US2365602A - Oil circuit breaker - Google Patents

Description

Dec- 19, 1944 J. sLEPlAN 2,365,602

' on. CIRCUIT BREAKEP.

i Filed oct. 25. 1941` Patented Dec. 19, 1944 OIL CIRCUIT BREAKER Joseph slepian, Pittsburgh, Pit.,l assignmu westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application October 25, 1941, Serial No. 416,500

Claims. (01.'200-150) This invention relates to circuit breakers in general, and, in particular, to circuit breakers of the type which use an arc extinguishing fluid to assist in the interruption of the arc produced when the circuit breaker is opened.

The use of such an arc extinguishing fluid in a circuit sbreaker is very common. A pumping system may be provided to lforce the arc exting-uishing fluid, generally oil, into the arc produced between the contacts of the circuit breaker when the latter is opened. The use of oil or other arc extinguishing fluid helps to quench the arc so drawn.

Since the arc drawn between the contacts of the circuit breaker when it is opened reacts on the oil or other arc extinguishing fluid to decompose the same and also to form gas, it is desirable to eliminate the decomposed or contaminated oil and also they gas formed during the quenching of the arc and to provide a fresh supply of oil or other arc extinguishing iiuid for the next opening operation of the circuit breaker. It is desirable also to provide a circuit breaker construction which will prevent the gas so formed during the quenching of the arc from being trapped in the chamber containing the oil or other arc extinguishing fluid. The fresh supply of arc extinguishing iiuid should be of the right quality and quantity, for otherwise the efcient operation of the breaker will be impossible.A The present invention concerns a novel construction of a circuit breaker which incorporates the above listed desirable features. The present invention provides a construction which results in a circuit breaker operating under the most efficient conditions.

The main object of the present invention is to provide a circuit breaker of such a construction that there is provided a fresh supply of oil or other arc extinguishing fluid to assist in the quenching of the arc drawn between the contacts of the breaker for each opening operation of the breaker. A

A second object of the present invention is to provide an improved circuit interrupter of such a construction that any gas bubbles formed by the action of the arc upon lthe arc extinguishing uid will be ejected and eliminated with the ejection and elimination of the decomposed and contaminated oil or other arc extinguishing uid.

A third object of the present invention is to provide an improved circuit breaker of such construction that the fresh oil or other arc ex'- tinguishingfiuid will be introduced into the arcing chamber at ,a point remote from the region of arcing.

A fourth object of the present invention is to provide an improved circuit interruptcr of such a construction that the quantity of fresh oil introduced into the arcing chamber after each operation of the breaker can be predetermined.

A fifth object of the present invention is to provide an improved circuit breaker of such a construction that the quantity of decomposed or contaminated arc extinguishing fluid ejected from the arcing chamber after each operation y of the breaker can be predetermined.

A sixth object of the present invention is to provide an improved circuit breaker of such a construction that the arc extinguishing fluid is caused to flow into the arc sides to effect the circuit interruption at current zero. It is, however, to be understood that the novel breaker cen-f struction hereinafter described can be used in a direct current system as well as in an alternating current system.

Further objects and advantages will become apparent in the following description when conlsidereii in connection with the accompanying drawing, the single figure of which is a crosssectional view of an upright circuit breaker constructed in accordance with the present invention.

Referring to the accompanying drawing, the reference numeral i represents a cylindricallyshaped casing made of insulating material, preferably porcelain. Within the casing i is centrally positioned a cylindrically-shaped metallic member 3 secured by a plurality of studs 'l and' nuts 9 to a closed cylindrically-shaped container indicated in its entirety by the reference numeral 'l I made out of insulating material. At vits upper end the cylindrically-shaped metallic member 3 is secured by screws I to a ring-shaped member 6, the latter being fastened by cement -8 to a threaded upper'portion of the casing l. The -spacebetween the inner surface of casing I and the outer surface of the cylindricallyshaped metallic member 3 is filled with fresh clean arc extinguishing fluid 5, preferably oil, up to the point a near the top of casing I. 'I'he means for pouring in the arc extinguishing uid are not shown in the drawing, this not being an essential part of the present invention. The

