US2456926A

US2456926A - Circuit interrupter

Info

Publication number: US2456926A
Application number: US548815A
Authority: US
Inventors: James M Cumming
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1944-08-10
Filing date: 1944-08-10
Publication date: 1948-12-21
Anticipated expiration: 1965-12-21

Description

. Dec. 21, 1948. J. M. CUMMING CIRCUIT INTERRUPTER 2 Sheets-Sheet 1 Filed Aug. 10, 1944 WITNESSES: 2 4

JNVENTOR 4%; James M. Gum/27mg d g S B ATTORNE" 1 1943- J. M. CUMMING I 2,456,926

CIRCUIT INTERRUPTER Filed Aug. 10, 1944 2 Sheets- Sheet .2

i8. 7 1a 22 19 3a Z3 11 :1 1L 1 37 l 33- 14 "f ,2; '..L] 23 44 3 I ,9 1 39 E WITNESSES: INVENTOR 4&4. James M'zzmming.

2W4: M I

Patented Dec. 21, 1948 CIRCUIT m'rsmwr'rsa James M. Cumming, Turtle Creek, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application August 10, 1944, Serial N 0. 548,815

18 Claims. 1

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

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

A more specific object is to provide an improved circuit interrupter comprising a substantially enclosed arc extinguishing unit within which the electrical circuit is interrupted and substantially 1 exterior to which the electrical circuit is closed.

Another object is to provide an improved circuit interrupter comprising a substantially enclosed arc extinguishing unit within which contact structure is operable to open the circuit. Disconnect means are provided for introducing an isolating gap into the electrical circuit exterior of the unit following circuit interruption, and I provide means for reclosing the contact structure within the unit following introduction of the isolating gap into the circuit so that completion of the electrical circuit through the interrupter shall take place substantially exterior of the unit.

Another object is to provide an improved circuit interrupter in which improved construction is provided for establishing a pressure-generating arc and an interrupting arc with improved means for effecting extinction of the interrupting are by a flow of fluid forced under pressure from the pressure-generating arc.

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

Figure 1 is a view partially in section of a circuit interrupter embodying my invention and shown in the closed circuit position; v

Fig. 2 is a vertical sectional view through the left-hand arc extinguishing unit of Fig. 1, the parts being shown in the closed circuit position;

Fig. 3 is a view similar to Fig. 2 but showing the disposition of the parts in the fully open circuit position;

Fig. 4 is a sectional view taken along the line IV-IV of Fig. 2; and

Fig. 5 is a sectional view taken along the line V-V of Fig. 2.

Referring to the drawings and, more particularly, to Fig. 1 thereof, the reference numeral l designates a tank filled to the level 2 with a suitable arc extinguishing fluid 3, in this instance circuit breaker oil. Depending from the cover 4 of the tank I are two insulating bushings 5, 6 through which extend terminal studs I, 8. Threadedly secured to the lower ends of the terminal studs 1, 8 are contact feet 9, III which rigidly support in place two identical substantially enclosed arc extinguishing units generally designated by the reference numeral ll.

Electrically interconnecting the two are extinguishing units II in the closed circuit position of the interrupter, as shown in Fig.- 1, is a conducting bridging member l2 vertically actuated in a reciprocating manner by an insulating operating rod l3. At the opposed outer ends of the conducting bridging member l2 are movable contacts l4, l5. Referring more particularly to Fig. 2 it will be observed that integrally formed with the contact foot 9 is an inverted cup-shaped member 16 having a plurality of apertures ll provided therethrough. Screws l8 passing through the member I6 serve to hold rigidly in place a conducting ring-shaped member l9 having an outwardly extending portion 20 through which the upper ends of insulating tie rods 21 extend in a manner as shown more clearly in Fig. 1. Nuts 22 threadedly secured to the upper ends of the tie rods 2| serve to hold them securely in place.

The lower ends of the tie rods 2| extend through an offstanding portion 23 of a bottom metallic plate 24 of the unit ll. Nuts 25 are threadedly secured to the lower ends of the tie rods 2|.

