US839079A - Time-limit circuit-breaker. - Google Patents

Description

PATENTED DEC. 18, 1906. W. M. SCOTT. TIME LIMIT CIRCUIT BREAKER. APPLICATION FILED 23.17, 1903.

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No. 839,079. PATENTED DEC. 18, 1906. W. M. SCOTT.

TIME LIMIT CIRCUIT BREAKER.

APPLICATION FILED FEB. 17. 1903.

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No. 839,079 PATENTED DEC. 18, 1906.

W. M. SCOTT.

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fl/ Wk witnesses v gwvefllfvo't M y/ h. M a 5 M No. 839,079. PA'TEIITEI) DEC. 18, 1906. w. M. SCOTT.

TIME LIMIT CIRCUIT BREAKER.

AHLIOATION FILED FEB.17, 1903.

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'ILLlA-M M. SCOTT, OF PHILADELPHIA, PENXSYLVASIA, ASSIGNOR TO CUTTER ELEGIRICAL AND MANUFACTURING COMPANY, A CORPORA- TION OF NEW JERSEY.

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Specification of Letters Patent. Airplication filed February 17, 1903. Serialh'o. 143,771.

' Patented Dec. 13 1906.

.To all whom it may concern: Be it known that I, WILLIAM 'Msoorr, a citizen of the United States, residing at Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented a new and useful Time-Limit Circu'itBreaker, of which the following is a specification.

. My inventionrelates-to electrical switches,

more particularly of the automatic magnetic type employed for theprotectio'n of electrical apparatus from the effects resulting from un- I My invention consists of an automatic circuit-breaker so arranged and constructed as 50, a sectional view on the desired conditions in an electric circuit; 1

cuit-breaker whose function is to disrupt or open an electricfcircuit upon the occurrence of predetermined conditions, such as underload or overload in the circuit, or upon the occurrence of a predetermined potential difference on a circuit.

My invention consists of an automatic cirto open an electric circuit under predetermined conditions, but notuntil such conditions have obtained for a certain interval of time. My inventionconsistsof a time-limit circuit-breaker so arranged and constructed as to open an electric circuit after predetermined conditions have'obt'ained for a definiteinterval of time, anddf such conditions disappear'within such predetermined interval of time the parts return to their normal condi-l tion and position without having opened the circuit.

after described.

. Reference is to be had'to the accompany-- ing drawings, in which- Figure 1 is a sideelevation of the circuit;

breaker in circuitclosingposition. Fig. 2 is g, a side view of the retarding element of the time device. Fig. 3 is an end View, partlyin section, of the same. Fig. 4 is an enlarged detailed view ofthe trippinga paratus of the Fig. 5 isa plhn'view'of the tripping-magnet associated with one of the main terminal blocks. Fig\- 6 is a front elevation of Fig. 5 on a reduced scale.

8 is a'plan view of-the on magnet. Fig. 9 1s a section on the line 9 9., Fig 8. 10 and,

11 are vfragmentary views' illustrating the predetermined and a My invention consists also of further do tails in principle and construction, as herein-- Fig. 7 is. line 7 7,,Fig. 5. Fig.

I. copper or other well-conducting material,

having their contactfaces in practically the same vertical plane. Circuit connections are made with the switch through the bolts or studs 3 and 4, which serve also to hold the main terminals 1 and 2' firmly against the switchboard A.

5 is a laminated movable contact member made up of numerous sheets of copper-whose beveled ends engage with a resilient wiping contact upon'the surface of the terminals 1 and ;2; These laminae are secured to, but insulated from, the casting 6, which carries at its low er extremity the roller 7, having a mo tion of translation the 'slot 8, formed in a member secured tothe base A. 7

' 9 is a reciprocating, contact secured to they base and w 'ch is engagedby the metallic spring-contact 10, which moves with themain laminated member 5, from which it is insulated, however. The casting or arm 6 has an up er extension 11, which rigidly supports, t ough insulated from it, the. up-

wardly-extending copper member 12, which issecured-at its lower end to the arm 6, but insulated from'said arm 6 and also from the laminated member 5... In the upper end of this element 12 a pivot 13, about which may rotate the shunt-carbon 14.

-15 is'the fixed shunt-carbon, pivoted at 16 -to the upwardly extending bracket 17, which 7 is electrical and mechanical communica'- tion with the main terminal 1.