fresh arc extinguishing fluid 5 does not now at any point to the interior of the cylindricanyshaped metallic member 3, but is solely con-l fined to the space between the inner wall of casing I and the Outer wall of member 3 and the interior of the closed cylindrically-shaped member II. As will be more fully described later, the interior of member 3 is reserved for the storage of decomposed and contaminated oil resulting from the use of the fresh oil in helping to extinguish the arc drawn when the breaker is opened.

Centrally located within the metallic member 3 is a long tubular-shaped armature member I3, preferably made of iron. The upper end of armature I3 has a diameter considerably smaller than the central portion of armature I3, and is indicated by the reference numeral I5. The upper end I5 loosely protrudes through a hole I1 bored centrally in a circular plate I9 made out ol insulating material. Member I9 is rigidlyfastened into place by screws 4. At the extreme upper end of I5 is rigidly secured a circular plate member 2I made of insulating material, which enables member I3 to be latched in its upper position by the latching mechanism indicated generally by the reference numeral 23.

The latching mechanism 23 comprises a pivotally mounted L-shaped member 25 biased in a counter-clockwise direction by a compression spring 21. A shoulder 29 integrally formed on the Lshaped member 25 latches under the circular insulating plate member 2| when the member I3 is in its upper position. Consequently member I3 is locked in its upper position until an operation of latching mechanism 23 occurs and releases member I3. Enclosed within a latch mechanism casing 3| is a solenoid magnet (not shown) which when energized causes a plunger 33 to move swiftly downward and thus to cause a clockwise rotation of the L-shaped member 25 and a consequent release of the member I3 from its upper position. The magnet (not shown) of the latching mechanism 23 could be push button operated on a separate electrical circuit, or the magnet (not shown) of the latching mechanism 23 could be so connected as to respond to overload conditions in the electrical circuit passing through the circuit breaker itself.

Rigidly secured to the inner wall of member 3 and extendinglradially inward from said inner wall is a circular metallic plate member 32, preferably of iron, with a central hole bored therein. This member 32 supports a solenoid magnet 35 which is provided to lift the tubular armature member I3 to its upper position against the downward biasing action of acompression spring 31 when the solenoid magnet 35 is energized. It is thus apparent that the energizing of solenoid magnet 35 will cause the circuit breaker to close since the lower end of the tubular armature member I3 is pivotally connected at 39 to a. frame, indicated generally by the reference numeral 4I, which carries the movable contact 43. Consequently, when the solenoid magnet 35 is energized member I3 will be drawn upward, compressing spring 31, and closing the circuit breaker. But once member I3 is in its upper position it is automatically latched mechanically by the latch mechanism 23. Although the solenoid magnet 35 may now be deenergized member I3 will continue to remain latched in its upper position holding the circuit breaker closed. Armature I3 will re-v main in its upper position, and the circuit breaker will consequently remain closed, whether or not the solenoid magnet 35 is energized; and armature I3 will only drop downward when the latching mechanism 23 is operated to release member I3 from its upper position. When, however, the latching mechanism 23 vis operated the armature I3 will quickly drop downward being acted upon by two downward forces. One force is the force of gravity and the second force is caused by the compression spring 31, which was compressed when the circuit breaker was closed. A very rapid opening operation of the circuit breaker thus takes place.

The frame, indicated generally by the reference numeral 4I, which is pivotally connected at 39 to armature I3 comprises a horizontal cross-bar member 45 made out of insulating material. The cross-bar member 45 is rigidly secured by two long studs 46 and four nuts 41 with two insulating sleeves 49 surrounding the studs 45 to a lower horizontal cross-bar 5I also made of insulating material. The lower cross-bar 5I carries the movable contact 43 which is electrically connected by a flexible pigtail conductor 53 to a stud 55 which passes through an opening 51 in the insulating casing I for making external electrical connection with a terminal conductor 53.

