US2623968A - Circuit interrupter - Google Patents

Description

Dec. 30, 1952 B. P. BAKER 2,623,968

CIRCUIT INTERRUPTER Filed June 9, 1950 4 Sheets-Sheet 1 Fig.l.

WITNESSES:

I BY 2 5 m4 Q ATTORNE INVENTOR Benjamin P. Baker.

Dec. 30, 1952 B. P. BAKER CIRCUIT INTERRUPTER Filed June 9, 1950 I 4 Sheets-Sheet 2 Fig.2.

WITNESSES: INVENTOR Ben'omin PIBcker. flm

Dec. 30, 1952 KE 2,623,968

CIRCUIT INTERRUPTER Filed June 9, 1950 4 Sheets-Sheet 5 Fig.3.

WITNESSES: l8 INVENTOR K4 I 7 Benjamin P. Baker.

71% M W AW Dec. 30, 1952 B. P. BAKER 2,623,968

CIRCUIT INTERRUPTER Filed June 9, 1950 4 Sheets-Sheet 4 I I I ll' WITNESSES: INVENTOR Benjamin P. Baker.

ATTORNEY Patented Dec. 30, 1952 UNITED STATES: FATENT ()F-FICE CIRCUIT INTERRUP TER' Benjamin P .'Baker,- Turtle Creek,Pa'., assignor to Westinghouse Electric Corporation,'East Pitts'-' burgh, Pa;, acor-poration of Pennsylvania Application J une.9,'1950, Serial No.'167',214'

7 Claims. 1

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

The general object of my'invention is to provide an improved high-speed type of liquid-break oil circuit'interrupter in which improved and more effective operation is obtained'over the entire current range;

Another object is to provide an improved cir-" cuit interrupter of repeatable unit construction in which any number of unitsimay be employed, being disposed in superimposed relation corresponding to the voltage requirements.

Another object is to provide .animproved highspeed type of interrupter in which the overall length of theinterrupter is reduced to a min-. imum by the employment of very effective 'arc'" extinguishing units of the multi orifice type."

A further 'object'is to provide animproved circuit interrupter of the type specified in the immediately preceding paragraph inwhich im-' proved liquid'oil' pumping means "are employed to facilitate the interruption of 'low'currents,

such as chargingcurrents, and" to providei a fiushing'fiow of .oil throughthe units during:

high-current interruption;

Further "objects andadva'ntages will readily become apparent upon :reading the following specification,- taken in" conjunction with the drawings'in which:

Figure 1 is a side elevational .viewoi' 'acircuit interrupter embodying my invention; partially in vertical section; the contact structure being" shownin the close'd'circuit position;

Fig. 2 is an enlarged fragmentary vertical sec tional' view-through the lower portion of'oneof the'arc-extinguishing assemblages of Fig. 1, the

view beingtaken' alongtheline II-l1 oi Fig; 4

looking in the direction of the arrows, and the contact structure being shownat an intermediate point in the opening operation;

Fig. 3 is .a view similar to that or" Fig.2'but takenalong the line III-I1I of Fig.4 looking in the direction of the arrows,'the contact 'structure being shown atv an .intermediatepoint in ing unit taken along the'line VI-.-VI of Fig.4;

the contact structure beingishown in the'full'y open circuit position;

Referring to the drawings, and more particularly to Figure 1 thereof, the reference numeral I designates a tank filled to the level 2 with a suitable arc-extinguishing liquid 3, in this instance circuit-breakeroil; Depending from the cover 4 of the tank i are a pair of terminal bushings '5; 6 to the lower ends of which are secured identical arc-extinguishing assemblages, generally designated bythe reference numeral 1.

Electrically interconnecting the two arc-extinguishing assemblages I is a conducting crossbar 8 reciprocally actuated in a vertical direction by an insulating lift-rod 9.