Disposed between the ring-shaped plate 19 and the bottom plate 24 are a plurality of suitably shaped plates formed of insulating material and disposed in superimposed relation. Each of the several plates has four notches 26 formed therein (see Fig. 5) which cooperate with the tie rods 21 to maintain the several plates in proper position.

The upper plate 21 of the unit H is substantially of cylindrical shape and forms a piston chamber generally designated by the reference numeral 28 within which operates a piston 29 biased downwardly by suitable biasing means, in this instance assuming the form of a battery of compression sprin s 30.

The piston 29 is rigidly secured to and movable with a pressure-generating contact 3| which cooperates with'an intermediate contact 32. Associated with the intermediate contact 32 is a first biasing means 33 in this instance comprising a compression spring having its upper seat against an insulating plate 34 and having its lower seat against a flange 35 integrally formed' with the intermediate contact 32. Disposed be-- tween the flange 35 and an insulating plate 36 is a second biasing means, in this instance comprising a compression spring 31 which acts in opposition to the compression spring 33.

The lower end of the intermediate contact 32 cooperates with the movable contact l4 disposed at the outer extremity of the conducting bridging member 12 to establish an interrupting are within a vented interrupting chamber or passage N which leads out of the unit ll. Also the pressure-generating contact 3| cooperates with the intermediate contact 32 to draw a pressuregenerating are within a substantially confined pressure-generating chamber 5|.

In the closed circuit position of the interrupter as shown in Figs. 1 and 2, the electrical circuit therethrough comprises the terminal stud 1, contact foot 9, cup-shaped member i6 composed of conducting material, several screws l8, metallic ring-shaped member l9, flexible conductor 38, pressure-generating contact 3 I, intermediate contact 32, movable contact l4, and through the conducting bridging member I! to the right-hand arc extinguishing unit ll, through which the circuit passes in an identical manner to its passage through the left-hand unit H, to the terminal stud I.

To open the electrical circuit passing through the interrupter suitable means, not shown, causes downward motion of the insulating operating rod II. The downward motion of operating rod I3 causes downward motion of the conducting bridging member l2 guided by a cooperating pair 1 of fingers 39 integrally formed with the bottom metallic plate 24 of each unit ii. The downward movement of the movable contact it permits following movement of the intermediate contact 32 for a distance D indicated in Fig. 2, which for the voltage under consideration is preferably about one inch. Consequently, there is a hesitating downward travel of the intermediate contact 32 due to the striking of the flange 35 against the compression spring 31, the piston 29 holding the pressure-generating contact 3! in its upper position because of the oil disposed within the piston chamber 28-.

When the intermediate contact 32 has followed the lower movable contact M for the distance D there then occurs a separation between the intermediate contact 32* and the lower movable contact lfl to establish an interrupting arc,

not shown.

During the interruption of relatively high amperage currents the considerable pressure generated at the pressure-generating are within the pressure chamber 5| will maintain the piston 29 and hence the pressure-generating contact 3| in their raised position. This high pressure will also act within the piston chamber 28 to force fluid, in this instance oil, downwardly through fluid flow passage means including two vertical flow passages generally designated by the reference numeral 40 and inwardly through a plurality, in this instance four, inlet passages designated by the reference numeral 4| into the interrupting chamber 50. After contacting the interrupting arc, not shown, the oil passes through orifices 42 formed by insulating orifice plates 43 to exhaust outwardly through two vent passages 44 more clearly shown by the dotted lines in Fig.

5 and formed by the cooperation of two identically shaped insulating plates 45.

The particular configuration of the passages herein disclosed are described and claimed in a patent application filed November 11, 1942, Serial No. 465,244, new 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.

