US2666118A - Circuit interrupter - Google Patents

Description

Jan. 12, 1954 v L. R. LUDWIG ET AL CIRCUIT INTERRUPTER 2 Sheets-Sheet 1 Filed June 29, 1950 Fig.9.

Fig.8.

INVENTORS Leon R. Ludwiq,Wlmhrop M. Leeds ,Banjumin P. Baker 8 James M.Cumminq,deceused,by Helen J. 0ummlnq,ExecuIrh 66a 4 1 i7 ATTO EY WITNESSES:

Z. 4? 63ml- 2 Sheets-Sheet 2 Filed June 29, 1950 Fig.5.

Fig.2.

a 1m Y B 2 f w a a 9 7 8 m w m FN 6 w INVENTORS Leon R. Ludwig ,WinthropM. Leeds, Benjamin F. Baker 8. James M.Gumminq,dcceased,by HelemLOummlnq,Executrix.

V/vVV/V//////////%///////////////Q \\\\\\\\\2 5W9 i l 2 8 H 3 I 2 mml Patented Jan. 12, 1954 UNITED STATES Far ENT OFFICE CIRCUIT lNTERRUPTER Application June 29, 1950, Serial No. 171,158

This invention relates to circuit interrupters in general, and, more particularly, to arc-extinguishing structures for circuit interrupters of the liquid-break type.

A general object of our invention is to provide an improved liquid-break type of circuit interrupter which will more effectively interrupt the circuit therethrough than has heretofore been attained.

Another object is to provide an improved liquid-break circuit interrupter in which an improved piston construction is employed to more effectively drive liquid through the arc to extinguish the same.

A more specific object is to provide an improved circuit interrupter of the type specified in the immediately preceding paragraph in which the arc is drawn along the central vertical axis of the interrupter, and in which the design is symmetrical with no unbalanced horizontal mechanical forces.

Still another object is to provide an improved piston construction for a liquid-break type of circuit interrupter in which improved time-delay means are providedbefore application of the liquid to the arc.

Another object is to provide an improved differential piston construction of the liquid break t p Further objects and advantages will readily become apparent upon reading the following specification taken in conjunction with the drawings, in which:

Figure l is a side elevational view, partially in vertical section, of a tank-type liquid-break circuit interrupter employing our invention and shown in the closed-circuit position; Fig. 2 is an enlarged vertical sectional view through the left-hand arc-extinguishing unit of Fig. 1, the contact structure being shown in the closed-circuit position;

Fig. 3 is a view similar to that of Fig. 2, but showing the disposition of the contact structure at an intermediate point in; the opening operation during the interruption of high-amperage currents;

9 Claims. (Cl. 200150) Fig. 4 is a sectionalview taken along'the line at an intermediate 'point in the opening Opera tion during the interruption-of high amperage currents;

Fig. 7 is a sectional view taken alOng the lin VIIVII'of Fig. 5;

Fig. 8 illustrates still another form of our in-'- vention, the contact structure being shown in the closed-circuit position;

Fig. 9 is a view similar to that of Fig. 8 but indicating the partially opemcircuitposition of the contact structure, and e r Fig. 10 is a sectional view taken along the line X--X of Fig. 8.

Referring to the drawings, and more particularly to Fig. 1 thereof, the reference character I designates a tank filled to the level 2 with a suitable arc-extinguishing liquid, in this instance circuit breaker oil. Depending from the cover 3 of the tank I are a pair of terminal bushings i, 5, to the lower ends of which are secured identical arc-extinguishing units, generally designat'ed by the reference numeral 6. Electrically interconnecting the units 6 in the closed circuit position, shown by the full lines in Fig. 1, is a conducting cross-bar I actuated vertically by an insulating lift rod 8, and having at its opposed extremities rod-shaped movable contacts 9.

