US3184567A

US3184567A - Apparatus for triggering a dropout fuse comprising a rotatably mounted trip arm which engages an operator in the fuse

Info

Publication number: US3184567A
Application number: US212236A
Authority: US
Inventors: William A Gussow
Original assignee: S&C Electric Co
Current assignee: S&C Electric Co
Priority date: 1962-07-25
Filing date: 1962-07-25
Publication date: 1965-05-18
Anticipated expiration: 1982-05-18

Description

May 18, 1965 w. A. eussow 3,184,567

APPARATUS FOR TRIGGERING A DROPOUT FUSE COMPRISING A ROTAIABLY MOUNTED TRIP ARM waxcn ENGAGES AN OPERATOR IN THE FUSE 8 Sheets-Sheet 1 Filed July 25, 1962 mok muao 025mm May 18, 1965 w. A. GUSSOW 3,184,557

APPARATUS FOR TRIGGERING A DROPOUT E MPRISING A ROTATABLY MOUNTED TRIP AR 11 ENGAGES AN OPERATOR IN THE FUSE Filed July 25, 1962 s Sheets-Sheet 2 29 6 M 13 19 w 0 3k 81/ 111' w JM 33 i 31 are H May 18, 1965 w. A. GUSSOW 3,184,567

APPARATUS FOR TRIGGERING A DROPOUT FUSE COMPRISING A ROTATABLY MOUNTED TRIP ARM WHICH ENGAGES AN OPERATOR IN THE FUSE Filed July 25, 1962 8 Sheets-Sheet 3 .153 3A. 7 m E Z5/.3-B.

W. A. GUSSOW May 18, 1965 APPARATUS FOR TRIGGERING- A DROPOUT FUSE COMPRISING A ROTATABLY MOUNTED TRIP ARM WHICH ENGAGES AN OPERATOR IN THE FUSE 8 Sheets-Sheet 4 Filed July 25, 1962 N\N I m mw 4 VWW/WWWA QMQXQQNQ W May 18, 1965 w. A. GUSSOW 3,184,567

APPARATUS FOR TRIGGERING A DROPOUT FUSE COMPRISING A ROTATABLY MOUNTED TRIP ARM WHICH ENGAGES AN OPERATOR IN THE FUSE Filed July 25, 1962 8 Sheets-Sheet 5 May 18, 1965 w. A. GUSSOW 3,184,567

APPARATUS FOR TRIGGERING A DROPOUT FUSE COMPRISING A ROTATABLY MOUNTED TRIP ARM WHICH ENGAGES AN OPERATOR IN THE FUSE Filed July 25, 1962 8 Sheets-Sheet 6 z 3 w\ \\\\\\/A\\\ g i|..//////////// n W M M 0 U m 1 1 1. III! 8 w w 1 4 /////v////v/ M Y\\\\ z N m 8 +4 6 i May 18, 1965 w. A. GUSSOW 3,184,567

APPARATUS FOR TRIGGERING A DROPOUT FUSE COMPRISING A ROTATABLY MOUNTED TRIP ARM WHICH ENGAGES AN OPERATOR IN THE FUSE 8 Sheets-Sheet 7 Filed July 25, 1962 W. A. GUSSOW May 18, 1965 3,184,567

G A DROPOUT FUSE COMPRISI A ROTATABLY MOUNTED TRIP ARM WHICH APPARATUS FOR TRIGGERIN ENGAGES AN OPERATOR IN THE FUSE 8 Sheets-Sheet 8 Filed July 25, 1962 APPARATUS FOR TRIGGERENG A DRQPOUT COMPRISING A ROTATABLY MQEUNTED Till? Rsltgll WHICH ENGAGE AN QPERATOR IN THE William A. Gussow, fit. Petershurg, Fla, assiguor to S dz C Electric Company, Chicago, Ill., a corporation of Delaware Filed July 25, 1962, Ser. No. 212,236 9 Claims. (Cl. Ziltl114) This invention relates, generally, to apparatus for causing the operation of circuit interrupters, such as dropout fuses, by means other than the blowing of their fusible elements and it has particular relation to the triggered fuse construction disclosed and claimed in the copending application of Sigurd I. Lindell, Serial No. 210,093, filed July 16, 1962, and assigned to the assignee of this application. The dropout fuse construction with which this invention can be used is shown in US. Patent No. 2,599,186, issued June 3, 1952, to S. I. Lindell.

As disclosed in the application above referred to it is sometimes desirable to cause a fuse of the kind shown in the above patent to interrupt the current flow and then to dropout and isolate the circuit in which it is connected in response to the operation of means other than the blowing of its fusible element. It is well understood that the fusible element has a certain time-current characteristic and it may become necessary to isolate the circuit under circumstances where the fusible element would not be responsive from either a time or a current standpoint. The speed of response may be too low or the current required may be too high. An example is found where the circuit is to be opened in which the fault current flow may be of insufficient magnitude initially to cause the fusible element to blow, or to blow within a short enough interval, to obtain the required circuit isolation. Such a situation may exist when one or more turns of the windings of a transformer protected by the fuse become short circuited and the fault must progress to a great extent before the current rises to a magnitude sufficient to blow the fuse. The fault current flow often can be detected only by a differential protective arrangement in which a differential relay is responsive to the fault and can be employed to trigger the fuse of this invention. This causes it to interrupt the current flow and isolate the circuit without blowing the fusible element. The above Lindell application discloses and claims preferred embodiments of triggered fuse constructions, one of which is shown herein, and also it discloses means external to the triggered fuse constructions for triggering them to which means the claims of the instant application are directed.

