US2428597A

US2428597A - Circuit interrupter

Info

Publication number: US2428597A
Application number: US494212A
Authority: US
Inventors: Roswell C Van Sickle; Benjamin P Baker; Erik H Hall
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1943-07-10
Filing date: 1943-07-10
Publication date: 1947-10-07
Anticipated expiration: 1964-10-07

Description

Oct. 7, 1947.

WITNESSES: W. W1. w

R. c. VAN SICKLE ETAL' 2,428,597

CIRCUIT INTERR'LIPTER Filed July 10, 1943 3 Sheets-Sheet l INVENTORS Roswell G Van Sickle,

Benjamin PBa/ker ZEN/k HHa/l.

Oct. 7, 1947. R. c. VAN SICKLE ET AL 2,428,597

CIRCUIT INTERRUPTER Filed July 10, 1943 3 Sheets-Sheet 2 Oct. 7, 1947. R. c. VAN SICKLE ETAL 2,428,597

CIRCUIT INTERRUPTER Filed July 10, 1945 3 Sheets-Sheet 5 2230 3529. fig] 1// 1211f 1i all '80 11a Y 124 WITNESSES: 35 31 INVENTORS 4% 0510811 6'. VarISZa/KZe,

' Benjamin Pg alrer ZEN}? AO /ail Patented Oct. 7,

UNITED STATES PATENT OFFICE Baker, Turtle Creek, and Erik H. Hall, Wilkinsburg, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corpora tion of Pennsylvania Application July 10, 1943, Serial No. 494,212l

19 Claims. 1

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

A general object of our invention is to provide an improved circuit interrupter in which the over-all space requirements are minimized by employin expandable and contractable or telescopic means relating the arcing contacts with the serially related disconnect contacts.

Another object is to provide an improved pumping arrangement which may readily be employed in conjunction with an interrupter of the foregos type.

Further objects and advantages will readily become apparent upon a reading of the following specification taken in conjunction with the drawings in which:

Fig. 1 is a vertical sectional View of a circuit interrupter embodying my invention and shown in the closed circuit position;

Fig. 2 is a fragmentary view similar to Fig. 1, but showing the disposition of the movable parts near the end of the opening operation;

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

Fig, 4 is a fragmentary view in cross-section taken on the line IV-IV of Fig. 1;

Fig. 5 is a fragmentary enlarged vertical sectional View taken on the line V-V of Fig. 1, and shows the disposition of the movable parts at an intermediate point in the closing operation;

Fig. 6 is a fragmentary enlarged vertical sectional view of a modified type disconnect structure, the parts being shown in the closed circuit position;

Fig. 7 is an enlarged fragmentary vertical sectional view of still another modified disconnect arrangement, the parts being shown in the closed circuit position;

Fig. 8 is a fragmentary vertical sectional view taken on the line VIII-VIII of Fig. 7;

Fig. 9 is a vertical sectional view of a modified arrangement for connecting the piston connect-- ing rod with the operating mechanism for the interrupter, the parts being shown in the closed circuit position of the interrupter;

Fig. 10 is a vertical sectional view of a modified type disconnect structure in which during the closing operation the arcing contacts make engagement before the disconnect contacts; and

Fig. 11 is a modified piston connecting arrangement, in which the piston is used entirely for flushing purposes, the parts being shown with the contacts in the fully open circuit position before the arcing pressure has died down.

Referrin to the drawings, and more particularly to Fig. l, the reference numeral l designates a suitable base structure which supports at its upper end a support plate 2. Resting on the support plate 2 is a weather-proof casing 3 preferably made of a ceramic material. A support plate 4 rests on the casing 3 and supports a metallic cylinder 5, which is closed at its upper end by a valve cap 6. Disposed internally of the casing 3 is an insulating casing I having its ends threadedly secured to a pair of annular brackets 8, the latter being secured, as by bolts '9, to the

support plates

2, 4.

The casing 'l is filled with a suitable arc extinguishing fluid l l, in this instance oil, which rises to the level I2 within the interrupter. Disposed within the insulating casing l is an arc extingishing device generally designated by the reference numeral [3. The arc extinguishing device l3 comprises a cylindrical casing I5, which encloses at its lower end a plurality of insulating washers l6, ll of different internal diameters. Con sequently, the insulating washers l6, l1 form a corrugated outer surface for an annular arcing chamber generally designated by the reference numeral 18. Above the washers I6, I! are a plurality of longitudinally extending segmental or first arcing contacts [9, which are biased radially inwardly by tension springs 20, stop rings 2| limiting the radial inward movement of the stationary first arcing contacts l9. Movable axially within the casing I5 is the movable contact structure for the interrupter generally designated by the reference numeral 22. The movable contact structure 22 comprises an insulating rod 23. An insulatin sleeve 24 encloses the insulating rod 23, and a nut 26 maintains a washer 25 against the insulating sleeve 24. Threadedly secured to the lower end of the insulating rod 23 is a movable arcing or first contact member 21. A plurality of

insulating rings

29, 30 are disposed about the insulating sleeve 24 between the movable first arcing contact member 21 and an insulating sleeve 3|, the latter being disposed about the insulating sleeve 24. A compression spring 32, disposed between the upper end of the insulating sleeve 3| and the washer 25, serves to maintain the insulating

rings

29, 30 in compressed relation. If, through continued use of the interrupter, the

insulating rings

29, 30 become warped or otherwise distorted in shape, the compression spring 32 will be additionally compressed; and as a result there will be no severe stress set up to distort the movable contact structure 22,

