US2691085A - Electric circuit interrupter - Google Patents

Description

Oct. 5, 1954 J. w. BEATTY I ELECTRIC CIRCUIT INTERRUPTER Filed June 26, 1951 Inventor John W.'Beattg,

His Attorneg.

Patented Oct. 5, 1954 IELECTRIC QUE/CUTE INTERRUPTER *JohnW. Beatty, Lansdowne, Pa., assignor to General" Electric Company, a corporation of New York Application June 26, 1951, Serial No. 2331337 15 Claims.

This .invention relates to electric circuit interrupters and more particularly to an improved contact arrangement for. electric circuit breakers of the fluid blast type.

In an electric circuit breaker of the type wherein a plurality of pivotallyzmounted movable contacts individually biased toward engagement with a fixed. tubular contactare separable from the tubular contact by a blast of gas, one or more of the movable contacts may fail .to separate from the fixed contact when a blast of gas is supplied'thereto due to thewell-known tendency lorthe contacts to become welded together. Of course, if any one of the. movable contacts fails to separate from the fixed contact,.the breaker cannot open itscontrolled circuit. Furthermore, thepivotal'mountings of the movable contact members may tend to become pitted or eroded somewhat .due to sparking so that the working surfaces forming the pivotal support forthe movable contacts do not functlonproperly.

A principal object of this inventionis to provide an improved contact arrangement for electric' circuit interrupterswherein a pluralit of movabl contacts of a circuit breakerare-caused to separate from a cooperating contact substantially in unison so as to insure that effective circuit interruption will be accomplished as desired.

Another object of this invention is the provision of an improved mounting arrangement for movable contact members of a circuit breaker which substantially eliminates pitting of the mounting surfaces andwhich is arranged to facilitate inspection and repair of the contacts and associated elements requiring maintenance.

Still another object of the invention is to provide a circuit breaker whereinready inspection and repair of the contacts is possible.

In accordancewith the invention, a plurality of contacts biased toward engagement with a cooperating contact are interconnected with limited lost-motion mechanical coupling structure so as to cause the plurality of contacts to move sub stantially in unison thereby to prevent one or more of these contacts from adhering to the cooperation contact of the interrupter. According to one feature of the invention, the plurality of contacts are provided with a fulcrum type mounting arranged to afiorda wiping action during movement of the contacts thereby to avoid pitting or erosion at the mounting surfaces. According to another feature of the invention the housing structure for the contacts is arranged sothat inspection and repair of the internal elements is readily accomplished.

The invention will be better understood from the following description taken in conjunction with the drawing in which Fig. 1 is a cross-sectional View of-an interrupter embodyingthe improved structure of the invention, in which Fig. 2 is an enlarged perspective view of one of the contact members shown in Fig. l and in which Figs. 13 and-4 representalternative constructions for the contact couplingmeans shown in Fig. 1.

The interrupter unit asshown in Fig. 1 is arranged so that ready access may be had to the contacts. To this end the enclosing structure comprises stationary supporting housing or base structure l on which is hingedly'mounted at the pivot 2 a cooperating enclosing housing structure t. Heusingstructur 3 is maintained in the position shown by means of bolts 6 which threadedl engage the stationary housing section I. When it is desired to inspect or repair the contacts, the bolts l are removed and the hingedly supported structure 3 is simply rotated in the counterclockwise direction about the pivot '2 to the position indicated bydotted lines.

The housingsection l is secured by means of bolts 5 tea clamping. ring t which is disposed in gripping relation to the cylindrical interrupter casing 'i by means of a pair of half ring members 8 having a wedge-shaped cross-section. As indicated in the drawing, a sleeve 9 of insulating material constitutes a liner Within the easing l and is secured in position by the arc resistant thrust ring it presseddown by the clamping nut l l which threadedly engages the base member l.

@ne of the-contacts of, the interrupter is constructed inthe formof a tubular member l2 and may either-be fixed or=arranged for axial downward mot on within the sleeve 9. Disposed at the upper end of the tubular contact I2 is a suitable arc-resistant ring member is brazed or welded on .the'cooperating nozzle member I i- Which, in turn, is removably secured for renewal by any suitablemeans to the tubular structure l2.

