US2138382A

US2138382A - Circuit breaker

Info

Publication number: US2138382A
Application number: US145273A
Authority: US
Inventors: Winthrop M Leeds; Ortensi Ennio
Original assignee: Westinghouse Electric and Manufacturing Co
Current assignee: CBS Corp
Priority date: 1937-05-28
Filing date: 1937-05-28
Publication date: 1938-11-29
Anticipated expiration: 1955-11-29
Also published as: CH207591A; DE713419C; GB495540A; FR830656A

Description

Nov. 29, 1938. w. M. LEEDS ET AL 2,133,332

CIRCUIT BREAKER Filed May 28, 1957 4 Sheets-Sheet 1 VE s W/nfhrop A4. Leeds 8 Enm'o Orfens/ W29 555: #422 a? M Nov. 29, 1938. w. M. LEEDS ET AL 2,138,382

CIRCUIT BREAKER Filed May 28, 1937 4 Sheets-Sheet 3 WITNESSE lNVENTOR$-' WGM v W/hfhrop M. Leeds; W Elm/'0 Orfens/ F4 19 H920 1792/ F4 22 5923 W. M. LEEDS ET AL C IRCUIT BREAKER 4 Sheets-Sheet 4 Nov. 29, 1938.

Filed May 28, 1937 INVENTORS K/mhmp M. Leeds 4? inn/'0 Orfensfi BY 4 Z ATTORNEY Patented Nov. 29, 1938 CIRCUIT BREAKER Winthrop M. Leeds, Wilkinsburg, Pat, and Ennio Ortensi, Bergamo, Italy, assignors to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa... a corporation of Pennsylvania Application May 28, 1937, Serial No. 145,273

23 Claims.

This invention relates to high-power circuit interrupters of the liquid-immersed type, and more particularly, to circuit interrupters that utilize an arc restraining channel or slot in which the arc is subjected to strong deionizing action by turbulently intermixing un-ionized gas and liquid particles with the arc stream. The instant invention is also, in certain aspects, an improvement of the inventions set forth and broadly claimed in the applications of B. P. Baker, Serial No. 230,946, filed September 21, 1938, and W. M. Leeds et al., Serial No. 144,626, filed May 25, 1937, both of which are assigned to the assignee of this application.

Heretofore attempts have been made to hasten the deionization of the are by driving it into a restricted passage and subjecting it to strong cross blasts of oil and gas immediately following the. establishment of the arc, irrespective of the instantaneous current conditions. We have discovered that forcing an arc into a very narrow slot and subjecting it to strong cross blasts during the major portion of the alternating-current cycle, particularly when instantaneous values of current are relatively large, produces a harmful effect on the interrupting ability of the arc rupturing device. Poor performance under these conditions is attributed to the resultant high are voltage and high internal pressure developed Within the-interrupting structure. Our study of arc-interrupting phenomena reveals that circuit interrupter performance may be improved by adhering to the following steps in the method of treating the arc during the circuit-interrupting operation.

First, during the greater portion of time are current is flowing, particularly in the region of the peak of the current wave, the arc should be disturbed as little as possible by cross blasts, restricting walls, or strong magnetic action, so as to keep the arc voltage and the consequent gas generation as low as possible; second, vents, passages and liquid flow should be arranged to drive the products of decomposition of the are out of the arc chamber as fast as they are formed so as to maintain high dielectric in theatre chamber and keep the internal pressure reasonably low; and third, just prior to current zero when the arc current is relatively low, strong deionizing action should be brought into play, as for instance, subjecting the arc to turbulent cross blasts of liquid and gas, confining the arc within a restricted passage or rapidly moving or lengthening the arc. These methods of treatment to produce rapid deionization either singly or in (c1. zoo-15o) combination, though preferably the latter, insure complete interruption of the circuit at current zero.

The main object, therefore, of

[our invention is to provide means for improving the arc-rupturing ability or a circuit interrupter of the liquid-immersed type.

position of the arc.

A more specific object of our invention is to provide a circuit interrupter in which improved performance is attained by effecting arc extinction in accordance with the steps enumerated above.

Other objects and advantages of the interrupter structure whereby the aforerelate to details named v objects are obtained and will appear more fully in the following description taken in connection with the accompanying drawings, in

which Figure 1 is a side elevation view partially in section showing an embodiment of our invention;

Fig. 2 is a fragmentary view of the arc-ex-.

tinguishing units of our circuit interrupter showing one of the arc-extinguishing section;

units in vertical Fig. 3 is a sectional view taken along line III-III of Fig. 2;

Fig. 4 is a cross-sectional view of one of the arc-extinguishing units taken along line IV-IV of Fig. 2;

Fig. 4a is a fragmentary cross-sectional view taken along line IVa-IVa of Fig. 3; Figs. 5 to 23 inclusive, are plan and sectional views of the respective individual platemembers which constitute each of the arc-extinguishing units of our circuit interrupter;

Fig. 24 is a vertical sectional modified arc-extinguishing unit;

View through a Fig. 25 is a plan view of the arc-extinguishing unit shown in Fig. 24 as viewed along the line Fig. 26 is a cross-sectional view taken along the line XXVL-XXVI of Fig. 24 and,

Fig. 27 is a fragmentary view partially in section showing the interrupter of Fig. .1 in the open circuit position.

