US2568155A

US2568155A - Automatic circuit breaker retarding mechanism

Info

Publication number: US2568155A
Application number: US740687A
Authority: US
Inventors: David C Hubbard
Original assignee: AB Chance Co
Current assignee: AB Chance Co
Priority date: 1947-04-10
Filing date: 1947-04-10
Publication date: 1951-09-18
Anticipated expiration: 1968-09-18

Description

Sept. 18, 1951 D. c. HUBBARD AUTOMATIC CIRCUIT BREAKER RETARDING MECHANISM Filed April 10, 1947 2 Sheets-Shae;

47-In5u/ation INVEN'I'OR.

ATTORNEY Patented Sept. 18, 1951 AUTOMATIC CIRCUIT BREAKER RETARDING MECHANISM David C. Hubbard, Centralia, Mo., assignor to A. B, Chance Company, Centralia, Mo., a corporation of Missouri Application April-; 1947;. SerialiNo. 740,687

12 Claims. 1

The present invention relates to automatic circuit recloser mechanism, and. is particularly concerned with circuit makers and breakers of the typewhich are adapted to be immersed in an insulating liquid, such as oil.

One of the objects of the invention is the-pro-- vision of an improved circuit maker and breaker Off the overload type which is provided with automatic reclosing mechanism adapted to provide ID! a; fast opening of the-circuit on the first and second operations in the event of an overload, and for thetime delay opening of the circuit on thethird andfour-thoperations, after which the circuit breaker is held in open position and can only. be closed by means of a manual operation.

Another object of the invention is the provision-cf. an improved circuit maker and breaker of the class described which is adapted to clear automatically all temporary line faults which include the majority ofline disturbances, thus increasing service continuity-and reducing theareas which are cut out to thesmallest possible size.

Another object of the invention is the provision of an improved automatic circuit breaker and recloser which is adapted to prevent the burning of contact surfaces byhigh speed opening; and high speed closing, which is sturdy in construction, capable of economicalma-nufacture, and adapted to be used for. along period of time Without necessity for repair or replacement.

Afurther object of the invention is the provision, of an. automatic circuit breaker and recloser in, which each. break of the contacts is not accomplished until a full measure of oil has been forced into a metering cylinder which progresses a predetermined amount in its travel during the first and second operations; which is adapted to eject oil across the contacts in such manner as to aid in breaking the are; which provides a time delay Without effecting any delay during the instant while the contacts are being made or broken; and which utilizes a small amountof the travel of the delaying mechanism for dampening the shock of its travel.

Still: a further object ofthe invention is the provision of an improved circuit breaker and automatic recloser which provides additional time delay in-theevent of heaviercurrents before the device recloses the contacts in order to allow more; time for the oil about the contacts to clear itself of gasand of carbon particles.

Another object is the provision. of an improved.

device of the class described which provides a predetermined. minimum time delay on recl'osing.

of, the circuit under ordinary conditions, and an additional time, delayis providedbefore reclosing. when the device has interrupted heavier current.

Another object of the invention. is the provision of a device of theclass described whichis adaptedto provide a proper time delaybeforethe contacts move to break the circuit, but which is also adapted to permit the parts to movethereafter at such a speed that they are adapted to eject oilacross the path of the arc in. order to. break the arc and protect the contents.

Another object of the invention is the provision of an improved device of the class described which may be provided with a suitable. lock-out mechanism for preventing therecloser from. re.- setting the contacts so that it is-necessary to. reset them manually afterthe third or fourth; opera tion; and in which the time delay mechanismit self is locked against return after the. third or fourth operation, so that after a prolonged outage, consumer equipment which is connectedto.

the line in the on position will not be the cause of another instantaneous operation of. the breaker, whichwill not occur whenthe time delay, is also looked out in itsthird or fourth position.

To summarize briefly the most important-features of the-present invention, it is a further. Ob?- ject of the invention to provide an automatic circuit recloser mechanism which has all of. the ad. vantages of thedevices of the priorart, and which isalso characterized by the following, features: (l) constant measure of oil, independent. ofpiston travel, for moving atime delaypiston; ('2) release of time delay pressure from the ar-- mature at the instant of contact break toallowthe full force of the dash pot piston to eject-oil across the resultant arc path; (3) cushion the rest of the piston travel; (4) ejection of oil across the arc path; (5) lock-out of the time delay.- mechanism in a time delayposition toprovide' a time delayupon reclosing in order toprevent the opening of the contacts by the surge of star-ting current which might be required by consumer equipment which has been connected to theline in the on position during a prolonged outage.