The structure disposed within and supported by the .hinged housing section- 3 comprises a cylindrical support member I5 the walls thereof bein provided with a plurality of bolt-receiving threaded bosses It. A bell-shapedexhaust member H is disposed with .its converging lower portion projecting coaxially within the cylindrical support member !5. The housing section .3 is provided with a weather-protecting domed cover member it which is secured in position b means of bolts it which also pass through a plurality of bosses 2t in the bell-shaped exhaust member ll. Tl1us,'the bolts 19 which extend through the webbed bosses 2! formed integrally with the housing l8, through the bosses of the exhaust member II, and through corresponding aligned openings in the inwardly projective flange portion 22 of the housing structure 3 are engaged by threaded engagement with the bosses l6 disposed on the tubular support member [5. In this way the several component parts of the structur supported within the housing section 3 are securely held in their proper coaxial relationship therewith.

The petal-like finger contacts 23, one of which is shown in perspective in Fig. 2, are arranged as shown in Fig. 1 in a circular fashion so as to constitute a generally fiat disk-like assembly having a central flow orifice therethrough. The contacts 23 are disposed about the projecting fulcrum rim 24 formed on the lower surface of the cylindrical support member l5 and are biased toward engagement with the contacting surface [3 of the tubular contact l2 by means of T-bolts 25 and their cooperating compressional springs 26. As will be obvious from Fig. 1, T-bolts 25 are axially slidable through aligned guide openings 2? and 28 formed in the housing section 3 and in the outwardly flanged portion of cylindrical support member l5 respectively. The head of each T-bolt 25 is anchored in the slot 29 which is formed in the outer end of the contact 23.

For a circuit breaking operation, the petal contacts 23, which are interrupting contacts, are separated from their cooperating arcing Contact surface i3 by means of a blast of gas supplied through the annular space 30 between the sleeve member 9 and the tubular contact member 12. Such a blast of fluid rocks the contacts 23 about the fulcrum rim 24 to compress the springs 26 and to draw an are between contacts 23 and the arcing rim 13. Such an arc is extinguished by this inward radial blast of fluid which divides in opposite axial directions to envelop the are by flowing downwardly in the direction indicated by the arrow in the tubular contact l2 and upwardly through the orifice constituted by the petal contacts 23, thence through the exhaust bell ll and through suitable exhaust cooling structure 3| to atmosphere through the radial openings 32 in the interrupter cover. The arc drawn between contacts 23 and arcing member l3 normally is transferred by the fiuid blast from the contacts 23 to the arcing electrodes 33 which may be formed integrally within the exhaust bell ll. These electrodes 33 are arranged so that they are tangential to a circle the center of which coincides with the axis of the tubular member [2. The effect of this particular arrangement of the electrodes 33 is to produce a magnetic reaction which causes the arc to shift from one to to the other of the electrodes, thereby to minimize erosion thereof. This particular feature is not a part of this invention and is disclosed and claimed in Patent 2,391,759Wilcox, granted December 25, .945, and assigned to the assignee of this invention.

In order to insure that a differential of pressure exists between the downstream and the upstream side of the contacts 23 after these contacts have moved to their fully opened position of engagement with the lower rim of the exhaust bell ll, openings such as are indicated at 34 are provided in the side walls of the exhaust bell. Since the space within the exhaust hell [1 above the electrodes 33 is in communication through the ports 34 and the space 35a with the upper surface of the finger contacts 23, the drop in of the contacts.

pressure between the upstream and the downstream surfaces of the contacts 23 is effectively utilized to maintain the contacts in the open position. This particular feature, which forms no part of this invention, is disclosed and claimed in Cox et al., U. S. Patent 2,427, 95, granted September 9, 1947, and assigned to the assignee of this invention.

Under certain interrupting conditions, the electrodes 33 may not retain the upper arc root. For the purpose of affording a so-called extremity arcing electrode to which the arc may be blown from the tangential electrodes 33, an electrode 35 is mounted by means of a bolt 33 to the cover member [8. This electrode as is indicated at 31 is provided with suitable arc-resistant material at its tip.

The circuit through the interrupter as above described comprises thetubular contact l2, radial contact fingers 23, the cylindrical support l5 and the housing sections l and 3. Terminals for connection to the external circuit for the interrupter are schematically indicated at 38 and 39.