With particular reference to Fig. 1, the reference numeral I designates a cylindrical casing preferably of metal, which forms part of the housing or the circuit interrupter.

The casing I is provided with an annular top plate 3, which is adapted to support a cylindrical strain cylinder 5, preferably of insulating material, such as flbre or a material known to the trade as Micarta." The lower portion of the strain member is provided with a metallic flange member 1 which, in turn, may be bolted to the annular plate 3, thereby securing it against lateral and longitudinal movement. The upper end of the strain member 5 is also provided with a flanged metallic member designated at 9. To the flange 9 may be bolted a top plate Surrounding the strain member 5 is a weather-proof casing |3 preferably of porcelain or some other suitable material having weather-resisting properties.

The weather-proof casing 3 in this instance, is adapted to rest at its lower end upon a metallic sub-casing IS. A metallic flange |1 secured to the lower edge of the weather-proof casing I3 permits bolting the latter casing to the sub-casing l5, as shown. A cork gasket l9 interposed between the casing I3 and the casing 5 provides a seal between these two casings so as to permit the annular space between the strain member 5 and the casing |3 to be filled with insulating liquid.

A resilient annular metal expansion member 2| having a C-shaped cross-section, is interposed between the upper end of the casing l5 and the top plate ll. A gasket 23 interposed between the resilient member 2| and the casing |3 provides the necessary seal for retaining the insulating liquid heretofore mentioned. A gasket may also be placed between the resilient member 2| and the top plate I l, as shown. The relative longitudinal dimensions of the strain member 5 and the weather-proof casing |3 are such that when they are in the assembled position, as shown, the resilient member 2| exerts a compressive force upon the casing 3. Thus the seal between the resilient member 2| and the weather-proof casing i3 is always maintained regardless of the difference in expansion of the inner strain member 5 and the outer weather-proof casing l3.

The top plate ii is provided with a hanger plate 25 to which is secured an arc interrupting assemblage generally indicated at 21. The are interrupting assemblage 21 may comprise a plurality of arc-extinguishing units 29, two of which are shown. Each arc-extinguishing unit 29 comprises a stack of plates, more specifically illustrated in Figs. 5 to 23 inclusive. These plates are assembled upon insulating tie rods 3|, the ends of which are provided with metallic portions 33 which are threaded for the reception of clamping nuts 35. The two units 29 in this instance are supported in spaced relation with respect to each other by means of four spacing sleeves 31 assembled on the rods 3|.

The uppermost arc-extinguishing unit 29 is suspended from the hanger plate 25 by four hanger rods 39, the lower portions of which are screwthreaded onto the respective metallic portions 33 of the tie rods 3| and the upper portions of which are screw-threaded and extend through the hanger plate 25 and are provided with nuts 4|. A spacing sleeve 43' surrounds each of the hanger rods 39 and is disposed between the hanger plate 25 and the upper arc-extinguishing unit 29.

Each of the arc-extinguishing units 29 has an upper plate 45 preferably of metallic: material, and as shown particularly in Figs. 5 and 6, is provided with a circular aperture 41 for the reception of a piston member to be described hereinafter, a rectangular aperture 49 for the reception of a stationary contact member, two rectangular apertures 5|, which serve as vent openings and a single circular aperture 53 which also serves as a vent opening. The following plate 55, as shown in Figs. 7, 8 and 9, as well as the remaining plates, have a circular aperture 41. Plate 55, which is preferably of insulating material, such as fibre, also has a circular vent aperture 53. The aperture 41 in plate 55 communicates with a slot 51 of irregular outline. The lower end of slot 51 is provided with beveled surfaces 58 on either side thereof, as shown more clearly in Figs. 8 and 9, the purpose of which will appear hereinafter.

Plate 6| of fibre or other suitable insulating material, is disposed adjacent the plates 55. The plate 6| as more clearly shown in Figs. and 11, has a relatively wide slot 53 therein which slot joins the circular aperture 41. The sides of the slot 63 are provided with a plurality of, in this instance 3, notches or indentations 55, the central one of which is considerably deeper than those on either side thereof.

The plate 5| also has an aperture 51 in alignment with the lower end of slot 63. The next plate in the stack is designated at 69 and is more clearly shown in Figs. 12 and 13. This plate has

circular apertures

41 and 53 positioned so as to axially align with the

apertures

41 and 53 of plate 45. These apertures are joined by a slot-like passage 1| having a narrow restricted portion 13 adjacent the aperture 53 and a wider portion 15 adjacent the aperture'41.

Immediately following the plate 69 is a plate 11, which in the main is composed of insulating material such as fibre, and has a U-shaped insert 19 of magnetic material. The plate 11 in all other respects is similar in construction to plate 69. The insert of magnetic material 19, as shown, is disposed about the slot-like passage 1|, and the purpose of which will appear more fully hereinafter.