Following interruption of the interrupting are drawn between the contacts i4, 32, and folowing a subsidence of pressure within the unit II the battery of compression springs forces the piston 28 and pressure-generating contact 3| downwardly, to also force the intermediate contact 32 downwardly to a position as shown more clearly in Fig. 3. It will, consequently, be observed from an inspection of Fig. 3 that during a subsequent closure of the electrical circuit through the interrupter the closure will take place between the contacts 32, I4 adjacent the lower wall 24 of the unit ii substantially exterior of the unit i I. Since the separation between the contacts 32, i4 is substantially exterior of the unit II, the oil between these contacts is uncontaminated and of high dielectric strength so that flashover between the contacts i4, 32 during the closing stroke will only take place when they unit ii.

are very near to one another. Furthermore, when fiashover does take place between the contacts I4, 32 durin the closing stroke there will be no substantial rise in pressure since striking of an arc will take place substantially exterior of the unit ll.

During the interruption of relatively low amperage currents, the pressure formed at the pressure-generating arc between the contacts 3|, 32 will be relatively low and will not greatly impede the downward movement of the piston 29 and consequent y the downward movement of the pressure-generating contact 3i. Consequently during the interruption of relatively low currents, the piston 29 moving downwardly within the piston chamber 28 will cause the requisite oil flow downwardly through the vertical flow passages 40 and toward the interrupting arc drawn between the contacts 32, I 4 to effect the extinction thereof. Following extinction of the interrupting arc the moving parts will assume a position as shown in Fig. 3.

It will be observed that I have provided contact means 3i 32 or a first pair of separable contact surfaces to establish a pressure-generating arc within the pressure-generating chamber 5!. Also I have provided other contact means I4, 32 or second pair of contact surfaces to establish the interrupting are within the interrupting chamber and upon further separation furnish an isolating gap in the circuit exteriorly of the One of the second pair of contact surfaces, namely contact I, is removed from the unit ll through the elongated passage or opening 50 of the unit. The first pair of contact surfaces 3i, 32 is reclosed in the fully open circuit position of the interrupter, and the other of the second pair of contact surfaces, namely contact 32 is forced out of the unit I i through the passage 50 so that prestriking, or arcing on closing with voltage on the line, will occur exterioriy of the unit Ii and not inside thereof.

From the foregoing description it will be apparent that my invention describes a method of circuit interruption in oil employing the principle of interrupting inside of a substantially enclosed arc extinguishing unit, disconnecting outside the unit, then closing the contact structure within the unit before closingthe disconnect contacts. In other words, I propose to open the electrical circuit inside the unit I l and close the electrical circuit outside the unit H. To make use of an arc extinguishing unit in circuit interruption. it is only necessary to confine the arc in a certain space where it can be more easily controlled and extinguished. After interruption has taken place and the line is held open through the safety feature of an isolating disconnect gap there is no reason for the contact structure within the unit to remain open because the several plates comprising the unit are not very good insulation and are never considered when figuring break distance. It is a more desirable arrangement to have the'breaker closed in finally on its disconnect contacts. When an arc is drawn in closing on the disconnect conelectrical circuit through the interrupter. In the case of quick reclosing this is not a handicap because the time lag of the relays for reopening is longer than the time necessary to charge the springs if the disconnect or movable contact I4 ismoving at only 11 feet per second, which is not very fast.

During the opening operation the disconnect or movable contact l4 being attached to the operating rod i3 moves downwardly four inches and then separates from the guide fingers 39 outside the unit ii and continues to the end of its predetermined travel as indicated by the dotted lines 46 of Fig. 1. This movement of the contact l4 and the following hesitating movement of the intermediate contact 32 with the consequent interruption of the interrupting arc is calculated to take place during the first four inches of disconnect travel and before the disconnect contact I4 leaves the fingers 39 integrally formed with the metallic plate 24 at the bottom of the unit II to continue on its downward stroke.

The use of the second biasing means 31 is necessary to give a hesitating travel to contact 32 so that a three inch gap for the interrupting arc is available for extinction of the interrupting arc. The fingers 39 on the bottom of the unit I I are a safety device to insure proper guiding and mechanical operation of the disconnect contact l4.

The travels mentioned above will, of course, change according to the breaker voltage rating. The third biasing means 30 which is relatively strong, preferably exerts a pressure of approximately thirty pounds per square inch.

