US2462795A - Circuit interrupter - Google Patents

Description

Feb. 22, 1949. J. R. WEBB ET AL CIRCUIT INTERRUPTER 2 Sheets-Sheet 1 Filed Jan. l5, 1945 l.. l l l l l l l l H INVENTORS Josephine 7?. webb and S E S S E N Vl. W

Herber J Webb.

ATTORNE Feb. 22, 1949. 1 R, WEBB ET AL 2,462,795

`CIRCUIT INTERRUPTER Filed Jan. 15, 1945 2 Sheets-Sheet 2 Figi WITNESSES'. INVENTORS 0 Josep/vine Web and Herbe/"f J Webb.

BY W ,e M ATTOR Y Patented Feb. 22, 1949 UNITED STATES PATENT OFFICE CIRCUIT INTERRUPTER tion of Pennsylvania Application January 13, 1945, Serial No. 572,593

(Cl. ZOO-150) 8 Claims. l

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

A general object of our invention is to provide an improved circuit interrupter of improved construction to more effectively interrupt the circuit therethrough than has heretofore been achieved.

A more specific object is to provide an improved circuit interrupter in which hydraulic means are utilized for causing the separation of separable contacts to draw an arc therebetween. Such a construction has peculiar advantages as applied to an interrupter of the type employing both a pressure-generating arc and an interrupting arc in which simultaneous operation of the contact structure is desired.

A more specific object is to provide an improved circuit interrupter in which hydraulic means are employed to cause the separation of a pair of cooperable contact members and initiation of the hydraulic means is obtained by piston means operatively connected with a third contact member which cooperates with one of the aforesaid contact members to establish a second serially related arc.

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

Figure l is an elevational View, partly in section, of a circuit interrupter embodying our invention and shown in the closed-circuit position;

Fig. 2 is a sectional View taken along the line II--II of Fig. 4;

Fig. 3 is a vertical sectional View taken along the line III-III of Fig. 4;

Fig. 4 is a vertical sectional view taken through the left-hand arc extinguishing unit of Fig. 1, the parts being shown in the closed-circuit position;

Fig. 5 is a View similar to Fig. 4 but showing the disposition of the parts at an intermediate point in the opening operation;

Fig. 6 is an enlarged fragmentary view of a modied type of circuit interrupter embodying our invention; and

Fig. '7 is an enlarged fragmentary detailed View in Vertical section of the valve means which we employ in utilizing our invention.

Referring to the drawings and, more particui larly, to Fig. 1 thereof, the reference numeral l designates a tank in which a suitable arc extinguishing iluid 2 is disposed, in this instance circuit breaker oil, filling the tank I. Depending from the cover 3 of the tank I are two insulat- 2 ing bushings 4, 5 through which extend terminal studs G (see Fig. 4).

To the terminal studs 6 are threadedly secured contact feet 1 which serve to hold fixedly in poposition identical arc extinguishing units generally designated by the reference numeral 8. A conducting cross-bar 9 electrically interconnects the two arc extinguishing units 8 and is reciprocally operated in a vertical direction by an insulating operating rod I0. The operating rod I is 4actuated by suitable means not Shown.

Referring more particularly to Figs. 4 and 5 it will be noted that the contact foot I is secured by a bolt II to a casting member I2 which forms a pressure-generating chamber I3 being provided with an over-pressure valve I4 and a gas relief valve I5. The gas relief valve I closes during high pressure conditions within the chamber I3 and opens following an interrupting operation to permit accumulated gas to escape through the apertures I6. The over-pressure valve I4 is operative to prevent the attainment of excessive pressure within the pressure-generating chamber Positioned within the pressure-generating chamber I3 is a first piston means generally designated by the reference numeral I'I and in this instance comprising a piston chamber I8 threadedly secured adjacent its lower end I9 to the top metallic plate of the unit 8. Within the piston chamber I8 moves a piston 2l having secured to its lower end a second or pressure-generating contact 22 which cooperates with a first or intermediate contact 23 to establish a pressuregenerating arc 24 as shown in Fig. 5.

