US2452476A - Circuit interrupter - Google Patents

Description

OCt. 26, 1948. W- M LEEDS CIRCUIT INTERRUPTER 2 Sheets-Sheet 1 Filed Aug. 15, 1944 IPP:

WITNESSES:

Patented Oct. 26, 1948 UNITED STATES PATENT OFFICE CIRCUIT INTERRUPTER Winthrop M. Leeds, Forest Hills, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application August 15, 1944, Serial No. 549,575

14 Claims. l

This invention relates to circuit interrupters in general and, more particularly, to arc extinguishing structures therefor.

A general object of my invention is to provide a circuit interrupter of improved construction which will interrupt more effectively the current passing therethrough than has been achieved heretofore.

Another object is to -provide an improved circuit interrupter in which contact and piston means are operable to draw an arc and simultaneously force fluid adjacent the arc. Preferably the arc is rotated between a pair of ringshaped contacts by magnetic means to not only minimize contact burning but also to render the ow of fluid more effective in bringing about arc extinction.

Another object is to provide an improved circuit interrupter in which improved operating means are utilized to effect an interruption of the circuit. More specifically, the operating means may establish two serially related arcs in sequence, the first established arc being subjected to deionizing action especially adaptable for high current interruption, whereas the second serially related arc is subjected to deionizing action which is especially adaptable for low current interruption. Preferably a single operating means is employed to draw the aforesaid two serially related arcs in sequence.

Another object is to provide an improved circuit interrupter of the type which establishes an arc and rotates the same between a pair of cooperable ring-shaped contacts. Preferably I ernploy piston means to effect a radial inward or a radial outward flow of fluid adjacent the established arc.

Another object is to provide an improved circuit interrupter in which a rotating arc is subjected to a longitudinal fluid blast. It has been `found that if a radial flow of uid is employed in extinguishing a rotating arci, the arc has a tendency to be bowed in. the direction of the radial fluid blast and consequently to assume a configuration which is substantially parallel to the magnetic iield. Such a bowing thus not only minimizes the effect of the transverse field necessary to continue rotation of the arc but also the bowed shape of the arc increases both the arc length and the arc power, especially during the peak of the alternating current wave.

It is an object of my invention to solve the aforementioned problem by subjecting the rotating arc to a fluid blast, which may be either gaseens er man iangituqinalu f sais are t@ @lininate the tendency toward bowing. Preferably, I employ an annularly shaped orifice which more effectively directs the fluid blast toward the rotating arc to effect the extinction thereof.

.Further objects and advantages will readily become apparent upon a reading of the following specifcation taken in conjunction with the drawings; in which:

Figure 1 shows a vertical sectional view through a circuit interrupter embodying my invention and shown in the partly open circuit position;

Fig. 2 is a sectional View taken along the line II-II of Fig. l;

Fig. 3 is a vertical sectional view through a modified type of circuit interrupter embodying my invention. and shown in the -partly open circuit position;

Fig. 4 is a sectional view taken along the line IV-IV of Fig. 3;

Fig. 5 is a vertical sectional view through a modified type of circuit interrupter embodying my invention; and

Fig. 6 is a sectional View taken along the line VI-VI of Fig. 5.

Referring to the drawings and more particularly to Fig. 1 thereof, the reference numeral I designates an insulating cylindrical casing closed at its upper end by an insulating plate 2 and also closed at its lower end by a metallic cup-shaped member 3. An overpressure valve 4 is provided in the plate 2 and a gas venting check valve 5 is also provided in the plate 2. Movable through the plate 2 is an operating rod 6 composed of conducting material and having a vent 'l' provided therethrough. The operating rod 6 carries a piston 8 rigidly secured thereto by a press fit having a flap valve 9 associated therewith. A strong compression spring I0 has its upper seat on a ring-shaped insulating plate Il which is limited in travel by a shoulder in the cylinder wall ZI. The lower end of the strong spring I0 is seated on a hollow operating member I2 composed of insulating material and having secured thereto at its lower end a movable ring-shaped contact I3.

The contact I3 is cooperable with a relatively stationary ring-shaped contact I4 fixedly supported in place by an insulating plate member I5. Associated with the relatively stationary contact I4 is a series field coil IE. This coil when energized serves to provide a radial magnetic field between the contacts I3, I4. Associated with the movable contact I3 is another series eld coil I'I wound so as to produce an opposing magnetomotive force. This coil has its upper terminal serially connected with a plurality of segmental ngers I8 collectively forming a contact which is carried by the operating member I 2.