The plate 11 is followed by a second plate 59. Adjacent plate 59 is a plate of greater thickness designated at 8| and shown in Figs. 16 and 17. The plate 8| has a configuration similar to that of plate 6|, except that the slot 83 is somewhat narrower than the slot 63 and also tapers in the direction towards the lower end thereof. The aperture designated at 85 is also somewhat wider than the aperture 51 in plate 6|, thereby providing for a narrower strip of material between the aperture andslot than in the plate 6|. The intervening

portions

81 and 68 of plates 8| and 6|, respectively, serve as barriers, the purpose of which will be fully explained hereinafter.

The remaining plates of the stack, with the exception of several adjacent the lower end of the stack, which will be hereinafter described, comprise successive groups of

plates

69, 11, 69 and 8| in the order named, Towards the lower end of the stack is provided a plate designated at 89 which is similar to plate 11 with the exception that the vent aperture 53 has been omitted. Plate 89, however, is disposed between plates 69 in a manner similar to the arrangement of the plates above. The second to the last plate in the stack is designated at 9| and is similar to plates 6| and 8| with the exception that the slot 93 has a width intermediate .that of the aforenamed plates. The plate 9| plates 5| and 8| in that the slot 93 is extended so as to eliminate the barrier such as barriers 58 and 81 found in plates 5| and 8|, respectively.

The lowermost plate of the stack, which is desalso distinguishes from ignated at 95 has considerably more thickness than any of the. previously described plates, is preferably composed of insulating material, as fibre or the like, and differs substantially from the construction of the foregoing plates. The aperture 41 in this instance, is threaded for the purpose of receiving a bushing to be hereinafter described. Adjacent the aperture 41 is a short slot 91 having a depth substantially equal to onehalf the thickness of the plate.

From the foregoing specific description of the individual plates comprising the stack of each unit 29, it will be apparent that when the various plates are assembled upon the tie rods 3I, the apertures 41 will be in alignment and form a cylindrical passage IN. The slots H in

plates

69, 11 and 89 generally define the outlines of an arc passage I03. The passage I03 has a narrow slotlike restricting portion I05 defined by the slot portion 13. The enlarged portion 15 of the respective slots 1I defines the walls of an enlarged portion I01 of the passage I03, which enlarged portion communicates with the cylindrical passage IOI. The arrangement of this passage is more clearly shown in Fig. 4.

As indicated in Figs. 2 and 3, the upper plate 45 of each unit 29 is provided with a contactcarrying member I09, which is mounted transversely across the aperture 49 and is retained in position by two spaced bolts III, the lower ends of which are secured to the plate 45. The contact-carrying member I09 has a limited amount of movement in the vertical direction, determined by a coil spring II3 interposed between the head of each bolt II I and the contact-carrying member. The springs II3 thus bias the contact-carrying member I09 toward the plate 45.

The contact-carrying member I09 is provided with a contact II5 secured to the lower side thereof and adapted to extend through the aperture 49 and-into the slot 51 of plate 55. The plate 45 also carries an upper arcing horn II1 secured thereto by screws H9 and disposed so as to extend into the slot 51 of plate 55 immediately adjacent the stationary contact H5.

The aperture 41 in plate 45 is provided with a guide bushing I2I for the reception of a piston I23 movable in the cylindrical passage IOI. Though the piston I23 may have a smooth outer surface it is preferably of tubular form having circumferential grooves formed therein and is also preferably of insulating material such as fibre or the like. The circumferential grooves increase the break-down voltage longitudinally of the piston and permit'a flow of liquid from the remote side of the passage IOI towards the arc passage I03. The piston I23 also forms a part of the movable contact assemblage including a movable contact I25 of rectangular crosssection integrally secured to a cylindrical portion I21, which in turn is mounted upon a tubular metallic coupling I29.

The metallic coupling I29 is adapted to receive a tie rod I3I preferably of insulating material, which is adapted to extend through the bore of the piston I23 and is provided at its upper end with a metallic coupling member I33. The metallic. coupling member I33 has a threaded portion shown at I35 for the purpose of receiving a spanner nut I31, whereby the piston I23 and the movable contact I25 with its carrier I21 are accordingly maintained in the assembled position. The upper metallic coupling member I33 is joined to an operating rod I39, which as more clearly shown in Fig. 1, extends upwardly through hanger plate 25 and is provided at its upper end with base of easing I.

a guide plate I. Guide plate MI is adapted to slide within a cylindrical housing I43 secured by bolts I45 to the top plate II. The housing I43 is closed at its upper end so as 'to provide a bearing surface for an accelerating spring I41 interposed between the closed end of the casin and the guide plate I4 I. The accelerating spring I41 urges the operating rod I39 downwardly and consequently, carries the piston I23 and the movable contact I25 to the open circuit position as indicated in Fig. 2.