As is well known, prestriking of an arc during certain closing conditions may tend to weld separable contacts together. Thus, if one of the contact fingers 23 should have become welded to the surface I3 with the blast ineffective to raise it, the interrupter would fail to interrupt the circuit. For the purpose of insuring that all the contacts 23 move substantially in unison, coupling means are provided according to this invention whereby opening movement of some of the contacts imparts opening movement to the remainder One particular structure comprises a coupling member 40 and a cooperating tubular insulating member 4|. The member 4| is of hard material with a smooth finish and is chosen for the purpose of miniminzing the friction between the coupling structure and the internal surface of the contact support member 15. Each of the contacts 23 is interconnected with the coupling member 40 by means of a link 42 which is pivotally connected with its associated contact 23 by a pin 43 and which is provided with a short lost-motion slot 44 which cooperates with a pin secured to the coupling ring 43. The lost motion achieved through the agency of the slot 44 allows proper settling of the contact fingers 23 against the arcing surface 3 and in addition allows a limited movement of the contact fingers 23 with respect to each other. In this way contact fingers which have no tendency to become welded to the ring l3 may readily separate therefrom and the kinetic energy thus achieved due to the limited movement of certain of the fingers 23 together with the continuing blast of pressure fluid effectively aids in forcibly separating any one or more of the fingers 23 from the member l3'wh1ch tend to adhere thereto.

Since the fulcrum ring 24 formed at the bottom surface of support member 55 is a currentcarrying surface which cooperates with a recessed portion 45 of the contact fingers 23, these cooperating surfaces may tend to become pitted due to sparking. In order to minimize this tendency, the contact fingers 23 are provided with a depression 45 which clears the fulcrum rim 24. In this Way the contact pressure is taken by those portions 41 of the recessed portion 45 which are adjacent the edges of the contacts 23. In this way the fingers 23 are assured of pivoting about a broad base so that they all rock in a uniform manner and are prevented from wobbling appreciably. Furthermore, in accordance with one .aeenoss i5 feature of the invention, the curvature of the recessed portion 55 is such that this surface coincides or mates with the curvatureiof the'rim 26 only when the fingers-23 aresubstantially in 'a horizontal position. Because of this fact the' actual contact areas ofthe recess lii creep-with respect to those of the cooperating rimduring the pivoting action therebyafiordinga'nefficient wiping contact action for minimizing, pitting or erosion of these surfaces.

Ready inspection of the internal parts is'possible since opening of the housing section 3 :moves the whole assembly. comprising the contacts 23 out of engagement :with the arcing ring it. of the tubular contact I2. within the housing section 3 when'that member is opened due to the fact that flange-'48 on sup- .port l5 acts as astop to limitmotion of the contacts 23 due to the biasing springs 25.

The arrangement abovedescribed is adaptable for use in conjunction with a circuit-breaker of the type disclosed in application Serial No. 202,100--Beatty, now Patent No. 2,645,697, filed December 21, 1950, and assigned to the assignee of this invention. The structure of the present invention may be used as an interrupting unit or as a combination interrupting-isolating unit depending upon whether the tubular contact is stationary or reciprocable. If the present invention is used solely as an interrupting unit a contact such as it would be stationary and a separate isolating blade would be associated therewith at another part of the circuit breaker structure. If the unit is used as a combination interrupti.ng-islating unit, the tubular contact l2 would constitute the isolating blade and would be withdrawn downwardly as a sequence to, or coincident with, the extinguishment of the are at the blown-open interrupting contacts 23 so that the air supply could be cut off with the finger contacts moving back to their biased positions without danger of reestablishing an are through the breaker.

Instead of employing indirect .means, such as the above-described commoncoupling ring 40, for interlocking the petal fingers 23 to insure their movement inunison, I might choose to have them directly interlocked one with another. For achieving this I might construct the petal-like fingers 23', as shown in Fig. 3, to have a recess provided at one edge. and with a corresponding lug or projectionfill at the opposite edge. When arrayed in a complete circle, a segment of which is indicated by Fig. 3, it will betapparent that each finger is interlocked with its neighbor due to its lug snugly nesting in the recess of the adjacent finger. With such an arrangement, and with the lugs not extending above the surface of the contact, this circular assembly constitutes a thin smooth composite disk offering little impedance to the flow of the air blast during are interruption. It will be apparent that where one finger has tended to weld fast, it will be aided in pulling free by the neighboring fingers to one side thereof.

As a further modification; the interlocking lug may take the form of an overlapping sheath-| as shown in Fig. 4 for closing upthe clearance space between adjacent fingers. The sheaths 5| are secured by any suitable means to one side of each finger contact.