The circuit breaker is provided with an entirely closed (except for two valves to be described later) cylindrically-shaped arcing chamber indicated generally by the reference numeral 5I. The lower and upper circular end plates 63 and 65. respectively, of the cylindrical arcing chamber 6I are composed of insulating material. The cylindrical wall B1 of arcing chamber 6I is also cornposed of insulating material. The two circular end plates 63 and 65 and the cylindrical wall 81 are secured together by the studs 1 and nuts 9 to form a closed (except for two valves to be described later) insulated arcing chamber 6I. Resting upon the upper circular insulating plate 65 is a circular metallic plate 69. This circular metallic plate 69 is also secured in place by the studs I and nuts 9. The circular plate members 63 and S5 have three aligned holes bored therein, one hole 1I being centrally located, and the other two holes 13 and 15 located intermediate the central hole 1I and the'outer periphery of the two plate members 59 and 65. The two studs 46 surrounded by insulating sleeves 49 pass through holes 13 and 15 loosely, but with very slight clearance. A flanged perforated cylindrical member 11 servingas the stationary electrical contact of the circuit breaker is secured rigidly by a thread connection to the circular metallic plate member 69. The stationary contact 11 extends down through the hole 1I of the upper circular insulating plate'65. It is to be noted that the lower surface of the upper circular insulating plate member 65 is concave in shape, and that the lower end of the stationary contact 11 conforms to this concave shape. The reason for such a A shape is given hereinafter. The opening in the stationary contact 11 is such as to coact with the movable contact 43 in forming a good electrical vare two valves associated connection between the two when the circuit breaker is in the closed position, as is shown in the drawing. The movable contact 43 and the stationary contact 11 are made of metal, preferably copper. y

As was previously mentioned, the arcing chamber-BI is entirely closed. This statement must, however, be modified, for, in fact, there with the arcins chamber 6I, and also two holes 13 and 15, the latter, however, being illled by the insulating sleeves 49. The lower valve. indicated generally by the reference numeral 19, only admits oil or other the arcing chamber 5I.

generally by the refejection The upper valve, indicated erence numeral 8|, only permits the -apparent that when the pressure of the fluid within the arcing chamber 6| is reduced, the

ring-shaped member 83 will lift upward and permit oil or other arc extinguishing fluid to stream into the arcing chamber 6I through the two holes 81. When, however, the pressure in the arcing chamber 6I increases to an extent which is greater than the pressure outside the arcing chamber 6I, then the ring-shaped member 83 will be forced by the pressure of the uid in the arcing chamber 6I downward to close the holes 81 and to prevent the ejection of fluid out through the holes 81.

The upper valve 8|, which only permits the ejection of fluid from the arcing chamber 6|,A

comprises a valve 89 which coacts with the upper portion of the stationary contact 11, the upper portion of the stationary-contact 11 serving as a seat therefor.

The valve 89 is biasedtoward a closed position by a compression spring 9| which is compressed at one end by the valve 89 and at the other end by a horizontal cross-bar 93.

-which bridges two vertical studs 95 secured at their lower ends to the circular plate member 69. It is thus apparent that the valve 89 will remain closed except when the pressure of the fluid within the arcing chamber 6I is sufilcient to overcome the biasing action of the compression spring 9|, at which time oil or other arc extinguishing fluid will only pass out of the arcing chamber 6|, and not into said arcing chamber 6I.

