US2462733A - Circuit interrupter - Google Patents

Description

Feb. 22, 1949. G. J. EASLEY CIRCUIT NTERRUPTER 2 Sheets-Sheet 1 Filed Oct. 30, 1946 Feb. 22, 1949. v G. 'Jl EASLEY 2,432,733

CIRCUIT INTERRUPTER Filed Oct. 30, 1 946 2 Sheets-Sheet 2 WITNESSES: INVENTOR Patented Feb. 22, 1949 UNITED STATES PATENT OFFICE CIRCUIT INTERRUPTER Gilbert J. Easley, Forest Hills, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application October 30, 1946, Serial No. 706,733

(Cl. D-150) 10 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 an improved circuit interrupter of the type drawing both a pressure-generating arc and an interrupting arc in which contact parting is more quickly attained to obtain a high speed type of interrupter.

A more specific object of my invention is to provide an improved circuit interrupter of the foregoing type in which a substantially enclosed dashpot is associated with the intermediate contact to obtain practically simultaneous contact parting without the additional complication and i expense of including a side operating rod.

This invention is an improvement over that disclosed in U. S. Patent application, Serial No. 465,244, led November l1, 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, and in which there is disclosed and claimed a high speed type of circuit interrupter in which a pivotally mounted pressuregenerating contact is moved by a side operating rod relative to a stationary intermediate contact to establish a pressure-generating arc simultaneously with movement of a lower movable Contact from the intermediate Contact to draw the interrupting arc.

Such a construction, aside from the complication of a side operating rod, is high speed in action since both the pressure and interrupting arc are simultaneously drawn away from the intermediate contact the requisite arc length.

It is a further object of my invention to obtain the advantages of simultaneous break operation obtained in the interrupter described in the Ludwig et al. patent, while at the same time avoiding the necessity of utilizing the side operating rod for actuating the pressure-generating contact.

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

Figure 1 is a side elevational view, partly in section, of a circuit interrupter embodying my invention and shown in the closed circuit position;

Fig. 2 is an enlarged vertical sectional View, with a portion taken at a quarter section, as shown by the lines II-II of Fig. 3, of the lefthand arc-extinguishing unit of Fig. 1, the contacts being shown in the partly open circuit position; and

Fig. 3 is a sectional view taken substantially along the line III-III of Fig. 2 looking in the direction of the arrows.

Referring to the drawings and more particularly to Fig, 1 thereof, the reference numeral I designates a tank in which is disposed a suitable arc-extinguishing fluid 2, in this instance circuit breaker oil, filling the tank I to the level 3. Depending from the cover 4 of the tank I are two insulating bushings 5, 6 at the lower ends of which are secured rigidly in place identical arcextinguishing units, generally designated by the reference numeral 'I.

The arc-extinguishing units l are electrically bridged in the closed circuit position, as shown by the full lines in Fig. 1 by a U-shaped conducting cross-bar 8 reciprocally operated in a vertical direction, as viewed in Fig. 1, by an insulating operating rod S actuated by suitable mechanism, not shown.

Referring more specifically to Fig. 2, which shows enlarged the left-hand arc-extinguishing unit 'I of Fig. l, it will be observed that the terminal stud Ii) extending through the left-hand bushing 5 has threadedly secured and clamped to its lower end a top dome casting II. Positioned within the top dome casting II is a pivotally mounted pressure-generating contact I2 biased downwardly by a compression spring I3, the latter having its upper seat against an offstanding bracket I4, in this instance forming an integral part of a plate I la secured by bolts Mb to the casting I I. A eXi-ble conductor I5 electrically connects the pressure-generating contact I2 to the bracket I4 and hence to the dome casting II so that the pivot pin I6 does not need to carry the breaker current in the closed circuit position thereof.

Preferably, an over-pressure relief valve I'I is provided to permit the relief of excessive pressure formed within the pressure-generating chamber, generally designated by the reference numeral I8 and defined by the wall portions of the dome casting II. Also, a gas relie-f valve I is provided which closes during the interrupting operation and opens following the completion of the interrupting operation to permit accumulated gas to pass upwardly out of the pressure-generating chamber I8 and hence out of the arc-extinguishing unit l.