Other objects and advantages of the inven tion will be apparent from the following description and the accompanying drawings, in which similar characters of reference indicate similar parts throughout the several views.

Referring to the two sheets of drawings,

Fig. 1 is a fragmentary axial sectional view taken through an automatic recloser mechanism; embodying the invention, on a plane passing through the axis of the coils and pistons;

Fig. 2 is a fragmentary bottom planview show- 3 ing details of structure of the snap contact mechanism.

Fig. 3 is a fragmentary view similar to Fig. 1, showing a modification in which the solenoid coil is lowermost and the dash pot located above it to permit the interchange of coils of difierent characteristics for changing the recloser rating.

The present circuit interrupter and recloser mechanism is intended to be submerged in an enclosed tank in oil, the leads being brought out the top of the tank through elongated multiskirt insulators, the tank being grounded, and separate lightning arresters being provided between the ground of the tank and the conductor at the end of each insulator.

The present device preferably includes a supporting spool ID for an overload coil I I, the spool having a central bore l2 for receiving the substantially cylindrical armature 13. The assembly is carried by the cover of the enclosing tank, from which it depends. The spool ID supports at its lower end a housing member l4 which includes a cylinder l5 having an inner cylindrical chamber [6 serving as a dash pot.

The dash pot piston I! may comprise a disk l8 having a suitable clearance with respect to the cylindrical wall l6, and having a hub 19 with a bore 20 for receiving the armature E3 to which it is riveted by the rivet 2 1. Radial reinforcing flanges 22 connect the disk It; with the hub l9, and two of such radial reinforcing flanges are extended to form fins 23 which project latrally from two slots 24 in the cylinder wall l5 for supporting a pair of snap springs 25 by means of which the movable contacts are actuated.

The housing l4 also includes a laterally extending, U-shaped portion 26 comprising a pair of

parallel walls

21, 28, and the end wall 29. This U-shaped portion may be open at its top and bottom for access of oil to the contacts. The left wall 30, between this U-shaped portion and the cylinder I5, may be thickened toward the top to provide a diagonally and upwardly extending stop surface 3| for limiting the motion of the switch arm. The lower portion of this wall supports a pair of pivot flanges 32 separated by a slot 33 for receiving the switch arm 34, which preferably consists of an insulating shield.

The switch arm or shield 34 may consist of a laminated member of indurated fiber which is impregnated with a phenolic condensation compound, and which may be a sector, being provided at its axis with an aperture 35 for receiving the rivet or pintle 35 by means of which it is pivoted between the flanges 32.

The contact arm 34 supports adjacent its upper edge 31 a bridging contact 38 (Fig. 2) which may consist of an elongated cylindrical member having enlarged threaded portions 39 which pass through an aperture 40 in the shield 34 to which they are secured by nuts 4!. The projecting cylindrical portions 42 of this bridging contact are adapted to engage the

fixed contacts

44, 44 which are insulated from and supported by the parallel side walls 2'1, 28 of the U-shaped portion 26 of housing [4.

- Fixed

contact

44, 44 preferably have partially cylindrical socket formations 45 for receiving the cylindrical portions 42 of the bridging contact 38 and for limiting the downward motion of the bridging contact 38 and switch arm 34. The

contacts

44, 44 are connected to suitable connectors 46 for receiving conductors which connect the switch in a circuit.

At a point between the axis of the switch arm sector 34 and its periphery 41 this switch arm is provided with a transversely extending spring supporting post 48. Such a post may be secured to the insulating sector 34 in the same manner as the contact 38, and the post is preferably provided with a'pair of peripheral grooves 49, one adjacent each end, for receiving a loop 53 carried by the end of each spring 25. The other end of each spring 25 has its loop hooked through an aperture 5| in the fins 23 carried by dash pot piston ll.

Various forms of switch mechanism may be employed, and the one which has been selected to illustrate the invention is merely one of the forms which I contemplate using.

The U-shaped housing portion 23 may have its side walls 2?, 28 each provided with an oval aperture 52 extending upwardly from the'location of the fixed

contacts

44, 44 so that the oil which is projected toward the contacts may pass outwardly toward the right and left through these apertures.

The operation of the switch mechanism is as follows: When the shield 34 is in the position of Fig. 1, the fins 23 being below the pivot 35 of the shield 34, springs 25 pull the shield 34 downwardly so that the contact 38 engages fixed

contacts

44, 44.