A compression spring 25 is disposed within the piston chamber I8 and serves to bias the piston 2l downwardly.

A flexible conductor 21 electrically interconnects the second or pressure-generating contact 22 with the piston chamber I8.

Cooperable with the first or intermediate contact 23 is a third or lower movable contact 28 to establish an interrupting arc 29 more clearly shown in Fig. 5. The lower movable or third contact 28 moves out of the unit 8 during the opening operation to a position indicated by the dotted lines 3D of Fig. 1.

Positioned adjacent the lower end of the unit 8 is a second piston means generally designated by the reference numeral 3l and in this instance comprising a piston chamber 32 secured by screws 33 to the lower metallic plate 34 of the unit 8. A piston 35 carried by the conducting cross-bar 9 operates within the piston chamber 32 during a portion of its opening travel. Fluid passage means generally designated by the reference numeral 36 and in this instance comprising a liquid passage 31 interconnects the iirst and second piston means l1 and 3l, the purpose for which will appear more fully hereinafter.

rihe interrupting structure for the unit 8 will now be described. rihe interrupting structure is formed by a plurality of suitably shaped insulating plates secured in contiguous relation by insulating tie rods 38 and nuts 39. These plates form two vertical flow passages generally designated by the reference numeral 46 and a piurality of, in this instance three, pairs of inlet passages li as more clearly shown in Figs. 2, 4 and 5. Certain of the plates form orifices 42 separating the inlet passages ai from vent passages 43, the vent passages 43 being formed by similarly shaped insulating plates 44 positioned in the same horizontal plane.

From the foregoing description it will be apparent that oil under pressure generated at the pressure-generating are 24 will flow downwardly through the two Vertical iiow passages to pass inwardly through the six inlet passages di tward the interrupting arc 23. After striking the interrupting arc 29 the iiuid will pass through the orifices 42 to exhaust out of the arc extinguishing units 8 through the vent passages 43. The particular shape of the passages in the interrupting structure is more fully described and claimed in United States patent application Serial No. 465.244. filed November 11, 1942, now U. S. Patent 2,406,469, issued August 27, 1946, by Leon R. Ludwig. Winthrop M. Leeds and Benjamin P. Baker and assigned to the assignee of the instant application.

The lower insulating plates of the stack 8 form oriiicesY i5 through which the bayonet-shaped movable Contact 23 moves as it is withdrawn from the unit 3. An electrostatic shield 46 is secured by suitable means, not shown, to the upper metallic plate 26 of the unit 8 to minimize corona formation at sharp corners. Likewise, an electrostatic shield Li'! is secured by means, not shown, to the lower metallic plate 34 of the unit 8 to minimize corona formation at sharp corners.- A resistor tube i8 electricallyinterconnects the top metallic plate 2G with the lower metallic plate 36 of the` unit 8 and hence to a iiexible Contact clip 49 bearing against the movable contact 28 during a portion of the latters opening travel. The. function. of the resistor tube i3 and its correct numerical value is more fullyY described in the aforesaid Patent 2,406,469. Briey, its function is to divide the Voltage equally between the two arc extinguishing units 8 during the opening operation and to decrease the rate of rise and the amplitude of the recovery voltage transient following circuit interruption.

The operation of the interrupter will now be explained. In the closed-circuit position thereof as shown in full lines in Figs. 1 and 4, the electrical circuit passing therethrough comprises terminal stud 5, contact foot 1, bolt Il, casting member l2, top metallic plate 2i), piston chamber i3, iiexible conductor 21, piston 2|, second or pressure-generating contact 22, first or intermediate contact 23, third or lower movable contact 23, through the conducting cross-bar 3 and' through the right-hand arc extinguishing unit 8 in an identical manner to the right-hand terminal stud tof the interruptor.