19 a'metallic shunt-contact mechanic ally "secured to and in electrical communication with the element 12.

- 20 is the fixed metallicshunt-contact with which: the contact .19 cooperates and is in electrical'communication with the main terminal 1.

' To operate the main laminated member 5 about its movable pivot 7 there is supplied an operating-handle21,pivoted at 22 in the right end with the pin 33 in the frame '23.'

frame 23, secured to the base A. The operating-handle 21 extends beyond the pivot 22, such extension being represented at 24. 24 forms, in fact, one link of a toggle Whose other link is 25, pivoted to the arm 6 at 26. 27 is the pivot common to both links 24. and 25. When the circuit-breaker is in the open position, the toggle is collapsed and the arm 21 raised above the position shown in Fig. 1. To close the circuit-breaker, the operatinghandle 21 is forced downwardl this motion causing the straightening out o the toggle 24 25, with the consequent rotation of the laminated member 5 in a counter-clockwise direction about its pivot until'it engages with the main terminals 1 and;2. The closing movementdoes not cease with the first contact between-the member 5 and the main terminals 1 and 2, but is continued slightly thereafter, such continued motion bringing the pivots 22,. 27, and 26 almost into a straight line and simultaneously springing the laminae of the member 5, due to the pressure against the terminals 1 and 2. As this closing movement is completed the operating-handle 21 is locked in the position shown in Fig. 1 by a latch 28, which'engages a roller 29 in an extension 30 integral with the operating member 21. Latch 28 therefore restrains the'switeh in a circuit-closing position.

During the closing movement the spiral springs 31 and 32 are put under tension,-and so long as; the circuit-breaker is in the circuit-closing position these springsremain under tension. Spring 31 connects at its left end withthe pivoted arm 6 and at its Spring 32 is connected between the pin 33 and the extension 24 of the operating-handle 21. When the circuit breaker has been tripped, spring 31 pulls the arm 6 toward the right, causing it to move with a motion of translation, due to the slot 8, and thereafter with a motion of rotation about its pivot 7, which has then passed to the right end of the slot 8. Simultaneously spring 32 pulls downwardly on the extension 24, thereby aiding in breaking the toggle, opening the switch, and raising the handle 21.

When the current through the circuitbreaker attains a predetermined value, the iron armature 34 1s drawnupwardly by 'a magnet 34, depending for its strength upon the current flowing through the instrument. This magnet 34 consists of a U-shaped piece of iron, as shown in Fig. 8.v The inner wall of the circular portion is tapered, as clearly shown in Fig. 9. This tapered portion fits over a corresponding tapered portion of the main terminal block 2 and concentric with the stud 4. The disposition of this magnet with respect to the terminal block 2 is shown in Figs. 5, 6, and 7, from which it is seen that the iron of the magnet partially surr ounds the stud or terminalblock and is surrounded by or embedded in the terminal block. The magnet is shown at 101 and has a wedgeshaped opening between its pole-pieces, between which a correspondingly-shaped armature'may operate.

102 represents a depression in the terminal block to accommodate a bolt-head or nut of a bolt which may extend through the opening 103. w

The armature 34 is secured to the end of the member 35 pivoted in the frame 23 at 36. Pivoted at 37 in the member 35 is a downwardly-extending link 38, pivoted at 39 in a horizontal member 40, which is pivoted to the frame 23 at 41. Depending from the member 40 is a frame 42, having mounted in it the adjusting-screw 43, which 'When rotated will cause the wei ht 44 to be moved backwardly and forward y. To prevent the rotation of the Weight 44 With the screw 43, the former'is slotted and embraces with its slot the edge of the plate 45 mounted in the frame 42. Alon this late 45 are suitable calibration-mar s, an by adjusting the weight 44. to any desired calibration-mark the condition is determined at which the circuit-breaker will open. By shifting the position of the Weight 44. to different points the amount of, force that must be exerted by the triplpingmiagnet on the armature 34 is var1e 46 is a bracket secured to the frame 23 and at its lower extension is rovided with a hole 47, slightly larger than t e pin 48, carried by the frame 40. This construction of pin and hole is a limiting device for the upward movement of the member 40. At the right end of the member 40 is secured the electrode or contact-piece 49, which is, however, insulated from the member 40. 7

50 is a fixed electrode cooperating with the electrode 49 and included in the circuit of an electroma 'net having a single core, at the ends of which are secured by screws 51 the iron cheeks or pole-pieces 52. Pivoted at 53 in said poleieces is the movable armature 54, which w en the electromagnet is energized is attracted in a counter-clockwise direction.