Referring more particularly to Figs. 2-5, which more clearly disclose the internal construction of*'each arc-extinguishing assemblage I, it will be noted, with particular attention being directed to Fig; 2, that each arc-extinguishing assemblage l comprises a pair of arc-extinguishing units Hi disposed in superimposed relation and serially connected into the circuit. Eacharc-extinguishing unit It] includes suitable'con tact structure-comprising a relatively stationary pressure-generating contact II, an intermediate contact l2 and a lower movable interrupting The interrupting contacts [3 for contact l3. each arc-extinguishing assemblage l arethread-' edlysecured;as at Hi, to metallic plates 15,1554. The'pl'ates 15, I566 are'rigidly secured to a'pair of longitudinally extending insulating operating rods [6. The lowermost plate [50. has a'relatively stationarydisconnect contact ll associated therewith,- which makes abutting engagement, during the closing operation and also during the initial portion of the opening operation, with a movable rod-shaped disconnect contact l8, the latter-being disposed at each extremity of the crossbar 82' Thus upward closing motion of the lift-rod 9 and cross-bar 8 causes the movable disconnect contact 18 to strike the relatively stationary disconnect contact ll to pick up the plates l5, 15a the latter being interconnected by. the movable operating rods l6, and move the contacts ll, 12 and 3 to their closed circuit position, as shown more clearly in Fig. 1.

Associated with the intermediate plate 15 (Fig. 2) are a pair of movable cup-shaped insulating pistons 2u-havingupper 'flange portions 2|. The pistons 20 slide through apertures 22 provided in the'intermediate plate l5 and are biased downwardly "in a pumping direction by a pair of compression springs 23. The lower ends of the compression springs 23 seat at the lower ends 24 of the pistons 20, and the upper ends of the compression springs 23 seat against the lower metallic plate 25 of the upper unit it] of the assemblage l.

Disposed adjacent the lower ends 24 of the pumping pistons 20 are valves 26 biased closed by springs 27, and only opened during upward closing charging movement of the pistons 2t.

A pair of resilient split contact tubes 23 (Fig. are threadedly secured, as at 29, to the top metallic plate 30 of the lower arc-extinguishing unit It. These tubes 23 pass through apertures 3i provided in the conducting intermediate plate l5 of the assemblage 1, and serve to provide an electrical connection between the intermediate plate [5 and the top metallic plate 30 of the lower unit I t. Consequently, in the closed circuit position of the interrupter, as shown in Fig. l, the electrical circuit includes terminal stud 32 extending interiorly through terminal bushing 5, conducting clamp 33, through a suitable strap connection to the upper pressure-generating contact ll of the upper unit lil of the assemblage i. The circuit then extends through the upper intermediate contact I2, the upper interrupting contact 13, through the intermediate plate [5 to the contact tubes 28. The circuit then extends through the conducting plate 3% and through a conducting strap 34 to the lower relatively stationary pressure-generating contact H. The electrical circuit then proceeds through the lower intermediate contact l2 and through the lower interrupting contact l3 to the relatively stationary disconnect contact ii. The circuit then extends through the movable disconnect cont-act It of the assemblage 7, and through the conducting cross-bar 5 to the right-hand arc-extinguishing assemblage E (Fig. 1). The electrical circuit extends through the right-hand arc-extinguishing assemblage i in a similar manner to its passage through the left-hand arc-extinguishing assemblage i, just described.

The movable contact assemblage generally designated by the reference character 35, and including the plates 15, IM operating rods It and interrupting contacts I 3, is biased downwardly in a circuit opening direction by a plurality of accelerating compression springs 36. These compression springs 36 are preferably disposed about two of the tie-rods 38 between the lowermost metallic plate lea which is enlarged somewhat so that these tie-rods slide therethrough and the lower metallic plate 37 of the lower unit Iii.

It will be noted with particular reference to Figs. 3, 4 and 5 that the units it are supported fixedly in desired spaced arrangement by a plurality, in this instance four, insulating tie-rods 33 surrounded by spacing sleeves as, the latter serving to maintain the units It the desired distance apart. Nuts is disposed at the upper and lower ends of the tie-rods 38 serve to clamp the assemblages i to the upper clamps 33, the latter being threadedly secured and clamped to the lower ends of the terminal studs 32, M.

The plate structure for each arc-extinguishing unit it will now be described. Each arc-extinguishing unit it includes a plurality of suitably configured insulating plates disposed in contiguous relation, and held in position by the tierods 33 and spacing sleeves as. The top three plates d2, and id of the unit it have enlarged apertures formed therein to provide, upon alignment, the piston chambers 45. The insulating plates 62 and 43 also have centrally provided apertures ll to accommodate slight Vertical motion of the flange portion d3 of the relatively stationary pressure-generating contact I l, the latter having a contact compression spring 49 associated therewith. The insulating plate M has a slightly smaller central aperture 59 to terminate downward opening motion of the relatively stationary pressure generating contact H.