Among the objects of this invention are: To provide for externally triggering a circuit interrupter such as a dropout fuse without interfering with its dropping out once it has been unlatched from its normal operating position; to move a rod-like actuator or operator endwise of a dropout fuse for releasing a spring driven arcing rod for circuit interruption and for unlatching the fuse at its upper end from an upper line terminal by applying a force endwise of the fuse tube through it lower end as the result of rotation of a trip arm mounted on a bracket extending from the lower line terminal on which the fuse is pivotally mounted; to position the trip arm normally out of the path of the are products flowing from the dis charge end of the fuse so that when the fusible element blows and a heavy exhaust occurs on a severe fault there is no interference with the flow of the arc products due to the trip arm; to position the trip arm so that it does not interfere with the manual hook stick operation of the fuse as a disconnecting switch or the insertion on or removal from the fuse mounting of the fuse by a live Patented May 18, 1965 ICE line stick; to protect the trip arm from sleet without interfering with the normal dropout action of the fuse; to provide a trip free operating connection to the trip arm; to limit the swinging movement of the trip arm in either direction; to rotate the trip arm by an actuating lever insulatingly mounted about an axis parallel to the axis of rotation of the trip arm; to mount the actuating lever on a rotatable insulator extending parallel to and adjacent to the insulator that supports the lower line terminal; to operate simultaneously by external means a plurality of dropout fuses in a new and improved manner; and to release the energy stored in a spring operator to impact the operator of a triggered dropout fuse for effecting its operation with a snap action.

in the drawings:

FIG. 1 is a view showing a typical installation of triggered fuse constructions in accordance with this invention, the view showing the vertically extending supports with the insulator bases mounted thereon, one of the assemblies showing the construction at the lower end of the dropout fuse, and showing external trigger operating mechanism for one of the units together with means for commonly operating them to trigger all of the dropout fuse constructions.

FIG. 2 is a view, in side elevation, of the construction shown in FIG. 1 with the dropout fuse embodying the present invention mounted on laterally extending insulators from a support.

FIGS. S-A, 3-3, 3-C and 3E (FIGS. 3-C and 3-E being at an enlarged scale) placed end to end in the order named show certain details of construction in vertical longitudinal section in a dropout fuse embodying the present invention; FIG. 3-C showing the fusible element terminal latch means in the latched position and FIG. 3-D corresponding to FIG. 3-C but showing the fusible element terminal latch means in the unlatched position with the fusible element terminal released and moving upwardly to interrupt the circuits accompanied by release of the fuse tube latch release means to permit the dropout fuse to swing downwardly to the open position.

FIG. 4 is a horizontal sectional view, at a reduced scale, taken generally along the line 4-4 of FIG. 3-E.

FlG. 5 is a horizontal sectional view, at a reduced scale, taken generally along the line 55 of FIG. 3-C.

FIG. 6 is a horizontal sectional view, at a reduced scale, taken generally along the line 6-6 of FIG. 3C.

PEG. 7 is a view, at an enlarged scale, of the external trigger operating mechanism that is mounted at the lower end of each of the dropout fuses, the mechanism being shown in the non-operated position and the sleet hood being shown in section in order to illustrate more clearly certain of the parts of the mechanism.

FIG. 8 is a sectional view taken generally along the line 38 of FIG. 7.

FIG. 9 is a view, similar to FIG. 7, but showing the trip arm impacting the lower end of the operator to trigger the fuse release mechanism with the actuating lever being shown in the fully operated position to which it is moved for actuating the trip arm.

Referring now particularly to FIGS. 1 and 2 of the drawings, it will be observed that the reference character it} designates, generally, a dropout fuse construction which is intended for polyphase operation. For example, the dropout fuse construction 10 can be employed for controlling the connection of a three phase circuit to a suitable alternating current power supply circuit. While the dropout fuse construction ltl can be employed in circuits operating at various voltages, it is intended particularly for operation in connection with circuits operating at voltages of the order of 34.5 kv. and above depending upon the requirements of the system. It will be underanswer stood that three dropout fuse constructions 1d are employed for a three phase system and, since they are of identical construction, a description of one will suffice for a description of all of them.

Each dropout fuse construction It) includes a support 11 in the form of a channel base that is arranged to be supported suitably (by means not shown) so as to extend generally vertically. The support 11 carries upper and

lower insulators

12 and 13 in laterally extending relation. At the distal ends of the

insulators

12 and 13 upper and

lower line terminals

14 and 15, respectively, are mounted. They are interconnected by a dropout fuse that is indicated, generally, at 16. The details of construction of the dropout fuse 16 are generally similar to the construction shown in the patent above referred to. According-1y, only a general description thereof will be set forth herein.

The dropout fuse 16 includes a fuse tube 17 of suitable insulating material which carries an upper fuse tube terminal, shown generally at 18, in contact engagement with the upper line terminal 14. The fuse tube 17 also has a lower fuse tube terminal, shown generally at 19, which is suitably connected to and mounted on the lower line terminal 15. A latch arm 2.11 on the upper line terminal 14 serves to latch the upper fuse tube terminal 18 in contact engagement therewith. The lower fuse tube terminal 19 is pivoted, as indicated at 21, on the lower line terminal 15. For a complete understanding of the manner in which the upper fuse tube terminal 18 is latched to the upper line terminal 14 and the lower fuse tube terminal 19 is pivoted to the lower line terminal reference can be had to US. Patent No. 2,578,255, issued December 11, 1951, to S. I. Lindell. However, it will be understood that other latching and pivot means can be employed as may be desired.

In order to move the latch arm 21) to the unlatching position, a flange 24 is provided on the lower end of a slidable unlatching tube 25. As set forth in the patents above referred to, provision is made on blowing of a fusible element for moving the unlatching tube 25 uptwardly to lift the latch arm for the purpose of unlatching the upper fuse tube terminal 18 from the upper line terminal 14 and permitting the dropout fuse 16 to pivot at 21 on the lower line terminal 15 to an open position. The unlatching tube can be moved upwardly manually by causing an arm 26 on a pull ring 27 to lift the same. The pull ring 27 is pivoted at 28 on the upper fuse tube terminal 18 and the arrangement is such that, when the prong of a live line stick is inserted in the pull ring 27 and sufficient force is applied thereto, the pull ring 27 is rotated about its pivot 28 to cause the arm 26 to engage the underside of the flange 27 and move the unlatching tube 25 upwardly and at the same time swinging the latch arm 20 to the unlatched position.