'52 and 52)- are shunt ma net-windings disposed upon the horizontafiy extending cores having poleieces 52. 52 and 52 are inc uded in a circuit exten ing from 52, one side of the main circuit,

he windin s.

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through the winding 52*, contacts49' and 50,

winding 52' and contact 9', which 006 eratos with the s ring-contact 10 adapte to be connected y a flexible conductor, as 10, with the contactebridge 5 or either of the main terminals 1 or 2, which are connected in the other main conductor 52.

Extending downwardly below the polepieees 52 are the brackets 55, between which is pivoted at 56 upon a horizontal pivot the eeao've cylindrical chamber 57. On the same axis -56 is pivoted the triangular plate 58, which carries at its one corner the pivoted roller .59

and at the other corner the pin or roller 60, which is adapted to engage with one of the flanges 61 of the chamber 57 to limit the rotation of the plate'58 in a counter-clockwise direction. 62 is another flange of the chamber 57, said chamber being, in fact, in two portions, which are secured together by said anges 61 and 62.

The armature 54 is provided with an ex- 1 tension beyond the pivot 53 (indicated at 63) and provided at its lower end with the-horizontally-disposed cam-plate 64. A spring 65,

i joined at its one end to the member 63 and at its other end at 66in a fixed portion of the instrument, tends to hold the armature 54 in its retracted position.

The chamber 57, as previously stated, is -made up of two portions which are secured "together by means of their flanges 61 and 62.

The end walls of the chamber 67 and 68 ex tend laterally, and in their extremities is mounted the screw 69, which maybe turned by thumb-nut 70.

71 is a weight which is screw-threaded to receive 69 and slides alohg the guide-rod 72 and is prevented from rotating with screw 69 by said guide-rod 72. Turning the thumbsc'rew 7 0' changes'the position of the center of' i gravity of axis 56.

the device with respect to the v Pivoted with'in the chamber'is the trapdoor 73, pivoted, at 74 and havin one or I I more small openings 75. The mem er 73 is of such dimensions and so disposed that it can never become perpendicular to the axis 8 of the cylinder 57, but is always at some inclined position, asshown in Fig. 2. It's rotation, therefore, can proceed no farther than V 1 shown in Fig. 2 in a clockwise direction, but

.45 H member 73 and the lower internal surface of the cylinder 57 placedaquantity of mercury or other suitable heavy liquid or mass, which, from its 5 .trap=do.or 73, normally maintains the cylinder 57in the inclined-positionshown in Figs. 1

its rotation in a counter-clockwise direction maybe considerable, thereby allowing arelatively large gap between the lower edge of Within the cylinder 57 is weight and because of the disposition of the 1 and 4. .Upon tilting the cylinder 57 in a 'counter -iclock-wise I direction, as viewed in Fig. 1", the level of the mercury will rise to or.

above the'holes 75in the trap-door 73 and will flowthrough these restricted passages or orifices into the left-hand portion of the cylinder; If the cylinder 57 be tilted to such enough mercury will have passed into the position for a sufficient interval of time,

left end of the cylinder 57 to cause such cylinder to become heaviest at its left end and to rotate about its axis 565 The tilting of the cylinder 57 is accomplished by the armature its electromagnet, a cam-plate 64 presses downwardly on the roller 59, which transmits the force through the plate 58 to the cylinder 57, rotating it to. a certain position, where the mercury will be enabled to flow through the orifice in the trap-door 73. If the armature 54 remains attracted sufficiently long, enough mercury will have found its wayinto the left-hand end of the cylinder 57, causing it to rotate voluntarily about its axis 56, such rotation being through a very considerable angle, as will be hereinafter described.

The latch 28, heretofore referred to, is pivoted to a fixed po rtion of the instrument at 76. Mounted foi'rotation about this same pivot 76 is the member 77, joined to the latch28 by the spring 78. a

79 is a projection from the member 77 which engages with a downward projection from the latch 28. The member 77 con tinues beyond'the pivot 76 in a portion 80, between whose outer end and the bracket 46 is the spiral spring 81 which in the position In the extension there is pivoted at 82 a tog: gle-link 83, at whose lower end is the pivotal connection i l with the second toggle-link 85, pivoted in the bracket 46"at 86. The toggle member 85 has a downwardly-extending portion at 87 and having a portion 88 extending approximately horizontally from the approxirrfately vertical portion 87. The toggle 83 85 when extended as shown in Figs. 1 and 4 holds the member 77 in the position shown and maintains the spring 81 under tension.