Referring to Figs. 2-4, which more clearly show the internal construction of the arc-extinguishing units 6, it will be apparent that we have provided an elongated insulating casing Ill having an internally disposed insulating sleeve II, the latter having an enlarged portion I2 and a restricted portion I3. An aperturedpartition plate I4 is disposed upon an internally provided flange I5 of the casing I 0. The aperture I6 provided in the partition plate I4 accommodates longitudinal travel of a movable contact assembly, generally designated by the reference character I1, and including an intermediate contact I8, a hollow piston member I9 and a driving piston 20.

It will be noted that in the closed circuit position, shown in Fig. 2, the movable contact 9 engages the intermediate contact I8, the latter in turn engaging a relatively stationary contact 2|, which is preferably resiliently mounted by means of a stem 22 and a compression spring 23. A shunt 24 electrically connects the stem 22 with the apertured cover plate 25 of the unit 6. The cover plate 25 may be suitably secured by a clamp 26 (Fig. 1) to the lower end of the terminal bushings 4, 5.

The hollow piston member I 9 consists of a plurality of apertured insulating plates 21, 28 having different internal diameters. Preferably, insulating tie rods 29 (Fig. 4) are provided to se- Valve means 33 are provided to permit oil to leave the chamber 34 in back of the piston 2|! during the closing operation. Such valve means preferably includes a valve sleeve .35 picked up by a flange 36 secured to and movable with the movable contact 9. Apertures 31 are provided in the piston 20 to permit the ,exit of oil out of the chamber 34 during the closing stroke.

The opening operation of this form of our invention will now be described. In the closed circuit position of the interrupter, shown in Figs. 1 and 2, the electrical circuit therethrough includes terminal bushing 4, conducting cap 25, flexible shunt 24, relatively stationary contact 21, intermediate contact 18, lower movable contact 9 and through the conducting cross-bar 'l :to the right-hand unit 5. The circuit extends through the right-hand unit 6 in the same mannor previously described to the right-hand terminal bushin 5.

During the opening operation, suitable mechanism, not shown, either responsive to manual operation or to the existence of overload condition existing in the electrical circuit controlled by the interrupter, operates to cause downward opening movement of the lift rod 3. The downward, motion of lift rod 8 carries with it the two movable contacts ,19, iConsidering only the lefthand unit L6, ,it will be apparent that the com pression spring 32 forces the driving piston 20 and the entire movable contact assembly ll downwardly, drawing an are 38 more clearly Shown in Fig. 3. Since the valve 33 is open, the assembly 11 moves downwardly freely until the piston member 19 e ters the restricted portion 13, at which time oil is ,forced through the inlet passages 39 and against the are 38 and upward-v 1y through the interior 40 of the hollow piston member la. Since the movable contact assembly I! slows up after the piston member l9 enters the restriction 13, the movable contact s will separate from the intermediate C nt ct F8 to draw a second serially related arc 4|, more clearly shown in Fig. .3,

During the interruption of heavy currents, the pressure generated by the are 4! within the piston chamber 34 will be high, closing the valve 33 and assisting the compression spring 32 in driving the piston '20 downwardly, as shown in Fig. 3. During the interruption of light currents, where the pressure generated by the are 4:! is negligible, dependence must be had upon the compression spring 32 alone to bring about the necessary downward opening motion of the movable contact assembly [1.

"The upward flow of oil indicated by the arrows in Fig. 13 through the interior ,40 f the his- .ton member l9 causes extinction of the are 38 and hence circuit interruption, In the ;fully open circuit position, the lower movable contact 9 is withdrawn out of the piston member '20 to an open circuit disconnect position indicated by the dotted lines 42 of Fig. ,1.

During the closing operation, the lift rod 8, cross-bar 1 and movable contacts 9 move upward- 13/. The contact 9 enters the valve means 33 of the piston 20 and causes enga ment between the flange 3.6 and the valve sleeve 35, thereby opening the valve means .33.

,The movable contact 9 strikes the intermediate contact [8 and moves the intermediate contact l8, and hence the assembly I1, upwardly until engagement is made between relatively stationary contact 2| and intermediate contact I8, the compression spring 23 providing the requisite contact pressure. The circuit is then closed.