The next lowermost plate within the unit H1 is designated by the reference character 5! and also has the pair of apertures 55 provided therein.

In addition, the plate 5! has an elongated slot 52 formed therein which provides a pair of outwardly extending vent passages 53 from the pressure-generating are 54, the latter being established between the relatively stationary pressuregenerating contact H and the intermediate con tact l2. The two vent passages 53 terminate at their outer ends into a pair of vertical flow passages 55, the latter being shown more clearly in Fig. 3 of the drawings and extending downwardly within the unit Hi.

The next lowermost plate as of the unit H3 has the apertures 4'15 provided therein, a pair of apertures 5?, which assist in defining the vertical flow passages 55, and a centrally disposed orifice 53, through which the pressure-generating are 5 5 is drawn during the opening operation.

The next plate 59 of the unit It has an elongated slot as formed therein, more clearly shown by the dotted lines in Fig. 4, and providing a pair of inlet passages 6! leading from the piston chambers 46 to the pressure-generating are 54.

Then follows a second plate 55, a second plate El, and a third plate 56. The next six plates in the unit I ii are designated by the reference character 62. Each of these plates 62 has a pair of enlarged apertures 35 provided therein to define, upon alignment with the other plates, the two piston chambers 35. In addition, the plates 62 have apertures 57 formed therein to assist in defining the vertical flow passages 55 (Fig. 3). Furthermore, the plates 52 have a centrally provided aperture 63 formed therein to accommodate vertical reciprocal movement of the intermediate contact l2, the latter being biased downwardly in a circuit opening direction by a compression spring St. The compression spring E i seats at its lower end upon a flange portion 65 integrally formed with the intermediate contact l2.

The next five plates of the unit it are designated by the reference character 66 and are the same as the preceding plates 62 just described, with the exception that the pair of apertures 45 for defining the piston chambers 45 are omitted. Then follows a plate 56a which is the same as the plate 56 previously described, with the exception that the apertures 45 are omitted.

Then follows a vent plate, generally designated by the reference character 61, and comprising two half plates 68, 69 spaced laterally apart to provide a pair of vent passages It! leading laterally out of the unit It from the interrupting passage or chamber 1 I, within which the interrupting are '12 is drawn.

Then follows a second plate 56a, which, in turn, is followed by an insulating plate designated by r the reference character 13, and herein termed an inlet plate. The inlet plate 73 has an elongated slot is provided therein, which forms two inlet passages 15 which lead from the vertical flow passages 55 to the interrupting are 72 drawn Within the interrupting passage H between the intermediate and movable contacts 12, I 3.

Then follows a third plate 56a, a second vent plate 51, a fourth orifice plate 56a and a second inlet plate E3. The metallic plate 3? constitutes the lowermost plate of the unit it.

cal to the-lower unit It, and hence-neednot'be described.

The operation of this embodiment'of my invention will now be described. To open the interrupter; suitable mechanism, not shown, but which is responsive to manual operation or to the existence of overload conditions existing in the controlled circuit, causes downward opening motion of the insulating lift-rod 9. The downward opening motion of the lift-rod 9 is accompanied by downward opening motion of .the cross-bar 8 and both movable disconnect contacts l8;

The downward opening motion of .themovable disconnect. contacts it permits corresponding downward opening motion of the movable contact assemblies 35, the latter being biased downwardly by theaccelerating compression springs 36. The downward opening motion of the interrupting contacts [3, as-carried by the plates I5, I5a of one movable contact assembly 35, permits the compression spring 64 associated with the intermediate contact I2 to force the latter downwardly, thereby drawing a pressure-generating arc 54 between the contacts I l, 12, as more clearly shown in Fig. 2. This, of course, occurs after the static-nary pressure-generating contact I i has taken up the contact compression motion as permitted by the compression spring 49.

Further downward opening motion of the disconnect contact !8 and the movable contact assembly draws a serially related interrupting are 72 between the contacts [2, I3 after the intermediate contact l2 has been halted by the upper plate 56a. The position of the several parts at this stage of the opening operation during the interruption of relatively low currents is shown by Figs. 2 and 3.

