US2533545A

US2533545A - Circuit breaker with lever type current connection

Info

Publication number: US2533545A
Application number: US63932A
Authority: US
Inventors: Chester D Ainsworth; Gustav E Jansson
Original assignee: Allis Chalmers Corp
Current assignee: Allis Chalmers Corp
Priority date: 1948-12-07
Filing date: 1948-12-07
Publication date: 1950-12-12
Anticipated expiration: 1967-12-12

Description

C. D. AINSWORTH ETAL Filed Dec. 7, 1948 CIRCUIT BREAKER WITH LEVER TYPE CURRENT CONNECTION Dec. "l2, 1950 Patented Dec. 12, 1950 UNITED STATES iATENT QFFlCE CIRCUT BEEAKER WITH LEVER TYPE CURRENT CONNECTION 7, 1948, Serial No. 63,932

(Cl. 20G- 82) Application December 9 Claims. i

This invention relates in general to improvements in electric circuit breakers, and more particularly to means for conducting currents of relatively large intensity from onev stationary terminal of the breaker to the movable contact of the .breaker associated therewith.

Heretofore, the performance of exible conductors for electrically interconnecting a station ary terminal and a relatively movable solid con* ductor has often proven unsatisfactory, and their use for this purspose tended to become more objectionable as the speed and frequency of contact actuation increased.. Flexible conductors have a limited exural life due to fatigue or oxidation, thus requiring replacements at regular intervals of time.

It is, therefore, desirable to provide circuit breakers that are called upon to operate fren quently with solid interconnecting conductors rather than flexible interconnecting conductors. An arrangement of this type comprising a solid interconnecting conductor calls for spring means for establishing the requisite contact pressure between this interconnecting conductor and contact surfaces associated therewith. In high speed circuit breakers of the gas blast type the light weight movable Contact isy generally operated by a pneumatic motor having a piston which is moved to the contact open position thereof by gas under pressure, and which is returned to the contact closed position upon removal of the gas pressure therefrom by spring action. The spring means used to establish the requisite contact pressure :between the solid interconnecting conductor and the contact surfaces associatedtherewith may serve a dual function as claimed in this application by being adapted in addition to move the piston of the pneumatic motor and the movable contact associated therewith from contact open position to contact closed position.

It is therefore one of the objects of the present invention to provide a new and improved circuit breaker of the fluid blast type in which a rigid conductor is used to interconnect a movable conductor and a stationary terminal associated therewith.

Another object of the present invention is to provide a new and improved circuit breaker in which an element is used both to interconnect a movable contact and a stationary terminal element associated therewith and to transmit the requisite actuating force to the movable contact for movement thereof in one direction.

y A further object of the present invention is tc providea new and improved circuit breaker in which a spring means requiring minimum amount of space is used to reset a pair of cooperating contacts and wherein the spring means has a smaller stroke than the movable contact.

A still further object of this invention is to provide a new and improved circuit breaker in which a dual purpose spring means actuates a .movable contact and establishes contact pressure between a rigid element and the movable contact and terminal element associated therewith.

Objects and advantages other than those above set forth will be apparent from the following description when read in connection with the accompanying drawing in which:

Fig. 1 is a view in axial cross section, of an interrupting chamber of a gas blast circuit breaker involving the present invention; and

Fig. 2 is a top view of the solid interconnecting conductor and the guiding surfaces associated therewith in the embodiment illustrated in Fig. l.

Referring more particularly to the drawing by characters of reference, Fig. 1 illustrates an interrupting head l which comprises a flange or supporting base member 2 which is clamped by means of cap screws 3 on a cap (not shown) connecting the flange to a source or" arc extinguishing iiuid under pressure. Base member 2 supports a tubulaiinsulator l of ceramic or other suitable insulating material of which porcelain is an example. A force is applied toV a continuous clamping ring E by a series of screws E secured to base member 2 and a component of this force is transmitted through a split ring l onto the porcelain insulator in a direction substantially perpendicular to a surface 8 of p0rcelain insulator l to secure the porcelain insulator thereto. This clamping structure mini mines bending moments and shear stresses in the porcelain.

A conductive annular member 9 made in two parts is mounted on and supported by insulator il by means oi a continuous clamping ring it, a split ring il and screws l2 in a manner similar to that used to secure insulator l to base member 2. An insulating tube I3 mounted within and axially aligned with insulator fi is rigidly supported bybase member 2 through a pressure it and surrounds a downward extending cylindrical portion I5 of conductive annular member Q with a small clearance. Insulator tube it also surrounds a pair of cooperating arccontacts le and l? and cooperates withnconductive cylindrical member e to define an arcing chamber I8.