Figs. 5-7 illustrate another embodiment of our invention. In this embodiment, the modified unit .44 has anintermediate contact 45 connected by a lost-motion connection 46 with the movable contact assembly I]. In this form of our invention, :the piston member l9 moves along vertical walls provided by an insulating sleeve 41 disposed interiorly of the casing 10,

The operation is as follows. During the opening operation, the downward opening movement of the contact 9 immediately permits fast downward opening motion of the intermediate contact ,45 relative to the movable contact assembly ll because of lost motion mechanical connection 4.6 therebetween. The intermediate contact #5 is biased downwardly by a compression spring 4,0 to a stop '50 on the connecting sleeve 5i. :Since the intermediate contact 45 is comparatively li ht, the are 38 (Fig. 6) will be very rapidly formed. The intermediate contact 45 will so n come to its stop 50 and thereafter will move with the assembly ll, Thus the first few inches of arc length 138 are very rapidly formed. The movable contact assembly i 1 willbe driven downwardly by the driving piston 20 under the in fluence of the compression spring ,32. The'downward motion of the contact assembly H forces Oil within the region 48 through the inlet passages 39 and upwardly into the interior 4!] of the hollow piston member i9 against the arc 3,8 Because of the relatively slow downward travel of the assembly 1], the lower movable contact 8 will separate from the lower contact portion 52 of the intermediate contact 45 to establish the arc 4| asshown inFig. 6.

As before, during high current interruption. the pressure generated by the an M within the piston chamber 34 will be high, closing the valve means 33 and assistin the compression sprin 32 in driv n th driving piston 20 downwardly- This condition is shown in Fig. 6. During low cu rent interrup i n. on the other hand. th pressure formed at the arc 4| will be :unall, and the valve means .33 will remain open so that oil may be drawn through the apertures 31 into the region :34.

The upward flow of oil through thefhollow piston member I9 quickly 'extinguishes the are 38 and the circuit is interrupted. As before, the movable contact 9 is withdrawn to the disconnect piston shown by the dotted'lines 42 ofFig. '1.

Figs. 8-10 illustrate a third embodiment of our invention utilizing a differential piston construction in the modified unit 53. In this embodiment, the casing 10 has the sleeve 11 con" structed, as before, .With the enlarged portion t2 and the restricted portion 13. The differential piston membe ene ally desi nated y the reference character 54, includes a hollow piston member 1 9 and two piston surfaces 55 and ,56. Since the ar a of t e p stonsurface 5,6 is larger than the area of the piston surface .55, the piston member 54 will move downwardly, thereby aforeins oil out of the region 58. through inlet passages 5 8 and d wnwardly through the interior .40 of the hollow piston-member 1:9. The com.

pression spring. 32,.as before, assists downward motion of the driving piston 20.

'In this embodiment, we have only a single are 60 being drawn by cooperation of the contacts 21, 9. If the pressure generated by the are G is small, reliance is largely had upon the biasing action exerted by the compression spring 32. If the current being interrupted is high, the are 60 will generate a high pressure which will act upon the two surfaces 55, 56.. Because of their unequal areas, the pressure will have a net effect in forcing the differential piston assembly 54 downwardly, thereby causing oil to travel from the region 59 through the inlet passages 58, and through the interior 40 of the piston member H) to the region 34 in back of the lower piston 26. This condition is shown in Fig. 9. V

The foregoing description of three embodiments of our invention shows how we have providedan improved liquid break type of circuit interrupter utilizing novel piston constructions for bringing about effective circuit interruption. During the interruption of relatively light currents, dependence is placed upon the compression spring 32 in effecting downward opening motion of the contact assemblies I 1 or the differential piston assembly 54. During high current interruption, the pressure generated will assist the compression spring 32 in either forcing the driving piston 20 of Figs. 2 and 5 downwardly, or else forcing the diiierential piston 54 downwardly, thereby assisting the compression spring 32.