The lower fuse tube terminal 19 has an eye member 29 mounted thereon for receiving a prong of a live line stick to permit application of the dropout fuse to the lower line terminal 15 in conventional manner. Thereafter, the prong of the live line stick is inserted in the pull ring 27 and the dropout fuse 16 is swung to the position shown in FIG. 2 where the upper fuse tube terminal '18 is in contact engagement with the upper line terminal 14 and is latched in this position by the latch arm 20. A resilient bumper 31) is carried by the lower line terminal 15 for cushioning the downward swinging movement of the dropout fuse 16 after it has been released by operation of the latch arm 20 in the manner described.

As pointed out above, it is desirable to trigger the operation of the dropout fuse 16 under certain circumstances =when its fusible element is not required to blow and yet it is desired to take advantage of the circuit interrupting capabilities of the dropout fuse 1% for opening the circuit. For this purpose an external trigger operating mechanism, shown generally at 33 in FIGS. 1 and 2, is provided.

A part of the external trigger operating mechanism 33 is mounted on a support bracket 34 in the form of a plate which is mounted on the distal end of the lower insulator 13 of each fuse construction it? between it and the respective lower line terminal 15. Extending outwardly from the support bracket 34 is a sleet hood 35 which overlies a major portion of the external trigger operating mechanism 33 and is spaced, as indicated at as in FIG. 1, from the juxa posed side of the lower line terminal 15 a suiiicient distance so that ice does not form therebetween. The trigger operating mechanism 33 includes a rotatably mounted trip arm 37, a portion of which extends below the sleet hood 35 in the non-operated position and the details of construction of which are shown in FIGS. 7, 8 and 9 and described hereinafter. For operating the trip arm 37 an actuating lever 38 is provided. it is mounted for rotation with the distal end of a rotatable insulator 39 which extends generally parallel to and below the lower insulator 13 and is mounted in a bearing 40 that is carried by an extension plate 41 on the lower end of the support 11. An operating arm 12 extends radially from the base of the rotatable insulator 39 for rotating it between stop pins d3-43 which extend forwardly from the extension plate 41 and into the path of movement of the operating arm 42.

When a polyphase dropout fuse construction is en ployed, for example a three phase installation, three dropout fuses 16 are used and provision is made for effecting their simultaneous operation in order to dropout and clear all three phases at the same For this purpose each of the operating arms 4-2 is pivotally connected at to an interphase rod 15 and provision is made for longitudinally moving it to rotate simultaneously the three rotatable insulators 39 for operating the three external trigger operating mechanisms 33. Any suitable means can be employed for moving the interphase rod 45 endwise. Preferably provision is made for moving it with a snap action. For example, it can be connected pivotally at 16 to one arm of a bell crank 47 which is pivoted at 48 on a suitable support 49 in the form of a channel base. The other arm of the bell crank 47 is pivotally connected at 56 to a pull rod 51 that is connected at its lower end pivotally at 52 to an arm 53 of a spring operator that is indicated, generally, at 54. A handle permits manual cocking of an operating spring in the spring operator 54. The spring in the spring operator 54 can be triggered by any suitable means, such as by differential relay means or by a system such as disclosed in application Serial No. 172,017, now Patent No. 3,116,391, filed February 8, 1962, by S. I. Lindell and L. V. Chabala. Such current responsive means effects a release of the cocked spring to rotate the arm 53 with a snap action and effect a corresponding accelerated movement of the interphase rod 415 which is accompanied by a corresponding high speed rotation of the several rotatable insulators 39 and corresponding movement of the actuating levers 33 carried thereby. On return movement of the handle 55 the interphase rod 45' is returned to the position shown in FIG. 1 of the drawings. As will appear hereinafter, a trip free connection is provided between each actuating levers 3S and the trip arm 37 operated thereby. Accordingly, after each actuating lever 38 has caused the respective trip arm 37 to trigger the dropout fuse 16 associated therewith, the construction is such that the trip arm 37 is promptly retrieved to its non-operated position and out of the path of the dropout fuse 16 so that it can fall freely to the open position.

Reference now will be had to FIGS. 3-A, 3-13, 3C and 3E of the drawings. It will be recalled that these figures should be placed one above the other in the order named in order to provide a complete longitudinal sectional view of the details of construction of the dropout fuse 16. Also, it will be understood that FIGS. 3-C and 3-E are shown at a larger scale than FIGS. 3-A and 3-B in order to show more clearly the details of construction of the fusible element terminal laatch means forming a part of the trigger means that is operated by the external trigger operating mechanism 33 to release the dropout fuse 16 from its latched connection to the upper line terminal 14 and permit it to fall to the open position. Here it will be observed that the fuse tube 17, which may be formed of a phenolic condensation product, is provided with an insulating liner 57 that may be formed of high strength material such as fiber. Within the liner 57 is a stack of cakes 58 or boric acid or similar arc extinguishing material which are held in place by a layer 59 of cement. The cakes 58 are apertured to provide a longitudinally extending bore 6h therethrough. Extending and endwise movable through the bore 60 in the cakes 58 of arc extinguishing material is a rod-like terminal 61 which is provided at its upper end with a cylindrical contact 62 that is engaged by contact fingers 63 under substantial pressure exerted by a garter spring 64. The contact fingers 63 are secured to a contact fitting 65 to which electrical connection is made by a connector tube 66 which extends upwardly along the inner surface of the fuse tube 1'7 and is connected at its upper end to the upper fuse tube terminal 18. This arrangement provides a direct connection between the upper fuse tube terminal 18 and the rod-like terminal 61 through which the current normall flows.

