker, contributes to lower cost, and simplifies maintenance procedures.

It is desirable to terminate the contact opening stroke with a minimum of overtravel and yet without causing excessive bounce of the contacts back toward closed position and also without loading the parts of the linkage excessively by abrupt termination of the opening stroke. it is particularly important to limit this overtravel in the illustrated circuit breaker because of the harmful effects that excess overtravel can have on the life of the flexible bellows 48. FIG, 7 illustrates a scheme that has been employed for obtaining the above'described desired results. instead of the clevis being rigidly attached to the operating rod as in FIG. 3, a spring coupling comprising disked spring washers 152 is provided between these parts in F16. 7. When the clevis ll tl strikes the butter Mil at the end or" the opening stroke, the operating rod continues moving upwardly compressing the spring washers 152 between the clevis and the operating rod lib, thus cooherating with the butler 140 to decelerate the o-oerating rod tilt and the mass attached thereto at its lower end. A bolt 154 secured to the operating rod slides through an opening in clevis A1 to guide the operating rod during its overtravel.

"if he operating linkage is in eiiect separated into three linkage systems during this interval of the opening stroke. 11116 i'..l age system consists of the movable contact 36 l part connected thereto on the contact side of and located between the spring K ant The remaining linkage system oi aerating rod M and the mechanism connected thereto at its lower end. The second and third systems each have a relatively high natural frer ncy in comparison to the first system, and the butter and spring coupling 15% are relatively still compared These relationships enable rorest before the t 'l stystem can reach its peak deflection. Hence, the peak deflections of the systems are pred f. .m occurring simultaneously and accordingly there is substantial additive ellect of the deflections that could result in excessive overtravel and excessive bounce. The spr ng coupling i serves also to reduce forces iaposeo. on the operating red 11 3 when opening motion is terminated, thus permitting this rod to be of smaller cross section without increasing its tendency to buckle when stopped at the end of the opening stroke. This enables me to lighten this rod lllll, thus further assisting in obtaining the desired deceleration characteristics.

1 l Preferably the buffer 140 is considerably stiffer than the spring coupling 15%. Both of these spring devices are much stiffer than the spring 166.

It will be apparent that the spring coupling 15% and the buffer 14d have little effect on the opening stroke until the very end thereof since the buffer i l-ti is not impacted until that time and the spring coupling 15% is so stiff that it does not deflect until that time. Thus, movement through essentially the entire opening stroke can take place normally without interference from the buffer 140 or spring coupling 15%.

On closing, the spring coupling 150 does not enter the picture because the head of guide bolt 154 bears against the clevis 141 to provide a rigid coupling between the clevis and operating rod ill! during downward closing motion of the operating rod lit).

While I have shown and described particular embodiments of my invention, it will be obvious to those skilled in the art that various changes and modifications may be made without departing from my invention in its broader aspects, and I, therefore, intend in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

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

1. An electric circuit breaker comprising:

(a) a metallic housing,

(11) a pair of spaced apart terminal bushings extending through a Wall of said housing, each of said bushings comprising a conductor for carrying current between opposite ends of the bushing and means for insulating said conductor from said Wall,

(c) an electric circuit interrupter comprising a sealed envelope and a pair of separable contacts located within said envelope, one of said contacts being movable,

(d) means for mounting said envelope between the inner ends of said terminal bushings with one end of said envelope mounted on one of said bushings and the other end mounted on the other of said bushings,

(e) means for connecting the conductor of a first one of said bushings to the movable one of said contacts,

(f) means for connecting the conductor of the other of said bushings to the other of said contacts,

(g) a rotatable operating shaft extending generally perpendicular to a reference plane including said bushings, said shaft being located adjacent said wall and at a side of said first bushing opposite to the location of said other bushing,

(11) and insulating means for transmitting motion from said rotatable operating shaft to said movable contact to produce opening and closing movement of said movable contact.

2. In the circuit breaker of claim 1, an operating mechanism for actuating said rotatable operating shaft, and means comprising an operating rod extending along one side of said housing generally perpendicular to said rotatable operating shaft for transmitting motion between said operating mechanism and said rotatable operating shaft.

3. The circuit breaker of claim 2 in which said metallic housing has a side wall extending generally perpendicular to the wall through which said bushings extend, said side wall being located adjacent said operating rod and intersecting the wall through which the bushings extend in a corner region where said rotatable operating shaft and said operating rod are coupled together.

4. The interrupter of claim 2 in which said insulating means for transmitting motion from said rotatable operating shaft to one of said contacts isaiigned with said one contact in a direction lengthwise of said operating shaft and in which said operating rod is displaced from the plane in which said movable contact and said insulating means are located.