When sufficient mercury has gotten intov the left-hand compartment of the cylinder 57 by the process above described, such cylinder 57 rotates about its axis 56 through a great portion of a revolution until the upper right-hand portion of cylinder 57 strikes the .54. a When this armature 54 is attracted by outer end of the member 88. By this operation the cylinder 57 delivers a blow to the outer end of the member 88, causing the toggle member 85 to rotate in a clockwise directionabout its pivot 86, thereby breaking the toggle and permitting the spring 81 to con.-v

tract. In so contract ng spring 81 operates upon the extension 80, causing the member 77 to engage by its projection 79 with the latch 28, raising such latch and freeing the roller 29 from the latch 28. The roller 29 being disengaged from the latch 28, the cirvcuit-breaker is opened, due in part tothe springs 31 and 32 "and in part to gravity.

89 is a vertically-reel rocating rods pro-- vided' at itstop with arol ler 90 and interme diate its ends withlongitudinal slots 91 and 92. These slots embrace pins'93 and 94.----

respectively, 93 being supported by the bracket 95, secured to the frame of the device, and pin 94 is sup orted bya member 96, also extending from t e frame of the apparatus. Secured at its up er end to the bracket fices 75 in the trap-door 73 have already been 95 is the spring 97,.w ich is secured at its lower end, at 98, to the rod 89. This spring 97 therefore tends to keep the rod in its raised position. At the lower end of the rod 89 is ahorizontally-disposed cam-plate 99,

which is adapted to coeperate with the roller 100, secured to the movable chamber 57. The urpose of the rod 89, cam-surface 99, and r0 ler 100 is to reset the chamber 57 to the position shown in Figs. 1 and 4 as soon as the circuit-breaker has opened the circuit. During the opening movement of the circuitbreaker the member 24 of the main toggle rotates in a counterclockwise direction about its pivot 22, and its under surface acts as a cam pressing downwardly upon the roller 90, thusforcing the rod 89 and the cam-surface 99 downwardly. At the beginning of this downward motion of rod 89 the chamber 57 is not in' the position shown in Figs. land 4, but in its rotated position, as formerly described, and the roller 100 is therefore in a position considerably vertically above position shown in Fig. 4. The downward motion of rod 89 in consequence forces'downwardly the roller 100, which results in the rotation of the chamber 57 in a clockwise direction, and when the rod 89 has completed its travel the chamber 57 has again assumed its position as shown in Fig. 4. The dotted position of the member 24, rod 89, and camplate 99 shows the state of aflairs at the mo ment when the circuit-breaker has come to the end of its opening movement.

- During the rotation of the chamber 57 in the clockwise direction during the resetting movement the mercury-in the lower or lefthand compartment rushes back into the right-hand compartment under the edge ofthe trap-door 73, which permits of this rapid passage of the mercury because of its freedom to rotate about the pivot 74 in a direc-' tion suitable for the purpose, as seen in Fig. 2. Upon resetting or closing the circuit breaker the member 24 rises, andso also does the rod 89 under the influence of s ring 97, its upward movement being limite only by the slots .91 and 92 engaging at their lower ends with the pins 93 and 94; The cam-surface 99 then occupies the position shown in full lines in 4., The Inercur chamber 57 having returned to t e righthand compartment, said chamber remains in the position shown at Fig. 4 invirtue of the cam-plate 64 being in the path of travel of the roller 59 on the plate 58.

The operation of the device is as follows: Supposing the circuit-breaker be required to open a circuit in the case of current of two thousand amperes (or more) flowin in the circuit for a period of ten seconds. The weight 44 is adjusted until some reference-mark comes 0 posite the graduation corresponding to two t ousand amperes. The orifice or ori-' in the calibrated, so that in ten seconds a stream of mercury will flow into the left-handmompartment of the chamber 58 to cause the chamber 57 to rotate about its axis 56 ina counter-clockwise direction to engage the member 88. Upon the current reaching the value of two thousand amperes the armature 34 is attracted upwardly, raising the arm or frame 40, which rotates about the pivot 41 and brings the electrodes 49 and 50 into engagement with each other, thereby energizing the electromagnet whose pole-pieces are,