Secured to the lower end of the dome casting I I by insulating tie rods 2li are a plurality of suitably configured insulating plates forming fluid flow ally passages of the type set forth in the aforesaid Patent 2,406,469. The passage structure is fully set forth in the aforesaid patent to which reference may be had for the configuration of the several plates. For the purpose of understanding my invention, it is merely necessary to note that the insulating plates collectively align to form two Vertical new passages, generally designated by the reference numeral 2 l, and more clearly shown by the sectional view o1- Fig. 3. The two vertical now passages El permit communication between the pressure-generating chamber i3 and the interrupting chamber, generally designated by the reference numeral 22. The lower ends of the-two vertical new passages have communicating therewith pairs of inlet passages 23 which permit fluid under pressure from the pressure-generating are to ilow to radially inwardly toward the interrupting arc 2li established between the intermediate contact 25 and the lower movable contact 2li, which forms the upstanding portion of the cross-bar 8. The pressure-generating arc 2? is established between the pressure-generating contact l2 and the upper portion of the intermediate contact 25.

The oil under pressure formed by the establishment of the pressure-generating arc 2 Vows downwardly, as indicated by the arrows and radiinwardly through the inlet passages 23 toward the interrupting arc 24 to pass through orices 23 and outwardly from the arc-extinguishing unit 'ithrough a plurality of venting passages '29. The venting passages 25 pass out of the unit 'l in opposite directions in a direction perpendicular to the plane of the drawing of Fig. 2 and are `shown more clearly in Fig. 3.

31 formed therein which closely surrounds the upper portion of the intermediate contact 25.

Preferably, the region 3S below the iiange or ring 33 communicates with the region exterior of the arc-extinguishing unit l by means of a bre tube 39 having an adjusting screw @dat its outer end which acts as a valve to vary the size of the exhaust passage through vthe tube. One may cause the removal of the screw 34 from the ring 33 and intermediate contact' by inserting the end of a screw-driver through the fibre tube 39. When the screw Bil is removed from'the ring 33 and also the intermediate contact 25, the intermediate contact 25 may be removed vertically upwardly or downwardly for repair or replacement. Since there is relatively little wear on the flange 33, there is no need for the latters replacement.

The operation of the interrupter will now be explained. In the closed circuit position of the interruptor, as shown by the full lines in Fig. l, the electrical circuit therethrough includes terminal stud i9, top dome casting H, Ibracket I4, flexible conductor l5, rotatable pressure-generating Contact l2, intermediate contact 25, lower movable Contact 2S through the cross-bar B and through the right-hand arc-extinguishing unit'in an identical manner to the other terminal of the interrupter. To effect the opening operation of the interrupter, suitable mechanism, not shown but which is responsive to manual operation or to overload currents carried by the interrupter causes downward movement of the insulating operating rod 9. lThe downward movement of the operating rod 9 causes downward movement oi both lowermovable contacts 26.

Because of the provision of the compression springs i3, the three contacts, l2, 25 and 25 will initially move downwardly together making contacting engagement. However, the pressuregenerating contact l2 will, after a predetermined clockwise rotation, strike the stop screw 82a and be halted thereby. Further downward travel oi the contacts 25 and 26 will cause the establishment of a lpressure-generating arc 2l within the pressure-generating chamber i8, the provision of the bypassing means 32 permitting the intermediate contact 25 to maintain contacting engagementwithlower contact 2li during this time.

The downward movement of the intermediate contact 25 and the lower movable Contact 26 continues with the two making contacting engagement until the flange or ring 33 secured to the intermediate Contact 25 passes the lower ends of the grooves 32 provided in the insulating guide cylinder 3|. When this occurs, the dashpot 3&3 will be effective to cause halting downward movement of the intermediate contact 25 to thereby cause a separation to take place between the intermediate contact 25 and the lower movable contact 2li to establish an interrupting arc V2li within Ithe interrupting chamber 2i? of the unit 1t will consequently be noted that when the flange 33 passes the lower ends of the groove 132, the dashpot Sii will thereafter Cause the ntermediate Contact 25 to move downwardly at a slower speed than the speed of the lower movable contact 26. This draws the interrupting arc 2li in the interrupting chamber 22 which will be extinguished by the uid flow from the pressure-generating arc l. It will be observed that following `the time oi eiective operation of the dashpot Sil, that is, when the by-passing-means Vbecomes ineiicective, thereafter both the pressuregenerating and interrupting arcs 2i, E@ continue to lengthen to the requisite arc length in a manner simulating that of the aforesaid Patent 2,406,469.