The operating member I2 is guided by an upstanding insulating cylindrical member I9, the latter being closed at its upper end by a ringshaped insulating plate member 28 having integrally fori-ned therewith'an upstanding insulating cylindrical member ZI which serves to guide the piston 8. The operating rod 3 carries at its lower end a corrugated insulating follower 22.

operating member I2 is corrugated. A plurality of rods 2d have their lower ends threadedly; secured in the upper end of the operating member Also it will be observed that the upper portion 23 of they 4 not shown, drawn between the secondary contacts 26, 36 is particularly adapted for low current interruption. Certain features of such an interrupting structure are disclosed and broadly claimed in United States Patent 2,253,009 which issued August 19, 1941 to Benjamin P. Baker and which is assigned to the assignee of the instant application.v

During the downward stroke of the operating rod 6 the flap valve 9 will raise upwardly away from the piston 8 to provide unimpeded ydownward movement of the piston 3.

I2 and have their upper ends bent inwardly to serve as upper seats for a relatively weak compressor spring 25 which biases the operating member I2 to its upper position where it abuts against the plate 20.

In the closed circuit position or the interrupter, not shown, the electricall circuit therethrough comprises the operating rod 5 contact portion 26 thereof, segmental; ngers it,` upper series held coil I I, movable contact lf3, stationary contact ill, lower series i'leld coil I6, to a conducting cupshaped member 21 to the line terminal 28. In the closed circuit position of the interruptor the operating rod 6 is forced downwardly by suitable means not shown to a position which isiarther downward than is shown in Fig. l. In other words, the piston 8, through the cushioning; spring I0, forces the operating member lf2 downwardly so thaty the contacts i3, [4 make abutting engagement.

To open the circuit passing through the interrupter the operating rod 6 is moved upwardly to first permit the compression spring 25;; to raise the operating member I2 being assisted in .this action by the accelerating compression spring 29 which biases a conducting follower SI1 upwardly. The separation between the contacts I-, I4. establishes an arc 3l therebetween which is rotated by the radial magnetic field set up by the series field coils i6, Il. lThe upward movement of the operating rod 6, carries the piston` 8 therewith to cause a circulation of luid, in this instance oil, upwardly in the region 3,2 through apertures 33 provided inA the cylindrical member ZI,v downwardly through the annular region 3G and radially inwardly toward the arc 3l through` apertures 3,5 provided in the cylindrical member I;9 For relatively high amperage currents of the order of several thousand amperes or more, the, rapid rotation of the arc in conjunction with the radial inward flow of the oil will serve to bring about extinction of the arc 3l and a consequentbreaking of the electrical circuit passing through the interrupter. For lower amperage currents the magnetic eld produced by the series neld coils I6, I1 may be suiiciently weak so that interruption of the arc 3l may not take place,

In this event continuing; upward movement of the operating rod 6 will serve., to bring about a separation between the secondary contacts includ-- ing the contact portion 26l ofthe rod 6 andthe segmental contact 36, which is longer than the other segmental contacts I 8. Thus an arc will be drawn between the secondary contactsk 3 6 and 2B in the constricted portion of the operating member I2, the arc being forced against the corrugations provided by the follower 22` and the corr-ugations formed in the upper portion of the operating member I 2 (note Fig. 2).- The particular interrupting structure associated with the arc,

In the construction which I show herein, it will be noted that I have combined in a novel way three principles of alternating current circuit interruption in a single circuit interrupter. These three principles are: (l) fluid blast, which may be produced by piston action, compressed air, or an auxiliary series arc, (2) magnetic blowout, produced by magnetic means to lengthen the arc, increase turbulence and de-ionization, and reduce contact burning, and (3) arc constriction, forcing the established arc through small holes, subjecting it to guillotine action., or constrictions as in the aforesaid patent.

