US2678984A - Air blast breaker interrupting head with interrupted line contact - Google Patents

Description

May 18, 1954 J. M. RAMRATH 2,678,984

. AIR BLAST BREAKER INTERRUPTING HEAD WITH INTERRUPTED LINE CONTACT Filed Dec. 19, 1951 2 Sheets-Sheet l May 18, 1954 M RAMRATH 2,678,984

AIR BLAST BREAKER INTERRUPTING HEAD WITH INTERRUPTED LINE CONTACT Ffiled Dec. 19, 1951 2 Sheets-Sheet 2 5x5. 5 @2M/mn F/f Patented May 18, 1954 UNITED NT OFFICE AIR BLAST BREAKER INTERRUPTING HEAD WITH INTEERUPTED LlNE CONTACT waukee, Wis.

Application December 19, 1951, Serial No. 262,417

(Cl. 20G- 148) 7 Claims. 1

This invention relates in general to improvements in electric circuit breakers, and more particularly to means for improving the interrupting ability of circuit breakers of the uid blast type.

Circuit brealers of the fluid blast type, especially those of the air blast type, are used to interrupt relatively large currents in a short period of time. This type of circuit breaker is usually provided with arcing contacts for opening the power circuit and main contacts ior carrying the current when the circuit breaker is closed.

As the currents to be interrupted by circuit breakers of the fluid blast type become increasingly greater, it becomes desirable to operate the breaker in shorter periods of time and to utilizo the fluid blast at a higher degree of eniciency so that the blast might extinguish the within the shortest possible time.

To extinguish the arc rapidly the power current must be transferred from the main contacts to the arcing contacts with a minimum of arcing. It is imperative, therefore, to have the main contact separating line exposed to an air blast which will quickly extinguish any arcing which might occur between the main contacts.

In accordance with this invention a huid blast circuit interruptor is provided which employs a pair oi separable nozzle and plug type arcing contacts and a pair of separable annular main contacts which engage along contact surfaces of the circular Contact line type. At least one of the main contacts is convex immediately adjacent the circular Contact line. A plura 'ty of grooves are arranged in at least one of the main contacts and intersect the line type contact surface thereof substantially at right angles for subdividing the line type contact surface into a plurality of spaced sectors. The grooves and the gap formed between the line type contact surface upon separation of the main contacts are .l

substantially the only avenue for admitting fluid under pressure to the arcing nozzle Contact forining part of the arcing contact structure.

It is, therefore, one object of the present invention to provide a new and improved. circuit interrupting structure of the fluid blast type in which arcing at the main contacts is suppressed.

Another object of this invention is to provide a new and improved fluid blast arc extinguishing structure in which the fluid blast envelops laterally the arc formed between the arcing contacts and in addition thereto tends to separate the arcing contacts. l

A further object of this invention istoprovide a new and improved main contactstructure in 2 which the configuration of the contact structure aids arc extinguishment.

Objects and advantages other than those set forth will be apparent from the following description when read in connection with the accompanying drawings, 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;

Fig. 2 is a plan view of the stationary main and arcing contact structures; and

Fig. 3 is a vertical section through the contact structure taken along the line III-111 of Fig. 2.

Referring more particularly to the drawing by characters of reference, Fig. 1 illustrates an interrupting head i comprising a flange or supporting base member 2 which is clamped by means of cap screws 3 on a cap 2l connecting the flange to a source of arc extinguishing fluid under pressure. Base member 2 supports a tubular insulator of ceramic or other suitable insulating material of which porcelain is an example. A force is applied to a continuous clamping ring El 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 el in a direction substantially perpendicular to a surface s of porcelain insulator l to secure the porcelain insulator to base member 2. This clamping structure minimizes bending moments and shear stresses in the porcelain.

A conductive annular member 9 made in two parts is mounted on and supported by insulator l by means of a continuous clamping ring l0, 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 li is rigidly supported by a depending portion i4 of the annular member 9 and screwed thereto by a coupling I5. Insulating tube i3 also surrounds a pair of cooperating arcing contacts i6 and I1 of the nozzle and plug type and cooperates with conductive cylindrical member 9 to define an arcing or contact chamber i8.