It will be noted that a distinct advantage oi my invention is the substantially enclosed construction oi the dashpot 3Q. Thus, pressure within the pressure-generating chamber I8 is not permitted to act upon the top or rear side of the piston 33, asit moves downwardly during its opening stroke. If there were unication between the top or rear side of the piston and the pressure-generating chamber I8, during the Yinterruption of high values of current, the separation between the intermediate contact 25 and the lower movable contact 2d would be delayed inasmuch as the pressure would assist the compression spring 35 in driving the piston 33 and intermediate contact 25 downwardly more rapidly than would be the case in interrupting low values of current. However, during the interruption of high values of current the length of the pressure-generating arc need not be so long as during the interruption oi low values of current. Consequently, it is not desirable to delay opening of the interrupting contacts during the interruption o high values oi current which would result should lthere be communication between the rear side of the piston 33 and the pressuregenerating chamber i8, Also the downward speed of the intermediate contact is substantially independent of the pressure acting on the upper end of the intermediate contact for two reasons: lst, the pressure on the upper end is partly counterbalanced by the pressure on the lower end of the intermediate contact; 2d, it is characteristic of dashpot action, with fluid bleeding out oi an orifice of Xed size, to have a rate of fluid escapement substantially independent of driving force on the piston.

It will be also observed that the adjustment of the uid adjusting screw 40 will determine the rate of escape of oil from the region 38 in front of the piston 33 during its opening movement. Thus, the downward speed of the intermediate contact 25, as it moves within the 0perating cylinder 3l, may be regulated., Also, the by-pass means 32 permits the da-shpot 3@ to be ineffective duringthe initial portion of the downward travel of the intermediate contact 25 and piston 33.

The further advantage results from my invention that the number of operating parts is reduced as compared with a construction involving a side operating rod as set forth in the aforesaid Patent 2,406,469. Thus, by the arrangement which I have provided, the number of operative parts is practically the same as the case where one has a two-break type of interruptor, the breaks occurring sequentially. Although strictly speaking the two breaks in my improved interruptor occur in a sequential manner, the provision of the dashpot causes the two breaks to occur almost simultaneously, and more rapidly than the ordinary sequential break type of interrupter. Also, the insulation conditions are not impaired by the utilization of my invention since no metallic parts parallel any of the are gaps.

From the foregoing description, it will be apparent that I have provided an improved circuit interruptor of the two-break type in which by the use or" my invention the breaks occur practically simultaneously. Also, it will be noted that in the operation oi my invention, the interrupting arc 2d is drawn earlier than in the conventional consecutive part arrangement. This results by virtue of the by-passing means 32 which equalizes the pressure on both sides of the piston 33 to render the dashpot 30 ineffective during the initial portion of the opening stroke.

During the closing stroke, the movable contact 535 moves upwardly to pick up the intermediate contact 25 and raise the latter charging the compression spring 35 until the intermediate contact 25 makes engagement with the relatively stationary pressure-generating contact I2, the compression spring I3 providing the requisite contact pressure.

Although I have shown and described a specic structure, it is to be clearly understood that the same was 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.

I claim as my invention:

l.. In a circuit interrupter, a relatively stationary contact, an intermediate contact cooperable with the relatively stationary contact to establish an arc, a movable contact separable from the intermediate contact to establish a second serially related arc, a piston secured to and movable with the intermediate contact, an operating cylinder within which the piston moves, by-passing means associated with the operating cylinder to equalize the pressure on both sides of the piston only during the initial portion of the opening travel of the piston, and means preventing the arcing pressure from acting upon the piston to accelerate its opening movement.