Thus it is apparent that my invention covers a novel combination of all the three abovementioned principles designed to produce rapid arc rupture over a wide current range, particularly at very high currents. It will be observed that the motion of thek piston 8 circulates oil radially inwardly between the contacts I3, I driving products of arc combustion up around the operating rod 5 to` the space below the piston 8 and also o ut the vent 'I provided in the operating rod 6. Preferably the velocity of the flow between the contacts I3, Iii should be high enough` so that liquid replaces gas at a par-- ticular point in less than the time of one revolution of the arc. The turbulence of the arc 3 I` and the scavenging action of the liquidilowshould be suicient to interrupt the current at the iirst or second current zero. If this is not brought about, further upward movement of the rod S draws a second serially related arc between the secondary contacts 25, 3E, which is constricted. This restriction will readily effect thel extinction of lowcurrent arcs. Also the high velocity of thev liquid blast caused by the circulation produced by the piston 8 will cooperate with the insulating corrugations to` effect a ready extinction of the low current arc drawn between the secondary contacts 26, 3,6'.

In the embodiment of my invention shown in Figs. 3 and 4 it will be noted that again the operating rod 6 has a vent 'i' provided therethrough. But in this particular arrangement the vent 1 is closed by a valve 39 providedat the lower endy of the operating rod 5 and biased to its closed position by a compressiony spring llt. As in the previous embodiment of my invention the piston 8I is operable during the closing stroke to force the cushioning spring Ill to cause downward movement of the operating member I2 to eiect an engagement betweeny the ring-shaped contacts i3, I4.

However, it will be noted that I have provided means forming an annular orice through which the arc 3l is drawn and rotated by the series field coils I6, I'I. Furthermore the iuid blast which is driven adjacent the arc 3l by the piston strikes the arc 3l substantially longitudinally thereofI to thus minimize bowing of the arc 3 I.

In United States Patent 2,333,598 which was issued November 2, 1943 toA Albert P. Strom and which is assigned to the assignee of the instant application, there is disclosed means for drawing an arc between ring-shaped contacts and rotating the arc about said ring-shaped contacts by a radial magnetic field. In this patent a fluid blast strikes the rotating arc radially inwardly or radially outwardly thereof. However, in the operation of such an interrupter under certain conditions, the most effective operation has not been obtained due to the bowing of the arc either inwardly or outwardly depending upon the direction of the radial fluid blast. Not only does the bowing of the arc force it to assume a conguration which is parallel to the magnetic field but also the extreme length of such a bowed arc causes the interrupter to dissipate considerable energy especially during the peak of the alternating current wave because of the considerable arc voltage. In the construction which I show in Fig. 3 it will be observed that the fluid flow is substantially longitudinally of the rotating arc 3| as it rotates about the contacts I3, I4 within the annularly shaped orice 4I. This results from the merger of the fluid flow upwardly through the inner and outer annular passages 46. Thus there is no bowing of the arc and by the provision of the annularly shaped orifice 4I the fluid blast is very effectively directed toward the arc 3 I.

It will also be observed that valves 42 are provided in the annular region 34 and that ball valves 43 are provided in the plate member 2. By such a construction it will be apparent that downward movement of the operating rod 6 will serve to draw liquid, in this instance oil, through the ball valves 43 from the region 44 to the region 45, the valves 42 remaining closed during this time. Thus fresh oil of high dielectric strength is brought into the region 45.

During the opening operation upon upward movement of the operating rod 6 the upward movement of the piston 8 will effect a closure of the ball valves 43 and an opening of the valves 42. The result is a unidirectional flow of oil from the region 45 through the valves 42 downwardly through the annular region 34 and upwardly through the inner and outer annular passage 46,

and upwardly through the annular orice 4I adjacent the arc 3|. This oil flow may continue upwardly through passages 4l to the region 48 below the upwardly moving piston 8. Thus there is a circulation of oil during the opening operation. During `a subsequent closing operation the downward movement of the piston 8 will cause closure of the valves 42 and the passage of oil through the valve 39 through the vent 'I and out the apertures 49.

Circuit breakers using liquid flow, preferably oil, set in motion by a powerful piston for arc rupturing purposes are sometimes referred to as impulse type breakers. Commercial designs of these impulse breakers utilize oil flow in the order of 100 feet per second requiring very high mechanical driving force behind the oil piston. This embodiment of my invention covers, it will be observed, a more moderate oil flow type breaker with a magnetic field aiding by rotating the arc while it is being subjected to a longitudinal oil flow. Experimental results have shown that a rotating arc can be interrupted with considerably reduced oil velocity as compared to an arc held stationary in a circular orifice. Consequently, by employling a rotating arc construction in combination with a longitudinal oil flow, the interrupter renders increased interrupting performance with comparatively low oil velocity.

