US2530952A - Circuit interrupter - Google Patents

Description

Nov. 21, 1950 2 Sheets-Sheet 1 Filed April 16, 1947 figg.

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NQV- 2l, 1950 F. J. FRY 2,530,952

CIRCUIT INTERRUPTER Filed April 16, 1947 2 Sheets-Sheet 2 Fig 5.

francz'sJ/r'rg. BY @fg l/ATTORN Patented Nov. 21, 1950 CIRCUIT INTERRUPTER Francis J. Fry, Champaign, Ill., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application April 16, 1947, Serial No. 741,865

(Cl. 20G-159) 3 Claims.

This invention relates to circuit interrupters in general, and more particularly to arc-extinguishing structures for relatively high-voltage liquidbreak circuit interrupters.

In United States patent application filed December 15, 1943, Serial No. 514,366, subsequently abandoned, and continued in patent application filed February 5, 1948, Serial No. 6,436 by Winthrop M. Leeds, Robert E. Friedrich and Francis J. Fry and assigned to the assignee of the instant application, there was disclosed and claimed a method for interrupting relatively low currents, particularly in the charging current range, which involved delayed fluid motion toward one or more of the established arcs. In other words, uid or oil flow toward the arcs was deliberately delayed for a predetermined time which iell within a disclosed time range. The disclosed limits of this range were a time no earlier than 1/2 cycle before the contact separation gap is of suiiicient length to withstand double peak normal voltage when said g-ap is filled with clean uid, and a time no later than the time the contact separation gap is no longer than two times the length of the first-mentioned contact separation gap.

In the aforesaid patent application the predetermined delay of the iluid flow tow-ard the one or more established arcs was provided by employing a pumping piston which was connected by a lost-motion connection to the operating mechanism for the movable contact structure.

It is an object of my invention to provide delayed uid ow toward the one or more established arcs by an improved means, however following the broad principles set forth in the aforesaid patent application.

Also in United States patent application filed August 31, 1944, Serial No. 552,132, now U. S. Patent 2,445,442, issued July 20, 1948, to Winthrop M. Leeds and Robert E. Friedrich and assigned to the assignee of the instant application, there is disclosed and claimed an improved interrupting structure disposed adjacent to the pressuregenerating arc, assuming the form of a multiorifice interrupting construction in which fluid ilow is directed toward the pressure-generating are at a plurality of axially disposed levels and forced to flow longitudinally adjacent to the pressure-generating arc through a plurality of orifices to then exhaust out away from the pressure-generating arc through laterally provided vent passages.

A further feature of my invention is to improve the interrupting construction adjacent to the pressure-generating arc following the pattern of 2 teachings set forth in the aforesaid Patent 2,445,442.

Still a further object of my invention is to provide an improved arc-extinguishing unit of the liquid break type in which the piston means is disposed adjacent the lower end of the unit and in which the normal order of the pressure-generating and interrupting arcs is inverted so that the length of passage interconnecting the piston means and the pressure-generating arc is short.

Another object is to provide an improved arcextinguishing unit of the liquid break type in which piston means are disposed adjacent the lower end of the unit with the pressure-generating arc immediately adjacent thereto. Preferably the piston means is inoperative during high current interruption and is operative during low circuit interruption to force liquid sequentially through the pressure-generating break and then onto the interrupting break which is disposed at the other end of the unit.

Still a further object is to provide an improved interrupting Contact construction in which a pair of movable contacts move in opposite directions t away from -a relatively stationary intermediate contact through a plurality of orifices in which the pair of contacts serve as valve members to prevent fluid ow through the orifices for a predetermined time.

Another feature of my invention is to provide an improved construction according to the preceding paragraph in which the two movable contacts clear the two orifices associated therewith simultaneously. Preferably I employ a multiorifice interrupting construction adjacent each movable contact so that the orifices for both contacts are progressively simultaneously opened in the same order.