As the dash pot ll moves upwardly, the fins 23 carry the left end of the springs 25 upwardly, and when the fins 23 pass the line of centers of post 48, pivot 36, and spring attachment 5!, the spring 25 thereafter pulls upwardly on the shield 34, which snaps upward, breaking the circuit between contact 33 and

contacts

44, 44. The shield 3 is then interposed between the fixed contacts 44, M, and it continues upward until it leaves the dotted line position shown in Fig. 1, engag-' ing the stop surface 3 l.

Upon the return movement of the dash pot piston H, the closing of the switch is again accomplished with a snap action, and the springs 25 tend to hold the switch closed or open, depending upon the position in which they happen to be.

The piston is has a suitable clearance with respect to the cylinder bore l5 so that a predetermined amount. of oil may escape around the edges of the piston H to permit the armature E3 to move at a regulated velocity.

While the piston I7 is moving along the slots 24, oil is projected through these slots toward the contacts of the switch to assist in quenching the arc. The slots 24 terminate short of the end of the piston bore 25 so that after the piston passes the end of the slots 24 the escape of oil from the space above the piston is greatly diminished as it is limited to the oil which escapes between the edges of the piston and the wall of the bore l6. Thus the upper end of the cylinder is utilized for cushioning the shock of movement of the piston, armature, and associated parts. These parts are also brought to a quick stop.

The armature i3 is carried at its upper end by an extension rod 53, which also serves to support a plurality of valve members. Rod 53 is mounted in a cylindrical socket 54 in the armature I3 and secured by a transverse rivet 55.

Above the armature I3 the rod 53 supports an oil pumping bushing 55 which has a sliding fit in a tubular lining 51 located inside spool Hi. The oil pumping bushing 53 is secured to rod 53 by means of a transverse rivet 58, and it is provided at its upper end with a plane surface M. serving as: a cut-ofi' valve with. respect: to-=the transverse conduit or port 60:

The upper casting B l. comprises aimetalimemberprovided with a, tubular; portion. 62; having. itsend wall 6.3. provided. with a. cylindrical. bore- 64; The bore 6:4" has asliding fit. with a. cy1in.-. drical portion-6.51m the rod.53.; and-the rod has: an upwardly tapered portion 65 which, endsin, an abrupt shoulder $1 above, and taperstothe size of the cylindrical portion of; rod" 53;. at the point 68; The location of these parts is such that: when the shoulder 5901088813116 port 63,- the shoulder 61' passes the upper: surface 6:9aonr the tubular. housing Bil 'and -permits the escapeof: oil around the tapered portion; 65' of extension rod 53;

The upper housing 5| is: provided: with. a. lat'-.-. eral'tubular extension 10' which containszthe conduit 60,- and may terminate in a. threadedbore H closed'by a screwplug 722 This bore ma'y serve; as a clean-out opening by removal of the screw plug 12 Bore Gll communicates-with adownwardly. ex.- tending port 13 which is closed by av ball valve 14 which permits oil to enter the port13but pre vents its exit. A pin above the ball valve M2 prevents the ball 14 from leaving its seat, except for a predetermined movement; The conduit. 65 alsocommunicateswith an upwardly extending bore'iS-which is closed by a gravity actuated'ball valve 11, also having apin 18 to limit its: upward-j movement.

Tubular extension 10 is provided with a cir-. cul'ar plate 19 onits upper side, to which is attached another cylinder 80 by means of screw bolts 3 l. The'cylinder 8|} has an-in-ner cylindrical wall 32 for engagement with apiston 83 car-. ried by a piston rod 84'. The-wall of cylinder Bit has an enlarged outlet bore B5-locatedata-point: just below the dash line 86; which indicatesthe. second position of this piston. The dot line 8? below the enlarged outlet port 85 indicates thefirst position of piston 83. At itsupper endithecylinder 8! has a small outlet por-t 8B.

The piston rod 34 is provided onits end with. i:

aclevis 89 for attachment to a time delay lock out mechanism, and theextension-rodis is provided with a clevis as on its upper end for at tachment to a manual operation-lever.

Various types of lock-out mechanisms-may be employed with this automatic circuit recloser mechanism, provided the look-out mechanism is such that the contacts may again be cl'osedmanu ally, and provided also that the timing piston 8.3 is also locked out at the upper limit of its-move ment. The lock-out mechanism may: be housed in the cover of the tank inwhich the oil is contained, which surrounds th present mechanism.

