US2539175A - Liquid blast interrupter for electric breakers - Google Patents

Description

Jan. 23, 1951 c. J. BALENTINE LIQUID BLAST INTEPRUPTER FoR ELECTRIC BREAKERS 2 Sheets-Sheet 1 Filed July 50, 1948 Inventor: Conrad JBalehbrwe,

His bborney.

C. J. BAL-.ENTINE Jan. 23, 1951 LIQUID BLAST INTERRUPTER FOR ELECTRIC BREAKERS 2 Sheets-Sheet 2 Filed July 30, 1948 Inventor: Cox/wad J. Baierwb i ne,

H i 5 Attorney.

Patented Jan. 23, 1951 LIQUID BLAST INTERRUPTR FOR ELECTRIC BREAKERS Conrad J. Balentine, Philadelphia, Pa., assigner to General Electric Company, a corporation of New York Application-July 30, 1948,v Seriall No.41,612

(Cl. 20G- 150) e 2 Claims. I

My invention relates to electric circuit inter'- rupters for high voltage circuits, and particularly to high speed circuit breakers of the liquid blast type for opening high voltage alternating current power circuits within a few hahc cycles.Y

More specically, my invention is a further development and. an improvement upon the series-break type of nterrupter disclosed in U. S. -Patent 1,548,799 granted on an application led by J. D. Hilliard. which is assigned to the same assignee. as the present application.

Nowadays the principle upon which this type o-f. interrupter operates is known as oil blast action# this being the process whereby an arc that is drawn close to an expulsion port within an oil coniining structure is extinguished by' displacement of the oil caused by a pressure established therein in the. region adjacent the arc.

In the above-mentioned Hilliard patent, the pressure for displacing the arc to be interrupted is generated, by means of a series so-called pressure-generating arc, although it is well understood, that` other means may be employed for establishing blastaction such, for example, as an impulse piston. An example of a fluid blast vbreaker whereinthe oil blast action is produced by means of` an impulse piston is disclosed in U. S. Patent 2,147,497 to Prince et al., which is assigned to the same assignee as the present application.

Conventional forms'r that uid blast action may .assume arev well known and may be dened as radial blast, axialV blast,. and cross blast. These three, different. forms are shown clearly in Figs. ,1, 2 and` 3 respectively of the above-mentioned Hilliard. patent. Frequently, these several blast actions:y are combined;r For example, it will be apparent that the oil blast produced in the case of` Fig. 1 of the above Hilliard patent is an inward radial'- blast between the spaced superposed battles,- which blast continues as an axial blast down the bore of the. throat insulator as the contact rodpulls downward from the interrupter into the tank. In other cases an axial blast is vdirected through, say, a hollow contact andthen is caused" to diverge radially koutward as, for Example'ai'ri U', Si Patent 2,434,505 to Buchwald et all, which is assigned to the same assignee as the" present application:

A transverse or cross blast may be regarded as a concentrated inward radial blast stream which cutspdirectly across the axis" of the arc passa-'ge and then exhausts diametrically therethrough. In contradistinction thereto, in accordano@ witli--myf'inventiom Ifcause an. inward# ly directed blast stream to be deiiected and ventedy laterally from the immediate locality of the arc passage into which it is directed'. More specically, I employ oil blast action for causing substantially balanced opposite streamsof oil to impinge one another at different points along the arc drawn between a pair of relatively movableinterrupting contacts, and, immediately adjacent these points of impingement, I provide lateral venting means for exhausting these impinging blast streams as soon as they (have encountered the arc. In this manner, I provide for very effectively and expeditiously cooling the arc, scavenging the ionized products thereof and establishing a wall of high dielectric fluid between 'the separated' contacts whereby to' prevent the re-i'gnition and the re-establishment of the are in the interrupting circuit. Y