Another object is to provide an improved liquid break arc-extinguishing unit in which piston means are disposed adjacent one end of the unit, pressure-generating contact means disposed intermediate the ends of the unit and interrupting contact means disposed adjacent the other end. Preferably a multi-orifice interrupting construction is employed adjacent each break and the contact members serve as valve members to delay for a predetermined time liquid flow through the multi-orifice interrupting constructions, the time falling within a preferred time range.

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

Fig. 1 is a side elevational View, partly in secinbefore described in relation to the securing of the body portion 23 to the metallic sleeve 21. The lower end of the rod 59 is externally threaded to be threadedly received by an operating member 5|. The operating member 5| has a pivot pin 52 extending therethrough. The pin 52 extends through the right-hand ends of a pair of guide links 53, the left-hand ends of which are pivotally mounted by means of a pin 54 to a downwardly extending bracket portion 55 integrally formed with the lower casting member 56.

The pin 52 also has its ends passing through intermediate portions of a pair of actuating levers 51, the right-hand ends of which are pivotally connected by a pair of pins 58 to the lower ends of a pair of guide links 59. The xed upper ends of the guide links 59 are pivotally secured at 60 to a pair of downwardly extending lug portions of the casting 5S, not shown.

The left-hand ends oi the actuating levers 51 are connected by means of a pin 6| to a squareshaped lower head portion 82 of the lower movable rod-shaped pressure-generating contact 45. Thus upon downward opening motion or the operating rod 22 and of rod member 50 secured thereto as permitted by downward opening motion of the bridging member 1, the operating member 5| rigidly secured to the operating rod 22 will also move downwardly to thereby cause counterclookwise rotation of the actuating levers 51 about the movable centers 53. Thus the counterclockwise rotation of the actuating levers 51 will cause downward opening motion of the rodshaped lower movable pressure-generating contact 45 away from the relatively stationary intermediate contact 44 to establish a pressure-generating arc 53 within a multi-orice pressure-generating chamber, generally designated by the reference numeral 64 as shown in Fig. 7.

It will be observed that I have secured a colN lar 65 by means of a threaded connection to the lower end of the metallic rod 58. Immediately above the collar 65 is a washer 66 loosely mounted upon the rod 59 and serving as a lower seat for a battery of relatively heavy accelerating compression springs 91, the upper ends of which seat against a washer 68 also freely slidable about the rod 50. The washer 68 abuts against the upper end 69 of a recess 10 formed within a lug portion 1| integrally formed with the casting member 56. Thus the accelerating compression springs 61 force the downward opening motion of the operating rod 22 as permitted by the lowering of the bridging member 1.

Preferably I provide a dashpot, generally designated by the reference numeral 12, and including a cup-shaped member 1-3 threadedly secured at 14 within an aperture 15 provided in the lug portion 1|. The cup member 13 has laterally extending apertures 16 out of which oil may be forced by the piston action exerted when the extreme lower end 11 of the body portion 23 of operating rod 22 enters the dashpot piston chamber 18. Thus the downward opening motion of the operating rod 22 is arrested in a cushioned manner by operation of the dashpot 12.

Thus it will be apparent that I have provided a straight line linkage mechanism, generally designated by the reference numeral 19, interconnecting the motion of the operating rod 22 with the movable pressuregenerating contact 45.

Associated with the lower end of the movable pressure-generating contact 45 is a piston means, generally designated by the reference numeral 80, and including a piston 8| movable within a piston chamber 82, in this instance formed as an integral portion of the casting 56.