When it is desired to open the electrical circuit passing through the interruptor, or in re- CAD sponse to overload conditions existing in the circuit controlled by the interrupter, suitable actuating means, not shown, operates to cause downward opening travel of the insulating operating rod i3. The downward movement of the operating rod I3 causes downward movement of the conducting cross-bar 9 and hence downward movement of both the movable Contact 28 and the piston secured to the cross-bar 9. The intermediate Contact 23 follows the initial downward movement of the movable contact 28 until the shoulder 5U thereof strikes the plate 5l, at which time the interrupting arc 29 is drawn between the intermediate and movable contacts 23, 23. The piston 2| secured to the pressuregenerating contact 22 moves upward in response to downward movement of the piston 35 to thereby draw a pressure-generating arc 24 between the pressure-generating and intermediate contacts 22, 23. It will be noted that downward movement of the piston 35 with the cross-bar 9, the former moving within the piston chamber 32, draws oil downwardly through the liquid passage 31 from the region 52 in back of the piston 2l to the region 53 in back of the piston 35 to cause thereby upward movement of the piston 2| against the biasing action exerted by the compression spring 25. During this time the ballvalve 511 is opened. It will be apparent then that during the opening operation the hydraulic means which we provide causes substantial-ly simultaneous separation of the several Contact members to practically simultaneously establish both a pressure-generating arc and an inter- O rupting arc. The piston 35 will pull completely out of the piston chamber 32 as the movable contact 28 moves out of the unit 8. To prevent thereby rapid retraction of the piston 2l. and hence closing movement of the pressuregenerating contact 2,2, the ball-valve 53 can be provided which seats following withdrawal of the piston 35 from the piston chamber 32. The leak rate of the ball-valve 54 as determined by` the by-.pass channel 55 as shown in Fig. '7, will determine the rate of closing movement of the pressure-generating contact 22.

To prevent retardation during the closing stroke of the interrupter as the piston 35 enters the piston chamber 32, we provide a valve 56 which opens at a predetermined load during such a closing stroke, asy shown in Fig. 6, to permit oil within the region 53 to be forced out of the piston chamber 32.

In the modification of our invention as shown in Fig. 6, we provide a, piston 51 solely movable, within the piston chamber 32, its downward movement -being limited by the stop 58. TheA push rod 59 carried by the cross-bar 9 operates thel piston 51. A strong compression spring 6U biases the piston 51 downwardly during the opening operation to again draw oil downwardly through theliquid passage 3.1I from the rst piston means i1. In this embodiment of our invention,V inasmuch as the piston 51 is not movable out of the piston chamber 32, the ball-valve 54 will beomitted.

From the foregoing description it will be apparent that we have provided an improved circuit interrupter of the type drawing both a pressure-generating arc and an interrupting arc simultaneously without resort to av side operating rod as is shown. in U. S. patent application filed` December 22, 1945, S. N. 636,940, a divisional case of the aforesaid. patent. We have. disclosed a` means of producing a simultaneous parting. hy-

draulically. The cross-arm 9 and the lower movable contact 28 preferably move downwardly together for about 1/2 inch, at which time the intermediate contact 23 is halted. The pressure-generating arc 24 is drawn in the upper gap in response to downward motion of piston 35. It will be noted that the compression spring 25 associated with the first piston means l1 provides the contact pressure in the closed circuit position of the interrupter as shown in Fig. 4. The piston 2l may carry the pressure-generating contact 22 either directly on the bottom surface thereof or on an extension of any length depending upon how the upper contact should be lined up with respect to the grid stack 8. Piston 35 and piston cylinder 32 can be made larger than piston 2l and piston cylinder I8 as shown in Fig, 4 to compensate for leakage and the upper contact spring load, thus allowing the upper contact 22 to move upwardly at a pre-determined speed as the crossarm 9 moves down. The channel or liquid passage 31 is preferably formed by the alignment oi a plurality of holes in the ber plates of the grid stack 8 or it could be formed by other suitable insulated connecting means.