In the particular arrangement shown in Figs. 1 and 2, employing two arc-extinguishing units 29, the lower metallic coupling element I 29 is coupled to the upper magnetic coupling element I33 of the lowermost unit 29. Thus, the two pistons I23 in each unit 29 are coupled axially for simultaneous actuation. The metallic coupling member I29 of the lowermost unit has provided thereon a pair of laterally yielding contact fingers I5I which are adapted to engage a contact actuating member I 53, in this instance having a lower reduced section I55 of circular cross-section adapted for sliding movement in a tubular guide member I51 mounted through the Contact actuating member I53 is disposed in axial alignment with operating rod I39 and the tie rods I3I, so that if a reciprocating motion is imparted to the actuating member I53, a corresponding reciprocating motion will be imparted to the two pistons I23 and their associated contacts I25. In this manner, the movable contacts I25 are operated into and out of engagement with their respective stationary contacts H5.

The contact actuating member I23 is adapted to be operated by a suitable straight-line motion mechanism generally indicated at I59, which in turn, is provided with a crank arm I 6|, adapted to be actuated by a rod I63 by any suitable operating mechanism, not shown.

When the interrupter is in the closed circuit position, as shown in Fig. 1, the electrical circuit therethrough comprises the line terminal I65 forming part of the top plate II, a flexible conductor I61 connecting the top plate II with the contact-carrying member I 09 of the upper arcextinguishing unit 29, as shown at I69. The circuit proceeds from the contact-carrying member I09 to the contact II5, which is in engagement with the movable contact I25. The movable contact I25 in turn is secured to the contact-carrying member I21 which has a fixed. engagement with the metallic coupling member I29. The metallic coupling member I29 is, in turn, secured to metallic coupling member I31 of the next adjacent unit I29.

In the lower unit 29, a flexible shunt I1I is interposed between the nut I31 and the piston I23. The flexible shunt IN is preferably divided as shown in Fig. 3, and has the free ends secured to the respective ends of the contactcarrying member I09 by bolts I13 as shown. Thus the circuit continues from contact-carrying member I09 of the lowermost unit through its respective fixed contact II5, to its movable contact I25, and to the lower metallic coupling member I29. From the metallic coupling member I29 the circuit proceeds to the contact fingers I5I and hence to the contact actuating member I53.

The latter member is provided with a flexible shunt connection I15, which connects to a terminal I11, which terminal is connected by a conductor I19 to the base of casing I. The base of casing I may preferably be provided with a terminal I8I which serves as the other line terminal of the interrupter.

Each of the arc-extinguishing units 29 is also provided with a lower arcing horn I83, in this instance, secured as by screws or bolts I85 to the lower plate 95. The arc horn I83 is disposed within the slot 93 of the plate 9| and has one end adjacent the movable contact I25 when the latter is moved to the full open position, as shown in Fig. 2. A flexible connection I81 secured to the bolt I85 joins the arc horn I83 of the upper unit 29 with the contact-carrying member I09 of the lower unit 29, as shown in Fig. 2. A similar connection I89 is made to the resilient contacts ISI for the lowermost unit 29.

The operation of the interrupter during circuit interruption is as follows. Upon the occurrence of an overload in the connected circuit or upon the tripping of the operating mechanism (not shown), the rod IE3 is actuated upwardly, which in turn, actuates the mechanism I59 so as to move the contact actuating member I53 to its lowermost position. The movement of the actuating member I53 downwardly is accelerated by the action of spring I41, thereby greatly increasing the speed of separation of the contacts H5 and I25 in each unit. Upon the separation of the contacts H5 and I25, an arc is established within. the enlarged portion I07 of the arc passage I03. During the establishment of the arc the piston I23 has been moved into the cylindrical chamber IOI, thereby forcing arc-extinguishing liquid, in which the units 29 are submerged, upwardly past the moving contact I25 and longitudinally of the arc. This rapidly moving stream of liquid carries off the gases produced by the action of the arc on the arc-extinguishing liquid, forcing them upwardly away from the arc stream adjacent either side of the upper arcing horn I I! through the slot 5'! of plate 55, past the bevelled surfaces 59 of the plate 55 and finally to the two rectangular vent openings 5i. Thedisposition of the vent openings 5| with respect to the slot 51 of plate 55 and the upper. arc horn II! is more clearly shown in Fig. 4a. If the arc has been established at a time in the current cycle corresponding" to relatively high instantaneous current, the arc will have a relatively large crosssectional' area, but due to the relatively wide portion I01 of the arc passage I03, it will not be materially restricted.

On account of the magnetic reaction of the U- shaped plates I9 inserted in the plates TI and 89, the arc will be biased towards the entrance of the restricted portion I05 of the passage I03. However, due to the large arc section and the relatively weak pull of the magnetized plates I9, the arc will not be moved into the restricted portion, but will be permitted to play in the enlarged portion I01 of the arc passage I03. However, as the instantaneous value of the current decreases, the cross-sectional area of the are also decreases and at a point just prior to current zero when the arc section has decreased sufliciently, the arc will be moved laterally by the magnetic reaction of the U-shaped plates I9 into the restricted portion I05 of the arc passage I03. As soon as the arc is transferred to the restricted portion I05, the electrical circuit through each interrupting unit 29 proceeds from the contact-carrying member I09, the top plate 45, the upper arc horn I I1, through the arc stream to the lower arc horn I83, the bolt I85, flexible connector I87 to the contact-carrying member I09 of the lower unit 29. The circuit through the lower unit 23 is similar to that of the upper unit with the exception that the lower arc horn I83 of the lower unit is connected by flexible conductor I89 to the contacts I5I.