The piston 8| has a downwardly extending sleeve portion 83 surrounding the lower end of the rod-shaped movable pressure-generating contact 45 and having longitudinally extending slots 84 diametrically provided therein, as more clearly shown in Fig. '7. Thus the pin 6| has its ends slidably within the slots 84 so that motion of the pressure-generating contact 45 may be independent of motion of the piston member 8|. Preferably the lower end 85 of the sleeve portion 83 is threaded as at 86 to threadedly receive a cap 81.

f A plug 88 threadedly secured to the extremity'of the bridging member 1 abuts against the capv 81 near the end of the closing stroke and during the initial portion of the opening stroke. The plug 88 therefore cooperates with the cap 81 to cause upward charging motion of the piston 8| against the biasing action exerted by a battery of piston accelerating springs 89. The lower ends of the piston springs 89 seat against the piston 8| itself. The upper ends of the piston Springs 89 seat against a metallic washer 90 embedded in a recess 9| provided in an insulating plate 92.

It will be observed that the three insulating plates 93 immediately below the insulating plate 92 have laterally extending cut-out portions 94 removed therefrom so that the upper side of the piston 8| is exposed to substantially atmospheric pressure. Consequently, the downward opening pumping motion of the piston 8| will not draw a vacuum or produce cavitation effects above it.

The piston chamber 82, integrally formed with casting 59, has in this instance three apertures 95 which lead from the piston chamber 02 to a region 96 which extends almost around the annular casting 56, as shown more clearly in Fig. 7. Thus downward pumping motion of the piston 8| will compress the operating liquid, in this instance oil, within the piston chamber 82 to cause the liquid to flow outwardly through the three apertures 95 into the region 96 and upwardly through two apertures 91 provided in the top of the casting member 56, as shown more clearly in Fig. 7.

An over-pressure valve 98 is provided associated with the casting 56, and includes a Washer-shaped valve plate 99 which normally covers apertures provided through the lower Wall 43 of the casting 56. The valve plate 99 is biased to its closed position by a compression spring |0|, the lower end of which seats against a washer |02 encircling a bolt |03, which passes through an aperture |04 also provided in the lower wall 43 of the casting 56. A nut |05 threaded on the bolt |03 holds the washer |02 in position.

Upon the attainment of excessive pressure within the region 96 within the casting member 56, the over-pressure valve 98 will function to open and relieve the pressure within the region 95.

I also provide a ring-shaped valve plate |86 supported by bolts |91 having their lower ends threaded into the bottom plate portion 43 of the casting 56, as shown in Fig. 2. The valve plate |06 is biased upwardly by a plurality of compression springs |98 which encircle the bolts |91. Apertures 42 are provided through the bottom plate portion 43 of the casting 56, the fluid flow through which is controlled by motion of the valve plate |06.

Thus upon downward opening pumping motion of the piston 8| within the piston chamber 82 the oil pressure thereby caused will close the valve plate |06 over the apertures 42, which would otherwise permit oil to flow out through the bottom plate 43 of casting 56. Conversely, the upward charging motion oi the piston 8| within piston chamber 82 will permit the compression springs |38 to cause the opening of the valve plate |06 to permit oil to be drawn into the piston chamber 82 through the apertures 42 provided in the lower plate portion 43 of the casting 56. A unidirectional oil flow intoY the piston chamber 82 is thereby assured.

The multi-orifice insulating plate structure E4 adjacent the pressure-generating arc E3 will now be described. Referring to Figs. 8 and 9, it will be observed that I have provided three types of insulating plates adjacent the pressure-generating arc E3. The first type is herein designated an insulating inlet plate H2, being shown more clearly in Fig. 8. The insulating plate ||2 has recesses ||3 provided therein which permit reception of insulating tie rods H4. Also the insulating inlet plate H2 has a cut-out portion H5 removed therefrom to provide two inlet passages H6. The inlet passages H6 permit the flow of fluid, in this instance oil, upwardly through first iiuid iiow passage means or two vertical flow pas, sages from the region 96 provided in the casting member 55 toward the arc S3. The inlet plate H2 also has portions H3, I9 removed therefrom the purpose for which will appear more clearly hereinafter.