5. The circuit breaker of claim 1 in which said insulating means for transmitting motion from said rotatable operating shaft to one of said contacts is aligned with said one contact in a direction lengthwise of said operating shaft.

6. An electric circuit breaker comprising:

(a) a metallic housing,

(b) a pair of vertically-extending, spaced-apart terminal bushings extending though a top wall of said housing, each of said bushings comprising a conductor for carrying current between opposite ends of the bushing and means for insulating said conductor from said top wall,

(0) an electric circuit interrupter comprising a sealed envelope and a pair of separable contacts located within said envelope, one of said contacts being movable,

(d) means for mounting said envelope between the lower ends of said terminal bushings with one end of said envelope mounted on one of said bushings and the other end mounted on the other of said bushings,

(e) means for connecting the conductor of a first one of the bushings to the movable one of the contacts,

(1) means for connecting the conductor of the other of said bushings to the other of said contacts,

g) a generally horizontally-extending rotatable operating shaft located adjacent said top Wall at a side of said first bushing opposite to the location of said other bushing,

(h) insulating means for transmitting motion from said rotatable operating shaft to said movable contact to produce opening and closing motion from said movable contact,

(1') an operating mechanism for actuating said rotatable shaft located in a position below said bushings and said sealed envelope,

(j) and means comprising a rod extending generally vertically along one side of said housing for transmitting motion between said operating mechanism and said rotatable operating shaft.

7. The circuit breaker of claim 6 in which said insulating means for transmitting motion from said rotatable operating shaft to one of said contacts is aligned with said one contact in a direction lengthwise of said operating shaft and in which said operating rod is located in a position displaced along said operating shaft from the location of said insulating operating means.

8. A multiple pole circuit breaker comprising:

(a) a metallic housing having a top wall intersected by a plurality of spaced-apart, generally parallel reference planes,

(b) each pole of said circuit breaker comprising a pair of spaced-apart terminal bushings disposed generally in one of said reference planes and projecting through said top wall into the interior of said enclosure, the bushings of different poles generally located in different ones of said reference planes,

(0) each of said bushings comprising a conductor for carrymg current between opposite ends of the bushing and means for insulating said conductor from said top wall,

(a!) electric circuit interrupters for the respective poles, each comprising a sealed envelope and a pair of separable contacts located within said envelope,

(e) means for mounting the envelope of each pole between the lower ends of the terminal bushings of said pole with one end of the envelope mounted on one bushing and the other end of the envelope mounted on the other bushing,

(f) means for connecting said contacts in series with the conductors of said bushings,

(g) a rotatable operating shaft extending generally perpendicularly to said reference planes and located at a side of one bushing of each pole opposite to the location of the other bushing of that particular pole,

(11) means for transmitting circuit-controlling motion from said rotatable operating shaft to the one contact of each of said circuit interrupters nearest said rotatable operating shaft comprising insulating operating means individual to each pole extending between said one contact and said rotatable operating shaft.

9. The circuit breaker of claim 8 in combination with an operating mechanism for actuating said rotatable shaft located in a position below said bushings and said interrupters, and means comprising a vertically-extending operating rod extending along one side of said housing generally perpendicular to said rotatable operating shaft for transmitting motion between said operating mechanism and said rotatable operating shaft.

10. A multiple pole circuit breaker comprising:

(a) a metallic housing having a substantially horizontially-exten-ding top Wall and a substantially verticallyextending side wall disposed substantially perpendicular to said top Wall,

() said walls being intersected by a plurality of horizontally-spaced, vertically-extending reference planes generally perpendicular to said side wall,

(c) each pole of said circuit breaker comprising a pair of spaced apart terminal bushings disposed generally in one of said reference planes and projecting through said top wall into the interior of said enclosure, the bushings of diiierent poles being located in different ones of said reference planes,

(d) each of said bushings comprising a conductor for carrying current between opposite ends of the bushing and means for insulating said conductor from said top Wall,

(e) electric circuit interrupters for the respective poles, each comprising a sealed envelope and a pair of separable contacts located within said envelope,

(f) means for mounting the envelope of each pole between the lower ends of the terminal bushings of said pole with one end of the envelope mounted on one bushing and the other end of the envelope mounted on the other bushing,

(g) means for connecting said contacts in series with the conductors of said bushings,

(it) a rotatable operating shaft extending generally perpendicular to said reference planes and located adjacent said top Wall at a side of one bushing of each pole opposite to the location of the other bushing of that particular pole,

(1') means for transmitting circuit-controlling motion from said rotatable operating shaft to the one contact of each of said circuit interrupters nearest said rotat able operating shaft comprising insulating means individual to each pole extending between said one contact and said rotatable operating shaft,

(i) an operating mechanism for actuating said rotatable operating shaft located in a position below said bushings said circuit interrupters,

(k) and means for transmitting motion between said operating mechanism and said rotatable operating shaft comprising a substantially vertically-extending operating rod located adjacent said side wall and a coupling between said operating rod and said rotatable operating shaft located in the upper corner region of said housing where said top wall and side Wall intersect.