The outer diameter of the insulating rings 29 are greater than the outer diameter of the insulating rings 30. Consequently, the

insulating rings

29, 30 form a corrugated inner surface for the annular arcing chamber I8, the purpose for which will appear more clearly hereinafter.

The movable arcing contact member 21 has an annular arcing surface 33, which cooperate in the closed circuit position, as shown in Fig. 1, with the stationary arcing contacts 9. Passages 34 are formed in the movable arcing contact member 21 and at their upper end terminate adjacent the annular arcing surface 33. An annular valve ring 35 biased downwardly by a compression spring 38, serves to normally close the passages 34 as shown more clearly in Fig. 5. The movable arcing contact member 21, is threaded, as at 31, to threadedly engage a conducting cylindrical member 38, the latter forming a piston chamber generally designated by the reference numeral 39. The lower end of the conducting cylindrical member 38 is bifurcated to provide two integrally formed legs 40 more clearly shown in Fig. 5. A flexible conductor 42 is secured by a screw at one end to one of the legs 45 and at its other end is connected to a terminal stud 43. A piston 44 is slidably operative within the piston chamber 39, and is pivotally connected at 45 to a piston connecting rod 46, the latter having an elongated slot 41 formed at its lower end. A pair of compression springs 48 disposed within the piston chamber 39 serve to bias the piston 44 upwardly. A valve 59 is provided in the piston 44 and serves to control the flow of oil through apertures formed in the piston 44.

A pair of rotatable actuating members 52, pivoted at 53 to a bracket 54, support a pin 55 which extends through the slot 41 in the piston connecting rod 45 as shown more clearly in Fig. 5. A pin 56 is supported at the left-hand end of the actuating members 52 and serves to pivotally connect the actuating members 52 with a pair of operating members 51 intermediate the ends thereof. A pin 58 is supported at the left-hand ends of the operating members 51 and carries a roller 59 which moves horizontally in a roller guide 69 formed by two brackets 6|. Pins 63, secured to the right-hand ends of the operating members 57, pass through apertures 62 formed in the legs 40, thus pivotally connecting the piston chamber 39 with the operating members 51 as shown more clearly in Fig. 5.

A link 64 together with a crank arm 65 form a toggle generally designated by the reference numeral 68 which relates rotative movement of the operating shaft 61 to the actuating members 52. A compression spring 69, encircling a spring guide rod 14 and disposed between a spring seat welded to the rod 14 and a fixed bracket 16 through which the spring guide rod 14 slidably passes, serves to bias the knee pin 10 of the toggle 66 in a clockwise direction about the operating shaft 61. An insulating operatin rod 1| is pivotally connected at 12 to crank arm 13 fixed to the shaft 61. Consequently, upward or opening movement of the operating rod 1| rotates the operating shaft 61 in a clockwise direction and causes counterclockwise rotative movement of the actuating members 52, this opening movement being assisted by the accelerating spring 69. During the downward or closing movement of the rod 1| the accelerating spring 69 is compressed and the actuating members 52 are rotated in a clock- Wise direction about the pin 53.

A conducting sleeve 89, slidably passing through the cover M of the arc extinguishing device I3, is disposed about the insulating sleeve 3|, and has a lost-motion connection therewith. The slots 8| formed in the contact sleeve permit free downward movement of the movable contact structure 22 without tending to compress any oil between the conducting sleeve 88 and the insulating sleeve 3|, Disposed at the upper end of the conducting sleeve 80 is a movable disconnect or second contact 82. Energy storing means in this instance comprises a compression spring 83 which encircles the insulating sleeve 3|. The spring 83 has its upper end seated on the insulating. Washer 25 and has its lower end seated on a radially inwardly extending flange portion of the conducting sleeve 80. A stationar disconnect or second contact 81 cooperates with the movable disconnect or second contact 82 and is formed by a plurality of segmental contact members 85 biased radially inwardly by a plurality of tension springs 88. The segmental contact members 88 are secured by screws 94 to an oflstanding conducting bracket 89, the latter being supported by a bolt 90 to the support plate 4. A bolt 9|, having its lower end threadedly secured to the bracket 89, supports a washer 92 which serves as an upper seat for a compression spring 93, the latter biasing the Valve cap 8 to its closed position against the cylinder 5 as shown in Fig. 1. One of the screws 94 also serves to connect one end of a flexible conductor 95 to the conductingbracket 89, the other end of theconductor 95 being electrically connected to the terminal stud 96 extending through the cylinder 5.