By permitting the uid which flows inwardly in a radialdirection to exhaust laterally in' opposite radial directions 'with substantially no axial flow' along the arc length asin my invention, I have' improved the interrupting performance of' a high voltage interrupter while yet maintaining a simplestructure of low manufacturing cost. The improved performance has been" substantiated by comparative tests condu'cte'd in connection with the interrupter of my invention and other interrupters ofV thel same general type and presumably is due primarily to'my method of controllingthe flow ofA the oil with" respect to the arc. Otherwise stated, I achieve improved interrupting performance by immediately venting each blast stream upon" its injection' into the arc. By this method, the" ex`-,

tinguishing blast streams are more eiective'fo'r they are' not so subject to stalling'v or reversal from back arc pressure and-therefore flowz'nore readily int'o the Contact gap. l

Thusaprincipal'object of' my invention is" to provide aj circuit interrupter which'is capable o'f performing a circuit interrupting operation ina more eiiicient manner than in" prior arrange'iments and which, in addition, isV simple and compact'inconstructioni Another object of my invention-is the provision of a'n improved interruptingV unit for an` electric circuit breaker of the oil blast typewliereinopposed inlet and outlet streams of oil are' caused to ow into' and out" ofthe are pas'sagein'sub'stan- 'tially'the' same'plane so that axial flow of the'oil @o ivention of forced'oil'under pressure whichflow's radially into the arc from the Oppositely disposed blast passageways.

Still another object of my invention is to provide an interrupting unit for electric circuit breakers of the oil blast type wherein the products of an interrupting operation are simultaneously expelled from the unit through oppositely arranged vent passageways so that objectionable sidewise stresses imposed on the interruptor unit due to back pressure from the surrounding uid is substantially eliminated due to the fact that the thrusts from the oppositely disposed passageways tend to oilset or counterbalance each other.

Still another object of my invention is the provision of an interrupting unit for high voltage circuit breakers which, due to the particular disposition of the inlet and outlet passages communicating with the arc passage of the unit, permits the yarc to assume random positions within prescribed limits so that erosion of the insulating structure of the arcing chamber from burning is not concentrated appreciably at one side more than at another.

Further obiects and advantages of my invention will become apparent as the following description proceeds and the features of noveltv which characterize my invention will be pointed out with particularitv in the claims annexed to and form ing a part of this specification.

In the drawings. Fig. 1 represents a sectional view of a circuit interrupting unit embodying my invention; Fig. 2 is a perspective view partly in section of a baffle .structure embodying my invention, which structure is disposed within the lower portion of the unit shown in Fig. 1; Fig. 3 yis an alternative arrangement for the bale structure shown in Fig. 2; and Fig. 4 is a view of the various baffle plates utilized in the assembly of the structures shown in Figs. 2 and 3.

The interrupting unit shown in Fig. 1 of the drawings is adapted to be mounted along with another` similar unit inside a relatively large oillled enclosing m^tall1`c tank. These two interrupting units would cooperate with a reciprocating blade contact, such as is shown in Fier. 1 of `the above-mentioned Hilliard Patent 1.548,799.

With reference to Fig. l. the interrupting unit is shown secured to the electric bushing i constructed of insulating material through the bore -of which is disposed a conductor stud 2. As is well known in the art. the bushingr I. a part of which is shown would contain a mounting flange which would cooperate with an opening in the cover of the larve tank enclosing both the interrupting units. 'Ihreadedlv engaging the lower portion of the conductor stud 2 is a flanged metallic nut 3 which secures the metallic ange 4 compressively with respect to the bushing. Adapter unit 5 in turn is secured to the flange 4 bv means of bolts E. The enclosing pressure confining casing 1 for the interrupte unit is threaded onto the lower portion of the adapter unit at 8. For the purpose of tightening un the casing 7. wrench holes 9 mav be nrodded and a conventional. Set screw may be utilized for locking the tightened casing 1 with respect to the adapter unit 5. as shown, The lower portion oi the enclosing casing 1 is partially enclosed bv a throat member IEI constructed of insulating material. which throat is secured into the fasin" by means of dowel pins' or screws I I. Throat member In is provided with a conical opening I9. thi-meh which the movable Contact I3 vertically travels into or out of the tion respectively of the circuit breaker.