Movement of the are into the restricted portion I05 of the arc passage I03 is also assisted by the pressure within the enlarged portion III! of the arc passage created by the piston I23. As soon as the arc enters the restricted portion I05, it is subjected to a strong cross blast of oil and gas as a result of the intimate engagement of the arc with the, liquid entrapped by the notches 55 forming pockets along the walls of the passage I03. The gas thus produced must escape through the arc towards the rearward side of the restricted portion I05 of the passage and rises through the vent openings 53 which are in alignment so as to form a vent shaft for the entire stack of plates. This vent shaft communicates with the restricted portion I05 of the arc passage by way of the restricted slot portion I3 in the plates 69, TI and 89. The portions 58 and 81 of plates SI and 8i serve as barriers to prevent the are from moving entirely into the vent shaft 53.

Inasmuch as the restricted portion I 05 is extremely narrow, the escape passages for the gas into the vent shaft 53 are also restricted to the same degree thereby subjecting the are which may have moved to a point adjacent the barriers to a high velocity of flow or cross blast, which insures arc interruption at the time of current zero in the current wave of the arc.

The deionization of the arc while in the restricted portion I05 is especially rapid, due to the rapid rate at which dielectric strength is being built up along the arc stream. The oil pockets 65 along the walls of the passage provide an adequate supply of arc-extinguishing liquid, which when acted upon by the arc, produces sufficient quantities of un-ionized gas and liquid particles which are turbulently intermixed with the ionized particles of the arc stream, thereby causing a loss of ions so as to prevent the reignition of the are after current zero. The particular are interrupting device is eflicient for the reason that the arc energy is maintained at a low value, particularly at the current peak of the arc. This is accomplished by maintaining the arc in a relatively unrestricted passage during the time of peak current or during that portion of the current wave when appreciable instantaneous current is flowing. The action of the piston which is moved simultaneously with the movable contact, causes the flow of arc-extinguishing liquid longitudinally in the arc stream, thereby sweeping the products of decomposition of the are from the arc passage substantially at the rate in which these products are formed; thereby the internal pres.- sure of the arc-extinguishing unit is maintained at a low value; and circuit interruption is effected at a time most favorable for are extinction by subjecting the arc to strong cross blasts of unionized gas and liquid particles just prior to current zero. The particular venting arrangement for directing the gas and oil laterally through the are are also of importance in eiIecting the improved interrupting qualities of the arc-extinguishing units.

The foregoing description of the operation of the interrupter has dealt primarily with the interrupting operation within each of the arc rupturing units 29. During the opening movement of the interrupter, operating rod I33, pistons I23, contacts I25 and the contact actuating member I53 move downwardly as a unit until the contacts I25 engage the bottom of the slots 91 in the lower plate 95 of their respective units. The contact actuating member I53, however, is free to continue its downward movement until its lower end engages the base of the casing I. This additional movement permits the contact actuating member I53 to separate from the contact fingers I5I to thereby place an additional gap in the electrical circuit as shown in Fig. 27. Inasmuch as are extinction within the arc rupturing units 29 takes place within a relatively short period of time, the circuit will have been interrupted prior to the separation of the contact actuating member I53 and the contact fingers I5I. Thus the break between the contact fingers I51 and the contact member I53 provides further insulation in the circuit and insures a higher factor of safety against breakdown when the interrupter is in the open circuit position.

In closing the breaker, the contact actuating member I53 is operated upwardly by the mechanism I59 intoengagement with the contact fingers I5I and the coupling member I29 of the lower arcextinguishing unit 29. Continued upward movement of the member I53 carries the movable contacts I25 with their pistons I23 to the closed circuit position against the bias of the accelerating spring I41. .In the closed circuit position, contact pressure between the stationary contact H5 and the movable contacts I25 is maintained by the spring II3. These springs also assist the accelerating spring I41 in overcoming the inertia of the moving contact assemblage at the beginning of the circuit opening operation.

A modified form of arc-extinguishing unit is shown in Figs. 24 to 2'7 inclusive. This unit is substantially like the units previously described, with the exception that the oil circulating piston I9I is adapted to operate within a cylindrical passage I93, which communicates with the arc passage I95 only at its upper and lower ends as shown at I91 and I99, respectively. The stationary contact;'29l in this instance is provided with an aperture 293 extending axially thereof to the exterior of the arc-extinguishing unit. The aperture 293 provides ready means for venting the products of decomposition of .the arc during its maintenance between the contact MI and the movable contact 295.

As shown in Fig. 24, the movable contact 295 enters the lower. plate 291 and is supported by abracket 299 secured to the operating rod 2| I. Operating rod 2 extends axially through the passage I93 and also carries the piston I9I. The upper plate 2 I3 of the unit carries the upper arc horn 2I5 which has passages therethrough indicated at 2", which are adapted to communicate with a lateral passage 2I9 in theplate 2I3,

which in turn, mmunicates with the passage.