The so-called fixed arcing contact l'! is mounted on a piston iS for limited movement therewith. Piston i9 is arranged within a cylinder 20 which, in turn, is threaded into a hollow cylindrical main stationary contact forming a sleeve 22.

The main stationary contact 22 is secured to the base member 2 by bolts-23 inserted in the screw holes 24 shown in Figs. 2 and 3. Contact 22 may be considered as a part of a flow distribution member 33 and denes with insulator it an annular chamber therebetween. Notches or grooves are provided at the entrance of the screw holes 2t. One purpose oi grooves is to provide the necessary clearance for of bolts 23 and for a wrench serving to insert the bolts into the structure and to remove them therefrom. Another purpose oi grooves 25 is to provide a passageway for the iuid under pressure through the main contact structure to the arcing contacts.

The arcing contact i and piston assembly I9 are resiliently urged into engagement with the cooperating arcing contact It by a beryllium copper spring 2B. The spring has a dual purpose, namely, to provide contact pressure between the arcing contacts ld and il until the piston has been stopped in its upward movement by an abutment 5I on cylinder 2G and to act as a current carrier during the circuit interrupting operation.

The cooperating movable arcing contact iii comprises an annular shaped arcing portion defining an orifice 2l and adapted to partially surround the top portion oi fixed arcing contact il upon engagement therewith. Contact it is mounted on the sleeve shaped movable main contact 28 and iorms therewith the piston 32 of a iluid motor. Sleeve 2s is adapted to slide within guiding surfaces including downward ei:- tension portion '29 of the conductive cylindrical iember d and a bushing mounted within insulator i3. The upward strolte of sleeve limited by abutment or" an annular projection Sil thereof against a flange 3l 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 iii.

The arcing chamber I8 extends upward to a suitable outlet all extending between member s and a concave baille or cover secured thereto. Arcing chamber i3 contains an auxiliary arcing electrode This electrode, which is secured to cover and in electrical Contact with member is usually axially aligned with sleeve Ztl.

A plurality of rigid interconnecting conductors 3l electrically connect the movable contacts Iii and 28 to member il, which is provided with a ter inal lug and therefore constitutes a stationary terminal element. Base member il, which is electrically connected to the stationary contact 22 constitutes the seco-nd stationary terminal element and is provided with a suitable terminal lug (not shown).

Each rigid interconnecting conductor 3l is in the form of a rocking Contact lever which is in permanent contact with the conductive cylindrical member 9 and sleeve ii at all times. Sleeve may be provided with a groove 39 having a concave cross section extending around the circumference thereof and forms a bearing surface for engagement of one end of the interconnecting conductors 3l. rlThe conductor annular inember s, in turn, may be provided with a concave circular groove i6 having an annular supporting surface adapted to hingedly support the other end of conductors 3l. Levers Si? extend in radial directions from sleeve 23 and, while resting on their supporting surfaces, make with the axis of sleeve 23 an angle which varies with the longitudinal position of the sleeve. A plurality of dual purpose spring means il axially aligned with a plurality of pins fill, provide substantially constant pressure between anges si and interconnecting conductors 3l.

Thus, as piston 32 moves under the inno-ence or air pressure, sleeve E8 moves upward in the interrupting head l and interconnecting conductors 37 follow the vertical movement thereoi a combined rolling and wiping action over the two contact surfaces associated therewith. Pairs of ears 4E provided on member S guide each. interconnecting conductor 3l and align these interconnecting conductors in radially extending directions frorn the annular groove 39 on the outer surface of sleeve 28. Interconnecting conductors 3l 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 illlustrated in the drawing are provided with convex end portions in engagement with the supporting surfaces, whereby movement of interconnecting conductors 3l takes place with a minimum of friction.