The operation of the automatic-circuit recloser mechanism is as follows: The contactsiare cljosecli initially by means of the manual operating lever: which is attached tothe clevis 91!; This=lever must be pushed downwardly, whereupon the springs wil1 snap the shield downwardly-and;- move the contacts into closed position. When: a surge of current occurs in the circuit in which. the device is connected, this current, passing; through the coils ll, causes the armature It. to; be drawn upwardly, and; the. thrust exerted. Q 1 the armature is in. proportion to the amountofcurrent. The more current that is flowing, the: greater is the thrust onthearmature, and; the: faster the armature tends to travel.

The more current that: isflowing in. the coil; the greater the are between the; contacts. and;

6;. the: fasterth piston ll: travels, and ejects; oil? through the slots 24; at a greater velocity,- to quench-- the arc.

As the piston ll' travels upward, the, fins 23* carry the-springs 2.5, upward, opening the contacts with a snap action as the shield 34 moves up ward, the shield being interposed between the fixed contacts. When the piston ll reaches the; end; ofits travel; beyond the end of slots 24;,its.

; travel is: arrested by the oil entrapped in the end;

of; the cylindrical chamber 18, and the piston and its associatedparts are brought to a quick stop.

The motion-of the parts heretofore described is: regulated by means of the valves and associated:

; mechanism-at the top of the assembly as-follows-p The bushing; 56 isadapted to pump oil from thechamber 91: above it into the conduit 6,0 and; thence past the ballvalve Tl into the space below piston 83. The ball valve Ti prevents its return. intotheconduit 60. Thus a measured amount ofoil' is pumped into the space below the piston 83; during the initial movement of the armature- Hi; this pumpingaction continuing until the cut-off surface 59 of bushing 56 passes the upper side of the conduit 6!].

Immediately after the passage 69 is cutoff by the bushing 55, the contacts of the switch are. opened. Thus a full measure of oil is always. forcedintothe passage and transmitted to the space below the piston 83. The contacts then. part, and the rest of the armature travel is uti1ized= to eject oil across the resulting arc. As longas there is an are, energy is also flowing through the coil I I which, in turn, pulls the armature with; aspeed proportional to the current flow. Hence, the greater the arc, the more current that is flow-- ing, the faster. the armature travels, and: thegreater is the oil velocity across the arc path.

After the bushing passes the conduit 60, the shoulder 6'!" also passes the upper face 69, and oil pressure in the chamber 91 is relieved by pass.-. ing out of the bore fi i'ai'ound the tapered portion oithe extension rod 53. Prior to this time'the' opening 64has been kept closedby the cylindrical portion 65; of rod 53, thus tending to force allof' the oil in chamber 9! into the conduit 60.

Whenthe armature 18; is inits raisedpositi'on the lower cylindrical portion 92 of the extension. rod; 53 just above the bushing 56 closes the port"- 642 Thus downward motion. of the armature is; delayed while the oil seeps into the chamber-911' through the clearances 0f the shafts-inthe closed portsand along the armature l3 and armature bushing 56; i

The armature extension 5.3 may not be raised; to its extreme upper position by relatively smalli overloads which are to open, the contacts, but: it will be'raised, to that position by the heavier cur-. rents. On heavier currents which producezlargerarcs at the contacts and higher thrust'on the; armature; additionalitimr; delay will be, incurred before the device recloses-the contacts. This; al-.. lows more time for the oil about the contafi ifi to; clear itself of gas and carbon.

As the armature 5 downward, thecylin; drical portion 9?..passes out of the p rt 64, a-ndg the tapered portion 55 effects an opening-of; the: port 64 which, increases in size as the armature progresses downwardly; Oil may then pass into, the, chamber 9-! around the tapered portion 6,6. through port 84, but the port 69 is still cut ofi by; the-bushing;

As the armature l3 progresses downwardlxthes cylindrical portion- 65 of extension. rod: 53. closes theiportfi l nd-the b i sifi. p ns: he o t 6.0..

Thereafter, oil is drawn in by the pumping action of the bushing 58 through the valve port 13, the oil lifting the ball valve 14. The contacts of the switch are not closed until the piston I! has substantially reached the bottom of its travel. Thus, by properly proportioning the parts, a predetermined minimum time delay may be intro duced on the reclosing of the contacts in any event, and additional time delay is provided when the device has interrupted heavier currents.