It will be noted that the oil flow through the interior 40 of the hollow piston member 19 is effective in extinguishing the arc 38 or til. The interior 40 is corrugated to minimize breakdown longitudinally of the piston 19 due to carbonization of the insulating surfaces.

Although we have shown and described spe cific structures, it is to be clearly understood that the same were merely for the purpose of illustration, and that changes and modifications may readily be made therein by those skilled in the art without departing from the spirit and scope of the appended claims. a

We claim as our invention:

1. A circuit interrupter of the liquid break type including a casing, a rod-shaped relatively stationary contact disposed adjacent one end of the casing, a movable contact assembly movable within the casing including a hollow piston member through which liquid may flow, an intermediate contact and a driving piston, the intermediate contact being cooperable with the relatively stationary contact to establish an arc which is subjected to the liquid now passing through the hollow piston, a movable contact movable adjacent the other end of the casing and cooperable with the intermediate contact to establish a second serially related arc, the rodshaped relatively stationary contact protruding at least part way through the hollow piston member to engage the intermediate contact in the closed circuit position of the interrupter, liquid inlet passage means disposed in the movable contact assembly adjacent the point of engagement of the stationary and intermediate contacts, means biasing the movable contact assembly to the open circuit position, and the second serially related are assisting opening mo-v tion of the driving piston during high current interruption.

2. A circuit interrupter of the liquid break type including a casing, a rod-shaped relatively stationary contact disposed adjacent one end of the casing, a movable contact assembly movable within the casing including a hollow piston member through which liquid may flow, an in termediate contact and a driving piston, the intermediate contact being cooperable with the relatively stationary contact to establish an arc.

a movable contact movable adjacent the other end of the casing and cooperable with the intermediate contact to establish a second serially related arc, the rod-shaped relatively stationary contact protruding through the hollow piston member to engage the intermediate contact in the closed. circuit position of the interrupter, liquid inlet passage means disposed in the movable contact assembly adjacent the point of engagement of the stationary and intermediate contacts, means biasing the movable contact assembly to the open circuit position, the second serially related are assisting opening motion of the driving piston during high current interruption, the casing having a widened portion and a restricted portion, and the hollow piston moving from the widened portion into the restricted portion to thereby provide a time delay before application of liquid to the first said arc.

3. A circuit interrupter of the liquid break type including a casing having an apertured partition member, a relatively stationary rod-shaped contact disposed adjacent one end of the casing, the casing on one side of the apertured partition member having an enlarged portion and a relatively restricted portion, a movable contact assembly movable through the aperture in the partition member and including a hollow piston member through which liquid may flow, an intermediate contact and a driving piston, the rodshaped stationary contact extending through the hollow piston member to engage the intermediate contact in the closed circuit position of the interrupter, a rod-shaped movable contact movable through the driving piston to engage the intermediate contact in the closed circuit position, the relatively stationary contact and the intermediate contact being cooperable to establish an arc within the hollow piston member, the movable contact being cooperable with the intermediate contact to establish a second serially related arc, the hollow piston member moving from the enlarged portion of the casing to the restricted portion thereof, inlet passage means provided in the contact assembly adjacent the point of engagement of the stationary and intermediate contacts, the driving piston being disposed on the other side of the partition member, means biasing the movable contact assembly to the open circuit position, and the said second arc assisting the driving piston during high current interruption.

4. A circuit interrupter of the liquid break type including a casing, a rod-shaped relatively stationary contact disposed adjacent one end of the casing, a movable contact assembly movable within the casing including a hollow piston member through which liquid may flow, an intermediate contact and a driving piston, the intermediate contact being cooperable with the relatively stationary contact to establish an are which is subjected to the liquid flow passing through the hollow piston, a movable contact movable adjacent the other end of the casing and cooperable with the intermediate contact to establish a second serially related arc, the rodshaped relatively stationary contact protruding through the hollow piston member to engage the intermediate contact in the closed circuit positionof'the interrupter, liquid" inlet passage'means disposed in the movable "contact assembly ad jacent the point'ofengagement of the stationary current-interruption, and the intermediate "contact having a lost-motion mechanical connection with the movable contact assembly.