shown at 52, and this results in the attraction of the armature 54. The upward travel of the arm 40, and therefore of the armature i trolling-magnet that a current considerably 34, is limited by the hole 47, which is slightly larger than the pin 48. The purpose of thisconstruction is to prevent the armature 34 being attracted to a position so near its con less than two thousand amperesmight retain it in its attracted position, and thereby main-- tain the circuit closed at contacts 49 and 50. In other words, this structure insures the separation of contacts 49 and 50 should the current fall below two thousand amperes at any time before the expiration of ten seconds. As soon as circuit is made between 49 and 50 the armature 54 is attracted and.camplate 64 rotates the cylinder 57 into such position that the mercury. begins to flow through the small orifices 75in the trap-door 73. Now

in case this current of two thousand amperes continues for ten seconds contacts 49- and 50 will be in'engagement for ten seconds at least, arm-atnre54 will. remain attracted during the same period of time, and the chamber 57 willremain tilted during such.

period of time. At the expiration of ten seconds, however, enough mercury has flowed from the right-hand "compartment of chamber 57 .into the left-hand compartment to cause such chamber to rotate rapidly and forcibly about its pivot 56 and deliver a blow.

to the top side of member 88, as heretofore described. This operation causes the breaking of the toggle 83 85, the downward motion of the member 80 under the influence of the spring 81 resulting in the member 77 by its projection 79 lift-ing the latch 28 to release the roller; 29, and thereb I permitting the circuit breaker to open. broken armature 34 is no longer attracted and in consequence the arm 40 falls, breaking circuit between 49 and 50.

ith' the circuit- The operation of resetting the circuit-- breaker has been previously described, especially with reference to red 89 in its 0 ration resetting chamber 57. Suppose, owever, that at the-expiration of seven and a half' seconds the current in the instrument falls below the critical value of two thousand amperes, the .arm "40 reps ownwardly again,breaking circuit between 49 and 50 because of the limitedupward movement of the armature 34 in virtue of pin 48 and hole 47. Withflthe circuit broken at 49 and 50 the armature 54 moves to its retracted position, as shown in Fig. 4, and the chamber 57 returns to itsposition shown in Fig. 4, and whatevermercury has passed into the left hand compartment 'now returns quickly to v the right hand compartment under the lower edge of the trap-door 73. The circuitbreaker is then again .in recisely the same 49Iand 50 with reference to the field of the magnet whose armature is 54 is such that said magnet operates as amag'netic blow-out for any arcs bridging 49 and 50.

Though'I have shown my improved tripping mechanism as applied to a circuitbreaker to be operated upon abnormally high-current conditions, it is 'to be understood that my inventionis oliviously adapted to abnormally low-current conditions, predetermined high voltage, or predetermined lo'w' voltagcl', My tripping device may also be applied by anyone skilled in the art to com-. I

bmed current and potential features known as overload andunderload switches, overload and reversalswitches, or overload, un-

derload, and reversal switches; in fact, to any t e of electrical switch.

- hat I claim is '1. In an automatic magnetic circuitbreaker, fixed terminals, a member adapted to bridge said terminals, a latch restraining said bridging member in normal position, an

eleotromagnet in the circuit of said bridging member, a circuit controlled by said electromagnet, and a pivoted li uid-containing chamber having relatively ar'ge range of movement controlled by said circuit for delivering a blow to said latch a predetermined interval of time after the closure of said circuit.

2. In an automatic circuit-breaker, fixed terminals, a movable contact member cooperating therewith, a latch for restraining said contact member in normal position, an elec tromagnet in the circuit of said terminals and contact member, a circuit controlled by said electromagnet, va chamber controlled by said circuit for actuating said latch, a movable ,mass within said chamber, and means for retarding the passage of said mass from one portion of said chamber to another.

3. In an automatic circuit-breaker, fixed terminals, a movable contact member coopcrating therewith, a latch restrammg said contact member in normalposition, an electromagnet in the circuit of said terminals and contact member, a circuit controlled by said electromagnet, a chamber controlled by said circuit, a mass of liquid within said chamber,

and means for restricting the passage of said liquid from one portion of said chamber to another.