I91 leading tohe cylindrical passage I93. It will thus be seen that as the arc is established in the passage l95, internal pressure within the passage will react through the passages 2I1, 2I9, I91 and in back of piston I9 I, thereby tending to equalize the reactive force on the forward side of the piston I9I.

By utilizing the internal pressure of the interrupting unit to assist in actuating the piston I9I to the open circuit position, the external force required to actuate the interrupter to the open position is-great1y reduced. Thus a large volume of oil may be circulated with relatively small actuating force upon the operating rod 2I I. The arc-extinguishing operation in other respects for the interrupter of the type shown in Figs. 24 to 26 is substantially the same as the operation of the arc-extinguishing unit previously described.

Althoughv we have shown and described specific arrangements of arc-extinguishing units and their disposition within a circuit interrupter housing, it is to be understood that the same was for the purpose of illustration and that changes and modifications may be made in both structure and'the arrangement thereof by those skilled in the art, without departing from the spirit and scope of the appended claims.

We claim as our invention:

1. The method of extinguishing an are which hasbeen established within an arc extinguishing liquid comprising, positively moving a quantity of liquid into engagement with the are for displacing the products of decomposition of the are from the region thereof without substantially disturbing the continuity of the arc stream, moving the arc laterally through the liquid upon the occurrence of predetermined conditions, and finally subjecting the arc to intense blasts of liquid and the products of decomposition of the arc to break up .the continuity of the arc stream.

2. The method of extinguishing an are which has been established within an arc extinguishing liquid comprising, positively circulating a quantity of liquid in close proximity to the arc to displace the products of decomposition of the arc from the region thereof without causing substantial penetration of the liquid into the arc core, moving the arc laterally through the liquid and constricting its cross section and finally forcing the products of decomposition of the arc and liquid into and through the arc core to break the continuity of the arc stream.

3. The method of interrupting an electrical circuit comprising establishing an are within an arc-extinguishing liquid, subjecting the arc streamto a substantially longitudinal flow of insulating liquid until a predetermined time before current zero, moving said are laterally and constricting its cross section and finally subjecting the arc to a cross blast of insulating liquid while in said constricted condition.

4. The method of interrupting an electrical circuit comprising establishing an are within an arc-extinguishing liquid, displacing the products of decomposition of said arc longitudinally thereof at a rate substantially equal to the rate of formation of said products, moving said are laterally when it has reached a predetermined cross-sectional area and subjecting the moving arc to a cross blast of the products of decomposition formed during such lateral movement.

5. The method of interrupting an electrical circuit comprising establishing an arc within an insulating liquid, maintaining the are at least during the flow of maximum current in the current wave substantially free from cross blasts of gas by removing the gas longitudinally of the arc stream substantially as rapidly as it is formed, moving the arc laterally in the insulating liquid when it has reached a predetermined cross-sectional area and finally subjecting the arc to a cross blast of gas during such lateral movement. 6. The method of interrupting an electrical circuit comprising establishing an are within an arc-extinguishing liquid, maintaining the arc in a predetermined position during at least the flow of peak current in the current wave, removing the gas generated by the arc from the arc stream longitudinally thereof at a rate substantially equal to the rate of formation of said gas, moving the arc laterally in the liquid from said predetermined position and finally subjecting the arc to a combined cross blast of gas and liquid during said lateral movement.

'7. The method of interrupting an electrical circuit comprising establishing an are within an insulating liquid, holding the arc in a predetermined position until the cross-sectional area thereof has been reduced to a predetermined value, positively moving a s earn of liquid longitudinally of the arc while the arc is in said predetermined position for r moving the products of decomposition of the are substantially as rapidly as said products are formed, moving the arc laterally through the liquid from said predetermined position and finally subjecting the are to a combined cross blast of liquid and the products of decomposition of the are during said lateral movement.

8. In a circuit interrupter, means at least partially of insulating material defining a substantially completely enclosed arc passage, an insulating liquid within said passage, separabie contacts for establishing an are within said passage, means maintaining said arc in a predetermined position dtuing the initial stage of arc interruption, means for positively moving a quantity of insulating liq uid into engagement with said are without substantially breaking the continuity of the arc stream while the arc is in said predetermined position, means for subsequently moving the arc laterally through said liquid and means for sub-- jecting the arc to a turbulent fiow of gas produced by the action of the are on said liquid during the lateral movement of the arc.

9. In a circuit interrupter, means at least partially of insulating material defining a substantially completely enclosed arc passage, an insulating liquid within said passage, separable contacts for establishing an are within said passage, means maintaining said are in a predetermined position during the initial stage of arc interruption, venting means for said passage causing the products of decomposition of the arc to flow longitudiually of the arc while it is in said predetermined position, means for subsequently moving the arc laterally through said liquid and means for further venting the passage to cause the products of decomposition of the arc to flow laterally through the arc during said lateral movement of the arc.

10. In a circuit interrupter, means at least partially of insulating material defining a substantially completely enclosed arc passage, an insulating liquid within said passage, separable contacts for establishing an are within said passage, means maintaining said are in a predetermined position during the initial stage of arc interruption, a piston associated with said passage and operative during the establishment of said are to positivelymove a quantity of insulating liquid longitudinally of said are while said are is in said predetermined position, means for subsequently moving said are laterally through said liquid and means for directing a combined blast of insulating liquid and gas resulting from the action of said are upon the liquid laterally through the arc during lateral movement thereof.