Immediately above and below each insulating inlet plate H2 is an insulating orifice plate designated by the reference numeral |20, the configuration of which is more clearly shown in Figs. 8 and 9. t will be observed that each insulating orifice plate has portions I2| removed therefrom which upon alignment with portions |21 of the other plates form the two vertical iiow passages Also, each orifice plate |20 has portions |8, H9 removed therefrom as was the case with the insulating inlet plate ||2. Each orifice plate |20 also has the recesses l i3 provided therevin to accommodate the insulating tie rods H4. Furthermore, each orifice plate |20 has a cen-v trally provided oriice |22 which closesly surrounds the movable pressure-generating contact 45 so that the latter may control, by valve action, the flow of oil through the oriiice |22, the purpose for which will appear more clearly hereinafter.

On the other side of each insulating orifice plate 20 is an insulating vent plate having a configuration more clearly shown in Fig. 9 and designated by the reference numeral |23. Each vent plate |23 has the portions |2| removed therefrom to provide the two vertical flow passages I I'.' leading upwardly from the region 96 in casting 55 to the pressure-generating arc 63. Also, each vent plate |23 has a cut-out portion |24 removed therefrom to thereby provide two oppositely disposed vent passages |25 which lead from the pressure-generating arc G3 to second iiuid iow passage means or two vertical flow passages |26 leading from the pressure-generating arc 63 upwardly toward the interrupting arc 4S.

Thus from the foregoing description it will be apparent that the multi-orifice interrupting construction 64 disposed adjacent to the pressuregenerating arc 63 is such as to permit, during relatively low current interruption, the upward passage of oil upwardly from the region 96 through the apertures .'17 provided in casting 55, and upwardly through the two vertical flow passages radially inwardly toward the pressuregenerating arc 63 through the oppositely disposed inlet passages I I6. The oil then flows longitudi-` nally of the pressure-generating arc 63 through the orices |22 as provided by the insulating orifice plates |20, to exhaust out of the multi-orlnce interrupting construction 64 through the several pairs of oppositely provided vent passages |25 provided by the several vent plates |23.

The oil exhausting away from the pressuregenerating arc 63 through the several pairs of vent passages |25 flows upwardly through the two vertical flow passages |26 into the multi-orice interrupting construction 49 disposed adjacent to the interrupting arc 48 (Fig. '7).

The multi-oriiice interrupting construction 49 disposed adjacent to the interrupting arc 48 will now be described. The multi-orice interrupting construction 49 includes three different types of plates. The rst type is herein designated an insulating inlet plate |29 and is shown more clearly in Fig. 5. The insulating inlet plate |29 has recesses H3 formed therein to accommodate the insulating tie rods H4. The inlet plate |29 has a cut-out portion |30 provided therein to thereby furnish two oppositely disposed inlet passages |3| which lead from the two vertical flow passages |25 toward the interrupting arc 48.

Immediately above and below each insulating inlet plate |29 is an insulating orice plate |32 having a configuration more clearly shown in Fig. 5. The orice insulating plate |32 has the portions H8, i9 removed therefrom which upon alignment with such portions H8, ||9 in the other plates provide the vertical iiow passage |26. Each orince plate |32 has an orifice |33 provided centrally therein which closely surrounds the upper movable interrupting contact 9. The construction is such that the contact 9 controls, by valve action, the iiow of oil through the oriiice |33 provided in each insulating orifice plate |32.

On the other side of each insulating orifice plate |32 is a composite vent plate, generally designated by the reference numeral |34, and including two insulating halves |35, |33 laterally spaced apart so as to provide two opposed vent passages |37, as more clearly shown in Fig. 6, The irlsulating half |36 has the portion H8 removed therefrom and also has apertures |38 provided therein to accommodate the insulating tie rods H4. The insulating half of the composite vent plate |34 has the portion i9 removed therefrom and also has apertures |38 provided therein to accommodate the insulating tie rods ||4.