The helical spring means 4l act upon interconnecting conductors or levers 3l at points intermediate their ends to provide a sufficient amount o contact pressure between conductors 3l and the contact surfaces engaged therewith. However, these springs have a dual function and additionally effect resetting or reclosing of contact it upon the decrease of pressure in the arcing chamber i8 upstream of movable contact The helical spring means 4i are disposed so as not to increase the overall dimensions of the circuit breairer. The stroke or compression oi spring means fil upon movement of the movable contact it is smaller than the stroke of contact it.

Base member 2 provides a connection between a reservoir (not shown) constituting a source of arc extinguishing huid under pressure and an inlet portion 4 oi the arcing chamber I8 for directing a blast of arc extinguishing iiuid under pressure between the arcing contacts and through the arcing chamber. The arc extinguishing fluid under pressure may be an inert gas such as nitrogen, but it will be assumed herein that the iluid is air under press o1"- the order oi two hundred or more pounds per square inch supplied to the reservoir by a suitable compressor (not shown).

Inlet port IM is connected to a plurality oi passageways which conduct the iiuid under pressure from port da around the main stationary contact 2 to the out-side periphery of the main contact structure.

As shown more clearly in Fig. 2, the Contact surface 4S of the main stationary contact 22 is a iiat surface divided into a plurality of segments by the notches 25. The sleeve 23 is provided with a convex main contact surface 4l which provides upon contact with the cooperating flat contact surface it a circular line type contact. The notches 25 provided in the fiat contact surface Illia, however, divides the circular line contact into i'our circular line contact segments. A passageway 5i) is provided through the stationary contact 22 to the under side of piston i9. Part of the fluid under pressure passing through inlet port ifi will traverse passageway 5G to assisiJ spring 25 in urging contact in engagement with contact i6.

In operation, the circuit breaker being closed as indicated in Fig. 1, current flows through a. stationary terminal element (not shown), base member 2, main stationary contact 22, flat contact surface 46, convex contact surface 41, sleeve 28 of piston 32, conductors 31, conductive an- Abase member 2 and through the passageways 45 formed between insulating tube I3 and contact 22. Fluid under pressure passes through notches 25 to the annular surface of movable contact I6 against the action of the dual purpose springs 4I. Upon separation of the main contact surfaces 46 and 47 the current path is shifted and passes from the base member 2 to the main stationary contact 22, beryllium copper spring piston I9, arcing contact I1, arcing contact It, sleeve 23 of piston 32, conductor 31, conductive annular member 9, and stationary terminal element 38.

The shape of the stationary contact casting 22 permits maximum air flow over the main contacts at their time of separation. If the current transfer from main to arcing contacts is not perfect, possible arcing may occur at the main contact separating line. It is imperative, therefore, to have the main contact separating line under as good an air flow as possible. The rounded bottom of the movable main contact surface 41 provides a line contact on the top of the main stationary contact surface 4t, thus permitting the fluid blast from passageways 45 to be present at the separation of the main contact surfaces 46 and 41 and at the inception of any main contact arcing.

vThe arcing contact I'I is mounted on piston I9 which in turn is located on the inside of the stationary contact casting 22. The arcing contact assembly Il is carried by the beryllium copper spring 2d. This spring 25 has a dual purpose, namely to provide contact pressure until the piston is stopped in its upward movement by abutment 5I on its cylinder 2i), and to act as a current carrier. Spring 26 carries the total current after the main contacts separate and until the abutment 5i on cylinder 28 has been reached by piston IS, and from then on the spring 26 carries the arc current until arc extinction. One reason for mounting the arcing contact on a piston assembly is to use that assembly as an additional pressure area to provide upward movement for the movable main contact sleeve 23.

Initially, during the circuit breaker opening operation, there will be air leakage on the outside of the stationary main contact through paslsageways e5 through the notches 25, into the cylinder 25, and around the arcing contact piston I9. Further leakage of air occurs from passageway 5! and around the piston I9. This leakage of air around piston IS ceases when piston I9 reaches the abutment on cylinder 20. At this point the entire air supply is directed over the main line type contact into the hollow arcing contact piston 32. Lateral clearance around piston I9 provides self-adjustment of the arcing contacts IS, I'I.