11. In a circuit interrupter, a body of insulating liquid, means of insulating material immersed in, said liquid for defining an arc passage, said passage having an enlarged portion and a restricted slot-like portion, separamle contacts for establishing an arc in said enlarged portion, means biasing the arc laterally toward said res tricted portion, said restricted portion being sufliciently narrow to prevent arcs entering therein during the period of instantaneous currents above a predetermined value, said biasing means moving the arc laterally into said restricted portion following the reduction of instantaneous currents below said predetermined value, and vent means adjacent the rearward portion of said restricted portion of said passage for causing the products of decomposition of the arc to flow laterally through the are stream in escaping from the passage.

12. In a circuit interrupter, a body of insulating liquid, means of insulating material immersed in said liquid for defining an arc passage, said passage having an enlarged portion and a restricted slot-like portion, separable contacts for establishing an arc in said enlarged portion, means biasing the arc laterally toward said restricted portion, said restricted portion being sufficiently narrow to prevent arcs entering therein during the period of instantaneous currents above a predetermined value, vent means for causing the products of decomposition produced by the arc while the latter is maintained within said enlarged portion of the arc passage to flow longi-' tudinally of the are stream in escaping from the passage, said biasing means moving the arc laterally into said restricted portion following the reduction of instantaneous current below said predetermined value and additional vent means adjacent the rearward portion of said restricted portion of the arc passage for causing the proclucts of decomposition of the are produced during lateral movement thereof to fiow laterally through the arc stream in escaping from the arc passage.

13. In a circuit interrupter, a body of insulating liquid, means of insulating material immersed in said liquid for defining an arc passage, said passage having an enlarged portion and a restricted slot-like portion, separable contacts for establishing an arc in said enlarged portion, means biasing the arc laterally toward said restricted portion, said restricted portion being sufficiently narrow to prevent arcs entering therein during the period of instantaneous currents above a predetermined value, a vent opening adjacent one end of the enlarged portion of said are passage, means for positively moving a quantity of liquid longitudinally of the arc while the arc is within said enlarged portion of the arc passage for expelling the products of decomposition of the are from said enlarged portion of the arc passage through. said vent opening, and additional vent openings adjacent. the rearward portion of said restricted portion of the arc passage for causing the products of decomposition produced during lateral movement of the are within said restricted portion of the arc passage to be blown laterally through the arc stream.

14. In a circuit interrupter, a body of arcextinguishing liquid, an arc-extinguishing unit immersed in said liquid comprising means of insulating material defining an arc passage, said are passage having an enlarged portion and a restricted slot-dike portion, a pair of contacts within said enlarged portion, at least one of said contacts being movable to establish an are within said enlarged portion, means biasing said are laterally toward the restricted portion of said passage, said restricted portion being sufficiently narrow to prevent arcs of cross-sectional area greater than a predetermined cross-sectional area to be moved therein by said biasing means, means actuated simultaneously with said movable contact for positively moving a quantity of liquid longitudinally of the arc While the arc is retained within the enlarged portion of said arc passage, and means for causing liquid to flow laterally through the arc stream following the entrance of the arc into the restricted portion of the arc passage.

15. In a circuit interrupter, a body of arcextinguishing liquid, an arc-extinguishing unit immersed in said liquid comprising means of insulating material defining an arc passage, said are passage having an enlarged portion and a restricted slot-like portion, a pair of contacts within said enlarged portion, at least one of said contacts being movable to establish an are within said enlarged portion, means biasing said are laterally toward the restricted portion of said passage, said restricted portion being suificiently narrow to prevent arcs of cross-sectional area greater than a predetermined cross-sectional area to be moved therein by said biasing means, a vent opening adjacent one end of said enlarged portion of the arc passage, a piston operative in accordance with predetermined movement of said movable contact for driving arc-extinguishing liquid along the longitudinal axis of the arc to expel the products of decomposition of the are through said vent opening during the time said are is retained in said enlarged portion, said biasing means assisted by the flow of arc-extinguishing liquid moving said are laterally into said restricted portion following a reduction of the cross-sectional area of said arcbelow said predetermined cross-sectional area, and additional vent openings disposed rear- Wardly of said restricted portion of the arc passage for causing .the products of decomposition of the arc during its lateral movement within said restricted portion to flow laterally through the arc stream.

16. In a circuit interrupter, a body of arcextinguishing liquid, means of insulating material immersed in said liquid defining a narrow arc chamber and a cylindrical passage communicating with said chamber, a piston movable in said cylindrical passage, a stationary contact extending into said chamber, a cooperating contact movable for establishing an are within said chamber, means for moving said are laterally within said chamber upon the occurrence of predetermined conditions, actuating means for operating said cooperating movable contact to establish the arc and for operating said piston to move a quantity of arc-extinguishing liquid longitudinally of the arc prior to movement of the arc laterally in said chamber, and means for venting said chamber to cause the products of decomposition of the arc to flow laterally through the moving arc in escaping from the chamber.