In the closed circuit position of the interrupter, not shown, in Fig. 3 the electrical circuit therethrough comprises the operating rod 6, segmental ngers I8, upper series neld coil I'I, movable annular contact I3, stationary annular contact I4, lower series eld coil I6, connector 50, conducting cup-shaped member 5I to the line terminal 52.

In the construction shovwn in Figs. 5 and 6 it will be observed that I have provided an insulating casing closed at its upper end by a conducting plate 56 provided with ball valves 51 and through which operates a conducting operating rod 58. The rod 53 carries a piston 59 at its lower end having a flap valve @il associated therewith. The piston 59 operates within a conducting piston cylinder 6I having apertures 52 provided at its upper end. The lower portion 63 of the cylinder 6I forms a hollow stationary contact which is cooperable with a movable Contact 64 springbiased to its upper position by a compression spring 55 having a lower seat on a conducting dome-shaped member 65.

Disconnect means generally designated by the reference numeral G7 are associated with the operating rod 58 in a manner hereinafter described. The disconnect means 6'! comprise a stationary disconnect Contact 68 cooperable with a movable disconnect blade G9 pivotally mounted at 'III to a fixed pivot. The disconnect blade 69 may be latched in its open position by latching means generally designated by the reference numeral 'I I. In this instance the latching means 'Il comprises a bell-crank member 'I2 pivotally mounted at 'I3 to a fixed pivot. The bell-crank 'I2 lis pivotally connected to a link 'I4 the other end of which is pivotally connected at 'I5 to a second bell-crank 'It pivotally mounted at 'Il to a xed pivot. The bell-crank 'I5 is biased in a counterclockwise direction about the pivot 'Il by a compression spring 'I3 having its other seat against an insulatinfT cylindrical member 'I9 which serves to contain a suitable arc extinguishing liquid which may be oil. The operating rod 58 carries a flange BQ rigidly secured thereto and a washer 8! slidably movable thereon, being biased upwardly by a. compression spring 82 having a lower seat against a flange 83 rigidly secured to the operating rod 58.

In the closed circuit position of the interrupter, not shown, the electrical circuit therethrough comprises stationary disconnect contact 68, disconnect blade 59, washer 8l, conducting operating rod 58, conducting plate E36, conducting piston cylinder 6I, stationary contact 53, movable contact 54, iiexible connectors 84, conducting plate 85, to the line terminal 8B.

During the opening operation suitable means, not shown, causes downward movement of the operating rod 58. The downward movement of rod 58 causes downward movement of the piston 59 which forces oil downwardly in the direction shown by the arrows in Fig. 5 to cause opening movement of the movable Contact 5d against the biasing action exerted by the compression spring 65. This draws an arc, the original terminal positions of which are at the points 81, 8S. However, the radially outward flow of oil carries the arc outwardly to cause it to extend between the ringshaped contacts S9 and Q0 around which it is rotated by the field coils 9i, 92, which are cut into series circuit following transfer of the arc 93 to the contacts 39, Q53. Thus in the closed position the field coils 9i, 92 are shorted out, and they are only inserted in the series circuit following transfer of the arc to the contacts 89, 90.

The. radial; magnetic. field' set. up by the. field coils: 9L. 9.2; rotates the arc 93; about. the ringshaned contacts. 8&1, 9,0, while the', piston 59 subjectszsaidl` rotating arc' to a radi-al outward iiuid blast.. A ring-shaped' splitter 84 formed of insulatingrmateriai prevents the arc' 93 from bowing outward-ly..

During the; last portionof downward travel of cperating'rod. 53S, the. flange 80 picks up the movable; disconnect; blade Gli-and causes it to separate from the stationary disconnect contact 63 thereby introducing an. isolating gap into the electrical circuit following. interruption of the arc 93. This isY necessary inasmuch as when thev piston 59 ceases its. downward movement they compression spring 65. will cause. a reengagement between the contacts 63, 64. During the subsequent closing operation the operating rod 58- is moved upwardly by suitable means,l not shown. During the initial portion of the closing stroke the disconnect blade S9; remains latched open. Duringr this portion of the closing stroke the. washer Bl remains in abutting engagement with the movable disconnect blade 69, compressing the springl 82 until the flange'U-trips the bell-crank 12 to effect a clock.- wise movement of the bell-crank 'i6 about the pivot '17?. When thi-s occurs the movable disconnect blade 69 wi-ll bereleasedfrom its latched position. and the compression spring 82 will force the. disconnect blade. 69 into engagement with the; stationary disconnect contact- $3 by a snap action.