Accordingly, a new and improved circuit breaker structure has been disclosed comprising a pair of cooperating arcing contacts connected in parallel with a pair of cooperating main contacts. The main contacts provide a convex surface on one main contact to form a line contact with the flat surface of the other main contact.

A plurality of grooves are arranged on the flat t surface of the one main contact for intersecting the line contact substantially at right angles for subdividing the line contact into a plurality of spaced line or arcuate segments. Means are provided for conducting a flow of iiuid under pressure from a source through the groovesA and the gaps formed betweenthe main contacts upon separation thereof and over the cooperating surfaces of the arcing contacts to atmosphere. The iiuid path is substantially the only avenue from the source for admitting fluid under pressure to the arcing contacts.

Although but one embodiment of the present invention has been illustrated and described, it will be apparent to ythose skilled in the art that various changes and modifications may be made Atherein without departing 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 fluid blast circuit interrupter, a `source of iiuid under pressure, a contact chamber, a pair of main contacts mounted within said charnber and comprising a movable sleeve providing a convex contact surface cooperating with a stationary sleeve providing a flat contact surface, said movable and stationary sleeves engaging to form a line Contact, a pair of cooperating arcing contacts connected in parallel with said main contacts and adapted to draw an arc in said chamber, said arcing contacts comprising a movable contact arranged in said movable sleeve and defining an orifice and a fixed arcing contact arranged in said stationary sleeve for limited movement therein, means for separating said and arcing contacts, spring biasing means for maintaining said arcing contacts closed until said movable sleeve has moved a predetermined distance, and means defining a path for the flow of fluid from said source over first the cooperating surfaces of said main contacts, second the cooperating surfaces of said arcing contacts and third through said orifice defining movable arcing contact to atmosphere.

2. In a fluid blast circuit interroga-ter, a source oi' .ii-uid under pressure, a supporting base member, means defining a blast p: adapted to supplied with fluid under pressure from said source, a flow distribution member arranged coaxially within passage in spaced relation from the boundary walls thereof to define an annular chamber therebetween, a pair of separable annular znain contacts engaging along a pair of contact surfaces of the circular contact line type, at least one of surfaces being con- Vex immediately adjacent said circular contact line, one of said main contacts being arranged at the down-stream end of said flow distribution member and the other ci said main contacts being spring biased to contact closed position and having pressure reactive surface immediately adjacent said of line type contact surfaces for causing separaticn of said main contacts under the actie-n of under pressure supplied from said source, a pair of separable nozzle and plug type arcing contacts each supported by one ..g oi said main contacts, said flow distribution member having a plurality or" longitudinal angularly spaced grooves intersecting one jof said line type contact surfaces and subdividing said one of said line type contact surfaces into a plurality of spaced segments, sai-:l flow distribution member being provided with hoies coaxially aligned with said longitudinal angularly spaced grooves, Vand bolts inserted in said coaxially aligned grooves and holes and, threade into said base .member for securing said distribution member to said .base member.

3. in a iiuid blast circuit interrupter, a source of Huid under pressure, a contact chamber, a pair of main contacts mounted within said chamber and comprising a movable sleeve providing a convex contact surface cooperating With a stationary sleeve providing a at contact surface, said movable and stationary sleeves engaging to form a line contact, a plurality of grooves in one of said main contacts intersecting said line contact substantially at right angles for subdividing said line contact into a plurality of spaced segments, a pair of cooperating arcing contacts connected in parallel with said main contacts and adapted to draw an arc in said chamber, said arcing contacts comprising a movable arcing contact arranged in said movable sleeve and dening an orifice and a fixed arcing contact arranged in said stationary sleeve, means for sequentially separating said main contacts and said arcing contacts, and means defining a path for the flow of fluid from said source through said grooves, over the cooperating surfaces of said main contacts, over the cooperating surfaces oi' said arcing contacts and through said orifice to atmosphere.