In order to withdraw the rod-like terminal till through the bore 69 and extinguish the arc therein, the rod-like terminal 61 is provided with an extension rod 67 which is connected to the contact 62 at its lower end while its upper end is connected to a cable connector assembly 63 that is fiexible in nature and is trained over a pulley 69. The other end of the cable connector assembly 6% is connected to a strap 7%} which is connected at 71 to the contact fitting 65. This arrangement provides a connection between the rod-like terminal 61 and the contact fitting 65 after the contact 62 is moved out of engagement with the contact fingers 63. The pulley 69 is carried by a clevis '72 which depends from a yoke '73 that is carried by a tube end fitting '74 that is located at the upper end of the compression tube 75 which is slidable within the connector tube 65 and which has an annular fitting '76 at its lower end against which the coil compression spring 7'7 reacts. The lower end of the coil compression spring 77 reacts against the upper side of the contact fitting 65 and it serves to bias the compression tube '75 upwardly. it will be understood that the compression tube '75 and parts movable therewith constitute fuse tube latch release means, indicated generally at 73, with the arrangement being such that, when the rod-like terminal 61 is released, the coil compression spring 77 moves the compression tube 75 upwardly carrying with it the pulley 69. As a result the rod-like terminal 61 moves upwardly at a speed which is twice that of the speed of upward movement of the compression tube 75. The compression tube '75 is telescoped within the unlatching tube 25 and at the end of its upward movement the tube end fitting 74 engages the upper end 25' of the unlatching tube 25. It will be recalled that this movement is accompanied by upward movement of the flange 24 which lifts the latch arm 20 and unlatches the upper fuse tube terminal 18 from the upper line terminal 14 and permits the dropout fuse 16 to rotate about the pivot 21 to the open position.

Referring now particularly to PEG. 3-C it will be observed that a metallic annular fitting 80 is threaded into the lower end of the liner 5'7. Secured to the lower end of the fitting 8% is a metallic exhaust tube 81 which extends downwardly over the inner surface of the fuse tube 17 where it is joined through a spacing ring 82, FIG. 3E, to the inner surface of the lower fuse tube terminal 19 which is generally cylindrical in configuration and which extends over the outer surface of the lower end of the fuse tube 17 and projects downwardly therebelow. It will be understood that trunnions are provided on the lower fuse tube terminal 19 by means of a suitable fitting as described in more detail in US. Patent No. 2.578,255, issued December 11, 1951, to S. I. Lindell.

Referring again to FIG. 3-C, it will be observed that the lower end of the rod-like terminal 61 has connected thereto one end of a fusible element that is indicated, generally, at $3 and which serves to restrain upward move ment of the rod-like terminal 61 under the influence of the coil compression spring 77. The fusible element 83 is connected at its lower end to a fusible element terminal that is indicated, generally, at 84 and provision is made for restraining it and for releasing it that will be described presently. The fusible element 83 may include a fuse wire 85 in the form of a helical coil of silver wire surrounding a strain wire 86 of high strength metal such as a nickel chromium alloy. It will be understood that it is conventional to connect a fusible element terminal, similar to the fusible element terminal 84, to the metallic annular fitting 80 or to the upper end of the metallic exhaust tube 31. When such a construction is employed and the rod-like terminal 61 is to be released for operating the dropout fuse 16, it is necessary that the fusible element 83 blow. When this takes place, the rod-like terminal 61 moves upwardly through the bore of) in the cakes 58 of solid arc extinguishing material and the arc incident to the blowing of the fusible element 33 is drawn between the lower end of the rod-like terminal 61 and the upper end of the fusible element terminal $4 or some part of the metallic annular fitting St) or of the metallic exhaust tube 81 and, because of the intensity of the blast action and the accompanying pressure, it is desirable that the flow of these are products be substantially unimpeded in their escape downwardly through the metallic exhaust tube 81 to the atmosphere. However, such operation can be effected only by blowing of the fusible element 33 and this ordinarily takes place only when the current flow therethrough is of predetermined magnitude exceeding its normal load current carrying capacity.

As indicated hereinbefore it is sometimes desirable to release the rod-like terminal 61 for movement upwardly through the bore 60 in order to take advantage of its arc extinguishing capability under conditions where the fusible element 83 of the dropout fuse 16 would not respond or blow or would not respond or blow with the desired speed. Accordingly, trigger means, shown generally at 89, are provided for releasing the fusible element terminal 84 in response to operation of the external trigger operating mechanism 33. As a result the rod-like terminal 61 moves upwardly and carries with it the fusible element 83 and the fusible element terminal $4. This action would normally be made to take place only when load current or fault current of low value, as in stepdown substation transformer installations under overload conditions, secondary fault conditions or internal fault conditions, is flowing through the dropout fuse 16. Internal faults may occur when the transformers are carrying little or no load. Under such conditions the current to be interrupted may be only slightly higher than normal exciting current. Such relatively low currents can be readily interrupted and the arc drawn between the terminal 84- and the trigger means 89 or the fitting 80 extinguished since the bore 60 in the arc extinguishing material 58 has suitable diameter and adequate length to effect these results. While there is a reduction in break distance due to the withdrawal of the complete fusible element 83 and the terminal 84, the length of the bore 60 is made sufficient to accommodate this extension of the rod-like terminal 61.

For cooperating with the trigger means 89 the fusible element terminal 83 is provided with an annular shoulder portion 9i) which has an annular latch surface 91 at its upper end that is arranged to be engaged by fusible element terminal latch means, shown generally at 92. The fusible element terminal latch means 92 is provided not only for making a mechanical connection between the fusible element terminal 84 and the lower fuse tube terminal 19 to restrain the coil compression spring 77 but also it is arranged to provide a high pressure electrical connection therebetween. in general, instead of directly interconnecting the fusible element terminal 84 to the upper end of the metallic exhaust tube 81 to provide the desired releasable mechanical and electrical connections thereto, the fusible element terminal latch means 92 at the upper end of the metallic exhaust tube 81 provides these releasable connections. As will appear hereinafter the latch means 92 extends to the lower end of the metallic exhaust tube 81 where the mechanical and electrical connections are completed to it and to the lower fuse tube terminal 19. I11 addition the construction of the fusible element terminal latch means 92 and parts associated therewith is such that a minimum of obstruction is offered to the flow of the are products through the metallic exhaust tube 31. It will be recalled that this is particularly important when the fusible element 83 blows as a result of the flow therethrough of high fault current which results in the evolution of a substantial quantity of arc extinguishing material from the bore and the generation of substantial pressure within the metallic exhaust tube 81 which should be promptly released to the atmosphere.