During the interruption of such relatively low currents, the pistons 26, biased downwardly by the springs 23, move with the intermediate plate l5 to provide liquid or oil flow out of the two piston chambers 46 and through thetwo inlet passages 6! toward the pressure-generating are 54. This oil flow, after striking the pressure-generating arc 54, passes away therefrom through the two pairs of vent passages 53. The oil thenpasses downwardlythrough the two vertical flow passages and into the interrupting passage H through the twopairs of inlet passages '15. After striking the interrupting arc E2, the oil passes through the orifices 58 associated with the several orifice plates 56a and passes out of the unit It) through the two pairs of vent passages 10. The foregoing action takes place during the interruption of relativelylow currents, such as charging currents, when the pressure generated at the pressure-generating arc 54 is relatively low. The -oil flow caused by the motion of the pistons 29 extinguishes one of the two arcs 54, 12 and hence clears the controlled circuit. Furthermore, downward opening motion of the movable disconnect contacts 13 causes them to separate from the relatively stationary disconnect contacts I1 to insert two isolating gaps into the circuit, as shown by the dotted lines 16 of Fig. 1.

During the interruption of relatively high currents, the pressure generated at the pressure-- generating arc c l will correspondingly be high, and will prevent downward pumping motion of the pistons 20 because of the high-pressure existing within the piston chambers 45. In this event, the high pressure generated at the pressure-generating are 54 due to the interruption of such high current, will cause increasedoil flow throughthe passages inthe. manner previously described tocauseincreased oildriving force to be directed at theinterruptingarc l2. Following extinction of the-interrupting arc .12, and a subsidence of the A pressure within the unit l0, the pistons 20-wi1l.

then be able to move-downwardly to cause afiushing fiow of oil to pass through the unit lfljto wash out contaminated and carbonized oil.

During the closing, operation, the lift-rod 9 moves, upwardly ,carrying with it the cross-bar 8 and;:the two, movable disconnect contacts l8. Each contact IBstrikes the relatively stationary disconnect contact: I! and carries the movable contact assembly35 upwardly so that th con tactlstructure is'closed;v Also the upward movement of. themovable contact assembly 35 carries the pistons 20 upwardly within the piston chambers 46, opening the valves 26 to permit oil to flow from the region Ti through the interior of the-pistons 20 and .past the valves 26 into. the piston chambers 46. In the closed position, the contact compression spring 49 provides the requisite contact pressure between the several contacts.

The foregoing description of one embodiment of my invention shows how I have utilized. a pluralityofmulti-orifice interrupting units. Ill. The units utilize a multi-orifice type of interrupting passage -ll for high current interruption, and.

for lowcurrent interruption also utilize a multiorifice pressure-generating arc passage 18. Thus, during low current interruption, the multi-orifice pressure-generating arc passage 18 functions as an interrupter in itself with the oil pumping pistons :Zll producing the requisite oil driving pressure. As -mentioned, during high current interruption, the pistons 26) are stalled, by the high pressure until the circuit is cleared, at which time they then function as an oil flushing means.

Any'number of these interrupting units Ware capable of being stacked one ontop of the other and operated in series without complicated coupling mechanism. The number of interrupting units [0 thus required will depend upon the voltage application. They may all be stacked in one column and utilized in an oil-poor breaker construction, as in United States Patent 2,479,381, issued August 16, 1949, to Leon R. Ludwig and Benjamin P. Baker, or the units may be divided into two groups for dead tank construction as shown" in Fig. 1 of the drawings.

