US1821761A - Automatic circuit breaker - Google Patents

Description

Sept. 1, 1931. G. N. LEMMON F 1,821,761

AUTOMATIC CIRCUIT BREAKER Filed Feb. 12, 1927 5 Sheets-Sheet, 1

' INVENTOR: George J Lemma/z ATTORNEYS Sept. 1, 1931, e. N. LEMMON v AUTOMATIC CIRCUIT BREAKER Filed Feb. 12, 1927 3 Sheets-Sheet. 2

z INVENTOR! fieorye fie/212002 I ATTORNEYS.

Sept. 1, 1931. G. N. LEMMON AUTOMATIC CIRCUIT BREAKER 3 Sheets-Shed. 3

Filed Feb. 12, 1927 ATTORNEY Patented Sept. 1, 1931 UNITED STATES PATIENT OFFICE GEORGE LEMMON, OF BIRMINGHAM, ALABAMA, ASSIGNOR TO SOUTHERN STATES EQUIPMENT 00., OF BIRMINGHAM, ALABAMA, A CORPORATION OF ALABAMA AUTOMATIC CIRCUIT BREAKER Application filed February 12, 1927. Serial No. 167,688.

'My invention relates to automatic circuit breakers, and particularly to the fuseopened type for high voltage lines. Among the objects of my invention may be mentioned (1) mechanism adapted to effect a more rapid and complete separation of the movable conductors from fixed conductors on operation of the circuit breaker; (2) simplified and improved construction of the parts; (3) protection of the fuse against deterioration by corona action; and (4) various details hereinafter described and shown in the accompanying drawings, in

. which v Fig. 1 is a more or less diagrammatic side elevation of a layout in whic my invention section through the unit;

Figure 4 is a view taken from the plane indicated by the line 44, Figure 3, and

showing a portion of the device in section.

Fig. 5 is an end elevation looking toward the trigger mechanism;

Fig. 6 is an end elevation indicated by the line 66, Fig. 3;

Fig. 7 is a detail section on the line 77, Fig. 4;

Fig 8 is a face View of .a group of detached braking washers;

Fig. 9 is an edge elevation of the washers;

Fig. 10 is a. broken longitudinal section of (ihe fuse element drawn to a larger scale; an Fig. 11 is a longitudinal section through a fuse housing of modified construction.

.Figure 12 is a broken longitudinal section through a modified fuse element.

An installation of the typetd which my invention relates comprises a pair of terminal members 15 and 16 supported upon spaced insulators a and b and to which appropriate connection is made by the sections 17 and 18 of the protected line. The connection between, the terminals 15 and 16 is established through fuse 19 .(Fig. 10), which is arranged within' a tubular, open 'ly connected to the housing cap 21 which carries a contact arm 22 adapted to make a detachable connection with jaws 23 of the terminal 16. While the fuse is intact, the

parts occupy the circuit-closing position indicated in Fig. 1. When the fuse blows, the parts automatically move to the position indicated in Fig. 2, 'thus completely opening the gap between the terminals 15 and 16 and causing any arc which may form, to rise upon the upright horns 24 and 25 respectively connected to the terminals '15 and 16. In order to effect the automatic opening of the gap between the terminals 15 and 16, I provide a mechanism more clearly illustrated in Figs. 3-9 inclusive. Thus, the terminal 15 comprises a pair of standards 26 and 27 in which are journaled the trunnions 28 and 29 of a pivoted carrier 30, to which the fuse housing 20 is secured. The body of the carrier 30 is channeled as illustrated in Fig. 4 to receive the end of the fuse housing 20 which is clamped in position by a hood 31 pivoted at 32 on the carrier 30 and having a bearing bridge 33 which rests on the fuse housing 20. Pins 34 in bridge 33 on the hood overlie lugs 35 on the carrier 30, the clamping hood and carrier being secured together by means of bolts 36 (pivoted on said pins 34) and wing nuts 37 While the hood is thus clamped in position and swings with the pivoted carrier 30, the-hood may be released to permit the housing 20 to be removed for more ready manipulation when replacing a blow fuse.