Thus, upon the upward iiow of oil upwardly through the vertical ow passages |26 as indicated by the arrows in Fig. 2, the oil passes radially inwardly toward the interrupting arc 43 through the opposed inlet passages |3| to strike the interrupting arc 48 and pass longitudinally thereof in intimate engagement therewith through the orifices |33 as provided by the insulating oriiice plates |32. The oil then passes radially away from the interrupting arc 48 out of the, unit l through the oppositely disposed vent passages |31 provided by the vent pla-tes |34.

It will be observed that the relatively stationary intermediate contact 44 has a pin |40 passing therethrough, above which seats a washer |4|. A` compression spring |42 is disposed above the washer |4| and has its upper end seating against an insulating plate |43. Thus the compression spring |42 biases the intermediate contact 44 downwardly into following engagement with the lower movable pressure-generating Contact 45 during the initial portion of the circuit opening operation. The result is the establishment of the interrupting arc 48 slightly aheadof the establishment of the pressure-generating are 63.

Such a construction of the intermediate contact 44 is set forth and claimed in United States patent application, Serial No. 704,884, filed October 22, 1946, now U. S, Patent 2,434,422, issued January 13, 1948 to Douglas J. Marsden, entitled Circuit Interrupter and assigned to the assignee of the instant application.

In the closed circuit position of the interrupter, as shown in Figs. l and 2, the electrical circuit therethrough includes terminal stud 3, contact foot 2, flexible conductors |44 to the head portion I0 of the movable interrupting'contact 9. The circuit then extends through the contact 9, through intermediate contact 44 and through lower movable pressure-generating contact 45. The electrical circuit then extends through the head portion 62 at the lower end of contact 45 and through a pair of flexible conductors |45 to the relatively stationary disconnect contacts |46, which make contacting engagement with the sides of the conducting bridging member 1. 'I'he circuit then passes through the other serially related arc-extinguishing unit to the other terminal stud 3 of the interrupter.

During the opening operation, suitable mechanism, not shown, but which is responsive to either manual operation or to the existence of excessive current conditions in the protected cirl cuit, caused downward opening motion of the lift rod la connected intermediate the ends of the bridging member 1. The downward motion of the lift rod 'la causes corresponding downward opening motion of the conducting bridging member 1.

During the interruption of relatively high amperage currents, the pressure generated within the pressure-generating chamber 64 will be relatively high. This pressure will act outwardly through the inlet passages I I6 provided by the inlet plates |2 and downwardly through the vertical flow passages to act through the region 96 and through the apertures 95 to thereby act upwardly upon the lower surface of the piston member 8|. Since the upper surface of the piston member 8| is exposed to substantially atmospheric pressure, and the lower surface thereof is exposed to the high pressure within the pressuregenerating chamber 64, the piston 8| is stalled during the interruption of high currents by the interruptor and will not move downwardly. However, the fact that the piston 8| may be stalled has no effect upon the opening downward motion of the contact 45, since the mechanism 19 associated therewith is independent of the motion of the piston 8| by virtue of the presence of the slots 84 provided in the sleeve portion 83 of piston member 8|,

Thus, even though the piston 8| may be stalled due to the high pressure caused by the interruption of high amperage currents, nevertheless the Contact structure will move independently therefrom as caused by the biasing action exerted by the battery of heavy compression accelerating springs 61.

The downward motion of the operating rod 22 as caused by the compression springs 61 causes upward opening motion of the interrupting contact 9 through the linkage 8 and downward motion of the contact 45 as caused by the linkage 19. Eventually the dashpot 12 arrests the downward opening motion of the operating rod 22 to thereby terminate the separating motion of th@ mpv.,- able contact structure,

lll

As mentioned previously, the intermediate contact construction follows the teachings of the Marsden patent so that the opening of the pressure-generating . contacts 44, 45 occurs subsequently to the opening of the interrupting contacts 9, 44, The movable pressure-generating cont-act 45 does not move past, and thus open by valve action, the rst orifice |41 (Fig. 2) associated therewith until the upper movable interrupting contact 9 opens, by valve action, at the same time the iirst orifice |48 associated therewith. Thus, the interrupting influence is delayed for a predetermined time which falls within the time range set forth above in connection with patent application Serial No. 514,366.