In. this embodiment of. my invention itv will be appa-rent that again I- have provided novel piston means for notv only eecting the establishment of an arc4 but also providingv uid motion to effect the extinction of saidv arc. The structure is simple and positive inv operation and the disconnect` means lil.r insures that an isolating gap will. be.. provided prior to reclosure of the contacts 63., 64.

My arrangement hasthe advantage over the use of the ordinary magnetic blowout which is weak atvv lowv currents, and inwhich at high currents, thev arc lengthening takes. place so rapidly as to produce excessively high. pressures in the breaker. I have made unnecessary theluse of a piston. and driving mechanism large enough to interrupt the maximum rupturing capacity current, and have avoided they use oi all this eiort even on low power switching operations.

The. construction disclosed in Fig. 5| describes a new type. of high speed interrupter. which requires only a moderate size operating mechanism and utilizes.. a radial magnetic iield for rotating the arc without lengthening it so as to interrupt high currents with the liberation of only a reasonably small amount of arc energy. It will be observed that the radial magnetic field rotates thefarc at high speed whilethe oilA i'lowy scavenges the arc' products, driving them out of passages on. either side. of theA arc splitter. i-en to twenty teet per second linear oill Velocity at thesplitters should be'V adequate. compared: to seventy-five to Onahundredffeet per second required by a straight oi-l blast' device. The, high relative velocity between arc and oil' requiredv for high current interruptionA is provided bythe rapid arc motion on the annular arc horns.

For lowl current interruption. where the magnetic action is wea-1r, thev arcis extinguished by the. cross-blast oil flow alone produced by the pistonv 59;.

Fronrthe, above construction` it will be. apparent that I have provided'. novel disconnect means in which. they disconnectv switch blade is; latched open' and doesv not: move during the IrstV part: of the.: closing stroke, but: the spring 8:2' under the switch blade is.; merely compressed. The. ap valve llt associated with the pistonz 59. permits thev piston to. move; upward. freely during the: closing, stroker.. Since pressure; due. to. the. gasy generation is communicatedto both sides: of the pistonI 5.9. during. the opening: operation, there is no appreciable. tendencyv to slowA down the operation..

From the foregoing: description of several em,- bodiments of my invention it will be apparent that I have provided a circuit interrupter of. improved construction inV which the arc established. during the opening operation is rotated while simultaneously being' subjected tov a uid blast which may be radially inwardly,y radially outwardly or longitudinally of the established arc. By the use of a. single operating means to eiTect the extinction of the arc and thev fluid ow, it will be noted that the construction is exceedingly simple in operation and e'ective in performance.

Although I haveshown and described specific structures, it is to beclearly understood that the same; were merely for the purpose-'of illustration and` that changes and modicationsr mayreadily be made therein by those skilled in the art ywithout departing from they spirit andy scope of the appended. claims.

I claimasv my invention: v

1.. In a ycircuit interruptor of the liquid break type, a substantially enclosed casing anl operating rod movable: through awall of thefcasing. a liquid moving. piston secured to and movable.x with thev operating rodv Within the casing', a; cylinder Within: which the piston moves to: drive liquid', a relatively stationary ring-shaped contact, an op.- erating member carrying a movable ring-shaped contact and adapted` for limited movement axial.- ly of the casing, biasing means. surrounding the cylinder biasing the operating member and movable ring-shaped contact. to the open position, a resilientmeans interposed between the piston and the operating member sov that `closing movement of the operating rod will. eiect through the. resilient means closing motion oi thefoperating. mem.- ber andmovablering-shaped contact against the biasing action exerted by the biasing means, and liquid passage means communicating at one end with the piston movable within the. cylinder and at the other end with the two. ring-shaped contacts.