The trunnion 29 of the carrier is journaled in the capped head of the standard 27 of the terminal 15 and is engaged in appropriate fashion by one end 38 of a coiled ,suitably stressed. The anchorage of the spring end 38 to the trunnion 29 may be readily accomplished by splitting the trunnion as indicated at 43, while the anchorage of the opposite end 40 of the spring may be similarly secured in the split boss 44 at the opposite end of the housing. The organization of the parts is such that when the fuse is in operative position (Fig. 1) the spring 39 is 'under substantial stress tending to throw the housing 20 to the upright position indicated in Fig. 2.

To detain the housing and fuse-in operative position, indicated in Fig. 1, I provide a detaining nose 45 fast with the terminal 15. Cooperating therewith is a swinging detent 46 pivoted at 47 on the carrier 30 and maintained in engagement with the'nose 45 by a spring 48, which engages the pin 49. The spring 48 is carried by atrigger 50 also pivoted at 47 and having a beveled nose 51 .which is engaged by the roller 52 of a latch link 53 pivoted at 54 on the carrier. The engagement of the roller 52 with the beveled nose 51 is maintained by a cross pin in the loop end 55 of the fuse element 56 (see Fig. 10). At its opposite end the fuse element 56 has a similar-loop which is engaged by a cross pin 57 that bears against a pair of plugs'58 supported by springs 59 in sockets 60 of the housing cap 21. The stress imparted by these springs to the fuse element maintains the cross pin at the opposite end of the link against the swinging latch link 53.

Upon rupture of the fuse, however, the

latch 53 is released. The stress of the spring 39 which tends constantly to cause the carrier to swing upward, now exerts, through the beveled end 51 of the trigger 50, a displacing pressure upon the roller 52 of the latch 53, and the latter swings out of obstructing position. The trigger 50 being now no longer restrained, swings on its pivot 47, releasing the stress of its spring 48 on the pin 49 of the detent 46. The engagement of the latter with the nose 45 is no longer maintained, and the housing is free to swing up.

Since the upward swing of the fuse housing 20 israpid under the action of the Spring 39, I preferably provide some appropriate means for braking its movement toward the end of its travel. For this purpose I may use a group of friction washers 61, 62, 63, arranged around the slotted trunnion 29 of the carrier and engaged within the head 64 of the standard 27. The washers 61 and 63 are spaced apart by washer 62. Washers 61 and 63 are appropriately pierced tc afford cross webs 65' and 66 adapted to enter the slot 43 of the trunnion, thus being engaged to move therewith. The washer 62 is provided with a central aperture permitting it to sleeve over the trunnion, while peripheral lugs 67 take into suitable-notches 64 in the boss 64. The adjacent faces of the washers are provided with cams 68, 69 and 70 so located that when the carrier is in circuit-closing position the cam surfaces are out of engagement, Whereas when the washers 61 and 63 rotate with the trunnion 29 on the upward swing of the fuse housing, these cam surfaces are brought into frictional engagement and because of the increased axial space requirement spring 39 is compressed. "his effectually brakes the travel of the housing toward the end of its upward swing. The frictional pressure of these washers against each other may be regulated by varying the pressure of the spring 39 thereagainst. An adjusting screw 44 may be used for this purpose.

In order to more freely release the contact.22 from engagement with the jaws 23 of the terminal 16, I mount each of these jaws on a pivot 71 and associate therewith a spring contact brush 72 which insures the establishment of a good connection between the parts, without retarding or substantially opposing the upward swing of the contact 22 on the upward swing of the fuse housing as the parts move to open-gap position.

The fuse unit is illustrated on a larger scale in Fig. 10. The fuse proper 19 is connected in any suitable way with the conducting strands 56 which extend in opposite directions from the fuse. These strands are secured in any appropriate fashion to the fuse casing 73. glass, and its connection to the strands 56 may be by fusing, soldering or appropriate clamping plug, such as that indicated at 74.