It will, therefore, be apparent that in the closed circuit position of theinterrupter, as shown in Fig. 1, the electrioal'circuit therethrough c0mprises terminal stud 96, flexible, conductor. 95, screw 94, stationary disconnect'or secondcontact 81, movable disconnect or second contact 82, conducting sleeve 89, longitudinal segmental stati'onary or first arcing contacts l9, annular arcing surface 33 of mova ble first arcing contact member 21, conducting cylindrical member 38, leg dil and ilexibleconductor 42 to terminal stud 43. When it is desired to break the electrical circuit through the interrupter, or in response to overload conditions existing in the circuit. controlled by the interrupter suitable operating means, not shown are actuated. to cause upward or opening movement of the insulating operating rod 1|. The upward movement of the insulating rod 1| rotates the operating shaft 61 in a clockwise direction being assistedby accelerating spring 69. The clockwise rotation of the operating shaft 61 moves the toggle 66,to cause counterclockwise rotative movement of the actuating members 52 aboutpin 53, The counterclockwise movement of actuating members, 52 causes the operating members 51 t 'rotate in a clockwise direction about the roller 59, the roller 59 meanwhile moving toward the left, as viewed in Fig. 1 in the roller guide 53.

The clockwise rotative movement of the operating members 51 serves to move the legs 40, and hence the movable contact structure 22, downwardly. This draws an are 99 between the stationary first arcing contacts l9 and the arcing surface 33 of the movable first arcing contact member 21. The are is shown more clearly in Fig. 2. Durin the initial downward movement of the movable contact structure 22 the conducting sleeve 80 remains stationary, and the washer 25 compresses the compression spring 83, frictional engagement between the stationary and movable

second disconnect contacts

81, 82 being suflicient to maintain the conducting sleeve 89 in a stationary position. The friction between the conducting sleeve 80 and the upper end of arcing contacts 19 also helps to maintain the sleeve 80 stationary during the initial portion of the opening operation.

Therefore it is apparent that the movable first arcing contact 33 is expanded relative to the movable second disconnect contact 82 as shown in Fig. 2, whereas in the closed circuit position of the interrupter, as shown in Fig. 1, the movable contact 33 and the movable disconnect contact 82 are contracted relative to one another.

The drawing of the arc 99 between the stationary and

movable arcing contacts

19, 33 within the annular arcing chamber l8 serves to raise the pressure therein, the arc reacting upon the oil to form gaseous products of decomposition under pressure.

It will be observed that during the initial downward movement of the piston chamber 39 the pin 55 moves up in the slot 41 provided in the piston connecting rod 46 as shown in Fig, 2. Since the oil disposed within the piston chamber 39 is unable, because of the high pressure, to move through the passage 34 and out of the piston chamber 39, the compression springs 48 remain compressed and the pin 55 merely moves upwardly in the slot 41 disposed in the piston connecting rod 46 as shown in Fig. 2.

Continued downward movement of the movable contact structure 22 results in lengthening the are 99, and further storing energy in the energy storing means. That is, the compression spring 83 associated with the disconnect structure is further compressed. As the are 99 is lengthened it engages fresh oil disposed in the recesses between the insulating

rings

29, 39 and the insulating washers l6, l1. Various aspects of the arc extinguishing device 13 are described and claimed in the United States Patent 2,253,009, which issued August 19, 1941, to Benjamin P. Baker and which was assigned to the assignee of the instant application.

When the movable parts assume the position shown in Fig. 2, the pin 55 is approaching the position where it will strike the top of the slot 41 provided in the piston connecting rod 46 and positively interrelates opening movement of the actuating members 52 with upward movement of the piston 44 relative to the chamber 39. This does three things. First, the upward movement of the piston 44 opens the valve 35 and forces oil within the piston chamber 39 upwardly through the passages 34 and adjacent the are 99 to facilitate the extinction thereof. Secondly, the upward movement of the piston 44, as positively caused by the pin 55 striking the top of the slot 41, slows down the high speed opening movement of the operating means for the interrupter, This occurs near the end of the opening stroke and at a time when it is desirable to slow down the high speed opening movement of the operating mechanism. Thirdly, the continued upward movement of the piston 44 following extinction of the are 99 under the biasing action exerted by the compression springs 48, as permitted by the slot 41-, produces a flushing action fOlIOWiIlg arc extinction to flush carbonized products of decomposition upwardly out of the annular arcin chamber [8 through the Vent Ill.