It will be apparent that my invention eliminates the troubles heretofore encountered as a result of closing the circuit through interrupters in a confining space within an arc extinguishing unit. The disadvantages were: (1) The contaminated oil would permit breakdown to occur during the closing stroke at a relatively great distance because of the poor dielectric strength of the oil. (2) This arc drawn during the closing stroke within the unit of considerable length would create high pressure within the unit which would make present a hazard of explosion during the closing stroke. With my invention, by closing the circuit exterior of the unit the foregoing disadvantages are completely eliminated because the drawing of the arc during the closing stroke takes place when the disconnect contacts are relatively close to one another because of the high dielectric strength of the oil, and furthermore no pressure is created within the unit because the drawing of the arc during the closing stroke takes place substantially exterior of the unit. Also it will be readily observed that the construction which I show is very simple and high speed in operation because of its sim-- ticular type described and claimed in the aforesaid patent application,'it will be readily apparent to one skilled in the art that my invention is applicable to other different types of interrupting structures and is not confined in application to the particular interruptingstructure herein disclosed. 1

Although I have shown and described a specific 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 by those skilled in the art without departing from the spirit and scope of the appended claims. V

I claim as my invention? 1. In a circuit interrupter, a pressure-generating contact, an intermediate contact, a movable contact, a first biasing means biasing the intermediate contact to its open circuit position, and a second biasing means associated with the intermediate contact and acting following a predetermined opening travel of the intermediate contact in opposition to the first biasing means to obtain a hesitating opening travel of the intermediate contact.

2. In a circuit interrupter, a pressure-generating contact, an intermediate contact, a movable contact, a first biasing means biasing the intermediate contact to its open circuit position, a second biasing means associated with the intermediate contact and acting following a predetermined opening travel of the intermediate contact in opposition to the first biasing means, and a third biasing means associated with the pressure-generating contact to bias-the same toward its open circuit position.

3. In a circuit interrupter, a pressure-generating contact, an intermediate contact, a movable contact, a first biasing means biasing the intermediate contact to its open circuit position, a second biasing means associated with the intermediate contact and acting following a predetermined opening travel of the intermediate contact in opposition to the first biasing means, a third biasing means associated with the pressuregenerating contact to bias the same toward its open circuit position, and a piston secured to and movable with the pressure-generating contact.

4. In a circuit interrupter, a substantially enclosed arc extinguishing unit having a substantially confined pressure-generating chamber and a vented interrupting chamber, a pressuregenerating contact cooperable with an intermediate contact to establish a pressure-generating arc within the pressure-generating chamber, a movable contact movable out of the unit and cooperable with the intermediate contact to establish an interrupting are within the interrupting chamber, and biasing means operable to force reengagement of the pressure-generating and in-. termediate contacts following circuit interruption.

5. In a circuit interrupten-a substantially enclosed arc extinguishing unit having a substantially confined pressure-generating chamber and a vented interrupting chamber, a pressure-gencrating contact cooperable with an intermediate contact to establish a pressure-generating arc within the pressure-generating chamber, a movable contact out of the unit and cooperable with the intermediate contact to establish an interrupting arc wthin the interrupting chamber, and biasing means operable to force reengagernent of the pressure-generating and intermediate contacts following circuit interruption, the one end of the intermediate contact being forced to a position adjacent a wall of the unit following circuit interruption.

6. In a circuit interrupter, a. pressure-generating contact, an intermediate contact, a movable contact, a first biasing means biasing the intermediate contact to its open circuit position, a second biasing means associated with the intermediate contact and acting following a predetermined opening travel of the intermediate contact in opposition to the first biasing means, a third biasing means associated with the pressuregenerating contact to bias the same toward its open circuit position, the third biasing means being sufliciently strong to reclose the pressuregenerating and intermediate contacts, a substantially enclosed arc xtinguishing unit through one wall of which the movable contact is movable, and one end of the intermediate contact being forced adjacent one wall of the unit following interruption of the electrical circuit.