The construction should be such, however, as to prevent tension strain being placed upon the fuse 19.

It will be appreciated from the above description of the apparatus that a characteristic feature of this interrupter is a dependency between the fuse unit and the latch mechanism which normally resists the action. of the torsion spring in tending to move the fuse housing away from circuitclosing position. In the embodiment shown,

the fuse unit in a sense formspart of the' latch mechanism as a whole and therefore, as a concomitant of the function of latching or' restraining the fuse housing and its removing means, a mechanical stress is put on the fuse unit. To relieve the fuse 19 itself the fuse unit from between the terminals to prevent destructive arcing.

The use of fuses for high tension current is deemed impractical at line voltages above 50,000, since the fuse metal rapidly deteriorates as the result of corona action. This action may be entirely eliminated, I have found, by a corona shield 75 of appropriate character applied to the fuse casing 73. This may be accomplished by paintingthe outer or inner surface of this casing 73 with an appropraite conducting paint such, for example, asaluminum paint, which has a very high resistance, but sufficient conductivity to serve as a coron shield. A silver film of extreme thinness may be applied to either the interior of 6'.t8I'lOI ofthe casing 73, and extending between the conductors 56, provided its conductivity is so slight that it does not affect the rating of the fuse. A

shield of greater conductivity may be used if its continuity between the conductors 56 is interrupted. For example, as indicated in Figure 12 at 76, a protective film or coating of greater current carrying capacity, may be applied to the exterior of the casing 73, but electrically connected at one end only to one or the other of the conductors 56. This construction requires less precision of conductivity determination for the shield.

It will be noted that the tubular housing 20 is of varying cross-sectional diameter, its least cross-sectional area corresponding to the area in which the fuse is accommodated. This construction is of great benefit from several standpoints, notably (1) the additional strength of the casing at the point of the heaviest rupturing strains when the fuse blows, (2) more rapid expulsion of the flame which follows the blowing of the fuse, (3) more complete check to the establishment of an arc. The variation in crosssection may be gradual, as illustrated in Fig. 3, or it may he stepped, as illustrated in the modification, Fi 11. The latter form may afford some facilities of manufacture where the housing is bored out from a solid rod or bar.

The operation of the-mechanism will be readily understood. After the fuse unit has been inserted in the tubular housing 20, the housing assembled with the carrier, and the circuit closed so that the trigger mechanism is set as illustrated in Fig. 1, current passes from one of the terminals 1516 to the other through the fuse. When excessive current is impressed on the line the fuse 19 blows, rupturing the frangible casing 73 and releasing the fuse strands 56. The re lease of the end 55 permits the trigger mechanism to operate, as above explained,

and the housing swings upward under the action of the torsion spring 39, being braked toward the end of its travel to the position indicated in Fig. 2. The expulsion "produced so far as I am aware.

of the hot metallic gases in opposite direction from the open end of the tubular housing, tends to prevent arc formation, but if an arc is established it is at once transferred from the terminals to the horns 24 and 25, and is there attenuated and extinguished. The fuse housing is swung to a position outside of the space between the horns and therefore any are which forms must be between the horns.

I am aware that an expulsion type fuse and swinging housing therefor, have been proposed heretofore; but many disadvantages have attended its construction and operation which are eliminated by my invention. Moreover, no fuse of this type appropriate for high voltage lines has been Various modifications of construction will readily occur to those dealing with the problem which do not depart from the thoughts which underlie what I claim as my invention.

I claim 1. In a circuit interrupter, a pair of spaced terminals, a fuse housing hinged at one end and adapted to contain a fuse electrically connected between said terminals, and means automatically operative upon the blowing of said fuse to swing said housing upwardly out of the fuse path between said terminals and to completely open the gap therebetween,

together with upright arcing horns 'associated with said terminals to which any are which forms on rupture of the fuse. is transferred from the housing as the latter moves to open-gap position, said swinging means being adapted to put the free end of said housing outside of the space between said horns.