11. The circuit breaker of claim 10 in which said vertically-extending operating rod is located approximately midway between an adjacent pair of said reference planes and. in which said insulating means individual to each pole is located generally in the reference plane of. its respective pole.

12. An operating linkage for a pair of separable contacts disposed within an evacuated envelope, comprising:

(a) a reciprocable rod-like driven member coupled at its inner end to one of said contacts and having its outer end located ouside said envelope,

(b) means for guiding said driven member along a substantially straight line path,

(0) a reciprocable driving member movable along a path extending transversely with respect to said straight line path,

(d) force-transmitting means for converting motion of said driving member in one direction into contactolosing motion of said driven member and for converting motion of said driving member in an opposite direction into contact-opening motion of said driven member,

(2) said force-transmitting means comprising (1) an intermediate link pivotally connected at one end to one of said members and pivotally connected with 10st motion at its opposite end to the other of said members, (2) spring means between said members bodily movable with said intermediate link for transmitting contact-closing motion of said driving member to said driven member permitting lost motion of said driving member in a contact closing direction relative to said driven member after said contacts engage, and (3) a stop on said intermediate link for limiting lost motion of said driving member in a contact-opening direction and for thereafter transmitting contact-opening motion of said driving member to saiddriven member by means of forces loading said intermediate link in tension,

( said driving member being loaded in compression during contact-closing and in tension during contactopening.

13. The operating linkage of claim 12 in which the pivotal connection between said intermediate link and said driving member approaches the pivotal connection between said intermediate link and driven member during said lost motion in a contact-closing direction and departs from the latter pivotal connection during lost motion in a contact opening direction.

14. The circuit breaker of claim 1 in which said means for transmitting motion from said rotatable operating shaft to said movable contact comprises:

(a) a reciprocable rod-like driven member coupled at its inner end to one of said movable contacts and having its outer end located outside said envelope,

([2) means for guiding said driven member along a substantially straight line path,

(d) force-transmitting means for converting motion of said driving member in one direction into contactciosing motion of said driven member and for converting motion of said driving member in an opposite direction into contact-opening motion of said driven member, 7

(c) said force-transmitting means comprising (1) an intermediate link pivotally connected at one end to one of said members and pivotally connected with lost motion at its opposite end to the other of said members, (2) spring means between said members bodily movable with said intermediate link for transmitting contact-closing motion of said driving memher to said driven member and permitting lost motion of said driving member in a contact closing direction relative to said driven member after said contacts engage, and (3) a stop on said intermediate link for limiting lost motion of said driving member in a contact-opening direction and for thereafter transmitting contact-opening motion of said driving member to said driven member by means of forces loading said intermediate link in tension,

15. The electric circuit breaker of claim 1 in which said means for transmitting motion from said rotatable operating shaft to said movable contact comprises a contact-wipe mechanism located adjacent said movable contact and means for supporting said contact wipe mechanism on the inner end of one of said terminal bushings in a position located entirely inwardly of the inner end of the insulation of said one terminal bushing.

16. The circuit breaker of claim 1 in which the contact engaged by said movable contact is rigidly secured to the conductor of one of said terminal bushings in Which closing impact applies a force transversely of the longitudinal axis of said conductor, and means is provided for resiliently mounting said latter terminal bushing on said wall of the housing to suppress contact-bounce incident to a closing operation, the resilient mounting between said one terminal bushing and said wall being capable of gradually decelerating without abrupt termination return movement of said bushing after displacement of said bushing by initial impact between the contacts.

17. The circuit breaker of claim 16 in which the other of said terminal bushings is also resiliently mounted on said wall.

18. In an electric circuit breaker:

(a) a terminal bushing comprising an elongated concuctor and an insulating shell disposed about said conductor,

(b) a suport for said terminal bushing,

(c) an electric circuit interrupter comprising a stationary contact rigidly mounted on said terminal hushs,

(d) a movable contact that engages said stationary contact upon closing,

(e) means for driving said movable contact through a closing stroke extending transversely of the longitudinal axis of said bushing so that closing impact between said contacts loads said bushing cantilever,

(f) and means including a contact-bounce-suppressing resilient mounting between said bushing and said support for gradually decelerating without abrupt termination return movement of said bushing after displacement thereof by initial closing impact between said contacts, said mounting comprising a flange rigidly secured to said insulting shell and a yieldable member of a rubber-like material normally compressed between said flange and said support.