It will be noted that when the upper arc 24 is drawn, the pressure produced thereby will tend to increase the upward opening motion or the upper piston contact 22, supporting the action produced hydraulically. If it is desired to delay the return of the top arcing contact 22 to the closed position, the check valve 54 may be employed, being inserted in the channel 31. This valve is free to open when oil is flowing downwardly during the opening operation and its backward leak rate will determine the time it takes the upper piston 2l to resume its closed position. In addition, the small valve 56 is employed in the wall of the cylinder 32 which will open when the interrupter is closing to control the pumping action to the upper cylinder I8 on closing. A piston 35 of about three inches diameter is adequate to impart suiricient force to overcome the contact pressure spring 25 and move the upper contact 22 upwardly at l5 feet per second on opening.

The modification as shown in Fig 6 is to have the lower piston 51 spring-biased downwardly powerfully enough to overcome the contact biasing spring 25 and add accelerating force to open the top gap by oil flow. This piston 51 can be designed for less leakage and closer tolerances since it does not leave the cylinder 32 but is merely operated by the plunger 53 attached to the cross-arm 9. In this modication the check valve 54 which is optional in the rst modification would not be used.

From the above description it is apparent that our design will reduce the size and complication of the interrupter, and remove a possible source of voltage breakdown by eliminating the side operating rod and associated mechanisms. Correct contact compression and travel are inherent in the design and will require little adjustment, Whereas the present mechanical system, as set forth in the aforesaid divisional application, is sensitive to the setting of four stops on the side operating rod and the contact springs. All parts of our invention can be readily made accessible without the removal of the stack 8 from a pole unit so that the contacts may be renewed or parts examined.

From the foregoing it will be apparent that we have provided an improved interrupter which employs hydraulic means to simultaneously open both the pressure and interrupting gaps. Size and complication are considerably reduced and contact pressure is easily obtained. By eliminating the side operating rod and the rocking pressure-generating contact as disclosed in the aforesaid divisional application, the mechanism is considerably simplied and voltage breakdown possibilities are eliminated.

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

We claim as our invention:

l. In a circuit interrupter of the liquid break type, an arc extinguishing structure forming a pressure chamber, a rst contact cooperable with a second contact to establish a pressure-generating arc within the pressure chamber, a third contact cooperable with said. first contact to establish a second serially related interrupting arc, operating means for said interrupter for moving said third contact to an open circuit position, a iirst piston means connected to said second contact and arranged to be acted on at one side thereof by the pressure within the pressure chamber, a second piston means and an insulating liquid filled conduit connecting the other side of said rst piston means to said second piston means, said second piston means being actuated by the opening movement o said third contact to cause a reduction in pressure in said conduit whereby the pressure in said pressure chamber acts in conjunction with the reduced pressure in said conduit to cause opening oi said second contact substantially at the same time upon opening movement of said third contact and to maintain said second contact Aopen during interruption of the arcs.

2. In a circuit interrupter of the liquid break type, an arc extinguishing structure forming a pressure chamber, a first contact cooperable with a second contact to establish a pressure-generating arc within the pressure chamber, a third contact cooperable with said rst contact to establish a second serially related interrupting arc, operating means for said interrupter for moving said third contact to an open circuit position, a first piston means connected to said second contact and arranged to be acted on at one side thereof by the pressure within the pressure chamber, a second piston means, and an insulating liquid lled conduit connecting the other side of said first piston means to the second piston means, means actuated during the rst part of the opening movement of said third contact for actuating said second piston means to cause a reduction in pressure in said conduit whereby the pressure within the pressure chamber acts in conjunction with the reduced pressure within said conduit to cause opening o said second contact substantially simultaneously with the opening of said third contact.

3. In a circuit breaker of the liquid break type, an arc extinguishing unit having a pressuregenerating chamber and an interrupting chamber, a rst contact cooperable with a second contact to establish a pressure-generating arc within said pressure-generating chamber, a third contact cooperable with said -rst contact to establish a serially related interrupting arc within said interrupting chamber, fluid passage means interconnecting said pressure-generating and interrupting chambers generated by the pressure-generating arc within the pressure-generating chamber, operating means for moving said third Contact to an open circuit position externally of said arc extinguishing unit, hydraulic means comprising a rst piston means connected to said second contact and arranged to be acted upon at one side thereof by the pressure of pressure-generating chamber, a second piston means, an insulating liquid lled conduit connecting the other side of said first piston means tothe second piston means, and means for causing the actuation of said second piston means during the iirst part of the opening movement of said third Contact to reduce the pressure in said conduit and thereby cause opening of said second contact.