During the interruption of high amperage currents, the oil flow toward the interrupting arc 48 is governed entirely by the pressure produced at the pressure-generating arc 63, the piston it being stalled at this time by virtue of the high pressure within the pressure-generating chamber 64. Oil ow passes upwardly from the pressuregenerating arc 63 through the vent passages |25, through the vertical ilow passages |26 to eiiect extinction or" the interrupting arc 48 by the voil iiow through the multi-orice interrupting structure 5:9, in the manner previously mentioned. After arc interruption and the consequent subsidence of the arcing pressure, the piston 8| will then be eiective to force a flushing flow of fresh oil out of the piston chamber S2 and upwardly into the multi-orifice interrupting construction 64. After passing through the interrupting structure 54 the oil flows upwardly into the multiorice construction 49 to raise the dielectric strength in both the pressure-generating chamber and the interrupting chamber 84, 49 respectively. Continued downward movement of the bridging member 'l inserts two isolating gaps in the circuit, as indicated by the dotted lines of Fig. l.

During the closing operation, the bridging member "l meves upwardly in response to upward motion of the lift rod la so that the plug 88 strikes the cap 8l to charge the piston 8| against the opposition provided by the pump springs 89, while at the same time the upstanding portion |49 of the bridging member l strikes the operating member 5| to cause closing of the contact structure and compression of the accelerating springs El. The contact pressure between the several contacts is provided by the lost-motion connection 2| and the springs 35 disposed at the upper end of the operating rod 22.

During the interruption of low currents, such as charging currents or the like, the piston 8| will at this time be effective to cause oil flow out of the piston chamber 82 and upwardly through the vertical flow passages ||i toward the pressuregenerating arc E3 through the inlet passages I6. After striking the pressuregenerating arc 83 the oil flows out of the pressure-generating chamber |34 through the vent passages |25 and upwardly through the vertical now passages |26 toward the interrupting arc 48. After contacting the interrupting `arc i8 the oil flows out of the unit through the vent passages |317 provided by the several composite vent plates |34.

It will be noted from Fig. 7 that the insulating plate |59 terminates the upper ends of the verti- -cal ow passages ||7 so that the piston action is effective to first force oil only toward the pressure-generating arc 53. Thereafter it may ilow through the exhaust passages |25 and upwardly through the vertical now passages |26I 11 toward the interrupting arc 48. Thus the piston action is eiiective to force oil flow progressively through the interrupting structures 64, 49 disposed in series, Iassociated respectively with the pressure-generating and interrupting arcs 63, 48.

As mentioned previously, the piston action is only eiective during low current interruption, when the pressure generated at the pressuregenerating arc 63 is not adequate enough to send the requisite flow oi oil upwardly toward the interrupting arc 48 to effect the extinction thereof.

The speed of the contacts 9, 45 and the plate spacings are such that during the interruption of all currents, both low and high, the interrupting inuence is delayed for a predetermined time by virtue of the fact that the valve action of the contacts 9, 45 through the rst orifices |48, 241 associated respectively therewith is such as to prevent oil :dow until both contacts simultaneously clear both orifices. Thus the contacts 3, 45 serve as slide valves in controlling the ow of oil through the rst oriiices |48, |41. Until the contacts 9, 45 have cleared the orices |48, |41 respectively, there is no interrupting influence brought to bear upon the arcs.