While I have described particular embodiments ofmy invention, it will be-obvious to those skilled Contacts 23-are retained tion, and I therefore intendin the appended claims to cover all such changes and modification as fall within the true spirit andscope of .my invention.

What I claim as new and desire to secureiby Letters Patent in the United States is:

l. A contact arrangement for an electric'circuit breaker comprising a first'contact, a plurality of contacts'biased towardone position with respect to said first contact, means for supplying a blast of pressure fluidto said contacts to cause movement of saidplurality of contacts to another position, and coupling means, interrelating said plurality of contacts, said coupling means positively interconnecting :all of said plurality of contacts to move'substantially in unison from either oisaid'positionsto the otherposition.

2. A contact arrangement for an electric circuit breaker comprising a first contact, a plurality of contacts biased toward engagement with said first contact, means for supplying a blast of pressure fluid directly to said contacts to cause opening movement of said plurality of contacts, and coupling means interrelating said plurality of contacts, said coupling means positively interconnecting all of said plurality of contacts to move substantiallyinunison during opening and closing movement thereof.

3. A contact arrangement forv an electric circuit breaker comprising a first contact, a plurality of contacts biased toward engagement with said first contact, means for supplying a blast of fluid pressure to said contacts to cause opening movement of said pluralityof contacts, a movable coupling member, and a plurality of connecting links interconnecting said member and said plurality of contacts, said member and said links being eirective to cause all of said plurality of contacts to move substantially in unison.

ll A contact arrangement for an electric circuit breaker comprising a tubular contact, a pinrality of contacts biased toward engagement with one end of said tubular contact, means for supplying a blast of fluid pressure to said contacts to cause opening movement of said plurality of contacts, a movable coupling member, and a plurality of connecting links interconnecting said member and said plurality of contacts with a lost motion connection, said'member and said links being effective to causeall of said plurality of contacts to move substantially in unison.

5. A contact arrangement for an electric circuit breaker comprising a tubular contact, a plurality of contactsbiasedtowarol engagement with one end of said tubularcontact, means'for supplyinga blast of fiuidpressure to said contacts to cause opening movement of said plurality of contacts, a reciprocally movable coupling mem her, and a plurality oficonnecting linksarranged with each link pivotally connected with one of said plurality of contacts and with said .member to form a lost motion connection therebetween, said member and said links being effective to cause all of said plurality of contacts to move substantially in unison.

6. A contact arrangementfor an electric circuit breaker comprising a first contact, a cylindrical support member having-a projecting fulcrum rim, a plurality of contacts disposed on said rim for pivotal support thereby and biased toward engagement with said first contact, means for supplying a blast of fluidpressuredirectly to said contacts to cause openingmovement of said plurality of contactaandcoupling meansinterrelating said plurality'of contacts, said coupling means positively interconnecting all of said plurality of contacts to move substantially in unison during both opening and closing movement thereof.

7. A contact arrangement for an electric circuit breaker comprising a first contact, a tubular support member having a projecting fulcrum rim, a plurality of contacts biased toward engagement with said first contact and pivotally mounted on said rim, means for supplying a blast of fluid pressure to said contacts to cause opening movement of said plurality of contacts, a reciprocally movable coupling member the movement of which is guided by said tubular support, and connecting means interrelating said coupling member and said plurality of contacts, said coupling member and said connecting means being effective to cause all of said plurality of contacts to move substantially in unison.

8. A contact arrangement for an electric circuit breaker comprising a first contact, a cylindrical support member disposed in spaced relation to said first contact and having a projecting fulcrum rim, a plurality of pivoted contacts each having one end thereof biased toward engagement with said first contact and each having a transverse recessed portion intermediate the ends thereof which is biased into engagement with said rim, said recessed portion and said rim having their mutually engaging surfaces shaped so that portions of each of said engaging surfaces are curved and have the same radius of curvature, the remaining portions of said engaging surfaces being shaped so that the center of curvature of the identically-curved portions coincide only when the pivoted contact is pivoted to a position substantially at right angles to said support member, means for supplying a blast of fluid pressure to said contacts to cause opening movement of said plurality of contacts, and coupling means positively interconnecting said plurality of contacts to move substantially in unison during opening and closing operations.