It will be observed that the fusible element terminal latch means 92 includes a pair of latch hooks 93-93 that are laterally movable and are formed of good conducting material such as copper. The latch hooks 93-93 are provided with jaw portions 94-9 3 the undersurfaces 942-94 of which are arranged to engage the annular latch surface 91 and restrain upward movement of the fusible element terminal 84. The jaw portions 94-94 are provided with facing cylindrical surfaces 95-95,

FIG. 6, which may be V-shaped and are arranged to engage opposite sides of a shank 96 that forms an integral part of the fusible element terminal 84 and from which the annular shoulder portion 9% depends. Also, the jaw portions 94-94 have outflared surfaces 97-97 for guid ing a beveled lower end 93 of the annular shoulder portion 90 between the jaw portions 94-94, which are spaced apart as described hereinafter, when the fusible element terminal 84 is drawn downwardly through the fuse tube 17 to tension the spring 77 and to place the fusible element terminal 84 in engagement with the fusible element terminal latch means 92.

To facilitate this latching operation the annular shoulder portion 90 is internally threaded, as indicated at 99, for removably receiving a tool 10% which is shown by broken lines in FIG. 3C. tool 1% is in the form of an elongated rod which is threaded at one end for engagement with the threaded opening 99 in the annular shoulder portion 90 of the fusible element terminal 84. The tool 100 is long enough to extend out of the lower end of the fuse tube 17 and out of the lower end of the lower fuse tube terminal 19 while it is in engagement with the threaded opening 99 of the annular shoulder portion 9t) and the fusible element terminal 84 is retracted to a position within the bore as. An application of endwise tension to the tool 199, the fusible element terminal 84 is drawn downwardly through the bore 60 and the spring '77 is compressed to store the energy for moving the rod-like terminal 61 upwardly when it is released. After the fusible element terminal $4 has been latched by the fusible element terminal latch means 92, the tool ltltl is unscrewed and withdrawn.

As shown in FIGS. 3-C and 5 the latch hooks 93-93 are provided with flat shanks 102-192 which are secured by transversely extending rivets 1%3-103 to the bifurcated ends 194-104 of flexible beam members 105-165 which may be formed of good conducting material such as spring temper beryllium copper. The lower ends of the flexible beam members 195-195 are secured by press fit and by rivets res-see to a lower bridge 197, FIGS. 3-13 and 4, which is formed of good conducting material,

It will be understood that the rease? such as brass, and which extends into contact engagement with and is suitably secured by brazing or by screws to th lower end of the metallic exhaust tube 81 and to the spacing ring ('52 and in contact engagement with the inner surface of the lower fuse tube terminal 19. In order to increase the flexibility of the beam members 165-105 they may be provided with reduced diameter or flattened intermediate portions as indicated at 193-108. Now it will be apparent that the fusible element terminal 84 is electrically and mechanically connected to the lower fuse tube terminal 19 through the latch hooks 93-93 carried by the flexible beam members 1395-105 which are supported on the lower bridge 107 that is mechanically and electrically connected to the lower fuse tube terminal 19 and parts immediately associated therewith.

With a view to holding the jaw portions 94-94 of the latch hooks 93-93 in high pressure latching engagement with the fusible element terminal 84 and to insure that the engagement here is positive and will be unaffected by vibration, lower wedging surfaces 111-111 face outer sides 112-112 of slotted openings 113-113, FIG. 5, in a cam member 114, which may be formed of brass, and which is secured at 115 to the upper end of an operator 116 that is in the form of a metallic tube having a central opening 117 extending through it for receiving the tool liltl previously referred to. As shown in FIG. 3-E, the lower end of the operator 116 is slidably mounted in a central opening 118 in the lower bridge 107. A coil compression spring 119 reacts between the underside of the lower bridge 107 and a shouldered fitting 129 on the lower end of the operator 116 to bias the latter downwardly. This maintains the lower portions of the outer sides 112-112 of the slotted openings 113-113 in the cam member 11 in wedging engagement with the lower portions of the wedging surfaces 111-111 and springs the beam members 105-195 toward each other. As a result the jaw portions 94-94 are firmly held in resilient pressure engagement with opposite sides of the shank 96 of the fusible element terminal 84 and the undersurfaces 94-94 thereof are held in latching engagement with the annular latch surface 91 on the annular shoulder portion 90.

When the fusible element terminal is to be latched or to be released, it is desirable that the jaw portions 94-94 be moved laterally apart simultaneously and completely out of engagement with the annular latch surface 94 to the end that there is no likelihood on release that it will be hung up on one of the jaw portions 94. In part, this is accomplished through the provision of upper wedging surfaces 123-123, FIG. 3-C, on the inner sides of the shanks 102-102; of the latch hooks 93-93. When the operator 116 is moved upwardly to permit latching of the terminal 34 or to release it, the operator 116 carries with it the cam member 114. The inner sides 124-124 of the slotted openings 113-113 engage with the upper wedging surfaces 123-123 and move the jaw portions 94-94- apart to permit entry of the shoulder portion 90 as drawn down by the tool 199 or its release as the case may be. This is permitted because the outer sides 112-112 of the slotted openings 113-113 move upwardly with respect to the lower wedging surfaces 111-111. Additional time for release of the terminal 84 from the latch hooks 93-93 can be obtained by causing the inner sides 124-124 of the openings 113-113 in the cam member 114 to engage wedgingly flat sides 126-126 of the shanks 192-192. Such action is obtainable by providing for a corresponding endwise inward movement of the operator 116 and the jaw portions 94-94 are held apart.