' Many faults which occur on distribution lines are only temporary, and are cleared automatically by the time delay reclosing of the circuit. In order to vary the amount of time delay during which such faults may be automatically cleared it is desirable to provide for a plurality of instantaneous operations, such as, for example, two openings of the circuit and two time delay closures of the circuit, with a minimum time delay on the reclcsing between each contact break and re-make. This sequence of operations should be normally available at any time, regardless of former operations, provided a reasonable time has elapsed since the last operation, such as, for example, fifteen or twenty minutes.

After two or more time delay operations of the switch, each comprising an opening and a reclosing, it is then desirable to introduce a greater time delay, and finally to lock out the switch mechanism in open position if the line disturbance has not cleared itself automatically by that time.

During the first opening of the circuit the timing piston 83 has been moved up to the dotted line position 81. Little resistance is encountered to the escape of oil from the space above the piston 83 at this time, because the oil may'pass out of the large escape port 85 as well as the small escape port 88. When the armature l3 returns to its lower position after the first opening operation, the timing piston 83 remains substantially in the dotted line position 81, since the only leakage which is encountered with regard to the space below the piston 83 is that which is incurred by virtue of suitable clearances and leakage past valves.

Thus a measured quantity of oil has been injected into the timing cylinder 88 on the first opening and reclosing of the contacts. This is always a constant amount, regardless of the armature travel, provided the circuit is interrupted, since the contacts do not part until the bushing 58 closes the passage 68 and contact is not reestablished until the armature l3 descends by gravity to the bottom of its travel. Therefore, the same volume of oil is pumped into the timing cylinder 80 with each interruption of the circuit, independent of the magnitude of th operation or the intensity of the current, or the viscosity of the oil.

After the first interruption of the circuit, if the overload or short-circuit condition still exists on the power line, and is of the proper magnitude to cause an operation, the armature I3 again rises, unimpeded by the timing cylinder, since the large escape port 85 is still open, and the oil can flow unimpeded into the passage 60.

Thus the second circuit interruption of the device is also a fast opening, and a second measured quantity of oil advances the timing piston 83 to the position indicated by the dash line 86, closing the large outlet port 85 of the timing cylinder.

When the contacts are again closed, the timing piston 83 remains for the short time required to permit a third operation, substantially in the position indicated by the dotted line 86. Upon the occurrence of a third operation immediately following the re-establishing of the contact, the upward travel of the armature I3 is then impeded by the pressure which is established above the timing piston 83 in the timing cylinder 80, since the oil in this chamber can now only escape through the small port 88, plus leakage. If no third operation of the plunger occurs while the timing piston remains in the dotted line position 86, the timing piston 83 will gradually settle downward to the position of Figure l by gravity, due to the leakage of oil past the piston and into the

apertures

88 and 85.

The size of this small port 88- can be readily proportioned to provide the proper amount of time delay which is desired before the contacts again break the circuit on the third operation and before the armature extension 53 opens the port 64 by raising the reduced portion 86. Thereafter, free travel of the armature I3 is again provided at normal speed to eject oil across the path of the arc, since bushing 58 closes the passage 88 as the port 64 opens up, and the timing cylinder is no longer in the active oil stream propelled by the armature l3.

Thus the present device is able to provide an increased time delay for the opening of the contacts upon the third operation, without, however, preventing the contacts from opening quickly on a snap action, and without preventing the ejection of oil at high speed to quench the arc.

The lock-out mechanism is preferably so adjusted that it is still free to reset the contacts after the third operation, and it may operate a fourth time similar to the third operation, since the port 85 is stlil closed by the piston 83. Upon the reopening of the circuit a fourth time, the piston 83 raises a suitable spring biased lever I22 on the look-out mechanism, which is attached to the clevis 89, and this lever engages a suitable mechanism on a linkage attached to the clevis 98, preventing the armature l3 from descending sufliciently to reset the contacts, and also looking the piston 83 in the raised position.

This is-a very important feature of the invention, as none of the devices of the prior art with which I am familiar are capable of locking out the time delay condition in the third or fourth position like the present device. Under these conditions, the device can only be placed back in service by a manual operation, which, in this case, consists in tripping the lock-out mechanism so that the armature can move to reset the contacts. When the piston 83 is locked out or latched in its upper position the lower end of the piston 83 has cleared the opening 85, and the port 85 provides a vent for passage of oil which may be pumped into the cylinder 88 under these conditions.