Contact I is a fixed contact shaped as a streamlined solid of revolution and is bolted to a tubular portion 28 of base member 2 extending into insulating tube I3. Contact IS has an arcing tip I9 of refractory conductive material in the form of a plug and is providedwith a plurality of grooves 29 extending radially from substantially the tip of the plug along the outer surfaces thereof. These grooves provide passage Ways for a limited flow of fluid under pressure through the arcing contacts during contact engagement thereof. The base of Contact I3 comprises a plurality of iin-like appendages 2l adapted to form a plurality of air passages.

The cooperating movable contact l1 comprises an annular shaped arcing portion defining an oriiice 22 and adapted to partially surround the top portion of stationary contact i3 upon engagement therewith. Contact I1 further comprises a sleeve portion 23 and forms therewith the piston of a fluid motor. Sleeve 23 is adapted to slide within guiding surfaces which, in turn, constitute downward extension portions i5 and 32 of the conductive cylindrical member 9. The Vupward stroke of sleeve 23 is limited by abutmentv of an annular projection 23a thereorc against' a flange 25 backed by suitable shock absorbing material, The interior of sleeve 23 is insulated by a suitable material and forms with hollow insulator I3 the arcing chamber I3. Y

When the arcing contacts I9 and I'I are closed they substantially close orifice 22 and'essentially divide arcing chamber I8 into an inlet chamber 26 andan outlet, chamber 21. The inlet chamber 26 is generally dened by insulating tube I3 and the hollow upward extending portion 23 of base member 2. The outlet chamber 21 is generally conductors 33. Thus, as piston 24 moves under the influence of air pressure, sleeve 23 moves upward in the interrupting head I and interconnesting conductors 33 follow the vertical movement thereof by a combined rolling and wiping action over the two contacting surfaces 36 and 33 associated therewith. Pairs of ears 4I provided on member 9 adjacent the sliding surfaces 38 guide each interconnecting conductor 33 and align these interconnecting conductors in radially extending directions from the annular groove on the outer surface of sleeve 23. Interconnecting conductors 33 may be shaped in any one of a number of ways, however, the chosen configuration must permit a freedom of movement over the supporting surfaces engaging therewith. The operable interconnecting conductors illustrated in the drawing are provided with convex end portions in engagement with the supporting surfaces, whereby movement of interconnecting conduotors 33 takes place with a minimum of friction.

The helical spring means 39 act upon interconnecting conductors or levers 33 at points intermediate their ends to provide a sufficient amount of contact pressure between conductors and the Vcontact surfaces engaged therewith. However, these springs have a dual function and additionally eiect resetting or reclosing of concontained within sleeve 23 and extends upward i to a suitable outlet 29 extending between member 9 and a concave baiiie or cover 39 secured Outlet chamber 21 contains an auxthereto. iliary arcing electrode 3|. This electrode, which is secured to cover 39 and in electrical contact with member 9, is'usually axially aligned with sleeve 23.

A plurality of rigid interconnecting conductors 33 electrically connect the movable contact I1 to member 9, which is provided with a terminal lug 34 and therefore constitutes a stationary ter- Vminal element. Base memberr2, which is electrically connected to the stationary contact I6, constitutes the second stationary terminal elementand is provided with a suitable terminal lug (not shown).

Each rigid interconnecting conductor 33 is in the form of a rocking Vcontact lever which is in permanent contact Vwith the conductive cylindrical member 9 and sleeve 23 at allV times. Sleeve 23 may be provided with a groove 35 having a concave cross section extending around the circumference thereof and forms a bearing sur- Yface3ii for engagement of one end of the interconnecting conductors 33. The conductive annular member 9, in turn, may be provided with a concave circular groove 31 having an annular supporting surface 32 adapted to hingedly support the other end of conductors 33. Levers 33 extend in radial directions from sleeve 23 and,

while resting on supporting surfaces 36 and 38,

make with the axis .of sleeve 23 an angle which Vvaries with the longitudinal position of the sleeve. A plurality of .dual purpose spring means 39, axially-'aligned .with a plurality of .dual purpose spring means 33, axially aligned with a plurality of pins 40, provide a substantially constant pressure between flanges 25 and interconnecting tact I1 upon the decrease of pressure in the inlet chamber 25 upstream of movable contact I 1. The

helical springmeans 39 are disposed so as notY to increase the overall dimensions of the circuit breaker. The stroke or compression Vof spring means 39 upon movement of Vthe movable contact I1 is smaller than the stroke of contact I1.