When the contacts 0, 45 eventually do clear the orifices |48, |41 then a ow or" oil adiacent the arcs through the said orifices is possible,

The predetermined time before the interrupting influence is brought to bear upon the arcs 48, 63 by a simultaneous clearing of the orifices |41, |48 falls within the above time range as set forth in the aforesaid patent application, Serial No. 514,366, particularly suitable for the interruption of charging currents. Thus, in this particular embodiment oi my invention, instead of providing a delayed action pistion as was utilized in patent application Serial No. 514,366, I provide a delayed action as determined bv the contact speed and the plate spacings before the first orices |41, |48 are simultaneously uncovered by the two contacts 45, 9. Thereafter, succeeding orices are simultaneously uncovered at thel same rate in the pressure and interrupting chambers 64, 49.

It will be observed that by disposing the pressure-generating arc S3 at the lower end of the unit l and the interrupting arc 48 at the upper end of the unit in an inverted order than was heretofore employed, the length of the oil passage from the piston 3| to the pressure-generating arc 63 is considerably less than with previous constructions.

Thus I have provided an improved circuit interrupter in which the upper contact 9 passe@ the iirst oriice |48 at the same time the lower contact 45 passes the rst orice |41 associated with it. No interrupting iniiuence is available from the piston 8| until the orices are cleared, due to the slide valve action of the contacts. When the rst orifice |41 of the lower contact 45 is cleared, there is available simultantously one orifice in the bottom section and one orice in the top section; and succeeding orices in both sections are introduced at the same time. On low currents then, each region is equally efective as an interrupter, whereas on high currents most of the de-ionization takes place in the interrupting gap, which is the top gap in my improved interrupter.

The intermediate contact 44 is designed with spring bias in the down direction as caused by the compression spring |42. This intermediate contact 44 will come down, as shown in Fig. 7,

.even though the lower section of the unit is the pressure section since the pressure drop from the bottom end of the contact 44 to the top end thereof is only due to losses around the intermediate Contact enclosure.

The check valve |06 is normally biased open to allow some cooling convection currents of oil to pass upwardly through the unit while the breaker is in the closed circuit position carrying load current. The check valve |09 controlling apertures l0 in the top casting member 5 assists in this convection action.

During a tripping operation, a slight delay in building up pressure under the piston 8| is obtained due to the displacement of oil required to close check valve |06. This delay is normally less than provided by the valve action oi the contacts 9, 45 in simultaneously pulling through the first orices |41, |48, thereby permitting oil now.

However, where additional delayed action is desirable beyond the rst orices |41, |48, this may be provided by a modified type of check valve |06 with sufficient area and vertical length of travel.

When the oriiices |41, |48 are allowed to burn away excessively due to heavy duty service without adequate maintenance, valve action delay by contacts 9, 45 would be affected. In such a case, the modified check valve |06 could be dimensioned to give delayed action coinciding with that of the contacts 9, 45, or even more delay if desirable.

Fig. 10 illustrates a modified type of delayed action piston means |52 in which there is a lostmotion connection between the fluid moving piston |53 and the outwardly extending flange |54 at the top of the actuating cylinder 455 lamounting to the vertical height X as shown. A co1- lar |5a` secured to the movable actuating cylinder |55 picks up and charges the piston |53 during the closing operation, against the biasing action exerted by the relatively light compression spring |51. This spring |51 ensures that the piston |53 will always rest against the collar |56 in the closed position so that the lost motion X will remain constant for successive opening operations. The piston spring B9 is relied upon to do the actual moving of the fluid.

Such a modified type of delayed action piston means |52 would be employed with the check valve |05, unbiased to the open position. The lost-motion mechanical connection between piston E53 and actuating cylinder |55 amounting to the distance X would take the place of check valve |05 of Fig. 2 biased to the open position to obtain a time delay before the piston 8| would be eective. As before, the time delay equivalent to the distance X could be less, coincide with, or be greater than the time delay achieved by the contact valve action of contacts 9, 45 uncovering the rst orifices |41, |48.