The purpose of holding the piston 83 on lockout in the fourth position is as follows: When contact is re-established on a line, especially after a prolonged outage, considerable consumer equipment may be connected to the line in the on position. The starting currents of these equipments may be sufiicient to cause an instantaneous operation of the breaker, but because of the short duration of the surge of current, a time delay would hold the breaker against this transient surge. Thus the time delay which is provided by having the time delay cylinder in its uppermost position prevents the circuit from being broken again unnecessarily, due to a transient surge of vequipment which has been connected :to the line in the on position.

If, onthe other hand, aline fault still exists,

the device would operate only once, and again lock out without further damage to the line or without strain on line equipments supplying the .power,,and withmuch less wear on the circuit ous operations upon a manual reset, due to the transient inrush currents which are caused by the switching operation plus the starting currents of the connected load. These operations, caused by transient currents, are avoided by the use of the present invention.

It will thus be observed that I have invented an improved automatic circuit recloser mechanism adapted to provide for a plurality of fast openings of the circuit upon the existence of a fault in the circuit with a time delay closing, and, thereafter, with a time delay opening of the circuit on the third and fourth operations.

Referring to Fig. 3, this is a fragmentary sec- .tional view, similar to Fig. 1, of a modification which includes all of the same elements as Fig. 1, except that the solenoid coil H and its armature I3 are arranged lowermost, with the dash pot above the solenoid.

All of the similar parts have been given similar numerals, and the operation of the device is still the same. I

The location of the solenoid lowermost in the assembly makes it possible to remove the solenoid coil and substitute another coil to change the rating of the circuit recloser. To do this it is only necessary to remove the lower bolts H30 and the closure cap IOI, which is provided with a tubular extension I02 for receiving the armature l3.

This modification also reduces manufacturing costs by simplifying machining and by eliminating the liner tube 51 which extends through the armature coil into the chamber 9|, although a tubular sleeve 5'! is still employed as a part of the spool on which the coil is mounted.

It is unnecessary to disturb the contact mechanism or any other part of the assembly, except the bolts I and cap I01, in removing the coil H and substituting another coil.

According to my invention, the greater the current, the faster the armature travels and the faster oil is ejected to quench the are which is drawn between the contacts. At each opening of the circuit a measured amount of oil is passed into the timing cylinder, independent of the magnitude of the operation or the viscosity of the oil.

In addition to the armature being locked out, the timing mechanism is locked out on the third or the fourth operation, and thus the device is kept in such condition that it will not be actuated again and again, due to the transient surges of current caused by the closing of the circuit and the connection of consumer equipment to the line in the on position.

The armature is released from time delay pressure at the instant of contact break to allow the full force of the dash pot piston to eject oil across the path of thearc, yet the travel-of the -pist on is cushioned d s pped-quickl i tz he end the dash pot.

Wh l I h v i ustrated a pr er e embod m t of my vent on mod fic o ma he made without departing ;=f'romthe.spirit of the invention, and Ido not wishtobelimited-to the precise details of construction-set forth, but desire to avail myself of all changes within the scope of the appendedclaims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States, is:

1. In a-circuit maker and breaker, .a container, asup-ply of insulating oil in,.said container and a switching unit immersed in said oil comprising a support, fixed contact .means carried by .said support, a movablymounted barriercarry'ing-a movable contact for bridging said contact means, a cylindercarried by tif e support, said cylinder having a longitudinally extending slot directed toward the space between said fixed contact .means, a solenoid, a plunger armature mounted in said solenoid and carrying a piston in said cylinder, said piston acting on the oil in the cylinder as acombined pump and clash-pot and pumping said oil out of saidslot between said fixed contact means toextinguish an arc, simultaneously with the interposition of 'said barrier between said fixed contact means.

2. In a circuitmaker and bre aker, acontainer, a supply of insulating ;oil 'i n s aid container and a switching unit immersed in said oil comprising a support, fixed contactmeans carried bysaid support, a movably mounted barrier carrying a movable contact for bridging said contact means, a cylinder carried-by the support, said cylinder having a longitudinally extending slot directed toward the space between said fixed contact means, a solenoid, a plunger armature mounted in said solenoid and carrying a piston in said cylinder, said piston acting on the oil in the cylinder as a combined pump and dash-potand pumping said oil out of said slot between said fixed contact means'to extinguish an arc, simultaneously with the interpositionof said barrier between said fixed contact means-the said barrier being pivotally mounted-on said support and being connected to said 'pistonbya spring having its points of connection located so that the line of centers of the spring and its attachment passes the point of pivotal attachment of the barrier to effect a snap action.