It will, therefore, be apparent that the initial upward movement of the piston 44 is caused positively by the pin 55 strikin the upper end of the slot 41 and that continued upward movement of the piston 44 is permitted by the slot 41. Consequently, the extinction of the arc 99 is not only assisted by the extinguishing action provided in the arc extinguishing device I3, but also by the oil flow out of the piston chamber 39.

The are 99 may or may not be extinguished at the time in the opening operation indicated in Fig. 2. Heavy current arcs will probably have been extinguished before this point is reached. Light current arcs may not have had sufficient pressure developed to cause their extinction and in this case the flow of oil produced by the piston is of assistance in producing arc extinction.

It will be observed that in the position of the parts shown in Fig. 2 the washer 25 is just engaging the sleeve 84, which is fixed to the sleeve 80, to positively drive the conducting sleeve downwardly. The conducting sleeve 83 is forced positively downward by the washer 25 striking the sleeve 84 at a time when the are 99 is normally extinguished, and when it is desirable to provide a disconnect gap of suflicient length in the interrupter so that breakdown through the interrupter will not occur as a result of voltage surges passing along the electrical line connected to the interrupter.

Referring to Fig. 3 it will be observed that the washer 25 has served to move the conducting sleeve 80 downward out of frictional engagement with the stationary disconnect contact 81. After the conducting sleeve 89 has been positively disengaged from the stationary disconnect contact 81, the force of gravity, and the energy which has :been stored up in the energy storing means, in this instance comprising the compression spring 83, serves to drive the conducting sleeve 80 downward to separate the movable disconnect contact 82 from the stationary disconnect contact 81. This provides a disconnect gap of length A as shown in Fig. 3. Fig. 3 shows the disposition of the movable parts in the fully open circuit position of the interrupter, with the movable arcing contact 33 and the movable disconnect contact 82 contracted relative to one another.

It will be observed that in Fig. 3 the piston 44 is disposed at the upper end of the piston chamber 39. Consequently, the upward movement of the piston 44 within the piston chamber 39 not only serves to drive oil out of the passages 34 adjacent the are 99 to facilitate the extinction thereof, but also the continued upward movement of the piston 44 following extinction of the are 99 serves to flush decomposed products of decomposition upwardly out of the annular arcing chamber I3 and out through the vent 10.

It will be observed in Fig. 2 that the distance B indicates the amount of expansion between movable arcing contact 33 and movable disconmeet contact 82. Thus, there is a saving of longitudinal space in the interrupter of the distance B. It will, therefore, be apparent that we have provided a novel circuit interrupting structure in which in the fully closed and in the fully open circuit positions the movable arcing contact 33 and the movable disconnect contact 82 are contracted relative to one another, whereas during the initial portion of the opening operation the movable arcing contact 33 and the movable dis connect contact 82 are expanded relative to one another. The valve cap 6, biased downwardly toward the closed position by the compression spring 93, serves to relieve excess pressure created within the interrupter.

To close the electrical circuit through the interrupter the insulating operating rod II is moved downwardly by suitable mechanism not shown. The downward movement of the operating rod lI rotates the operating shaft 61 in a counterclockwise direction to straighten the toggle '66 and to move the actuating members 52 in a clockwise direction about the pin 53. In the fully open circuit position of the interrupter, as shown in Fig. 3, the pin I53 is below the pin 55. In the fully closed circuit position of the interrupter, as shown in Fig. 1, the pin 53 is above the pin 55. It will, thereiore, be apparent that during the closing operation the piston 44 is moved downwardly relative to the piston chamber 39 to draw fresh oil through the opening Iflll in the cylinder member 38, through the apertures and into the piston chamber 39 by suction action, the annular valve ring meanwhile remaining closed over the passages 34. The purpose of the annular valve ring 35 is to prevent oil which hasv been contaminated in the arcing chamber from being drawn into the piston chamber 39 during the closing stroke. This gives the oil circulation which forces fresh clean oil upward through the interrupter and prevents the downward flow of dirty oil.

Fig. 5 shows the disposition of the parts. at, an intermediate point during the closing stroke with fresh oil being drawn into the piston chamber 39. During the closing operation the pin 55 is constantly maintained at the lower endof the slot 4'1, not only due to the suction drawn within the piston chamber 39, but also because of the upward bising action exerted by the compression spring 43. It will, therefore, be apparent that during successive opening and closing operations of the interrupter a unidirectional flow of oil takes place through the piston chamber 39, the oil entering the vent i239 leaving the piston chamber 3t through the passages 3 d. The piston 44 is completely charged in the closed circuit position of the interrupter, as shown in Fig. 1, fresh uncontaminated oil now being present within the piston chamber 39 ready to be used during the next opening operation of the interrupter.