'7. In a circuit interrupter, an arc extinguishing unit, means defining a substantially confined pressure-generating chamber within the unit, means defining a vented interrupting chamber within the unit, a pressure-generating contact, an intermediate contact, the pressure-generatingand intermediate contacts being cooperable to establish a pressure generating are within the pressure-generating chamber, a movable contact, the movable contact being cooperable with the intermediate contact to establish an interrupting are within the vented interrupting chamber, a piston chamber, a piston secured to the pressuregenerating contact and movable within the piston chamber to impede its opening movement, fluid flow passage means interconnecting the pressuregenerating and interrupting chambers, and means for moving the pressure-generating contact and piston within the piston chamber.

8. In a circuit interrupter, an arc extinguishing unit, means defining a substantially confined pressure-generating chamber within the unit, means defining a vented interrupting chamber within the unit, a pressure-generating contact, an intermediate contact, the pressure-generating and intermediate contacts being cooperable to establish a pressure-generating are within the pressure-generating chamber, a movable contact, the movable contact being cooperable with the intermediate contact to establish an interrupting are within the vented interrupting chamber, a piston chamber, a piston secured to the pressuregenerating contact and movable within the piston chamber to impede its opening movement, fluid flow passage means interconnecting the pressuregenerating and interrupting chambers, and biasing means biasing the pressure-generating contact toward the intermediate contact.

9. In a circuit interrupter, an arc extinguishing unit, means defining a substantially confined pressure-generating chamber within the unit, means defining a vented interrupting chamber within the unit, contact means for establishing a pressure-generating arc within the pressuregenerating chamber. other contact-means for establishing an interrupting are within the vented interrupting chamber and for providing an isolating gap in the circuit exterio-rly of the unit in the open circuit position of the interrupter, fluid fiow passage means interconnecting the two chambers so that fluid under pressure from the pressure-generating chamber may flow through the fluid passage means to the interrupting arc to effect the latter's extinction, means for reclosing the first-mentioned contact means in the fully open circuit position of the interrupter, and means for closing the circuit during the closing operating by closing said other contact means exteriorly of the unit so that prestriking will occur only exteriorly of the unit during the closing operation.

10. In a circuit interrupter, means at least partially of insulating material defining an are extinguishing unit, means providing a substantially enclosed pressure-generating chamber within the unit, means providing a vented interrupting chamber within the unit, a pressure-generating contact, an intermediate contact,ia movable contact, the pressure-generating contact and the in-- termediate contact being separable to establish a pressure-generating are within the pressure-generating chamber, the movable contact being separable from the intermediate contact to establish an interrupting are within the vented interrupting chamber, a passage leading out of the unit through one wall thereof, the movable contact being movable out through the passage and away from the unit in the fully open circuit position of the interrupter, and means for reclosing the pressure-generating and intermediate contacts in the fully open circuit position of the interrupter and for moving the intermediate contact to a position so that a portion thereof is disposed exteriorly of the unit, the arrangement functioning during the closing stroke so that the circuit is made exteriorly of the unit and any prestriking will occur exteriorly of the unit.

11. In a circuit interrupter of the liquid break type, means defining an arc extinguishing unit, a passage leading out of the unit, a pair of contacts separable to establish an are within the passage, one of the contacts being movable out of the unit along the passage so that in the fully open circuit position of the interrupter it is spaced from the unit to form an isolating gap in the circuit, and means for moving the other contact along the passage to a position so that a portion thereof is disposedv exteriorly of the unit, the arrangement operating to close the circuit during the closing stroke exteriorly of the unit to prevent contamination of the liquid within the unit.

12. In aliquid break circuit interrupter, an arc extinguishing unit, a passage leading out of the unit, a first pair of contacts separable to establish an are within the unit, a second pair of contacts separable to establish a second serially related are within the passage, at least one of the second said pair of contacts movable along the passage and out of the unit to be spaced from the unit in the fully open circuit position of the interrupter, means for reclosing the first said pair of contacts and for moving the other of the second said pair of contacts along the passage so that a portion of the said other contact of the second said pair extends exteriorly of the unit in the fully open circuit position of the interrupter, the closing of the circuit taking place entirely exteriorly of the unit to prevent contamination of the liquid within the unit.