.interrupter duringr the opening.r or closing opera- I The contact structure disposed within the enclosing casing 'I comprises a relatively fixed butt Contact I4 `and an intermediate floating contact I5. The relatively fixed contact I4 is mounted for limited resilient movement about a fixed guide rod I6 which is screwed into the flanged cylindrical spring retainer member I'I, the two latter being united together by means of the pin I8.

It will be observed that the butt contact I4 and its associated parts which are` mounted about the guide rod I6, together with the guide rod I6 and its spring retainer II, constitute a complete sub-assembly which is screwed into the adapter 5. This easily renewable contact unit is prevented from slacking back by any conventional means, such as the locking plate I9, which may engage a suitable flat surface on the side of the spring retainer II and which is held xedly by the screw 20.

Electrical contact is maintained between the ybutt contact I4 and the adapter 5 by means of conventional flexible connecting braids, such as is indicated at 2 I.

The limited resilient vertical movement or wipe of the xed Contact I4 provides for slight variations in the closed position of the movable contact I3 and also for subsequent erosion of the arcing contact Vfaces. Nested springs 22 and 23, of suitable strength for adequate contact pressure, bias the fixed contact I4 toward its lower extreme position as determined by the head 24 of the guide rod It which abuts the lower rim of the threaded sleeve member 25. The sleeve 25 is screwed xedly into Contact I4 and may be equipped with an anti-friction bushing 26.

As pointed out above, pressure could be established for causing the oil to blast and extinguish the interrupting arc in any suitable manner. I have chosen to illustrate my inven tion in conjunction with an interrupter wherein pressure is established by a set of series contacts, such as I4 and I5, which draw a pressure generating arc just before the interrupting arc between the contacts I 3 and I5 is drawn. Thus, the enclosing casing 'I is shown as including a pressure-generating chamber generally indicated by the numeral 2l and an interrupting chamber generally indicated by the numeral 28. These two chambers are separated by a common Wall 30 having communicating apertures therein as shown. The arc confining bailies 29 in the pressure generating chamber and the wall 30 are secured within the casing I by means of suitable insulating spacer sleeves or rings 3l, 32, 33 and 34, which are all maintained compressively in place by means of the threaded ring nut shown at the upper end of the casing.

The intermediate contact I5 is biased in the downward direction by means of springs, such as 35 and 355, which engage a ring 31 of insulating material which is secured to the lower portion of the Contact I5 by means of a pin 38.

When the interrupter contacts are in the open position, as shown in Fig. 1, the intermediate contact I5 assumes its fully open position by engaging the lower baiile structure generally designated by the numeral 39 which is held compressively in position between the lower throat member it and the insulating spacer sleeve 34. To close the interruptor contacts from the open position shown, the contact I3 rst is elevated through the arcing chamber passage generally designated by the numeral 40 which passage is constituted by the generally hollow bafe strucassures.

ture 39. AfterI the contact I3A closes the inter-y rupting arc gap by engagingthe lower end of they intermediate contact I-5-, both or thesey conf-Y tacts` rise in unison. Contact I5 now is elevated slidingly in the wall Sii against the bias of its f springs 35 and 36 so that it` eventually'closes the pressure generating arc gap by engaging the lower surface of the relatively xed contact member I4.

Moving contact I3 is iinally arrested by its opev erating mechanism (not shown) when'the fixed contact I4 has been moved upward a short suit-y able wipe distance by the intermediate contact I5. n

When the circuit breakeris tripped open, the

movable contact i3 moves` downwardly at highy speed with the intermediate contact I5 in followup engagement due to its springs 35 and 36, as will be understood from Fig. 1, until the contact I5 is arrested by engagement ofv its ring 3lwith the baille structure. Vliuring'this initial down'- ward movement, the gap produced bet-weencontacts I4 and I5 establishes an initial arc which generatesk pressure within the upper chamber 21. This pressure will urge oil to move downwardly through the openings in both the baille plates 29' and the wall 30 into the interrupting chamcentthe inward blast passages 43.

, it will be clear that these venting exhaust pasber 28. As soon as the moving contact I3 leaves the intermediate contact I5; a second or series arc is established within the arcing passage 40.