5. A circuitinterrupter'of the liquid'breaktype including .-a casing having an apertured partitionmember, a relatively stationary rod-shaped contactadisposed:adjacentone end'of the casing, a movable contact assembly movable through the :aperture in the partition member and including a hollow piston member through which liquid may now, an vintermediate contact and adriviing piston,'the rod-shaped stationary contact extending at least part way through the hollow piston memberto engage the intermediate contact in the closed circuit position of the interrupter, a trod-shaped mov'abl'e contact movable through the driving piston to engage the intermediate contact in the closed circuit position, the relatively stationary contact and the intermediate contac't being coopera'ble to establish "an are within the hollow piston member which is subjected to the liquid flow passing through :the :hollow piston member, the movable contact being co'operable with the intermediate contact to establish :asecond serially related :arc, inlet passage means provided in the movable contact assembly adjacent the point of engagement of the stationary .and intermediate con tacts, the driving piston being disposed on the other side of the partition member, means bias-- ing the vmovable contact (assembly to the "open circuit position, the said second are assisting the driving piston during high current interruption, and the intermediate contact having a lost-motion mechanical connection with the movable contact assembly.

6. A circuit interrupter of the liquid break type including a casing, a differential piston movable within the casing carrying a movable hollow member of appreciable length therewith through which liquid may flow, a relatively stationary contact extending into the hollow member, a rod shaped movable contact making engagement with the stationary contact in the closed circuit position, and means biasing the differential pic ton. member to the open circuit position.

'7. A circuit interrupter of the liquid break type including a. casing having an apertured partition member, a movable differential piston assembly movable through the aperture and carrying a movable hollow member of appreciable length 8 therewith through which liquid 'mayflowm'rela'e tively stationary contactga movablecontaict gaging the stationary contact adjacent'the lint'e'rio'r of the hollow memberyand means biasing the differential pistonmember totheope'n circuit position.

8. A circuit interrupteref the liquldbreak'type including a casing having-an apertured partitioh member, a movable ='difierentia1 :pi'ston assembly movable through "the aperture and carrying "a movable holl'o'w member of appreciable l'ngth therewith through which liq'ilid may fl6W, "a 1 61 tively stationary contact, a "movable contact engaig'ing the stationary contact the interior of the hollow'meinber, 'mea'nsbiasin'g the differential pisto'n member to the open circuit position, the difiereritial pistonmember having two piston surfaces or unequal area, the eas ng having on one Side of the partition member -an enlarged portion and a iistricted portion, and the smaller piston *s'urface moving from the "ehlarged portion into the restricted portion.

9. A circuit interrupterof the lidiiid br'eaktype including a casing-a relatively s'tatioha'rfy' coiitblct disposed adjacent one end of the casing, e mov able contact assembly including a pis'ton, a able intermediate contact and a driving ipistbnthe movable intermediate eontact sepam g from the relatively stationary contact to' establish an arc, the "first said 'piston'de'iiiiing cashmere orifices through which said are i the opening operation, the "opening motion of the first said piston causing now or I liquid through said one or more orinees adjacent said arc, a movable contact disposed adjacent the other end of the casing and cooperable with the intermediate contact to establish a second serially related arc, means utilizing the pressure from the second arc to accelerate motion of the driving piston during high current interruption, and the movable contact having an opening movement in the same direction as opening movement of the intermediate contact.

LEON R. LUDWIG, WINTHROP M. BENJAMIN 1'2. BAKER. J-. CUMMING, Executrix of the estate of James -M. Cumming,

deceased.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,077,338 Lingal et a1 Apr. 13, 193"? 2,235,901 Ronnberg Mar. 25, 1941 2,420,889 Leeds May 20, 19 1": 2,456,926 Cumming Dec. 21, 1948

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