3. In a circuit maker and breaker, a container, a supply of insulating oil: in;said containenand-a switching unit immersed insaid oil .comprisingra support, fixed contact meanscarried .bysaidsuD- port, a movably mounted barrier carrying a movable contact, for, bridgin gsaid contact, means, a cylinder carried by the support,' said cylinder having a longitudinally .extendingslot--directed;to-

switching unit carried by the container and imdelay the motion of said solenoid for a time interval, depending upon the duration and intensity of a surge of current in said solenoid, contact means controlled by said piston and opened at a predetermined point of the motion of said piston, a time delay cylinder, a pumping cylinder formed by an extension of said bore having a laterally extending conduit leading to said time delay cylinder having a piston, a piston below said conduit on said rod in said pumping cylinder, said latter piston pumping oil into said time delay cylinder until said latter piston passes said conduit and valve means in said conduit for preventing the return of the oil from said time delay cylinder.

5. In a circuit maker and breaker, a container, a supply of insulating oil in said container and a switching unit carried by the container and immersed in said oil, said switching unit comprising a solenoid mounted upon a member having a cylindrical bore, a plunger armature mounted for movement in said bore and including a member slidably mounted in the bore, said plunger armature being mounted upon a rod, a cylinder located axially with said bore, a piston connected to said armature and located in said cylinder to delay the motion of said solenoid for a time interval, depending upon the duration and intensity of a surge of current in said solenoid, contact means controlled by said piston and opened at a predetermined point of the motion of said piston, a time delay cylinder, a pumping cylinder formed by an extension of said bore having a laterally extending conduit leading to said time delay cylinder, a piston below said conduit on said rod in said pumping cylinder, said latter piston pumping oil into said time delay cylinder until said latter piston passes said conduit and valve means in said conduit for preventing the return of the oil from said time delay cylinder, said time delay cylinder having a piston actuated by the oil pumped into said latter cylinder.

6. In a circuit maker and breaker, a container, a supply of insulating oil in said container and a switching unit carried by the container and immersed in said oil, said switching unit comprising a solenoid mounted upon a member having a cylindrical bore, a, plunger armature mounted for movement in said bore and including a member slidably mounted in the bore, said plunger armature being mounted upon a rod, a cylinder located axially with said bore, a piston connected to said armature and located in said cylinder to delay the motion of said solenoid for a time interval, depending upon the duration and intensity of a surge of current in said solenoid, contact means controlled by said piston and opened at a predetermined point of the motion of said piston, a time delay cylinder, a, pumping cylinder formed by an extension of said bore having a laterally extending conduit leading to said time delay cylinder, a piston below said conduit on said rod in said pumping cylinder, said latter piston pumping oil into said time delay cylinder until said latter piston passes said conduit and valve means in said conduit for preventing the return of the oil from said time delay cylinder, said time delay cylinder having a piston actuated by the oil pumped into said latter cylinder, said time delay cylinder having an enlarged aperture located above its piston for discharge of oil during the first pumping of oil into said latter piston.

'7. In a circuit maker and breaker, a container, a supply of insulating oil in said container and a switching unit carried by the container and immersed in said oil, said switchin unit comprising a solenoid mounted upon a, member having a cylindrical bore, a plunger armature mounted for movement in said bore and includin a member slidably mounted in the bore, said plunger armature being mounted upon a rod, a cylinder located axially with said bore, a piston connected to said armature and located in said cylinder to delay the motion of said solenoid for a time interval, depending upon the duration and intensity of a surge of current in said solenoid, contact means controlled by said piston and opened at a predetermined point of the motion of said piston, a time delay cylinder, a pumping cylinder formed by an extension of said bore having a laterally extending conduit leading to said time delay cylinder, a piston below said conduit on said rod in said pumping cylinder, said latter piston pumping on into said time delay cylinder until said latter piston passes said conduit and valve means in said conduit for preventing the return of the oil from said time delay cylinder, said time delay cylinder having a piston actuated by the oil pumped into said pumpin cylinder, said time delay cylinder having an enlarged aperture located above its piston for discharge of oil during the first pumping of oil into said latter piston, and said time delay having a second limited discharge opening for discharge of oil from said latter cylinder upon the second pumping of oil into said latter cylinder after its piston has passed the enlarged discharge opening.