It will also be observed that during the closing operation the movable arcing contact 33 engages the stationary arcing contact Ill substantially the same time that the movable disconnect contact 82 engages the stationary disconnect con-- tact Bl. Therefore, we have provided an interrupter in which the disconnect contacts or second contacts remain in engagement while the arcing contacts or first contacts separate to draw an are 98. Following extinction of the are 93 the disconnect contacts separate to produce an iso lating gap in the interrupter in the fully open circuit position thereof. During the closing operation the arcing contacts engage substantially simultaneously with the engagement of the disconnect contacts. This reduces the electrical stress on the interrupter produced during the closing operation.

This reduced electrical stress is particularly important for high speed reclosing service, during which the contacts must b reclosed before all are products have been expelled from the interrupter. The simultaneous closing of the serially connected disconnecting break in the uncontaminated oil will thus minimize prestriking and areing on the reclosing part of the operation and thus assure more favorable conditions in the interrupter for the second opening operation in case the fault still persists.

It will be observed that in the interrupter shown in Figs. 1 through 5 friction is th only force which maintains the disconnect contacts in engagement while the compression spring 83 is being compressed by downward movement of the movable contact structure 22. In certain applications it is desirable to supplement the force of friction holding the

disconnect contacts

82, 81 in engagement by positive latching means, and in Figs. 6 through 8 we disclose two such latching arrangements.

Referring more particularly to Fig. 6 it will be observed that we have provided a latching member I05 pivotally mounted at I08 and biased in a clockwise direction about pivot I09 by a compression spring Ifi'l. The latch I65 is biased into a latch opening I08 provided in the conducting sleeve 80. Thus should the force of friction tending to maintain the disconnect contacts in engagement decrease through wear of the parts or otherwise, still the provision of the latch I05 would prevent downward movement of the conducting sleeve and movable disconnect contact 82 under the biasing action exerted by the compression spring 83 before interruption of the arc 99. Therefore, downward movement of the movable contact structure 22 causes the washer 25 to compress the compression spring 83, the latch I05 meanwhile positively maintaining the conducting sleeve 80 in its raised position thereby maintaining the

disconnect contacts

82, 81 in engagement. However, when the insulating washer 25 strikes the portion I89 of the latch member I05, the latch I will be forced in a counterclockwise direction about pin I06 to permit the conducting sleeve 80 to move downward thereby separating the

disconnect contacts

82, 81 at a time when the arc 99 is extinguished.

In Figs. '7 and 8 another latching arrangement for the disconnecting structure is shown. Here a latch H3 is disposed within the stationary disconnect contact SI and is pivotally mounted on a pin I M, a coil spring I I5 biasing the latch H3 in a clockwise direction about pin II4 as viewed in Fig. 8. A latch portion II6 of the latch II3 latches under a pin III which is fixed to and extends diametrically across the movable disconnect contact 82. A U-shaped latch release wire H9 is secured, as by welding, to a sleeve II8 slidable on the sleeve 3| as shown more clearly in Fig. '7. A light compression spring I24 biases the sleeve H8 and the release wire II9 upwardly against an inwardly extending flange portion I25 of the movable disconnect contact 82 as shown in- Fig. 7. The latch release wire IIB slidably extends through two apertures I20 formed in washer 25. Consequently, during the initial downward movement of the movable contact structure 22 the latch H3 will maintain the

disconnect contacts

82, 81 in engagement, the washer 25 meanwhile moving downwardly to compress the compression spring 83. Th washer 25 strikes the sleeve H8 at a time when the are 99 has been extinguished. When the washer 2'5 strikes the sleeve H8 and compresses spring I24 under the sleeve H8, the latch release wire II9 will b positively driven downward. The downward movement of the release wire H9 will serve to force the release portion I2I of the latch I I3 in a counterclockwise direction about the pin H4 thereby permitting the latch H3 to release the pin II'I. Resulting downward movement of the conducting sleeve 8|] and separation of the

disconnect contacts

92, 81 is caused by the force of gravity and release of the energy stored in the energy storing means 83.

The flange portion I25 of movable disconnect contact 82 will force the release wire H9 and sleeve H8 downward with the conducting sleeve 80 after the pin II'I has been unlatched.

If the interrupter is designed to interrupt currents of such magnitude that the arcing pressure created Within the annular arcing chamber I8 is not extremely high, it may be desirable to posi tively relate upward movement of the piston 44 with opening movement of the operating mechanism during the entire opening stroke. Referring to Fig. 9 it will be observed that the pin 55 is pivotally connected to the piston connecting rod 46 and that in this embodiment of ou invention the elongated slot 41 is omitted. By utilizing this construction opening movement of the operating mechanism simultaneously positively causes upward movement of the piston 44 relative to the piston chamber 39 to cause oil to flow upward through the passages 34, past the valve ring 35 and into the annular arcing chamber I8 to facilitate the extinction of the are 99.