Since the baffle structure is vented to the* low pressure region in the enclosing tank (not shown) through suitable expulsion ports such as 4I provided in opposite walls of casing l, and because of the high pressure generated in the upper chamber 2l, the oil in the lower chamber 28 consequently is caused to stream through the baffle structure 39 whereby the series interrupting arc drawn in the passage 40 is extinguished by this oil blast action produced by the pressure generating arc in the upper chamber 21.

In accordance with my invention, the bailio structure 3S is so. constructed, as will be more clearly pointed out hereinafter, that arc ex*- tinguishing fluid under pressure is radially directed into the arcing" passage 4D while this uid and the associated arc` products exhaust from the passage 4t througl'i' passages within the baffle structure Se which radiate directly outwardly therefrom. As will be more fully. explained hereinafter, the exhaust passageways are arranged so that the extinguishing iluid escapes from the arcing passage 4G after its entry thereinto without substantial movement axially'along the arc itself.

The baiiie members shown in Fig. 4 and designated by the letters A, B, B1", C and D arey assembled to form the bolted, stacked, baille structures shown in Figs. 2 or 3, the baille C being used only in the Fig. 3 arrangement. Although the exact assembly of the former will be readily discernable by comparing Figs. 2 and 4, a brief explanation of the composite extinguishing structure as shown in Fig. 2 will nevertheless bey included here. n

The interrupting arcing passage is dened centrally within the baffle structure 39 by reason of the appropriate vertical alignment of the differently coniigured apertures in the several kinds of bales which constitute the complete stack. Deiined on opposite sides of this central passage 4G are two similar vertical ducts 42 down through which extinguishing iluid must flow in passing from the interrupting chamber 28 toward the arcing passage 40. From these vertical ducts 42 the uid is diverted or directed radially into the sages are constituted by the spacing 44a pro-A The ow arrows shown in Fig. 4 depict the oil blast vided between the half baffles B and B1.

action of my novel interrupter and illustrate clearly how the extinguishing fluid is urged in- Wardly in a pair of' opposing streams which im pinge one another in the arcing passage 4i) andtheni readily vent laterally, with no intervening axial iiow, through the substantially balanced" and equal vent passages 44. These flow arrows reveal how an arc in passage 4i! is subjected to a squeezing effect between the dynamically opposed blast streams which probably quickly resolves into a lateral blast effect (comparable to a cross blast) as the arc becomes displaced to the right or left against one or the other set of exhaust vents 44 adjacent either side of the blast passages 43.

driven to one side or the other in the centraly passage 4E), the arc is efficiently extinguished and:

prevented from re-establishing itself because of the effectiveness of this blast action.

It will be apparent that exhaust productsv expelled through the oppositely disposed radiallyv extending vents 44 will not produce an appreciable sidewise stress on the interrupter unit because the back thrust produced by the expulsion on one side of the interrupter will offset that produced on the opposite side of the interrupter. Furthermore, long life of the baflle structure 39 is achieved because tests show that uniform arc burning occurs around the arcing passage- 40', thus indicating that the burden of arcing is shared by both sides of the passage throughout a number of interrupting operations. Accord-` ingly, erosion of the walls of the arcing passage 40 by burning from the arc is not concentrated along a particular surface but ratherv is likely to occur more or less uniformly along opposite sides of the arc passage.. Also, by eliminating axial ow along the arc passage 4Q, excessive burning temperatures within the passage are avoided.

In view of the above description, it is clear that each pair of inward radially extending blast passages, such as 43, has a corresponding pair of outward venting passages 44 through which the huid streams are free to escape after blasting the arc in the central passage 4i). It is not vital, however, to the effective performance of an interrupting unit constructed in accordance with my invention that the blast passages must be arranged in such a precise fashionv as is shown specically in Fig. 2.