4. In an automatic circuit-breaker, fixed terminals, .a movable contact member coop crating therewith, a latch restraining said contact member in normal position, an electromagnet in the circuit of said terminals and contact member, a circuit controlled thereby,

liquid mas's operating as a trip actuated by said magnet, and means for preventing the operation of said mass for a definite interval or time.

' a magnet-winding included in said circuit, a

5. In an automatic circuit-breaker, fixed terminals, a movable contact member coopcrating therewith, a latch restraining said contact 'member in normal position, a latchactuating device comprising a chamber hav ing relatively large range of movement and 0 containing a mass ofliquid, and electrorcsponsive means for controlling said latch actuating device.

6. In an automatic circuit-breaker, fixed terminals, a movable contact member coop 5 crating therewith, a latch restraining said contact member in normal position, a hammer for actuating said latch, and means controlled by the current passing through said contact member for starting said hammer, said hammer comprising a chamber having 'a relatively large range of movement and containing a liquid restricted in its passage from one portion of said chamber to another. 7. In an automatic circuit-breaker, fixed terminals, a movable contact member cooperating therewith, a latch restraining said contact member in normal position, an elecv tromagnct, a circuit controlled thereby, a I

hammer, and means controlled by said circuit for starting said hammer to deliver a blow to said latch, said hammer comprising a chamber having relatively great range of movement andcontaining a mass of liquid. 8. In an automatic circuit breaker, fixed terminals, amovable contact member coop- .erating therewith, alatch restraining said contact member in normal position, means for actuating said latch, a toggle restraining said latch-actuating means in normal position, and a-retarded hammer for breaking said toggle.

9. In an automatic circuit-breaker, fixed terminals, a movable contact member coopcrating therewith, means forrestraining sald contact member 1n normal position, means responsive to predetermined electrical condi tions in a circuit, a hammer controlled thereby and comprising a chamber having large range of movement and contamlng a movable mass, means in said chamber for retarding said movable mass, and means engaged by said hammer for controlling said -restraining means. '10. In-an automatic circuit-breaker, fixed terminals, a movable contact member cooperating therewith, a latch restraining said contact member in normal position, means for actuating said latch, a toggle restraining said latch-actuating means in normal position, electroresp'onsivemeans, and .means controlled .thereby'fo-r breakin said toggle aftera redetermined interval time.

ll. 11 an automatic circuit-breaker, fixed terminals, a movable contact member cooperating therewith, a latch restraining said contact member in normal position, vmeans for actuating said latch, a toggle restraining.

' said latch-actuating means in normal positerminals, a movable contact member coopcrating therewith, a latch restraim'ng said contact member innormal position, a retarded hammer for actuating said latch, electroresponsive means for startin said hammer, an

means for restoring said ammer to normal position after the actuation of said latch.

14. In an automatic circuit-breaker, fixed terminals, a movable contact member coop- -erating therewith, means restraining said contact member in normal'position, a hammer, comprising a chamber having large range of movement and containing a retarded movable mass, for controlling .said restrainin means, means responsive to, prede- -termine electrical conditions in a circuit, a circuit controlled thereby, and n'ieans' controlled by said circuit for starting said-ham- 15. In an automatic circuit-breaker, fixed terminals, a movable contact member coopcrating therewith, means restraining said contact member innormal position, a local circuit a hammer, means responsive to abnormal current-flow for closing said local circuit, and means controlled by said circuit for starting said hammer for controlling said restraining means, said hammer comprising a 'chambercontaining a movable mass and means for retarding the movement of said mass.

16. In an automatic circuit-breaker, fixed terminals, a movable contact member coopcrating therewith, a toggle for operating said movable contact member, means for restraining said toggle in normal position, a'chambcr having large range of movement and containing a mass restricted in its movement for actuating said restraining means, and means responsive to predetermined electrical conditions in a circuit, for starting said chamber.

, 18. In an automatic circuit-breaker, fixed terminals, a movable contact member cooperating therewith, a latch restraining said contact member in normal position, a magnet, an armature therefor, means for preventing the near approach ofsaid armature to said magnet, a retarded hammer for actuating said latch and means controlled by said armature for starting said hammer.

19. In an automatic circuit-breaker, separable'cooperative contacts, a latch for restraining said contacts in normal position, and a pivoted liquid-containing chamber, having relatively great range of movement for delivering a blow to said latch.

20. In an electric switch, separable cooperative contacts, a latch for restraining said contacts in normal position, and a pivoted chamber having relatively great range of roe movement containing a liquid mass for. de-

.livering a blow to said latch.