2. In a circuit interrupter, a pair of spaced terminals, a fuse housing adapted to span said terminals and hinged at one end thereof, means at the hinge end of said housing tending constantly to swing the latter out of terminal spanning position, a fusewithin said housing, a frangible fuse casing surrounding said fuse and adapted to relieve it of mechanical stresses, and a latch released by the blowing ofsaid fuse and rupture of said casing controlling the operation of said means.

In a circuit interrupter, "a pivoted fuse housing, means tending to swing the housing to open-circuit position, and means for frictionally braking the throw of the housing as it approaches fully open position.

4. In a circuit interrupter, a pivoted fuse housing, means tending to swing the housing to open-circuit position, and means for braking the throw of the housing as it reaches fully open position, said braking'means comprising relatively movable friction surfaces brought into engagement during only the CAD latter portion of the opening swing of the housing.

5. In a circuit interrupter, a hinged member, a torsion spring for swinging the same on its hinge, in combination with brake means placing said torsion spring under compression during swinging of said member.

6-. In a circuit interrupter, a fuse element, flexible conductors under mechanical stress connected to each end thereof, a frangible insulating casing bridging said element and mechanically connected to said conductors to relieve said element of mechanical stresses, and afhousing for said conductors and easing witha bore changing progressively in steps to a minimum diameter at said casing.

7. In a circuit interrupter, a pair of spaced terminals, a fuse housing movable between closed and open circuit positions, a fuse within said housing, means electrically connecting the fuse with the terminals, a latch mechanism restraining said housing from moving and concomitantly imposin a stress upon said connecting means and a frangible element associated with said fuse adapted to relieve the fuse of the mechanical stress, said latch mechanism being adapted to release said housing upon rupture of said element.

8. In a circuit interrupter, a pair of spaced terminals, a fuse yhousing provided with means tending to move it with respect to said terminals to an open circuit position, a fuse within said housing, means electrically connecting the fuse with said terminals, latch mechanism normally resisting the tendency to move said housing and concomitantly imposing a stress upon said electrically connecting means, and a frangible casing around said fuse adapted to relieve the fuse of the mechanical stress upon the means electrically connecting it with the terminals, said latch mechanism being adapted to release said housing upon rupture of said casing. p

9. In a circuit interrupter, a pair of spaced terminals, a fuse housing movable from closed circuit position, means electrically connecting said terminals and including Within said housing a fuse with an associated frangible element adapted to relieve said fuse of mechanical stress put upon said means and to be ruptured upon blowing of said fuse, and latch mechanism for restraining said housing from moving from closed circuit position, saidmechanism being held in restraining position by said connecting means and being adapted to release said housing upon rupture of said element.

10. In a circuit interrupter, a pair of spaced terminals, a fuse unit connecting said terminals, said unit comprising conductive elements with a fuse and a frangible link therebetween, the frangible link b ing adapted to relieve said fuse of mechaniis broken.

11. In a circuit interrupter, a tubular fuse housing having a bore of varying cross sectional area and having at least one end open to the atmosphere, a fuse unit within said housing and including a portion of relatively great current carrying capacity and a fuseelement, the fuse element being accommodated in the portion of said housing of least cross-sectional area.

12. In a circuit interrupter, a tubular fuse housing having a bore formed as a number of stepped portions of different diameters and having at least one end open to the atmosphere, a fuse unit within said housing and including a portion of relatively great current carrying capacity and a fuse element, the latter being accommodated in the portion of said housing of least cross-sectional area.

13. A circuit breaker comprising spaced terminals, arcing horns associated with said terminals, a switch arm pivoted adjacent one terminal and adapted to swing its free end upward from the other terminal past the arcing horn adjacent its pivoted end, said switch arm comprising an expulsion tube of insulating material and means including a fusible element within said tube for normally completing a circuit between said terminals through said arm, together with means operative upon fusing of said element to effect swinging of said arm.