However, the piston construction which we disclose in Figs. 1 through 5 is considered preferable because high speed initial opening movement with no retardation is possible, whereas in the piston arrangement of Fig. 9 the movement of oil out of the piston chamber 39 necessitates the employment of strong accelerating springs to get high speed initial opening movement. For the interruption of low currents with correspondingly low arcing pressures, or in an interrupter of such design that high arcing pressures are not encountered, and where a continued pumpin action during the entire opening stroke is desired, the piston construction of Fig. 9 may be used. The charging during the closing operation of the piston chamber 39 in Fig. 9 is identical to that disclosed in connection with the piston arrangement shown in Figs. 1 through 5; consequently, a further description thereof is not deemed necessary for a full understanding of this embodiment of our invention. Since the piston 44 in Fig, 9 is positively related to the operating mechanism, no compression springs 48 within the piston chamber 39 need be used. 7

In the disconnect construction shown in Fig. provision is made for closing the arcing contacts, or first pair of contacts 33, I9 during the closing operation prior to the closure of the disconnect contacts or second pair of

contacts

82, 81. Therefore, if the interrupter is closed during the existence of overload conditions in the circuit controlled by the interrupter, the resulting arc will form at the

disconnect contacts

82, 81 and not within the casing I5. Consequently, there is no possibility of contaminating, or lowering the dielectric strength of, the oil within the casing I5 during a closing operation which would be detrimental during the subsequent opening operation. Instead, the arc would be formed at the

disconnect contacts

82, 81 in a region of freely circulating oil which will rapidly recover its dielectric strength. The construction in Fig. 10 utilizes a greater wiping action between the arcing contacts 33, I9 than in the construction shown in Fig. 1. Consequently, the arcing contacts 33, I9 engage before the engagement of the

disconnect contacts

82, 81 during a closing operation. The arcing contacts 33, I9 remain in sliding engagement until the movable disconnect contact 82 fully engages the stationary disconnect contact 81, at which time the movable contact structure 22 comes to rest. The openin sequence for the contacts in the embodiment of our invention shown in Fig. 10 is the same as that previously described in Figs, 1-5, that is contacts I9, 33 separate before

contacts

82, 81.

In the modified piston connecting arrangement of Fig. 11, a longer slot I22 is provided, so that the operating mechanism may move to the fully open circuit position (as shown in Fig. 11) without the pin forceably causing the piston 44 to move. The slot I22 is, consequently, longer than the slot 41. Thus the piston 44 in Fig. 11 remains down until the pressure has subsided in the arcing chamber I8, at which time the piston moves upward solely under the biasing action exerted by the springs 48. The charging of the piston 44 in Fig. 11 during the closing stroke is identical to that previously described. The longer slot I22 permits the piston 44 in Fig. 11 to be operative exclusively as a flushing piston, there being no positive interconnection between the pin 55 and the slot I 22 during the opening operation.

It will, therefore, be apparent that we have provided a novel circuit interrupter having a pair of movable contacts which are expandable and contractable relative to one another, the arrange ment operating to reduce the longitudinal space occupied by the interrupter. By maintaining both disconnect contacts substantially stationary during the initial portion of the circuit opening operation, the inertia of the moving parts during the initial portion of the circuit opening operation is reduced and a Weaker accelerating spring 69 may be employed.

It will be observed that we have provided an energy storing means, comprising the compression spring 83, which stores energy during the initial portion of the opening movement of the movable contact structure 22. The release of energy from the energy storing means 83 serves to result in 'high speed opening movement of the movable disconnect contact 82.

It will be observed that the novel pumping means which we disclose is moved with the movable contact structure 22 and serves to force oil adjacent the movable arcing contact 33 adjacent the arc 99. The piston 44 may be positively interrelated with the opening movement of the operating means as shown in Fig. 9, or the piston 44 may have a lost motion connection 41 with the actuating members 52 so that only near the end of the opening stroke is there a positive interconnection between the piston 44 and the actuating members 52. The latter arrangement results in (1) facilitating arc extinction if the arc is not already extinguished at this time, (2) providing a flushing flow of oil following are interruption, and (3) serving to slow down the high speed opening motion of the movable contact structure 22 near the end of the opening opera- 11 tionat a time when it is desirable to bring the moving parts to a gradual cushioned stop.

If a longer slot I22 is used the piston 44 will function exclusively as a flushing piston as in Fig. 11. It will be noted that we have provided two alternative latching arrangements to supplement the forces of friction for maintaining the

disconncct contacts

82,81 in engagement during the initial portion of the opening operation.

Although we have disclosed and described specific structures it is to be clearly understood that the same. were merely for purposes of illustration, and, that changes and modifications may readily be made by those skilled in the art without departingfrom the spirit and scope of the invention.