13. In a liquid break circuit interrupter, an arc extinguishing unit, a passage leading out of the unit, a first pair of contacts separable to establish an are within the unit, a second pair of contacts separable to establish a second serially related are within the passage, at least one of the second said pair of contacts movable along the passage and out of the unit to be spaced from the unit in the fully open circuit position of the interrupter, means for reclosing the first said pair of contacts and for moving the other of the second said pair of contacts along the passage so that a portion of the said other contact of the second said pair extends exteriorly of the unit in the fully open circuit position of the interrupter, the closing of the circuit taking place entirely exteriorly of the unit to prevent contamination of the liquid within the unit, and passage means of such configuration to direct liquid under pressure from the arc established at the first said pair of contacts at the are established at the second said pair of contacts to effect the latters extinction.

14. In a circuit interrupter, means defining an arc extinguishingunit, means defining an elongated passage leading out of the unit, a pair of contacts separable within the passage to establish an are along the passage, means other than the arc for forcing fiuid into the arc stream while in the passage to effect its extinction, means for moving one of the contacts out of the unit through the passage to bespaced from the unit in the fully open circuit position of the interrupter, and means moving the other contact along the passage to be positioned exteriorly of the unit in the fully open circuit position of the interrupter so that closing of the circuit during the closing stroke will occur exteriorly of the unit to prevent coning the opening operation, the said means continuing'the separation of the contact surfaces by causing removal of one of the contact surfaces through the opening to be spaced from the unit ,to furnish an isolating gap in the fully open circuit position of the interrupter, and means for moving the other contact surface through the rupter, means for opening the circuit by causing the separation of both the said pairs of contact surfaces within the unit to establish two serially related arcs\within the unit and for removing one of the two contact surfaces of the second said pair out'of the unit through the opening to provide an isolating gap in the fully open circuit position of the interrupter, and means for reclosing the first said pair of contact surfaces and for forcing the other of the second said pair of contact surfaces out of the unit through the openingisolating gap in liquid exteriorly of the unit in the fully open circuit position of the interrupter,

andthe circuit being closed between said two contact surfaces exteriorly of the unit in uncontaminated liquid during the closing stroke so that prestriking may occur exteriorly of the unit.

18. In a circuit interrupter, a substantially enclosed arc extinguishing unit, means defining a substantially confined pressure-generating chamber within the unit, means defining a vented interrupting chamber within the unit, a pressuregenerating contact, an intermediate contact, a movable contact, the pressure-generating contact and the intermediate contact being cooperable to establish a pressure-generating are within the pressure-generating chamber, the movable conopening in the fully open circuit position of the interrupter to be positioned exteriorly of the unit so that the circuit may be closed during the closing stroke exteriorly 'of the unit to prevent contamination of the fluid within the unit.

therefrom, contact structure including a first pair I of separable contact surfaces and a second pair of separable contact surfaces, both the said pairs of contact surfaces being positioned withinthe unit in the closed circuit position of\ the inter-' tact being cooperable with the intermediate contact to establish an interrupting are within the interrupting chamber, a passage lead out of the unit; the movable contact being removed from the unit through the passage in the open circuit position of the interrupter, and means for forcing the pressure-generating contact and the intermediate contact projects exteriorly of the unit along the passage in the. open circuit position of the interrupter.

JAMES M. CUMMING.

REFERENCES CITED The following references are of record in the flleof'this patent: r

UNITED STATES PATENTS Number Name Date 1,904,519 Paul Apr. 18, 1933 1,918,151 Turnpenny et al. July 11, 1933 2,144,372 Keller et all Jan. 17, 1939 2,158,846 Balachowsky May 16, 1939 2,180,673 Prince May 80, 1939 2,275,885 Bartlett. Mar. 10, 1942 2,292,547