17. In acircuit interrupter, a body of arcextinguishing liquid, means of insulating material immersed in said liquid defining a narrow arc.

by said rod into and out of engagement with said.

stationary contact, means for actuating said rod to simultaneously establish an are within said chamber and to cause said piston to move a quantity of arc-extinguishing liquid longitudinally of the arc and means for moving the arc laterally within said are chamber.

18. In a circuit interrupter, a body of arcextinguishing liquid, means of insulating material immersed in said liquid defining a narrow arc chamber and a cylindrical passage having continuous communication with said chamber adjacent one side thereof, a stationary contact within said chamber adjacent said cylindrical passage, a piston movable in said cylindrical passage, an operating rod for said piston, a cooperating contact carried by said operating rod disposed adjacent one end of said piston and adapted to be moved by said rod into and out of engagement with said stationary contact, means for actuating said rod to simultaneously establish an are within said chamber and to cause said piston to move a quantity of arc-extinguishing liquid longitudinal- 1y of the are, means for moving the arc laterally within said are chamber in response to predetermined conditions, and means for venting one side of said are chamber to cause a lateral flow of gas through the arc stream as the arc is moved within said are chamber.

19. In a circuit interrupter, a body of arcextinguishing liquid, means of insulating material immersed in said liquid defining a narrow arc chamber and a cylindrical passage having continuous communication with said chamber adjacent one side thereof, said are chamber having a restricted slot-like portion and an enlarged portion of greater width, said enlarged portion being adjacent said cylindrical passage, a stationary contact within the enlarged portion adjacent said cylindrical passage, an operating rod movable through said cylindrical passage, a cooperating contact carried by said operating rod and adapted to be actuated thereby into and out of engagement with said stationary contact, a piston carried by said operating rod and movable in said cylindrical passage, venting means adjacent one end of the enlarged portion of said are chamber, actuating means for said operating rod for causing a predetermined separation of said contacts to establish an are within the enlarged portion of said are chamber and to cause said piston to move a quantity of arc-extinguishing liquid longitudinally of the arc, said moving arc-extinguishing liquid expelling the products of decomposition of the are through said venting means, means for moving said are laterally into the restricted portion of the arc chamber in response to predetermined conditions and means for venting one side of said restricted portion of the arc chamber to cause the products of decomposition of the arc resulting from movement of the arc laterally within said restricted portion to flow laterally through the arc stream.

20. In a circuit interrupter, a body of arcextinguishing liquid, means of insulating material immersed in said liquid defining a narrow arc chamber and a cylindrical passage, each end of said cylindrical passage having a fluid connection with said are chamber, a piston in said cylindrical passage movable between said fluid connections, a stationary contact extending into said chamber, a cooperating contact movable for establishing an arcwithin said chamber, means for moving said are laterally within said chamber upon the occurrence of predetermined conditions, actuating means for operating said cooperating movable contact to establish the arc and for operating said piston to move a quantity of arc-extinguishing liquid from said cylindrical passage through one of said connections longiare laterally in said chamber, and means for venting said chamber to cause the products of decomposition of the arc to flow laterally through the moving arc in escaping from said chamber, said fluid connections from said arc chamber to said cylindrical passage causing the pressure within said arc chamber to react substantially equally upon both sides of said piston.

21. The method of interrupting an electrical circuit comprising, establishing an are within an arc extinguishing liquid, maintaining the arc in a predetermined position until a predetermined time before current zero, subjecting the arc stream to a mild blast of arc extinguishing liquid when in said predetermined position, moving the arc in one section from said predetermined position and constricting its cross section and finally subjecting the arc to an intense blast of arc extinguishing liquid while in said constricted condition.

22. In a circuit interrupter, a body of arc extinguishing liquid, means of insulating material immersed in said liquid defining an arc chamber, a pair of separable contacts within said arc chamber for establishing an arc therein, a piston chamber having a fluid connection with each end of said are chamber, a piston movable within said piston chamber, and actuating means for operating said contacts for establishing the arc and for operating said piston to move a quantity of arc extinguishing liquid from said piston chamber through one of said connections into engagement with the arc stream, said fluid connections from said are chamber to said piston chamber causing the pressure within said arc chamber to react substantially equally upon both sides of said piston.

23. In a circuit interrupter, a body of arc extinguishing liquid, means of insulating material immersed in said liquid defining a narrow arc chamber, a pair of separable contacts within said are chamber for establishing an arc therein, means for moving the arc laterally within said arc chamber upon the occurrence of predetermined conditions, a piston chamber having a fluid connection with each end of said arc chamber, a piston movable within said piston chamber, and actuating means for operating said contacts to establish the arc and for operating said piston to move a quantity of arc extinguishing liquid from said piston chamber through one of said connections into engagement with the arc stream prior to movement of the arc laterally in said are chamber, said fluid connections from said are chamber to said piston chamber causing the pressure within said are chamber to react substantially equally upon both sides of said piston.

WINTHROP M. LEEDS.

ENNIO ORTENSI.