8. In a circuit maker and breaker, a container, a supply of insulating oil in said container and a switching unit carried by the container and immersed in said oil, said switching unit comprising a solenoid mounted upon a member having a cylindrical bore, a plunger armature mounted for movement in said bore and including a member slidably mounted in the bore, said plunger armature being mounted upon a rod, a cylinder located axially with said bore, a piston connected to said armature and located in said cylinder to delay the motion of said solenoid for a time interval, depending upon the duration and intensity of a surge of current in said solenoid, contact means controlled by said piston and opened at a predetermined point of the motion of said piston, a time delay cylinder, a pumping cylinder formed by an extension of said bore having a laterally extending conduit leading to said time delay cylinder, a piston below said conduit on said rod in said pumping cylinder, said latter piston pumping oil into said time delay cylinder until said latter piston passes said conduit and valve means in said conduit for preventing the return of the oil from said time delay cylinder, said time delay cylinder having a piston actuated by the oil pumped into said pumping cylinder, said rod extending out of the upper end of said latter cylinder with a sliding fit, and said rod having a reduced portion located to provide an opening around the rod at the upper end of said latter cylinder for discharge of oil when said laterally extending conduit is shut off by said pumping piston.

9. In a circuit maker and breaker with regulated delaying action for its opening or closing, the combination of a solenoid and an armature, said solenoid being connected to receive surges of current on the line and to exert a force on the armature which is dependent on the intensity of the current, a cylinder, a piston in the cylinder connected to said armature, said cylinder and piston acting both as dash-pot and pump, fixed contact means and movable contact means controlled by said armature, said cylinder having an aperture directed toward said contact means to extinguish the are by discharge of oil from the cylinder, said cylinder and contact means being immersed in oil, a second pump cylinder and a piston connected to said armature and actuated by said solenoid, a time delay cylinder, a conduit extending from said second cylinder to said time delay cylinder having a piston, said second piston pumping oil into said time delay cylinder until it passes said conduit.

10. In a circuit maker and breaker with regulated delaying action for its opening or closing, the combination of a solenoid and an armature, said solenoid being connected to receive surges of current on the line and to exert a force on the armature which is dependent on the intensity of the current, a cylinder, a piston in the cylinder connected to said armature, said cylinder and piston acting both as dash-pot and pump, fixed contact means and movable contact means controlled by said armature, said cylinder having an aperture directed toward said contact means to extinguish the are by discharge of oil from the cylinder, said cylinder and contact means being immersed in oil, a second pump cylinder and a piston connected to said armature and actuated by said solenoid, a time delay cylinder, a conduit extending from said second cyl inder to said time delay cylinder having a piston, said second piston pumping oil into said time delay cylinder until it passes said conduit, said armature being connected to a rod slidably mounted in the end of said second cylinder, said rod having a reduced portion providing a discharge aperture around the rod after said second piston passes said conduit.

11. The combination of fixed and movable contact means with a support, a cylinder carried by said support and having a slot directed toward an are between said contact means, a piston in said cylinder controlling said movable contact means and acting both as a pump and a dashpot, said contact means and cylinder being immersed in oil and said piston pumping oil out of said slot toward said contact means, a solenoid having a plunger armature connected to said piston, said solenoid being connected in circuit to actuate its armature responsive to surges of current, said armature being retarded by said piston, a second cylinder and a second piston connected to and actuated by said armature, a third time delay cylinder and a conduit from said second cylinder to said third cylinder, said second piston acting as a pump and pumping oil out of said conduit from its cylinder into said third cylinder, said third cylinder having a piston mounted to be moved by the oil pumped into it.

12. The combination of fixed and movable contact means with a support, a cylinder carried by said support and having a slot directed toward an are between said contact means, a piston in said cylinder controlling said movable contact means and acting both a pump and a dash-pot, said contact means and cylinder being immersed in oil and said piston pumping oil out of said slot toward said contact means, a solenoid having a plunger armature connected to said piston, said solenoid being connected in circuit to actuate its armature responsive to surges of current, said armature being retarded by said piston, a second cylinder and a second piston connected to and actuated by said armature, a third time delay cylinder and a conduit from said second cylinder to said third cylinder, said second piston acting as a pump and pumping oil out of said conduit from its cylinder into said third cylinder, said third cylinder having a piston mounted to be moved by the oil pumped into it, said third cylinder having a series of apertures in its side wall for discharging oil from the opposite side of its piston at a rate depending on the position of the piston.

DAVID C. HUBBARD.

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

Wallace Nov. 2,