4. In a circuit interrupter of the liquid break type, an arc extinguishing unit, a second contact disposed adjacent one end of said unit, a i'lrst contact cooperable with said second contact to establish a pressure-generating arc, a third contact disposed adjacent the other end of said unit, said third contact being cooperable with said first contact to establish an interrupting arc, a rst piston means disposed adjacent said one end of the arc extinguishing unit and connected to said second Contact, a second piston means disposed adjacent the said other end of the arc extinguishing unit, hydraulic actuating means including an insulating conduit in one lateral wall of said unit interconnecting said rst and second piston means, operating means for causing actuation of the third contact and also substantially simultaneous movement of the second piston means.

5. In a circuit interrupter of the liquid break type, an arc extinguishing unit, a second Contact disposed adjacent one end of said unit, a irst contact coop-arable with said second contact to establish a pressure-generating arc, a third contact disposed adjacent the other end of said unit, said third contact being cooperable with said rst contact to establish an interrupting are, a rst piston means disposed adjacent said one end of the arc extinguishing unit and connected to said second contact, a second piston means disposed adjacent the said other end of the arc extinguishing unit, hydraulic actuating means including an insulating conduit extending longitudinally of said unit, and interconnecting said Erst and second piston means, operating means for causing actuation oi the third contact and also substantially simultaneous movement of the second piston means.

6. In a circuit interrupter of the liquid break type, an arc extinguishing unit, a rst Contact, a second contact ccoperable with said rst contact to establish a pressure-generating a-rc, a third contact cooperable with saidV first contact to establish an interrupting arc, said thirdl contact being movabie out of said arc extinguishing unit, actuating means for the third contact, hydraulic means comprising a piston means connected to said second contact, a second piston sol as to cause said inter-V- rupting arc to be acted upon by the pressure means adapted to be actuating means, and an insulating conduit interconnecting said rst and said second piston which allows hydraulic liquid to flow substantially uninhibited when said liquid is flowing in such a direction as to cause opening movement of said second contact and to partially block ow of said hydraulic liquid when said hydraulic liquid tends to ow in a direction such as to allow closure of said second contact, said actuating means being movable to a position disconnected from saidV second piston means whereby a clean break in liquid exists between said actuating means and said arc extinguishing unit.

7. In a circuit interrupter of the liquid break type, an arc extinguishing unit, a rst contact, a second contact cooperable with said rst contact to establish apressure-generating arc, a third vcontact cooperable with said rst contact to establish an interrupting arc, said third Contact being movable out of said arc extinguishing unit,

hydraulic means comprising a piston means connected to said second contact, a cylinder, a piston connected to said third contact and movable to a position out of contact with said cylinder, and an insulaing conduit interconnecting said piston means and said cylinder.

8. In a circuit interrupter of the liquid break type, an arc extinguishing unit, a rst Contact, a second Contact cooperable with said rst contact to establish a pressure-generating arc, a third contact cooperable with said rst contact to form an interrupting arc, said third contact being movable completely out of said arc extinguishing REFERENCES CITED The following references are of le of this patent:

record in the UNITED STATES PATENTS Number Name Date 2,155,263 Flurscheim Apr. 18, 1939 2,160,673 Prince May 30,` 1939 2,219,171 Balachowsky Oct. 22, 1940 2,235,901 Ronnberg Mar. 25,. 1941 2,258,376 Clothier et al Oct. 7, 1941 2,372,589 Leeds et al Mar. 27, 1945 FOREIGN PATENTS Number Country Date 486,050 Great Britain May 30, 1938 moved by operation of said means for the third contact, hy-

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