19. The circuit breaker of claim 18 in which the means for driving said movable contact comprises a linkage including a spring near the driven end of said linkage for causing said movable contact to closely follow said stationary contact during oscillations following closing impact.

20. In an electric circuit breaker:

(a) a terminal bushing comprising an elongated con ductor and an insulating shell disposed about said conductor,

(b) a support for said terminal bushing,

(c) an electric circuit interrupter comprising a stationary contact rigidly mounted on said terminal bushing,

(d) a movable contact that engages said stationary contact upon closing,

(e) means for driving said movable contact through a closing stroke extending transversely of the longitudinal axis of said bushing so that closing impact between said contacts loads said bushing in cantilever,

(f) and means comprising a contact-bounce-suppressing resilient mounting between said bushing and said support for gradually decelerating without abrupt termination return movement of said bushing after displacement thereof by intial impact beteen the contacts.

21. The combination of claim 20 in which said contacts are butt-type contacts and in which an evacuated envelope is provided enclosing the space about said contacts.

22. An operating linkage for a pair of separable contacts comprising:

(a) a first linkage system coupled to one of said contacts,

(b) a second linkage system for driving said first linkage system during a contact-opening operation,

(c) first spring means coupling said first and second linkage systems together and yieldable to decelerate said first system upon termination of the opening movement of said second system,

(d) a third linkage system for driving said second linkage system during a contact-opening operation,

(e) second spring means coupling said second and third linkage systems together and yieldable to decelerate said third system upon termination of the opening movement of said second system,

(f) yieldable buffer means for engaging said second linkage system near the end of an opening stroke to terminate motion of said second system,

(g) said buffer means and said second. spring means each having a high degree of stilfness relative to the stiffness of said first spring means,

(h) and said second and third linkage systems each having a relatively high natural frequency relative to the natural frequency of said first linkage system.

23. The operating linkage of claim 22 in combination with a flexable metallic bellows attached to said one contact and providing a seal thereabout, the bellows being protected from excessive flexing by the overtravel lirniting characteristics of said linkage at the end of a contactopening operation.

Reterences Cited by the Examiner UNITED STATES PATENTS 2,981,815 4/61 Leads et al 200146 X 3,025,375 3/62 Frank 200-l44 3,054,975 9/62 Barr 174-18 X BERNARD A. GILHEANY, Primary Examiner.

ROBERT K. SCHAEFER, Examiner.

Claims

1. AN ELECTRIC CIRCUIT BREAKER COMPRISING: (A) A METALLIC HOUSING, (B) A PAIR OF SPACED APART TERMINAL BUSHINGS EXTENDING THROUGH A WALL OF SAID HOUSING, EACH OF SAID BUSHINGS COMPRISING A CONDUCTOR FOR CARRYING CURRENT BETWEEN OPPOSITE ENDS OF THE BUSHING AND MEANS FOR INSULATING SAID CONDUCTOR FROM SAID WALL, (C) AN ELECTRIC CIRCUIT INTERRUPTER COMPRISING A SEALED ENVELOPE AND A PAIR OF SEPARABLE CONTACTS LOCATED WITHIN SAID ENVELOPE, ONE OF SAID CONTACTS BEING MOVABLE, (D) MEANS FOR MOUNTING SAID ENVELOPE BETWEEN THE INNER ENDS OF SAID TERMINAL BUSHINGS WITH ONE END OF SAID ENVELOPE MOUNTED ON ONE OF SAID BUSHINGS AND THE OTHER END MOUNTED ON THE OTHER OF SAID BUSHINGS, (E) MEANS FOR CONNECTING THE CONDUCTOR OF A FIRST ONE OF SAID BUSHINGS TO THE MOVABLE ONE OF SAID CONTACTS, (F) MEANS FOR CONNECTING THE CONDUCTOR OF THE OTHER OF SAID BUSHINGS TO THE OTHER OF SAID CONTACTS, (G) A ROTATABLE OPERATING SHAFT EXTENDING GENERALLY PERPENDICULAR TO A REFERENCE PLANE INCLUDING SAID BUSHINGS, SAID SHAFT BEING LOCATED ADJACENT SAID WALL AND AT A SIDE OF SAID FIRST BUSHING OPPOSITE TO THE LOCATION OF SAID OTHER BUSHING, (H) AND INSULATING MEANS FOR TRANSMITTING MOTION FROM SAID ROTATABLE OPERATING SHAFT TO SAID MOVABLE CONTACT TO PRODUCE OPENING AND CLOSING MOVEMENT OF SAID MOVABLE CONTACT.