It is desirable that the annular shoulder portion 90 of the terminal 84 be centered and that the jaw portions 94-94 be guided to move in a plane to the end that they engage or disengage the contact shank 96 and the annular latch surface 91 of the annular shoulder portion ans ass? 9% when the fusible element 3 is to be engaged or released when the operator lid is moved endwise to actuate the latch hooks 9393. This is partly accomplished by guiding the jaw portions 9494- in their lateral move ment together or apart between upper bridge members l27ll27, FIGS. 3-C and 6, which are secured at their ends to the lower end of the metallic annular fitting 8t) as by brazing. Intermediate the ends of the upper bridge members 1273l27 transverse grooves l28128 are formed for receiving and guiding the annular shoulder portion 9%. Because of corrosion or for other reasons after the dropout fuse 16 has been in service a long period, there may be the tendency for the annular latch surface 911 to become attached to the undersurfaces 9d-9d' of the jaw portions 9d94. When the jaw portions 94-9d are moved apart, unless they completely disengage the opposite sides of the annular latch surface 91, it might be possible that the annular shoulder portion 9d would hang up on one of the jaw portions 94. This is prevented since the transverse grooves l2-S12ti in the upper bridge members 127-l27 hold the annular shoulder portion 90 in centered relation with respect to the oppositely moving jaw portions 94-94. Since their movement apart is insured by the engagement of the upper wedgiug surfaces l23-123 with the inner sides E i-41% of the slotted openings 113-413, the fusible element terminal 84 always is positively released as a result of the upward movement of the operator M6.

Referring now particularly to FIG. 3-D, it will be observed that this shows the construction illustrated in FIG. 3-C but with the operator lid and cam member 14 thereon moved upwardly to disengage the lower wedging surfaces ill-Alli and engage the upper wedging surfaces l23l23 to move the jaw portions 9d-94 apart and out of engagement with the annular latch surface 931. As a result the fusible element terminal 9d is released to move upwardly, as indicated by the arrow 129, under the influence of the coil compression spring 7'7. the releasing movement of the fusible element terminal 84, the annular shoulder portion 9th thereof is centered by the transverse grooves, one being shown at 123 in FIG. 3-D, while the jaw portions 94-94 are moved apart in one plane as guided by the upper bridge members 127-127. As a result of the release of the fusible element terminal 84, in the manner described, it moves upwardly under the influence of the coil compression spring 77 in the direction indicated by the arrow 129, FIG. 3D, and, if current is flowing in the circuit in which the dropout fuse T6 is connected, an arc is drawn between the lower end of the annular shoulder portion 9% and one or the other or both of the jaw portions M-9d. The are is extended into the bore 6% and extinguished as the rodlil'e terminal moves upwardly therethrough together with the fusible element $3 and fusible element terminal 84.

As a further result of the release of the fusible element terminal Sid by separation of the jaw portions 9'49l, the coil compression spring 77 moves the compression tube 7:? upwardly sufficiently far to cause the tube end fitting 7 to engage the underside of the upper end 25 of the unlatching tube 25. he unlatching tube 25 moves upwardly carrying with it the flange to lift the latch arm 2d and permit the dropout fuse T6 to rotate about the pivot 21 on the lower line terminal 15 downwardly to open position where it engages the resilient bumper Sit and its movement in the full open position is arrested thereby.

It is desirable that the lower end of the lower fuse tube terminal l9 be closed off in order to prevent the entrance of extraneous material such as insects and the like into the interior of the dropout fuse to. For this purpose, as shown in FIG. 3-33, a frangible or flexible closure disc 13b is employed. It is located in an annular groove 131 near the lower end of the lower fuse tube terminal 19 and extends underneath thelower endof the fitting A snap ring 132, also located in the groove 131, serves to hold the frangible closure disc 139 in place. When the dropout fuse 16 is operated in a manner such as to cause the flow of are products downwardly through the metallic exhaust tube 81 and through the lower fuse tube terminal 19, the frangible or flexible closure disc 136i is readily ruptured or blown out to permit their escape to the atmosphere. Also it can be broken or sprung readily, as described hereinafter, by an external blow applied to move the operator 116 upwardly for triggering the dropout fuse 16.

The details of construction of the external trigger operating mechanism 33 are shown in FIGS. 7, 8 and 9 of the drawings to which reference now will be had. Here it will be observed that the trip arm 37 is rotatably mounted on a reduced diameter outer end portion of a stud 1% that extends through the support bracket 34 and is secured thereon by nuts 13'] which are threaded on a threa ed portion of the stud 136 as shown in FIG. 8. It will be understood that-the trip arm 37 rotates about the longitudinal axis of the stud 135, the axis being indicated at 158 in FIGS. 7 and 9. The axis 138 extends in spaced relation to the longitudinal axis of the fuse tube 17 and transversely thereof when it is in the closed position shown, for example, in FIG. 2. The trip arm 37 is biased to its non-operated or retrieved position, shown in FIG. 7, by a helical spring 139 which surrounds the stud 136 having one end ll i-tl anchored to the support bracket 34 and its other end 141 anchored to a hub portion 142 of the trip arm 37. It will be noted in FIG. 9 that the trip arm 37 has a curved outer end portion the distal end 1 34 of which is arranged to impact through the frangible closure disc 1%, FIG. 3E, the lower side of the shouL dered fitting 126 on the lower end of the operator 116 for the purpose of moving it upwardly to effect the release of the trigger means 89, FIG. 3-C, in the manner previously described. The closure disc 130 is ruptured by this action.