It has been found that one orifice fed by oil from an adequate pressure-generating arc is capable of interrupting 25 to 33 kv. each on high values of current, i. e., 500 to 25,000 amperes. It hasalso been discovered that one orifice fed by a pressure source capable of producing 40 pounds per square inch can interrupt low (leading power factor) capacity currents without restriking if the voltage does not exceed 12 to 16 kv. Thus, if a dead tank 345 kv. breaker were to be built out of interrupting units It, such as shown in Figs. 1-5, the maximum voltage for high current operation would be 87 of 3&5 or 300 kv. Therefore, twelve orifices would be required, each working at 25 kv. On charging current, the restored voltage would be 34-5/ /3, or 200 kv. At 111 kv. per orifice, eighteen active orifices would be required. It is, therefore, evident that four interrupting units [9 would be required, such as the four shown in Fig. 1. If it is too diflicult to meet the time requirements to move the contacts, say 2%; inches, for the interrupting gap, plus 1 inches, say, for the pressure-generating gap, plus /2 inch overtravel, to create contact pressure, then an interrupting unit 81, such as shown in Fig. 6, may be utilized. This modified type of interrupting unit M has two interrupting orifices and one orifice around the pressure-generating arc. In this case, a total of six interrupting units 8! would be required, that is, three on each bushing 5, 6.

The modified type of interrupting unit 8|, as shown in Fig. 6, is identical to the preceding units l0, except it has one orifice, instead of two, at the pressure-generating gap, and two orifices, instead of three, at the interrupting gap. Since the gap distances for the unit 8! are less than the gap distances of the unit IE9, it will take a shorter time for the contacts to move to their fully open position, as shown in Fig. 6, than it would for the contacts of the units It.

It will be observed that Fig. 6 shows a broken vertical sectional view through the modified unit 81 on the line VI-VI of Fig. 4 so as to disclose only one piston 263, whereas, actually, there are in reality two such pistons disposed 180 apart. The view of Fig. 6, taken on such a broken sectional line, indicates more clearly the general direction of the oil flow through the unit.

As mentioned, during high current interruptions the oil pumps to do not follow the operating rods due to the high pressure generated by the pressure-generating are 54, which has to be relieved by forcing the oil in the flow reservoirs 55 through the interrupting orifices 58 and out through the vents it. After the arc is extinguished and the pressure has subsided, the spring-driven pumps 2b flush the carbonized oil from the units id, 8!. When the units open on low charging currents, the oil pumps 20 function to force oil through the orifices 58 in both the pressure-generating gap and the main interrupting gap. When the breaker is operated at no-load, the valves 26 at the lower ends of the pistons 20 produce circulation of clean oil through the interrupters.

The foregoing description of two embodiments of my invention show how I have provided a simplified type of high-voltage circuit interrupter of repeatable unit construction, so that the units may be stacked and used in any type or rating of high-voltage oil circuit breakers. It will also be noticed that the interrupting units can be stacked for series operation, and the operating forces for the contacts and for the pitsons 20 are all symmetrical and balanced. it will furthermore be noticed that the piston chambers 45 are very close to the pressure-generating are 5, and hence there results very little pressure drop through the interconnecting passage. Also the pressure are space F3 is connected to the main interrupting passage H through a pair of oil reservoirs 5-5 of considerable volume and cross-section.

Although I have shown and described specific structures, it is to be clearly understood that the same were merely for the purpose of illustration, and that changes and 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:

1. A circuit interrupter of the liquid break type including at least a pair of arc-extinguishing units disposed in end-to-end relation, each unit establishing a pressure-generating arc and having a movable interrupting contact for establishing a serially related interrupting arc, an operating rod movable longitudinally. of the units, means disposed between the units secured to and movable with the operating rod for carrying the inovable interrupting contact of one of the units, one or more pistons carried by said means operable within the other of said units, means biasing the one or more pistons to move in the direction of opening motion of the operating rod, and a sliding connection between the one or more pistons and said first-mentioned means so that during opening the one or more pistons may be stalled by the arc pressure without interference with opening motion of the operating rod.

2. A circuit interrupter of the liquid break type including an arc-extinguishing assemblage, the assemblage including at least a pair of arc-extinguishing units disposed in end-to-end relation, a pair of plates disposed on opposite ends of one of the units, an operating rod extending longitudinally of the assemblage and secured to the plates, one of the plates having a relatively stationary disconnect contact, a movable disconnect contact engaging the relatively stationary disconnect contact during the closing stroke to move the operating rod and the pair of plates, each plate carrying a movable interrupting contact, each unit having a relatively stationary pressuregenerating contact and an intermediate contact, the relatively stationary contact and the intermediate contact cooperating to establish a pressure-generating arc, the intermediate contact cooperating with the movable interrupting contact to establish a serially related interrupting arc, a piston carried during the closing operation by the other of said plates and movable within said one of the units to facilitate low current interruption.