2. In a circuit interrupter, a relatively stationary contact, an intermediate contact cooperable with the relatively stationary Contact to establish a pressure-generating arc, an enclosed dashpot protected from the arcing pressure associated with the intermediate contact to delay the opening movement oi the latter, a movable contact separable from the intermediate contact to establish an interrupting arc, and means rendering the dashpot ineiective during the initial portion of the opening operation.

3. In a circuit interrupter, a relatively stationary Contact, an intermediate contact cooperable with the relatively stationary contact to establish an arc, a movable contact separable from the intermediate contact to establish a second serially related arc, a piston secured to and movable with the intermediate contact, an operating cylinder within which the piston and at least a portion of the intermediate contact move, a longitudinally extending groove disposed on the inner wall of the operating cylinder to equalize the pressure on both sides of the piston only during the initial portion of the opening travel of the piston, and means preventing the arcing pressure from acting upon the piston to accelerate its opening movement.

4. In a circuit interruptor, a relatively stationary contact, an intermediate contact oooperable with the relatively stationary contact to establish an arc, a movable contact separable from the intermediate contact to establish a second serially related arc, a piston secured to and movable with the intermediate Contact, an operating cylinder within which the piston moves, a longitudinally extending groove disposed on the inner wall 0f the operating cylinder to equalize the pressure on both sides of the piston only during the initial portion of the opening travel of the piston, and means biasing the piston and intermediate contact in the opening direction, and means preventing the arcing pressure from acting upon the piston to accelerate its opening movement.

5. In a circuit interruptor of the liquid break type, a pair of contacts separable to establish an arc, a third contact separable from one of the aforesaid pair of contacts to establish a second serially related arc, means biasing the said one contact in the opening direction, and substantially enclosed dashpot means operative substantially independently of the arcing pressure for controlling the `opening movement of the said one contact.

6. In a circuit interrupter, a relatively stationary Contact, an intermediate contact cooperable with the relatively stationary contact to establish an arc, a movable contact separable from the intermediate contact to establish a second serially related arc, a substantially enclosed dashpot associated with the intermediate contact to control the latters opening movement, and means rendering the dashpot ineffective during the initial portion of the opening operation.

7. In a circuit interruptor, a relatively stationary contact, an intermediate Contact separable from the stationary contact to establish arcing, a movable contact separable from the intermediate contact to establish arcing, a substantially El enclosed dasli-pot--4 isolated .from the-1V areing4 pressure-:associated With the inter-mediate contactto regulate theopening movement; thereof, and fluid regulating means for determining the timeof actuation of the dashpot.

8. A circuitinterrupter including an arc extingushingunit submerged in liquid, a relatively stationary Contact, an intermediate contact cocperablevv'ith the relatively stationary contact to establish an arc, a movable Contact separable from the intermediate Contact to establish a secondA serially related arc, a piston secured to and movable: with the intermedia-te Contact, an operating4 cylinder Within which the piston moves, and'means venting the forward side of the pistn vtothe region exteriorly of the unit.

9. A circuit interrupter of `the liquid-break type includingan arc extinguishing unit submerged in the liquid, a relatively stationary Contact, an intermediate contact cooperable with the relatiVelyfsta'tiona-ry contact Ito establish a pressuregenerating arc, an enclosed dashpot protected `from the arclngl pressure associated wlth'the intermediate Contact to delay the opening movement of the latter, a movable contact separable fromthe intermediate contact to establish an interruptingA arc, and means venting the dashpot tothe region exteriorly of the unit.

8 10. Al circuit interrupter of the liquid-break type-incl udng an are extinguishing unit submerged-in the-liquid, a relatively stationary con-` REFERENCES CITED The following references are of record in the leoi this patent:

UNITED STATES PATENTS Number Name Date 1,872,530 Turnpenny Aug. 16, 1932 1,949,258- Paul Feb. 27, 1934 2,156,388" Grosse May 2, 1939 2,158,846 Balachowsky May 16, 1939 2,406,469, Ludwig et al. Aug. 27, 1946 2,412,858 Baker et a1. Dec. 17, 1946

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