14. In a circuit interrupter, a pair of spaced terminals, a fuse housing movable through approximately 90 degrees between closed and open circuit positions, a fuse within said housing, means electrically connecting the fuse with the terminals, a latch mechanism restraining said housing from moving and concomitantly imposing a stress upon said connecting means, said latch mechanism being adapted to release said housing upon separation of said connecting means.

15. A circuit breaker comprising a terminal contact,a switch arm pivoted to swing a free end through approximately 90 degrees or more from said contact, said switch arm comprising an expulsion tube of insulating material, a conducting member including a fusible element within said tube for normally completing a circuit through said arm, together with latch means to hold the arm in its closed circuitposition and concomitantly impose a strain upon said conducting member, and means operative upon fusing of said element to effect swinging of said arm from closed circuit position.

able upon overload conditions in the circuit to move the flexible member outwardly of the container, and means, operable immediately after said movement, to swing the container through substantially 90 degrees to its open circuit positi n.

17. In a circuit breaker, two spaced insulated supports, an 1I1f LllLt1ng tubular mem ber lunged upon one of saidsupports and adapted to move between closed and open circuit position, a conductor within the tubular member, spring means operable upon overload in the circuit to move the conductor from its normal position, and means,

' operable immediately after said movement,

to remove the tubular member from its closed circuit position.

18. In a circuit breaker two spaced insulated supports, an insulating tubplar member hinged upon one of said supports adapted to move between closed and open circuit position, a conductor within the tubular member, means operable upon overload in the circuit to separate the conductor, spring means to move part of the conductor from its normal position, and means operable immediately thereafter to remove the tubular member from its closed circuit position.

19. In a circuit breaker, two spaced insulated supports, an insulating tubular member, hinged upon one of said supports and adapted to be moved between closed and open circuit position, a conductor within said tubular member, spring means operable upon overload in the circuit to move part of the conductor from its normal position, and means operable immediately after said movement to remove the tubular member from its closed circuit position.

20. In acircuit breaker, an insulating tubular member pivotally supported at one end and adapted to be moved between closed and open circuit positions, a conductor within the tubular member, spring means operable upon overload'of circuit to move a portion of the conductor outwardly of the tubular member,.and automatic means operable immediately after said movement to remove the tubular member from its closed circuit position.

21. In a circuit breaker, an insulating tubular member pivotally su ported at one end and adapted to move fiom closed to open circuit position, latch means to hold the tubular member in-its closed circuit position, a conductor within the tubular member, spring means operable upon overload in the circuit to move a portion of the conductor outwardly of the tubular member, and means operable contemporaneously with said spring means to release said latch means.

22. An expulsion fuse comprising a tube having bores of different diameters and having one end unrestrictedly open to the atmosphere, a pair of contacts, anda fuse element within the tube and electrically bridging the contacts.

23. In an expulsion fuse of the character described, a tube having a bore of relatively small diameter and a bore of greater diameter, said bore of greater diameter being unrestrictedly open to the atmosphere, contacts carried by the tube, and a fuse element electrically connected with the contacts and positioned within the bores of the tube the fuse element having aportion of reduced cross sectional area, which is positioned within the bore of small diameter whereby initial rupture of the fuse element takes place within the bore of smaller diameter.

24. In a circuit interrupter, a pivoted insulating tube, a removable conductor within the tube, means tending to swing the tube to open circuit position, and means for frictionally braking the throw of the tube as it approaches open-circuit position.

25. A circuit breaker comprising a terminal contact, a switch arm pivoted to swing a free end through approximately 90 degrees or more from said contact, said switch arm comprising an expulsion tube of insulating material, a conducting member including a fusible element within said tube for normally completing a circuit through said arm, spring means to maintain a strain upon said conducting member during closed circuit conditions and means operative upon fusing of said element to effect swinging of said arm from its closed circuit position.

In testimony whereof I.have signed my name to this specification.

GEORGE N. LEMMON.

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