Let us assume that the circuit breaker is latched in the closed circuit position, as is illustrated in the drawing, and also that there is oil within the arcing chamber 6I. Assume further that the latching mechanism 23 is operated to release member I3. It is apparent that member.l3, when so released, and in thevabs'ence of current through solenoid magnet 35, will be forced downward by gravity and the force exerted by the compression spring 31. This will force frame 4I downward and consequently will force more of a portion of studs 46 and their surrounding sleeves 49 into the arcing chamber 6I. Armature I3 will descend until the ringshaped member 2| strikes the insulating plate I9. When this occurs member I3 'and frame 4I will come to rest, and the contacts 43 and 11 will be separated, the circuit breaker now being in the open circuit position. In the open circuit position of the breaker a large portion of the frame 4I will be within the arcing chamber 6|. Since the volume of arcing chamber 6I is fixed, and since a greater volume of the frame 4I is being forced into the arcing chamber 6I through the two holes 13 and 15 during the opening operation'of the breaker, the arc extinguishing fluid, which already lled the arcing cham ber 6I at thebeginningof the opening operation of the breaker, will be compressed; and the pressure of the fluid within the arcing chamber 6| willrise. This increased pressure of the fluid within the arcing chamber 6I will close lower valve 19 (if it is not valready closed) and will open valve 8I forcing part of the fluid out of the arcing chamber 6I. The breaker will remain in the open circuit position until the solenoid magnet 35 is again energized.

When solenoid magnet 35 is again energized, the armature I3 of the solenoid magnet 35, will be drawn upward, compressing the spring 31 until the armature is in its upper position. This closing operation of the breaker raises the frame 4I and closes the contacts 43 and 11 of the breaker. 'I'his closing operation of the breaker has moved part of the frame 4I out of the arcin'g chamber 6|, thus reducing the pressure of the fluid within the arcing chamber 6I. The consequent reduction of the pressure of the fluid within the arcing chamber 6| causes valve 19 to open, and the reduced pressure within the arcing chamber 6I draws fresh oil or other arc extinguishing fluid into the chamber 6| through the two holes 81 in the lower insulating plate member 63. It is thus apparent that the closing of the circuit breaker draws fresh oil into the arcing chamber 6I, whereas the opening of the breaker ejects from the arcing chamber 6I decomposed and contaminated oil together with any gases formed by the action of the arc upon the arc extinguishing oil. It will be observed that the oil which is forced out of the arcing chamber 6I during the opening operation of the breaker is oil in the near proximity of the arcing region, and not oil away from the arcing region. Hence the ejection of oil which takes place 4during the opening operation of the breaker effects only the contaminated or decomposed oil and formed gases in-the region where arcing takes place. I'he ejection does not'affect clean oil away from the arcing region.

It will be noted also that the reason for the concave shape of the lower surface of insulating plate member and the conforming shape of the lower end of stationary contact 11 is to prevent gas bubbles from being trapped within the arcing chamber 6I. By utilizing such a shape, any gas which is formed by the action of the arc upon the arc extinguishing fluid is not trapped'within the arcing chamber 6I, but instead rises and is forced out of the arcing chamber 6| together with the decomposed and contaminated oil during the opening operation ofthe breaker.

The dimensions of the holes 81 in the lower plate member 63, of the holes 13 and 15 in the v construction has proved to be very effective in operation, whether the breaker is used in a direct f current system or in an alternating current system.

It will be noted that the position of the valve 19 and of the holes 81 associated therewith is such that the oil or other arc extinguishing fluid which is drawn into the arcing chamber 61 is drawn into the chamber 6I from a point remote from the region of arcing. Such a construction of the breaker insures that the oil entering the arcing chamber 6I will be clean, fresh and of good quality.

The electrical circuit through the breaker beging at the lower terminal connection 59 and then passes through stud 55, pigtail 53, movable contact; 53, stationary contact 11, metallic plate 69, the cylindrically-shaped metallic member 3, to the terminal lug 91. A cap 99 of insulating material is provided for the circuit breaker to minimize the entrance of dust therein, and to :protect the moving parts of latching mechanism 23. A clamp IUI (only one-half being shown) is provided to support the circuit breaker in a frame (not shown).