It is important that the terminal positions of the trip arm 3'7 be accurately controlled and be adjustable in order to compensate for possible dislocation of parts of the trigger operating mechanism 33 in relation to each other and due to varying deflections of the insulators l3 and 39. For this purpose an adjustable stop screw 145 is threaded through the sleet hood 35, as shown in FIGS. 7 and 9, and it is locked in place by a lock nut M6. The distal end of the adjustable stop screw 145 controls the position to which the trip arm 37 is retrieved or its nonoperated position as shown in FIG. 7. Another adjustable stop screw 147 is provided. It is threaded through one leg of a transverse angle member M8 that is secured, as by welding, to the underside of the sleet hood 35. A look nut M9 serves to hold the stop screw 147 in adjusted position. As shown in FIG. 9, when a shoulder 37' on the trip arm 37 engages the head 147' of the adjustable stop screw 147, further forward movement of the trip arm 37 is prevented. The adjustment of the stop screw 147 is such that the distal end Md of the trip arm 37 is caused to move the operator 116 upwardly in a positive manner through a distance sufficient to move the cam member 114 to the unlatching position shown in FIG. 3-D of the drawings in order to uulatch positively the trigger means 89 and release the fusible element terminal 84. The adjustment of the stop screw 147 can be such as to permit movement of the operator 116 far enough to cause the inner sides 12d-l24 of the openings 113113 in the cam member 114 to engage wedgingly the flat surfaces l26fl26 previously described.

it will be observed that the end of the helical spring 139, which biases the trip arm 37 to the non-operated position, extends underneath the transverse angle member 148, FIGS. 7 and 9, and thereby is held against movement with respect to the support bracket 34.

it will be recalled that, when the fusible element terminal 84 is released as a result of the impact being applied to the lower end of the operator 116, the fuse tube 17 is unlatched from the upper line terminal 14 and swings downwardly to the open position. It is desirable that the trip arm 37 be returned to the non-operated position promptly by the spring 139 or at least moved to a position where the curved outer end portion 143 thereof is out of the path of downward swinging movement of the dropout fuse 16 so as not to interfere with such action. For this purpose a trip free connection, shown generally at 150, is provided for mechanically interconnecting the trip arm 37 to the actuating lever 33 with the arrangement being such that, after the trip arm 37 has completed its function of moving the operator 116 upwardly to trigger the trigger means 89, the operating connection is no longer maintained and the trip arm 37 is free to be returned to the non-operated position without regard to the position of the actuating lever 38 which may be returned to the non-operated position at a later time and at a relatively slow speed.

The trip free connection 156 includes a trip free arm 151 having one bifurcated end pivotally secured at 152 to a hub 37" that forms an integral part of the trip arm 37. As seen in FIGS. 7 and 9, the axis 153 of the pivot 152 about which the trip free arm 151 rotates is parallel to the axis 138 about which the trip arm 37 rotates on the stud 136. It will be noted that the trip free arm 151 has a shoulder 154 that is arranged to engage a juxtaposed portion of the trip arm 37 for the purpose of causing conjoint movement thereof when a force is applied to the trip free arm 151 by the actuating lever 38. The other end 155 of the trip free arm 151 is bifurcated and a roller 156 is located between the arms thereof on a pin 157 which extends therethrough and has an extension 158 to which one end of a spring 159 is secured. The spring 159 is a coil tension spring and its other end is connected at 160 to the trip arm 37.

The actuating lever 38 includes an upstanding arm portion 163 that is formed integrally with a base 164 which is secured by bolts 165 to the distal end of the rotatable insulator 39. The distal end 166 of the upstanding arm portion 163 is rounded and is arranged to engage the roller 156 when the insulator 39 is rotated to rotate the actuating lever 38. It will be observed that the axis of rotation of the rotatable insulator 39 is indicated at 167 and that this axis is parallel to the axis 133 of rotation of the trip arm 37.

When the rotatable insulator 39 is rotated about its axis 167 in a counterclockwise direction as indicated by the arrow 168 in FIG. 7 and the arrow 169 in FIG. 9, the trip arm 37 is rotated in a clockwise direction from its position shown in FIG. 7 to the position shown in FIG. 9 and in the direction indicated by the arrow 1170. The arrangement is such that the rounded distal end 166 of the actuating lever 38 engages the roller 156 and maintains mechanical engagement therewith until the trip arm 37 has rotated sufficiently far to cause the distal end 1% thereof to impact the underside of the disc 136 and thereby the fitting 120 on the lower end of the operator 116 to move it positively upwardly a distance sufiicient to trigger the trigger means 89 and positively release the fusible element terminal 84. Continued rotation of the actuating lever 38 in the direction indicated by the arrow 169 causes its rounded end 166 to move past the roller 156 and out of its path of movement. When this takes place, which is a result of the provision of the trip free connection 150, the trip arm 37 is no longer driven in the direction indicated by the arrow 170 and, since the helical spring 139 has been additionally tensioned by the previous rotation of the trip arm 37 to the operated position, the spring 139 is not restrained and it biases the trip arm 3'7 to the non-operated or retrieved position shown in FIG. 7.

When the actuating lever 38 subsequently is returned to its non-operated position by rotation of its insulator 39 in a clockwise direction, the rounded end 166 engages the roller 156. However, since the trip arm 37 is prevented sass? from any further rotation in a counterclockwise direction by the adjustable stop screw I145, the engagement of the roller 156 by the rounded end 166 swings the trip free arm 151 about its pivot 152 and tensions the spring 159. Then, after the rounded end 166 has moves to the position shown in FIG. 7 and out of mechanical engagement with the roller 156, the spring 159 retrieves the trip free arm 151 and rotates it in a clockwise direction until its shoulder i54- engages the trip arm 37 in the position shown in FIG. 7.