Base member 2 provides a connection between a reservoir (not shown) constituting a source of are extinguishing fluid under ypressure and the inlet portion 25 of the arcing chamber I8 for the purpose of directing a blast of arc extinguishing iiuid under pressure between the arcing contacts and through the arcing chamber. The arc extinguishing iiuid under pressure may be an inert gas such as nitrogen. but it will be assumed herein that the fluid is air Vunder pressure of the` order of 200 or more pounds per square inch supplied to the reservoir by a suitable compressor (not shown) Fig. 2 illustrates more clearly one of the inter- 4 In operation, the-circuit breaker being closed as indicated in Figgl, current flows through a stationary terminal element (not shown), base member 2, stationary Contact I6, movable contact I1, sleeve 23 of piston 24, conductors 33, conductive annular member 9, and stationary terminal element 33. Opening of the circuit breaker is initiated by applying a blast of air under pressure through base member 2 and into insulating tube I3 and the inlet chamber 25. Air pressure is thereby applied to the annular surface of movable contact I1 of piston 24. VPiston 24 accordingly lifts contact I1 against the action of the dual purpose springs 39. Y An arc is *thereby drawn between contacts I 5 and l1 and at the same time an air Yblast is established Ifrom the inlet chamber 25 through orifice 22, outlet chamber 21, and exhaust outlet 29. Movable contact The gap formed between the arcing contacts I6" lfascinantes and I1 is' then of' such a value as to provide the most 'efcient v'arc extinguishing 'action of the air blast therethrough.

The air blast causes one rootof the arc to move from its initial position on the annular surface of movable contact l'! surroundingv orifice 22 to the inner edge of orifice 22. The root of the arc on the stationary contact i6 moves from the point of arc initiation radially and in a downstream direction until it reaches the downstream end of arcing tip i9. The arc also gradually lengthens as its roots are displaced and sweeps through orifice 22,'and through a series of positions until one'portion of the extended arc loop contacts the auxiliary electrode'l positioned within the arcing `chamber i8. The arc then extends between arci'ngtip i9 and electrode 3|r and is readily extinguished by the air blast. After the arc is extinguished the pressure ci the air blast is reduced and the dual purpose springs 39 move piston 24 vbaclcto its original position and contacts IG and H'reengage for normal operation.

Although but one embodiment of the present invention has been illustrated and described, it will be app-arent to those skilled in the art that various changes and modifications may be made therein without departingy from the spirit of the invention or from the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1.'In a switching device, the combination of a pair of stationary terminal elements, a stationary contact electrically connected tor'one of sai-:l terminal elements, a movable contact adapted to cooperate with said stationary contact and to reciprocate between a pair 0f extreme positions, a substantially rigid lever resting upon and conductively interconnecting said movable contact and the other of said terminal elements, and dual purpose spring means for establishing contact pressure between said lever and said movable contact and between said lever and said other of said terminal elements and for moving said movable contact from one of said extreme positions to the other of said extreme positions.

2. A circuit interrupter comprising a stationary contact, a movable contact cooperating therewith and defining a first supporting surface, a pneumatic motor for separating said movable contact i from said stationary contact, said motor comprising a piston forming an integral part of said movable contact, means for extinguishing the arc formed between said contacts upon separation thereof, a conducting lever in engagement at one end thereof with and supported by said first supporting surface, a stationary conducting element defining a second supporting surface for the other end of said lever, and common spring means for resetting said piston from the contact open position to the contact closed position thereof and for exerting contact pressure between said lever and said supporting surfaces,

3. A circuit interruptor comprising a stationary contact, a movable contact cooperating therewith and deiining a iirst supporting surface, a pneumatic motor for separating said movable contact from said stationary contact, said motor comprising a piston forming an integral part of said movable contact, means for extinguishing the arc formed between said contacts upon separation thereof, a conducting lever in engagement at one end thereof with and supported by said rst supporting surface, a stationary conducting element defining a second supporting surface for the other endfof said conducting lever, a pair of earsron said stationary element'adjac'ent said second supporting surface for guiding said lever, and'co'mmon spring means for resetting said piston from the contact open position to the contact closed position thereof and for exerting contact pressure between said lever and said supporting surfaces.'