4. In a fluid blast circuit interruptor, a source of fluid under pressure, a contact chamber, a pair of main contacts mounted Within said chamber and comprising a movable sleeve providing a convex contact surface cooperating with a stationary sleeve providing a ilat contact surface, said movable and stationary sleeves engaging to form a line contact, a plurality of grooves in one of said main contacts intersecting said line contact substantially at right angles subdividing said line contact into a plurality of spaced segments, a pair of cooperating arcing contacts connected in parallel with said main contacts and adapted to draw an arc in said chamber, said arcing contacts comprising a movable arcing contact arranged in said movable sleeve and defining an orifice and a spring biased fixed arcing contact arranged in said stationary sleeve for limited movement therein, means for sequentially separating said main contacts and said arcing contacts, and means deuning a path for the flow of uid from said source through said grooves, over the cooperating surfaces of said main contacts, over the cooperating surfaces of said arcing contacts and through said orifice to atmosphere.

5. In a fluid blast circuit interrupter, a source of fluid under pressure, a contact chamber, a pair of main contacts mounted Within said chamber and comprising a movable sleeve providing a convex contact surface cooperating with a stationary sleeve providing a flat contact surface, said movable and stationary sleeves engaging to form a line contact, a plurality,7 of grooves in one of said main contacts intersecting said line contact for subdividing said line contact into a plurality of spaced segments, a pair of cooperating arcing contacts connected in parallel with said main contacts and adapted to draw an arc in said chamber, said arcing contacts comprising a movable arcing contact arranged in said movable sleeve and a fixed arcing contact arranged in said stationary sleeve, means for sequentially separating said main contacts and said arcing contacts, and means defining a, path for the flow of iiuid from said source through said grooves, over the cooperating surfaces of said main contacts, over the cooperating surfaces of said arcing contacts to atmosphere.

6. In a fluid blast circuit interruptor, a source of fluid under pr ssure, means defining a blast passage adapted to be supplied with fluid under pressure from said source, a flow distribution member arranged coaxially within said passage in spaced relation from the boundary Walls thereof to define an annular chamber therebetween, a pair of main contacts mounted Within said passage and comprising a movable sleeve providing a convex contact surface cooperating with a stationary flat contact surface arranged at the downstream end of said flow distribution member, said main contacts engaging to form a line contact, said movable sleeve being spring biased to contact closed position and having a pressure reactive surface immediately adjacent line contact for causing separation of said main contacts under the action of fluid under pressure supplied from said source, a pair of cooperating arcing contacts'connected in parallel with said main contacts and adapted to draw an arc in said passage, said arcing contacts comprising a movable arcing Contact arranged in said movable sleeve and defining an orifice and a nxed arcing contact arranged in said flow distribution member for limited movement therein, spring biasing means for maintaining said arcing Contact closed until said movable sleeve has moved a predetermined distance, said flow distribution member having a plurality of longitudinal angularly spaced grooves intersecting said flat contact surface and subdividing said line contact into a plurality of spaced segments for admitting a plurality of angularly spaced flows of fluid under pressure from said annular chamber to said pressure reactive surface.

7. In a fluid blast circuit interruptor, a source of fluid 4under pressure, means defining a blast passage adapted to be supplied with fluid under pressure from said source, a flow distribution member arranged coaxially Within said passage in spaced relation from the boundary walls f thereof to define an annular chamber therebetween, a pair of main contacts mounted Within said passage and comprising a movable sleeve providing a convex contact surface cooperating with a stationary flat contact surface arranged at the downstream end of said flow distribution member, said main contacts engaging to form a line contact, a pair of cooperating arcing contacts connected in parallel with said main contacts and adapted to draw an arc in said passage, said arcing contacts comprising a movable arcing contact arranged in said movable sleeve and a fixed arcing contact arranged in said flow distribution member for limited movement therein, spring biasing means for main- References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,117,261 Thommen May 10, 1938 2,287,039 Jansson June 23, 1942 2,533,545

Ainsworth et al. Dec. 12, 1950

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