We claim as our invention:

1., Ina circuit interrupter, a pair of arcing contacts separable to establish an are, a pair of disconnect contacts electrically connected in series with the arcing contacts, means for separating thedisconnectcontacts after the arcing contacts have separated to produce an isolating gap in the circuit after the arcing contacts have separated enough for arc extinction, and operating mechanism substantially simultaneously closing both the arcing contacts and the disconnect contacts during the closing operation of the interrupter.

2. In a circuit interrupter, an arc extinguishing chamber, movable contact structure comprising a pair of arcing contacts separable within the arc-extinguishing chamber to establish an arc therein and a pair of disconnectcontacts electrically'connected'in series with the arcing con tacts and separable. outside of the are extinguishing chamber, means for maintaining the disconnect contacts in engagement :during the initial portion of the opening operation of the arcing contacts, means for causing opening movement of thedisconnect contacts after separation of the arcing contacts, and means for causing substantially simultaneous closing of the arcing and disconnect contacts.

3. In a circuit interrupter, movable contact structure comprising a pair of arcing contacts separable to establish an arc and a pair of disconnect contacts electrically connected in series with the arcing contacts, means for maintaining the disconnect contacts in engagement during the initial portion of the opening operation, energy storing means in which energy is stored as a result of opening movement of the movable contact structure, and means permitting a, release of energy from the energy storing means to separate the pair of serially related disconnect contacts after the arcing contacts have separated enough for arc extinction, and means for causing substantially simultaneous closing of the arcing and disconnect contacts during a closing operation.

4. In a circuit interrupter, a relatively stationary arcing-contact cooperable with a movable arcing contact to establish an are, a relatively stationary disconnect contact, a movable disconnect contact, a lost-motion connection between the movable arcing contact and the movable disconnect contact, means for maintaining the two disconnect contacts in engagement and relatively stationary during the initial portion of the opening operation of the interrupter, means electrically'connectingthearcing contacts in series with the disconnect contacts, and means causing opening' motion of the movable disconnect contact in a direction toward the movable arcing contact after the initial portion of the opening movement of the movable arcing contact.

5.. In a circuit interrupter, a movable arcing contact separable from a relatively stationary arcing contact to establish an arc, a movable disconnect contact separable from a relatively stationary disconnect contact to produce an isolating gap in the circuit after arc extinction, means electrically connecting the arcing contacts in series with the disconnect contacts, expandable and contractable means interconnecting the movable arcing contact and the movable disconnect contact, and means for effecting a closing of the arcing contacts prior to a closing of the disconnect contacts during a closing operation of the interrupter.

6. In a circuit interrupter, a movable arcing contact separable from a stationary arcing contact to establish an arc, a movable disconnect contact separable from a stationary disconnect contact to produce an isolating gap in the circuit after arc extinction, means electrically connecting the arcing contacts in series with the disconnect contacts, telescopic means interconnecting the two movable contacts, and means for effecting a closing of the arcing contacts prior to a closing of the disconnect contacts during a closing operation.

'7. In a circuit interrupt-er, a relatively stationary arcing contact cooperable with a movable arcing contact to establish an arc, a relatively stationary disconnect contact, a movable disconnect contact, means electrically connecting the arcing contacts in series with the disconnect contacts, telescopic means for maintaining the two disconnect contacts in engagement and relatively stationary during the initial portion of the opening operation of the interrupter and meanwhile separating the arcing contacts, and latching means for insuring engagement of the disconnect contacts during the initial portion of the circuit interrupter opening operation.

8. In a circuit interrupter, a pair of spaced apart substantially stationary contacts, a pair of serially related movable contacts each engageable with one of said stationary contacts and completing a series circuit through both pair of contacts, expandable and contractable means interconnecting the pair of movable contacts, the pair of movable contacts being contracted in the closed and in the fully open circuit positions of the interrupter, and means for causing the pair of movable contacts to separate relative to each other to expanded position during the initial portion of the circuit interrupter opening operation While one movable contact separates from its stationary contact and the other movable contact remains in engagement with its stationary contact.

9. In a circuit interrupter, a pair of serially related movable contacts, a pair of relatively sta tionary contacts, expandable and contractable means interconnecting the pair of movable contacts, means for separating one of the movable contacts from one of the stationary contacts and causing an expansion between the pair of movable contacts, means for subsequently separating the other movable contact from the other stationary contact and causing a contraction between the pair of movable contacts.

10. In a circuit interrupter, a pair of spaced apart substantially tationary contacts, a pair of serially related movable contacts each engageable with one of said stationary contacts and completing a series circuit through both pair of contacts, expandable and contractable means interconnecting the pair of serially related movable contacts, the pair of movable contacts being contracted in the closed and in the fully open circuit positions of the interrupter, means for causing the pair of movable contacts to separate relative to each other to expanded position during the initial portion of the circuit interrupter opening operation while one movable contact separates from its stationary contact and the other movable contact remains in engagement with its stationary contact, and energy storing means in which energy is stored during the expansion between the pair of movable contacts for moving said movable contacts to their contracted position.