2.. In. a circuit interruptor of. the, liquid break type, a substantially enclosed casing, an operating rod movable through a wall of the casing, a.

liquid` moving piston secured to and movable with the operating rodwithirrthe'casing, acylin.- der withinl which. the piston movesto. drive liquid, a relatively stationary ring-shaped. contact,. an operating member carrying. a. movable, ring.- shaped contact and adapted. forv limited movement axially of the.- casing, biasing means. sur'- rounding the cylinder biasing the cperatingmem.- ber and movable ring-shapedcontact to the open position, a resilient mea-nsinterposedbetween.the pist-on1 and the operatingA member so.. 'thatv closing movement of the operatingrodwilleffectthrough the resilient means closing m-otionof. the operat.- ing member and movable ring-shaped contact against the biasing. action exerted by the. biasing means, andv liquidA passageV means. rcommunicating at one end with. the. piston. movable within the. cylinder. and at the other end with. thev two ring-shaped contacts, means.. moviding a radial `9 magnetic eld to cause rotation of the arc around the ring-shaped contacts, and a vent through the operating rod permitting exhaust of liquid out of the casing.

3. in a circuit interrupter of the liquid break type, a substantially enclosed casing, an operating rod movable through a wall of the casing, a liquid moving piston secured to and movable with the operating rod within the casing, a cylinder within which the piston moves to drive liquid, a relatively stationary ring-shaped contact, an operating member carrying a movable ring-shaped contact and adapted for limited movement axially of the casing, biasing means surrounding the cylinder biasing the operating member and movable ring-shaped contact to the open position, a resilient means interposed between the piston and the operating member so that closing movement of the operating rod will effect through the resilient means closing motion of the operating member and movable ring-shaped contact against the biasing action exerted by the biasing means, and liquid passage means communicating at one end with the piston movable within the cylinder and at the other end with the two ring-shaped contacts, means for causing rotation of the arc around the ring-shaped contacts, a movable lsecondary Contact carried by the operating rod, and a .relatively stationary secondary contact cooperable therewith and carried by the operating member.

e. lin a circuit interrupt-er, a relatively stationary ring-shaped contact, a movable ring-shaped contact separable from the stationary ringshaped Contact to establish an arc, means for causing only a radial inward flow of fluid between the separated contacts, venting means communicating with the interior of the movable ringshaped contact, and a member of insulating material positioned at least part of the time of the interruption process within the movable ringshaped contact closely adjacent thereto to confine and restrict the terminal of the arc playing on the movable ring-shaped contact.

5. In a circuit interrupter, a pair of ring-shaped contacts, means for establishing an arc between the ring-shaped contacts, means for causing a rotation of the are around the ring-shaped contacts, venting means communicating with the interior of one of the ring-shaped contacts, means for causing only a radially inwardly directed flow of iluid between the contacts and out through the venting means, and a member of insulating material positioned during a portion of the time of the interruption process within said one of the ringshaped contacts closely adjacent thereto to conne one terminal of the rotating arc.

6. In a circuit interrupter, a pair of ring-shaped contacts, means for establishing an arc between the ring-shaped contacts, means for causing a rotation of the arc around the ring-shaped contacts, venting means communicating with the interior oi one or" the ring-shaped contacts, means for causing a radially inwardly directed flow of uid between the contacts, and a member at least partially of insulating material positioned during a portion of the time of the interruption process within said one of the ring-shaped contacts, and the member having a plurality of corrugations thereon,

7. In a circuit interrupter, a relatively stationary ring-shaped contact, an operating member carrying a movable ring-shaped contact and adapted for limited axial movement, means for providing a radial inwardly directed fluid ilow between the ring-shaped contacts, venting means communicating with the interior of the movable ring-shaped contact, means fo rotating the arc around the ring-shaped contacts, an operating rod carrying an insulating follower member ex'- tending within the movable ring-shaped contact at least in the closed position of the interrupter, means biasing the operating member to the open position, and the operating rod causing closing movement of the operating member against the biasing action exerted by the biasing means.

8. In a circuit interrupter, a relatively stationary ring-shaped Contact, an operating member carrying a movable ring-shaped contact and adapted for limited axial movement, means for providing a radial inwardly directed iluid flow between the ring-shaped contacts, venting means communicating with the interior of the movable ring-shaped contact, means for rotating the arc around the ring-shaped contacts, an operating rod carrying an insulating follower member extending within the movable ring-shaped contact at least in the closed position of the interrupter, means biasing the operating member to the open position, and resilient means stronger than the biasing means interposed between the operating rod and the operating member.