3. A circuit interrupter of the liquid break type including an arc-extinguishing assemblage, the assemblage including at least a pair of arc-extinguishing units disposed in end-to-end relation, a pair of plates disposed on opposite ends of one of the units, an operating rod extending longitudinally of the assemblage and secured to the plates, one of the plates having a relatively stationary disconnect contact, a movable disconnect contact engaging the relatively stationary disconnect contact during the closing stroke to move the operating rod and the pair of plates, each plate carrying a movable interrupting contact, each unit having a relatively stationary pressure-generating contact and an intermediate contact, the relatively stationary contact and the intermediate contact cooperating to establish a pressure-generating arc, the intermediate contact operating with the movable interrupting contact to establish a serially related interrupting arc, a piston carried during the closing operation by the other of said plates and movable within said one of the units to facilitate low current interruption, said piston having a sliding connection with said other of the plates during opening, and means biasing the piston to move in the opening direction.

4. A circuit interrupter of the liquid break type including at least a pair of arc-extinguishing units disposed in end-to-end relation, each unit having contact means therein including a movable contact for establishing an arc, an operating rod movable longitudinally of the units, means disposed between the units secured to and movable with the operating rod for carrying the movable interrupting contact of one of the units, one or more pistons carried by said means operable within the other of said units, means biasing the one or more pistons to move in the direction or opening motion of the operating rod, and a sliding connection between the one or more pistons and said second-mentioned means so that during opening the one or more pistons may be stalled by the arc pressure without interference with opening motion of the operating rod.

5. A circuit interrupter of the liquid break type including an arc-extinguishing assemblage, the assemblage including at least a pair of arc-extinguishing units disposed in end-to-end relation, a pair of plates disposed on opposite ends of one of the units, an operating rod extending longitudinally of the assemblage and secured to the plates, one of the plates having a relatively stationary disconnect contact, a movable disconnect contact engaging the relatively stationary disconnect contact during the closing stroke to move the operating rod and the pair of plates, each plate carrying a movable interrupting contact, each unit having contact means including said movable contact for establishing an are within the unit, and a piston carried during the closing operation by the other of said plates and movable within said one of the units to facilitate low current interruption.

6. A circuit interrupter of the liquid break type including an arc-extinguishing assemblage, the assemblage including at least a pair of arc-extinguishing units disposed in end-to-end relation, a pair of plates disposed on opposite ends of one of the units, an operating rod extendin longitudinally of the assemblage and secured to the plates, one of the plates having a relatively stationary disconnect contact, a movable disconnect contact engaging the relatively stationary disconnect contact during the closing stroke to move the operating rod and the pair of plates, each plate carrying a movable interrupting contact, each unit having contact means including said movable contact for establishing an arc within the unit, a piston carried during the closing operation by the other of said plates and movable within said one of the units to facilitate low current interruption, said piston having a sliding 10 connection with said other of the plates during opening, and means biasing the piston to move in the opening direction.

7. A circuit interrupter of the liquid break type including an arc-extinguishing assemblage, the assemblage including at least a pair of arc-extinguishing units disposed in end-to-end relation, a pair of plates disposed on opposite ends of one of the units, an operating rod extending longitudinally of the assemblage and secured to the plates, one of the plates having a relatively stationary disconnect contact, a movable disconnect contact engaging the relatively stationary disconnect contact during the closing stroke to move the operating rod and the pair of plates, each plate carrying an axially movable interrupting contact, each unit having a relatively stationary pressure-generating contact and an axially movable intermediate contact, the relatively stationary contact and the intermediate contact cooperating to establish a pressure-generating arc, the intermediate contact cooperating with the movable interruptin contact to establish a serially related interrupting are, a piston carried during the closing operation by the other of said plates and movable Within said one of the units to facilitate low current interruption.

BENJAMIN P. BAKER.

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

UNITED STATES PATENTS Number Name Date 2,137,873 Dickinson et al. Nov. 22, 1938 2,403,103 Leeds July 2, 1946 2,412,897 MacNeill Dec. 17, 1946 2,420,889 Leeds May 20, 1947 2,462,708 Baker et al. Feb. 22, 1949 2,465,240 Leeds Mar. 22, 1949

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