What is claimed as new is:

1. Apparatus for triggering a dropout fuse including a fuse tube latched at its upper end to an upper line terminal and pivoted at its lower end to a lower line terminal, a fusible element controlling the latch at said upper end and adapted on blowing to draw an arc and discharge the are products through said lower end, trigger means to release said fusible element in its unblown state to unlatch said latch, and a rod-like operator movable endwise through said lower end upwardly into said fuse tube to trigger said trigger means for releasing said fusible element to interrupt the circuit and to unlatch the latch means at its upper end and permit it to swing downwardly to open position comprising, in combination:

(a) a support bracket extending laterally from said lower line terminal,

(11) trip arm means rotatably mounted at one end on said support bracket with its distal end normally out of the path of the are products that flow from said lower end of said fuse tube on blowing of said fusible element and arranged to swing about an axis spaced from and extending transversely of the longitudinal axis of said dropout fuse and parallel to the plane of swinging movement of said fuse tube for engaging at its distal end said rod-like operator and moving it endwise upwardly into said fuse tube, and

(c) means for rotating said trip arm to engage said operator.

2. The invention, as set forth in claim 1, wherein a sleet hood is mounted on the support bracket in overlying relation to the trip arm in its non-operated position and in spaced relation to the lower line terminal.

3. The invention, as set forth in claim 1, wherein:

(a) a trip arm spring reacts between the support bracket and the trip arm to bias said trip arm to its non-operated position, and

(b) a trip free connection is provided between said trip arm and the means for rotating it to engage the operator.

4. The invention, as set forth in claim 3, wherein adjustable stops are mounted on the support bracket and cooperate with the trip arm to limit the extent of its rotation in either direction.

5. The invention, as set forth in claim 3, wherein:

(a) the means for rotating the trip arm includes an actuating lever, and

(b) rotatable insulating means supports said actuating lever for rotation about an axis parallel to the axis of rotation of the trip arm.

6. The invention, as set forth in claim 5, wherein the trip free connection includes:

(a) a trip free arm pivoted at one end to the trip arm about an axis parallel to its axis of rotation, and

(b) a trip free arm spring biases said trip free arm into engagement with said trip arm,

(0) the distal end of the actuating lever when rotated in a fuse triggering direction engages the distal end of said trip free arm to rotate said trip arm, tension the trip arm spring, cause the distal end of said trip arm to engage the rod-like operator, interrupt the circuit and to unlatch the dropout fuse, and finally disengage said trip free arrn whereupon said trip arm is retrieved by said trip arm spring to its non-operated position,

(d) the distal end of said actuating lever when rotated in the opposite direction engages said distal end of 13 said trip free arm, rotates it away from said trip arm, tensions said trip free arm spring, and disengages said distal end of said trip free arm.

7. The invention, as set forth in claim 1, wherein:

(a) insulators extending laterally from a support carry the upper and lower line terminals at their distal ends, and

(b) an insulator rotatably mounted at one end on said support parallel to and adjacent to the insulator that carries the lower line terminal carries an actuating lever at its distal end for rotating the trip arm.

8. The invention, as set forth in claim 7, wherein:

(a) a plurality of actuating levers are mounted on a plurality of rotatable insulators for triggering a plurality of dropout fuses, and

(b) means are operatively connected to said rotatable l4 insulators for rotating them to trigger simultaneously said dropout fuses. 9. The invention, as set forth in claim 8, wherein an operator is mechanically connected to the rotatable in- 5 sulators to cause the respective actuating levers to impact the respective operators in the dropout fuses.

References Cited by the Examiner UNITED STATES PATENTS 2,344,113 3/44 Schultz 200-l49 X 2,849,578 8/58 Hart 200-146 2,889,434 6/59 Lingal 200-146 X 2,963,560 12/60 Koerner et al 200-48 15 BERNARD A. GILHEANY, Primary Examiner.

ROBERT K. SCHAEFER, Examiner.

Claims

1. APPARATUS FOR TRIGGERING A DRIPOUT FUSE INCLUDING A FUSE TUBE LATCHED AT ITS UPPER END TO AN UPPER LINE TERMINAL AND PIVOTED AT ITS LOWER END TO A LOWER LINE TERMINAL, A FUSIBLE ELEMENT CONTROLLING THE LATCH AT SAID UPPER END AND ADAPTED ON BLOWING TO DRAW AN ARC AND DISCHARGE THE ARC PRODUCTS THROUGH SAID LOWER END, TRIGGER MEANS TO RELEASE SAID FUSIBLE ELEMENT IN ITS UNBLOWN STATE TO UNLATCH SAID LATCH, AND A ROD-LIKE OPERATOR MOVABLE ENDWISE THROUGH SAID LOWER END UPWARDLY INTO SAID FUSE TUBE TO TRIGGER SAID TRIGGER MEANS FOR RELEASING SAID FUSIBLE ELEMENT TO INTERRUPT THE CIRCUIT AND TO UNLATCH THE LATCH MEANS AT ITS UPPER END AND PERMIT IT TO SWING DOWNWARDLY TO OPEN POSITION COMPRISING, IN COMBINATION: (A) A SUPPORT BRACKET EXTENDING LATERALLY FROM SAID LOWER LINE TERMINAL, (B) TRIP ARM MEANS ROTATABLY MOUNTED AT ONE END ON SAID SUPPORT BRACKET WITH ITS DISTAL END NORMALLY OUT OF THE PATH OF THE ARC PRODUCTS THAT FLOW FROM SAID LOWER END OF SAID FUSE TUBE ON BLOWING OF SAID FUSIBLE ELEMENT AND ARRANGED TO SWING ABOUT AN AXIS SPACED FROM AND EXTENDING TRANSVERSELY OF THE LONGITUDINAL AXIS OF SAID DROPOUT FUSE AND PARALLEL TO THE PLANE OF SWINGING MOVEMENT OF SAID FUSE TUBE FOR ENGAGING AT ITS DISTAL END SAID ROD-LIKE OPERATOR AND MOVING IT ENDWISE UPWARDLY INTO SAID FUSE TUBE, AND (C) MEANS FOR ROTATING SAID TRIP ARM TO ENGAGE SAID OPERATOR.