9. A contact arrangement for an electric circuit breaker comprising a first contact, a tubular support member disposed in spaced relation to said first contact and having a projecting fulcrum rim, a plurality of contacts each having one end thereof biased toward engagement with said first contact and each having an intermediate portion thereof biased into engagement with said rim, means for supplying a blast of fluid pressure to said contacts to cause opening movement of said plurality of contacts, a coupling member reciprocally movable within said tubular support, and connecting means interrelating said coupling member and said plurality of contacts, said coupling member and said connecting means being effective to cause all of said plurality of contacts to move substantially in unison.

10. A contact arrangement for an electric circuit breaker comprising a first contact, a tubular support member disposed in spaced relation to said first contact and having a projecting fulcrum rim, a plurality of contacts each having one end thereof biased toward engagement with said first contact and each having an intermediate portion thereof biased into engagement with said rim, means for supplying a blast of fluid pressure to said contacts to cause opening movement of said plurality of contacts, a coupling member reciprocally movable within said tubular support, and a plurality of connecting links arranged with each link pivotally connected with one of said plurality of contacts and with said coupling memher, said coupling member and said links being effective to cause all of said plurality of contacts to move substantially in unison.

11. An electric circuit breaker comprising a supporting base structure, a housing structure pivotally mounted on said base structure, removable holding means for securing said housing structure in its service position relative to said base structure, a first contact normally disposed within said base structure, a tubular support member removably secured within said housing structure and having a projecting fulcrum rim, a plurality of contacts biased toward engagement with said first contact and pivotally mounted on said rim, means for supplying a blast of fluid pressure to said contacts to cause opening movement of said plurality of contacts, a coupling member reciprocally movable within said support member, and a plurality of connecting links ar-- ranged with each link pivotally connected with one of said plurality of contacts and with said member.

12. A contact arrangement for an electric circuit breaker comprising a first contact, a support member disposed in spaced relation to said first contact and having a fulcrum surface, a second contact being pivoted and having a transverse recessed portion immediate its ends, said recessed portion being in engagement with said fulcrum surface, biasing means cooperating with one end of said second contact for biasing the other end thereof toward engagement with said first contact and said fulcrum surface, said recessed portion and said rim having their mutually engaging surfaces shaped so that portions of each of said engaging surfaces are curved and have the same radius of curvature, the remaining portions of said engaging surfaces being shaped so that the center of curvature of the identically-curved portions coincide only when the pivoted contact is pivoted to a predetermined angular position with respect to said support member.

13. A contact arrangement for an electric circuit breaker comprising a first contact, a support member disposed in spaced relation to said first contact and having a fulcrum surface, a second contact having a transverse recessed portion intermediate its ends, said recessed portion having a surface in engagement with said fulcrum surface and having a depression provided therein intermediate the edges of said second contact to facilitate the engagement of said fulcrum surface by the portions of said recessed portion which are adjacent the edges of said second contact, said depression extending transversely with respect to said recessed portion across the entire fulcrumengaging portion of the surface of said recessed portion, biasing means cooperating with one end of said second contact for biasing the other end thereof toward engagement with said first contact and said fulcrum surface.

14. A contact arrangement for an electric circuit interrupter comprising a first contact, a plurality of adjacent cooperating contacts biased toward one position with respect to said first contact, means for producing relative movement between said contacts from said one position to another position, and means for insuring unison of movement of said plurality of contacts comprising an essentially rigid extension positively joined to one cooperating contact and proceeding therefrom into an overlapping position with respect to its adjacent cooperating contact whereby to provide a positive coupling between said adjacent cooperating contacts.

15. A contact arrangement for an electric circuit breaker comprising a first contact, a plurality of contacts biased toward engagement with said first contact, means for supplying a blast of pressure fluid to said contacts to cause opening movement of said plurality of contacts, and an extension secured to each of said plurality of contacts and disposed in overlapping relation with an adjacent one of said plurality of contacts for minimizing the flow of pressure fluid between said plurality of contacts and for forming a mechanical coupling therebetween.

References Cited in the file of this patent Number Number UNITED STATES PATENTS Name Date Leopold Nov. 14, 1939 Flurscheim Dec. 31, 1946 Cox et a1. Sept. 9, 1947 Swinehart Aug. 1, 1950 Latour Mar. 11, 1952 FOREIGN PATENTS Country Date Great Britain Mar. 7, 1949 France Apr. 23, 1925

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