4. In a switching device, the combination of a pair of stationary terminal elements, a stationary contact associated with one of said terminal elements, a cooperating movable contact in coaxial relationv with said stationary contact, contact separating means for moving said movable contact in the direction of the common axis of said contacts, a plurality of conductive rocking levers arranged substantially radially with respect to said common axis for interconnecting said movi able contact and theother of said terminal elements, supporting means integral with said movable contact groo'ved to receive one end of said rocking levers and adapted to permit wiping movement thereon of said rocking levers-means integral with said other terminal element defining a supporting surface for the' other ends of said rocking levers, a plurality of stationary'supports for helical springs, and a plurality ofhelical springs each resting with one end thereof on one ofxsaid supports and with the other end thereof on one of said rocking levers.

5. In a switching device, the combination of a pair of stationary terminal elements, 'a stationary lcontact conductively connected to one of said terminal elements, amlovable contact adapted to cooperate with said stationary contact, contact separating means, a plurality of rocking levers for conductively interconnecting said movable contact and the other of said terminal elements, means integral with said movable contact grooved to receive and to support one end of said rocking levers and adapted to permit a wiping movement thereon, means integral with said other terminal defining a supporting surface for the other ends of said rocking levers, and spring means acting upon said rocking levers to' produce a wiping action between said rocking levers and surfaces contacting therewith upon movement thereof and to reengage said contacts upon separation thereof.

6. In a switching device, the combination of a pair of stationary terminal elements, a stationaryl contact conductively connected to one of said terminal elements, a movable contact adapted to cooperate with said stationary contact, lever means resting upon and conductively interconnecting said movable contact and the other of said terminal elements, a uid motor for separating said contacts, said motor comprising a piston forming an integral part of said movable contact, a Source of supply of fluid under pressure, means for admitting fluid under pressure from said source to said motor and adjacent said contacts to cause separation of said contacts and extinction of the arc drawn therebetween, and spring means acting upon said lever means to produce a wiping action between said lever and surfaces contacting therewith and to reset said piston from. the contact open position to the contact closed position.

7. in a switching device, the combination of a pair of stationary terminal elements, a stationary contact conductively connected to one of said terminal elements, a movable contact adapted to cooperate with said stationary contaict, a. piston forming an integral part of said movable Contact and defining an annular circular groove having a concave cross section around the circumference nl said levers havingA curved ends of which one Vend of said lever is supported by the annular circular groove of said .piston and the other end of said lever is hingedly supported by the supporting surface of said stationary element, a pneumatic Ameans for actuating said piston for separating said contacts and extinguishing the arc Vdrawn therebetween, and a plurality of helical springs arranged generally parallel to the axis of said contacts and each acting upon one of said levers' for resetting said piston from the contact open position to the contact closed position.

8. A circuit interrupter comprising a stationary contact, a movableV contact cooperating therewith land defining a first supporting surface, a pneu-v inatic motor for separating said movable contact from said StatiOnarycOntaCt, said motor comprising a piston forming an integral part of said movable contact, means 'for extinguishing the, are formed between saidlcontacts upon separation thereof a conducting lever in engagement at one Y Y end thereof with an supported by said first sup- 1f...

porting surface, a stationary conducting element Vdefining a. second supporting surface for the other end of said lever, and common spring means e for resetting said piston fro-m the contact open position to the contact closed position thereof 8 Y and Vfor exerting contact pressure between said lever and said supporting surfaces, said `Spring means having a Smaller stroke than the stroke of said movable contact.

9. In a switching'device, the combination of a pair of stationary terminal elements, a stationary contact associated with one of said terminal elements, a reciprocable movable contact adapted to cooperate with said static-nary contact, a substantially rigid conductive rocking lever disposed transversely of the directions of movement of said movable contact with one end thereof resting on only said movable contact and with' the opposite end thereof on only the other of said terminal elements, a stationary support for a spring means, and a spring means resting with one end thereof upon said support and With the other end thereof acting on said rocking lever substantialiy in one of said directions of movement for establishing contact pressure' between said'lever and said other of said terminal elements and for aiding movement oi said movable Contact in said one of said directions.

CHESTER D. AINSWOR'IH. GUSTAV Ef. JANSSON.

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

UNrrED STATES PATENTS Prince Apr. l5, 1941