It is apparent that the fresh oil or arc extinguishing fluid between the inner wall of casing I and the outer wall of member 3 will gradually descend in this space as it is used up. The decomposed oil will be collected and will rise within the cylindrically-shaped metallic member 3. Periodically, the contaminated oil can be removed and fresh oil supplied by suitable means (not shown).

Although I have shown and described a specific circuit breaker structure, it is to be understood that the same is only for the purpose of illustration, and that changes and modifications may be made 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 breaker of the type using an arc extinguishing fluid to assist in the breaking of the arc `drawn when the circuit breaker is opened, an arcing chamber, a stationary contact disposed in the wall of said chamber and a movable contact cooperating therewith, a supporting frame for said movable contact movable within said arcing chamber, part, of said supporting frame also being movable into and out of said arcing chamber, at least one aperture in said stationary contact, a valve associated with said aperture in said stationary contact, piston means for ejecting under pressure the decomposed arc extinguishing fluid from said arcing chamber through said aperture in said stationary contact, said valve associated with said aperture serving the purpose of preventing a return of the decomposed arc extinguishing fluid to said arcing chamber, said piston means being movable for supplying a fresh supply of arc extinguishing fluid to said arcing chamber during each operation of said circuit breaker, said piston means comprising the :part of said supporting frame movable into-and out of said arcing chamber.

2. In a circuit interrupter of the liquid break type, means deiining a substantially closed arcing chamber, a valve disposed in the wall of said means comprising at least part of said support means for predetermining the quantity of liquid admitted into said arcing chamber during the closing operation of said interrupter, said piston means also assisting in predetermining the quantity of liquid ejected from said arcing chamber through said first mentioned valve during the opening operation of said interrupter.

3.v In a liquid circuit interrupter, an arcing chamber, a relatively stationary contact, a movable contact cooperable with the stationary contact to establish an arc, actuating means for the movable contact, an aperture disposed in the wall of the chamber adjacent the stationary contact, valve means biased to close the aperture, and piston means comprising part of the actuating means nearest the movable contact operable during the opening operation of the interrupter to force arc extinguishing liquid adjacent the arc out of the arcing chamber through the aperture.

4. In a liquid circuit interrupter, an arcing chamber, a relatively stationary contact, a movable contact cooperable with the stationary contact to establish an arc, an aperture disposed in the wall of the chamber adjacent the stationary contact, valve means biased to close the aperture, a support rod for the movable contact disposed adjacent thereto, and piston means arcing chamber to permit only the ejection of liquid out of said arcing chamber, a stationary contact disposed adjacent said valve, a movable contact cooperable with said stationary contact to establish an arc and movable entirely within said arcing chamber, support means for said movable contact movable into and out of said arcing chamber, a second valve disposed in the wall of said arcing chamber to permit only the admission of liquid into said arcing chamber, piston comprising at least part of the support rod disposed adjacent to the movable contact reciprocally operable into and out of the arcing chamber during respective opening and closing operations of the interrupter, the piston means being operable during the opening operation of the interrupter to'force arc extinguishing liquid adjacent the arc out of the arcing chamber through the aperture, a second aperture and valve means therefore, and the piston means also being operable during the closing operation of the interrupter to draw through suction action fresh arc extinguishing liquid into the arcing chamber through said second aperture.

5. In a liquid circuit interrupter. an arcing chamber, a relatively stationary contact, a movable contact cooperable with the stationary contact to establish an arc, operating means for actuating the movable contact, the portion of the operating means nearest the movable contact being reciprocally movable into and out of the arcing chamber during respective opening and closing operations of the interrupter to increase and decrease the space in said chamber filled with said liquid, an outlet valve for the arcing chamber adjacent the relatively stationary contact and an inlet valve for the arcing chamber at a point remote from the outlet valve,

themovement of said portion causing a one-way circulation of arc extinguishing liquid through the arcing chamber, the liquid being forced by the inward movement of said portion into the chamber during an opening operation to engage the arc to eect the latter's extinction.

JOSEPH SLEPIAN.

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