21. In an automatic circuit-breaker, separable cooperative contacts, a latch for restraining said contacts in normal position, a tripping-magnet, and a liquid-containing chamber having relatively great range of movement for delivering a blow to said latch and controlled by said tri ping-magnet.

22. In a tripping mec ianism for electric switches, means for deliveringa blow comprising a chamber, a liquid mass-contained therein, and means for retarding the assage of said mass from one portion ofthe c amber -to another portion,

23. In a tripping mechanism for electric switches, -means for delivering a blow comprising a pivoted chamber, a liquid mass contained therein, and means for retarding the passage of said mass from one portion of said chamber to another portion thereof.

24. In a tripping mechanism for electric switches, a chamber, a li uid mass contained therein, means for retar ing the assage of said mass from one portion of said 0 amber to another portion thereof, and means for permitting an unretarded return of said mass.

' 25 A tripping mechanism for electric i .tarding the thereof, and

switches,

5 cuit embedded in said a block, a stud connected therewith, a di:;

switches, comprising a pivoted chamber, a liquid mass contained therein, means for reportion of said chamber into another portion electromagnetic means for ini-' tially tilting said chamber.

,26. In a tripping mechanism for electric switches, a chamber, a movable mass contained therein, means for retarding the pasro sageofsaidimass from. one portion of said and chamber ,to andther'*'portion thereof, means permitting the unretarded return of said mass. 1

27. A tripping mechanism for electric r5switches, comprising a pivoted chamber, a

movable'mass contained therein, means for retarding the passage of said massfrom one portion of said thereof, and electromagnetic means for tilt 2o ing-said chamber.

.28. A tripping mechanism for electric comprising a pivoted chamber, a mass contained therein, means for the passage of said mass from one movable retarding portion of said chamber to another ortion thereof, electromagnetic means for tilting said chamber, and means for returning said chamber to its normal position.

29. In combination, a terminal block, and

0 a magnetizable mass forming an unclosed magnetic circuit embedded in said block.

30. In combination, a terminal block, a conductor leading thereto, and a magnetizable mass forming an unclosed magnetic cirterminal block and embracing said conductor.

31. In an electric switch, a base, a termmal block secured against said base, a conductor extending through said base and con po heating with said terminal block, and a mag "i'letizable mass located between said base and terminal block in a recess in. said block.

32. In an electric switch, a base, a terminal block, a conductor extending through said .5 base; and connecting with said terminal block,

v and amagnetizable mass formingan unclosed magnetic circuit embedded-in said terminal block between said base and terminal block,

and embracing said conductor.

33. In an electric switch, a base, a massive terminalblock secured thereto, a conductor extending through said base and ccmmunicating with said terminal block, and magnetizable. mass embedded in said t 5 block, and maintained between said lock and base and embracing said conductc said magnetizable mass being substantiai. U-

shaped,

34. In combination, amassive te; inal respassage of said mass from one chamber to another portion i l I sion in said terminal block surrounding the juncture of said stud and block, and a magnetizable mass forming an unclosed magnetic circuit seated in said depression.

35. In combination, a terminal block, and

means for actuating said restraining means after a predetermined interval of time, said means comprising a mass of liquid retarded in its flow in one direction and unretarded in return.

38. In an electric switch, a movable contact member, means for restraining said contact member in normal position, electroresponsive means, a subsidiary circuit controlled by said electroresponsive means, a

chamber, a movable masscontained therein, electrically-actuated means included in said subsidiary circuit and adapted to tilt said chamber-to cause the same to control said restraining means, means for retarding the movement of said movable mass in said chamher, and means for permitting the unretarded return of said movable mass.

39. In circuit breaker tripping mechanism, a time-limit device comprising a chamher, a movable mass within the chamber,

means for retarding the passage of said mass in 1ts passage in said chamber, and meanspermitting the unretarded return of said mass.

40. In circuit-breakertripping mechanism, a timelimit device comprising a pivoted chamber, a movable 'mass contained therein, means for initially tilting'said chem-- ber, means for retarding the passage of said movable mass from one part of said chamber to another when in tilted position, a latch actuated by said chamber an interval of time after it has been tilted, and means for permitting the unretarded return of said movable mass.

I WM. M. SCOTT.

Witnesses CAROLYN V. HEENAN,

AGNES E. BEAN.

magnetizable mass forming an unclosed

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