11. In a circuit interrupter, a pair of spaced apart substantially stationary contacts, a pair of movable contacts, one of said movable contacts completing the circuit between said stationary contacts and the other of said movable contacts completing the circuit to one of said stationary contacts, when the interrupter is closed, expandable and contractable means interconnecting the pair of movable contacts, the pair of movable contacts being contracted in the closed and in the fully open circuit positions of the interrupter, the pair of movable contacts being expanded during the initial portion of the circuit interrupter opening operation, and means in which energy is stored during the expansion between the pair of movable contacts and then released to cause a rapid contraction between the pair of movable contacts during the latter portion of the circuit interrupter opening operation.

12. In a circuit interrupter, a pair of serially related movable contacts, expandable and contractable means interconnecting the pair of movable contacts, the pair of movable contacts being contracted in the closed and in the fully open circuit positions of the interrupter, and the pair of movable contacts being expanded during the initial portion of the circuit interrupter opening operation, and latching means operative to insure that there will be an expansion between v the pair of movable contacts during the initial portion of the circuit interrupter opening operation.

13. In a circuit interrupter, a pair of serially related movable contacts, expandable and contractable means interconnecting the pair of movable contacts, means moving the pair of movable contacts sequentially and causing an expansion therebetween during the initial portion of the circuit interrupter opening operation, the pair of movable contacts being contracted in the closed in the fully open circuit position of the interrupter, and means moving the pair of movable contacts simultaneously in their contracted positions during the closing operation of the interrupter.

14. In a circuit interrupter, a pair of relatively stationary contacts, a pair of serially related movable contacts, expandable and contractable means interconnecting the pair of serially related movable contacts, means causing the separation of one of the movable contacts from one of the stationary contacts before the separation of the'other movable contact from the other stationary contact during the initial portion of the circuit interrupter opening operation to effect thereby an expansion between the pair of movable contacts, the pair of movable contacts being contracted in the fully open circuit position of the interrupter, and means for moving the pair of movable contacts together in their contracted position during the closing operation.

15. In a circuit interrupter, a pair of relatively stationary contacts, a, pair of serially related movable contacts, expandable and contractable means interconnecting the pair of serially related movable contacts, means causing the separation of one of the movable contacts from one of the stationary contacts before the separation of the other movable contact from the other stationary contact during the initial portion of the circuit interrupter opening operation to effect thereby an expansion between the pair of movable contacts, the pair of movable contacts being contracted in the fully open circuit position of the interrupter, and means for moving the pair of movable contacts together in their contracted position during the closing operation and substantially simultaneously closing each of the pair of movable contacts with one of the pair of stationary contacts during a closing operation of the interrupter.

16. In a circuit interrupter, a pair of relatively stationary contacts, a pair of serially related movable contacts, expandable and contractable means interconnecting the pair of serially related movable contacts, means causing the separation of one of the movable contacts from one of the stationary contacts before the separation of the other movable contact from the other stationary contact during the initial portion of the circuit interrupter opening operation to effect thereby an expansion between the pair of serially related movable contacts, the pair of movable contacts being contracted in the fully open circuit position of the interrupter, and means for moving the pair of movable contacts together in their contracted position during the closing operation and causing a sequential closing of the pair of serially related movable contacts with the pair of stationary contacts during a closing operation of the interrupter.

17. In a circuit interrupter, first and second relatively stationary contacts, first and second serially related movable contacts, expandable and contractable means interconnecting the first and second movable contacts, means causing the separation of the first movable contact from the first stationary contact before the separation of the second movable contact from the second stationary contact during the initial portion of the circuit interrupter opening operation and causing an expansion between the first and second serially related movable contacts, and means for effecting the movement of both the first and second movable contacts in their contracted position during the closing operation and engaging the first stationary contact with the first movable contact before the engagement of the second stationary contact with the second movable contact.

18. In a circuit interrupter, a rotatable actuating member, an operating member, the actuating member having one end thereof pivotally connected to a position intermediate the ends of the operating member, a piston chamber, one end of the operating member being pivotally connected to the piston chamber, a piston operative within the piston chamber, and the actuating member being pivotally connected to the piston to cause the charging operation thereof.

19. In a circuit interrupter, a rotatable actuating member, an operating member, the actuating member having one end thereof pivotally connected to a position intermediate the ends of the operating member, a piston chamber, one end of the operating member being pivotally connected to the piston chamber, a piston operative Within the piston chamber, and the actuating member being operatively coupled to the piston.

ROSWELL C. VAN SICKLE. BENJAMIN P. BAKER. 5

ERIK H. HALL.

REFERENCES CITED The following references are of record in the file of this patent: 10

UNITED STATES PATENTS Number Name Date 1,935,222 Aemmer Nov. 14, 1933 2,095,441 Howe Oct. 12, 1937 5 Number