9. In a circuit interrupter, a relatively stationary ring-shaped contact, an operating member carrying a, movable ring-shaped Contact and adapted for limited axial movement, means for providing a radial inwardly directed fluid flow lbetween the ring-shaped contacts, venting means communicating with the interior of the movable ring-shaped contact, means for rotating the are around the ring-shaped contacts, an operating rod carrying an insulating follower member extending within the movable ring-shaped contact at least in the closed position of the interrupter, means biasing the operating member to the open position, the operating rod causing closing movement of the operating member against the biasing action exerted by the biasing means, and a pair of separable secondary contacts carried respectively by the operating rod and operating member.

l0. 1n a circuit interrupter, a relatively stationary ring-shaped contact, an operating member carrying a movable ring-shaped contact and adapted for limited axial movement, means for providing a radial inwardly directed uid flow between the ring-shaped contacts, venting means communicating with the interior o1 the movable ring-shaped contact, means for rotating the arc around the ring-shaped contacts, an operating rod carrying an insulating follower member extending Within the movable ring-shaped contact at least vin the closed position or the interrupter, means biasing the operating member to the open position, resilient means stronger than the biasing means interposed between the operating rod and the operating member, and a pair of separable secondary contacts carried respectively by the operating rod and operating member.

1l. In a circuit interrupter of the liquid break type, a relatively stationary ring-shaped Contact, a hollow insulating operating member carrying a movable ring-shaped contact adjacent one encl thereof and being interiorly grooved adjacent the other end thereof, means allowing only limited axial movement of the hollow operating member, means for rotating the are around the ring-shaped contacts, means for causing a radially inwardly directed liquid ow between the separated ring-shaped contacts, and an operating rod carrying a follower member extending through the hollow insulating operating member for causing the operating movement thereof, a secondary Contact carried by the hollow operating member, and a cooperable secondary contact carried by the operating rod.

' 12. In a circuit interrupter of the liquid break type, a relatively stationary ring-shaped contact, a hollow insulating operating member carrying a movable ring-shaped Contact adjacent one end thereof and being interorly grooved adjacent the other end thereof, means allowing only limited axial movement of the hollow operating member, means for rotating the arc around the ringshaped contacts, means for causing a radially inwardly directed liquid flow between the separated ring-shaped contacts, and an operating rod carrying a follower member extending through the hollow insulating operating member for causing the operating movement thereof, a secondary contact carried by the hollow operating memben a cooperable secondary contact carried by the op,- erating rod, and the follower member also bein-g grooved to constrct the arc drawn by the secondary contacts.

13. In a circuit interrupter of the liquid break type, a relatively stationary ring-shaped contact,v a hollow insulating operating member carrying a movable ring-shaped contact adjacent one end thereof, means allowing only limited axial move-V ment of the hollow operating member, means forrotating the arc around the ringo-shaped con. tacts, means for causing a radially inwardly directed liquid ow between the separated ring shaped contacts, and an operating rod carrying afollower member extending through the hollow insulating operating member for causing the op,- erating movement thereof, a secondary contact carried byl the hollow operating member, and av cooperable secondary contact carried by the op,- erating rod.

14. In a circuit interrupter, a relatively stationary ring-shaped contact, means dening-an annular orifice and shielding the aforesaid ringshaped contact, another ring-shaped contact, means for establishing an arc between the two ring-shaped contacts, means for rotating the arc around the ring-shaped contacts, passage means within the annular orifice on both the inner and outer sides of the stationary ring-shaped contact to direct uid in two annular converging jets to flow out of the annular orice longitudinally of the rotating arc and toward the other lring-shaped contact, the region outside of the annular orifice and between the two contacts being at relatively low pressure.

WLNTHROP M. LEEDS.

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

UNITED STATES PATENTS Number Name Date 776,849 Kingsland Dec. 6, 1904 1,093,292 Rieber Apr. 14, 1914 1,296,000 Michael Mar. 4, 1919 1,325,656 Richards Dec. 23, 1919 1,366,343 Arndt Jan. 25, 1921 1,719,302 Meyer July 2, 1929 1,864,369 Pepper June 21, 1932 2,063,173 Lange Dec. 8, 1936 2,073,102v Hodgkins Mal'. 9, 1937 2,303,492 Peterson et al Dec. 1, 1942 2,303,730 Fernier Dec. 1, 1942 2,333,598 Strom Nov. 2, 1943 FOREIGN PATENTS Number Country Date 429,997 Great Britain June 11, 1935

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