For example, the modified baiile structure shown in Fig. 3 is a practical equivalent of, and is equally proficient as, the structure of Fig. 2. In Fig. 3 the two vertically disposed oil ducts 42 of Fig. 2 are provided, as are also the inward blast passages 43 and the outward exhaustvents 44. The blast passages 43, however, are not so wide and are of a greater dimension in the vertical direction than those in Fig. 2; also the only irrespective of whether the arc is:y

means provided for separating these two tiers of blast and exhaust passageways is the provision of a single D type barrier. It should be noted here that in Fig. 3 each lamination is half the thickness of those depicted in Fig. 2, thinner laminations being more easily punched out from stock than the thicker. Accordingly, the single baifle D in Fig. 3 is constituted by a pair oi identical thin bales abutting one another. Thus, only one, rather than three, D type baffles is found effective for diverting the downwardly iiowing oil in the ducts 42 into inwardly flowing opposed oil blasts 43 on two different levels, one above and the other below the D baille, as indicated by the arrows. Furthermore the D baiiles prevent the are from wandering into the uid ducts 42. I may further modify the laminated interrupter structure of my invention by providing bales C having notches 45 intermediate the several B baffles as depicted in Fig. 3. It will be observed that the notches 45 of the C bailies are arranged in registry with the spaces 44a between the B and B1 baies. The effect of these C baffles is to subdivide the deep exhaust vents 44 into a greater number of small horizontal gas vents 44h with the result that the deep exhaust passages 44 now constitute a pair of arc pockets 46 rather than freely venting passages. Accordingly, the arc is entrapped loopingly into these pockets during the extinguishing process in the same manner as set forth and claimed in, and as shown in Fig. 2 of, U. S. Patent 2,156,450 to F. H. Cole, which is assigned to the same assignee as the present application.

From the above, it will be apparent that the structure of Fig. 3 is substantially like that of Fig. 2 in that axial flow of the oil along the path of the arc is substantially eliminated during its transition from inward blast to outward exhaust.

In such a modied arrangement, it will be readily understandable that appropriately long vertical expulsion ports would be provided in the wall of the casing 1 in lieu of the pair of rectangular ports 4 I one of which is shown in Fig. 1. These deeper, narrower ports would, lof course, lie in registry over the group of small vents 442) shown in Fig. 3.

While I have shown and described particular v embodiments of my invention, it will be obvious to those skilled in the art that various changes and modifications may be made without departing from my invention in its broader aspects and I, therefore, intend in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United [States is:

1. An interrupting unit for a fluid blast circuit breaker including an arc extinguishing structure, said structure comprising a composite assembly including a stacked series of flat insulating members each having an opening therein, said openings being arranged in registry to dene an arc passage through said structure and a uid flow duct adjacent thereto, other insulating members forming a part of, said assembly and comprising separated plate-like portions lying in the same plane some of which have a generally U-shaped notch therein, each said U-shaped notch deiining a portion of said fluid flow duct and a blast guiding means into said arc passage from said iiuid flow duct and the spacing between the said separated portions deninglateral exhaust guiding means from said passage for the fluid blast.

2. An interrupting unit for a fluid blast circuit breaker including an are extinguishing structure, said structure comprising a composite assembly including a stacked series of flat insulating members each having an opening therein, said openings being arranged in registry to dene an are passage through said structure and a fluid flow duct adjacent thereto, at least one of said plates having an opening dening a portion of said arc passage and another separate opening dening a portion of said fluid duct, the

portion of said one of said plates which is disposed between the separate openings therein being eiective to subdivide said fluid flow duct and to prevent the are in said arc passage from wandering` into said flow duct, other insulating members forming a part of said assembly and comprising separated plate-like portions lying in the same plane some of which have a generally U-shaped notch therein, each said U-shaped notch defining a portion of said iiuid iiow duct and a blast guiding means into said arc passage from said iiuid flow duct and the spacing betweenV the said separated portions defining lateral exhaust guiding means from said passage for the fluid blast.

CONRAD J BALENTINE.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES IFATENTSy Number Name Date 2,156,450 Cole May 2, 1939 2,385,008 Leeds Sept. 18, 1945 2,406,469 Ludwig Aug. 27, 1946 2,422,569 Leeds June 17, 1947

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