, In other words, time delay before piston action on low current interruption could be achieved entirely by the piston means 80 of Fig. 2 with a suitably dimensioned check valve |05 biased to the open position, or it could be achieved entirely by the piston means |52 of Fig.. 10 exclusive of any valve control by the contacts 9, 45 pulling through the tight fitting orifices |41, |48.

From the foregoing description it will be apparent that I have provided an improved circuit interrupter in which there is a more direct path for oil flow thanwith the piston at the bottom end of the unit and the pressure break at the top of the unit. Also, by having the contacts serve as slide valve members through the orifices 13 to simultaneously delay, for a predetermined time, uncovering of the oriiices, the interruption of charging currents is effectively increased.

Although I have shown and described specic structures, it is to be clearly understood that the same were merely for the purpose of illustration and that changes and modifications may readily be made therein by those skilled in the art without departing from the spirit and scope of the appended claims.

I claim as my invention:

1. In a circuit interrupter of the liquid break type, an arc extinguishing unit immersed in an arc extinguishing liquid, a relatively stationary intermediate contact positioned intermediate the ends of the unit, a pressure-generating multiorifice chamber disposed adjacent one end of the intermediate contact, a rod-shaped pressure-generating contact movable through the orifices into contacting engagement with the intermediate contact, an interrupting multi-orifice chamber disposed adjacent the other end of the intermediate contact, a rod-shaped interrupting contact movable through the orifices into contacting engagement with the intermediate contact, means orice in each multi-oriiice chamber, and a lost- 3 motion mechanical connection for delaying for a predetermined time actuation of the piston means.

2. In a circuit interrupter of the liquid break type, an arc extinguishing unit immersed in an arc extinguishing liquid, a relatively stationary intermediate contact positioned intermediate the ends of the unit, a pressure-generating multioriiice chamber disposed adjacent one end of the intermediate contact, a rod-shaped pressure-gen- ,A

erating contact movable through the orifices into contacting engagement with the intermediate contact, an interrupting multi-oriiice chamber disposed adjacent the other end of the intermediate contact, a rod-shaped interrupting contact movable through the orifices into contacting engagement with the intermediate contact, means synchronizing the motion of both contacts so that one contact clears the first orifice of its associated chamber simultaneously with the other contact clearing the first orifice of its associated chamber, piston means operative to sequentially send liquid through the pressure-generating multi-orifice chamber and only then on to the interrupting multi-oriiice chamber only when the contacts by Valve action have uncovered the rst orifice in each multi-orifice chamber, and delaying means for the piston means including a check valve biased to the open position and suitably dimensioned to allow a particular displacement of liquid before it is closed.

3. A circuit interrupter including means dening an arc extinguishing unit, means immersing the unit into a body of liquid at one end thereof, liquid flow producing means disposed adjacent the other end of the unit, means defining a pressure generating chamber disposed intermediate the ends of the unit, rod-shaped contact means for establishing a pressure generating arc within the pressure generating chamber, means defining an interrupting chamber disposed adjacent the said one end of the unit, rod-shaped contact means for establishing an interrupting arc within the interrupting chamber, the liquid flow producing means and the pressure generating chamber and the interrupting chamber being disposed in substantial alignment, first liquid flow passage means interconnecting the liquid flow producing means only with the pressure generating chamber, second liquid flow passage means interconnecting the pressure generating chamber only with the interrupting chamber, the liquid flow producing means surrounding the first-mentioned rod-shaped contact means to thereby avoid off-center stresses, and actuating means for the contact means and also for the liquid flow producing means disposed adjacent said other end of the unit.

FRANCIS J. FRY.

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

UNITED STATES PATENTS Number Name Date 2,134,572 Paul Oct. 25, 1938 2,147,497 Prince et al Feb. 14, 1939 2,155,263 Flurscheim Apr. 18, 1939 2,162,588 Prince June 13, 1939 2,412,858 Baker et al Dec. 17, 1946 2,434,422 Marsden Jan. 13, 1948 2,445,442 Leeds et al July 20, 1948

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