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Publication numberUS2328818 A
Publication typeGrant
Publication dateSep 7, 1943
Filing dateAug 1, 1940
Priority dateAug 1, 1940
Publication numberUS 2328818 A, US 2328818A, US-A-2328818, US2328818 A, US2328818A
InventorsLindell Sigurd I, Ryan Anthony Van
Original AssigneeSchweitzer & Conrad Inc
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Circuit interrupting apparatus
US 2328818 A
Abstract  available in
Images(7)
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Claims  available in
Description  (OCR text may contain errors)

SGPL 7. 1943- s. l. LINDELL ETAL CIRCUIT NTERRUPTING APPARATUS Filed Aug. l, 1940 7 Sheets-Sheet l Sept 7, 1943- s. l. LINDELL. ETAL 2,328,818

C IRCUIT INTERRUPTING APPARATUS i/ www m www J 'Sept .7, 1943 s. l. LINDELL Erm. 2,328,818

C IRCUIT INTERRUPTING APPARATUS Sept. 7, 1943.

s. l. LINDELL ETAL CIRCUIT INTERRUTING APPARATUS Filed Aug. l, 1940 7 Sheets-Sheet 4 ISept, 7, 1943. s. l. LINDELL Erm.

CIRCUIT INTERRUPTING APPARATUS V Filed Aug. l, 1940 7 Sheets-Sheet 5 Sept. 7, 1943. s 1 LlNnELL EVAL I 2,328,818

' CIRCUIT INTERRUPTING APPARATUS Fild Aug. 1, 1940 7 sheets-sheet fr Patented Sept. 7, 1943 CIRCUIT INTERRUPTDN'G APPARATUS Sigurd I. Lindell and Anthony Van Ryan, Chicago, Ill., assignors to Schweitzer & Conrad, Inc., Chicago, Ill., a corporation of Delaware Application August 1, 1940, Serial No. 349,264

(Cl. 200m-114) 23 Claims.z

This invention relates, generally, to circuit interrupters and it has particular relation to fuse devices.

An important object of this invention is to provide for positive arc interruption and positive dropout action in a fuse construction in which the fuse link is definitely tensioned and arcing at the contact members is avoided during arc interruption.

An object of this invention is to provide for installing a fuse link in a fuse tube under little or no tension and then for tensioning the fuse link in a predetermined amount in a new and improved manner.

Another object of this invention isto provide for tensioning a fuse link in a fuse tube during the movement thereof to the circuit closed position in a new and improved manner.

A further object of this invention is to provide for moving apart a pair of members carried by a fuse tube and biased toward each other to tension a fuse link previously installed in the fuse tube under little or no tension.

A still further object of this invention is to provide for striking a blow on a toggle mechanism supporting a fuse tube in the circuit closed position inI order to positively unlock the toggle.

Another object of this invention is to hold a fuse link extracting member stationary with respect to a fuse tube while it is being moved on a support to circuit closed position and at the same time to hold an operating member stationary with respect to the support in order to tension a fuse link in the fuse tube and to extract a portion of it when the fuse link blows.

Still another object of this invention is to employ the stress applied in tensioning a fuse link to increase the contact pressure with a line terminal.

A further object of this invention is to provide a shock absorber action to the recoil of a fuse tube when the fuse link therein blows.

It is another object of the invention to provide for guiding a fuse tube into engagement with an upper line terminal by means on the lower line terminal in a new and improved manner.

A still further object of this invention is to provide for closing and opening a transfer switch in a repeating fuse construction by the movement of a dropout fuse to open circuit and closed circuit positions, respectively in a new and improved manner.

Other objects of this invention will, in part, be obvious and, in part, appear hereinafter.

Accordingly, this invention is disclosed in the embodiments thereof shown in the accompanying drawings, and it comprises the features of construction, combination of elements and arrangement of parts which will be exempliiled in the constructions hereinafter set forth, and the scope of the application of which will be indicated in the appended claims.

For a more complete understanding of the nature and scope of this invention, reference may be had to the following detailed description, taken in connection with the accompanying drawings, in which:

Figure 1 is a view, in side elevation, of a dropout fuse device embodying the present invention;

Figure 2 is a view, in front elevation, of the fuse device shown in Figure 1;

Figure 3 is a longitudinal sectional view of the fuse tube, together with the associated parts, separate from the mounting therefor;

Figure 4 is a longitudinal sectional view of a fuse link that may be employed in practicing the present invention;

Figure 5 is a detail view, certain parts being shown in section, showing the relationship of the fuse link extracting and toggle breaking means after the fuse link has blown and before any movement of the fuse tube has begun;

Figure 6 is a view, partly in side elevation and partly in section, showing the position assumed by the fuse tube and the parts associated with the toggle mechanism shortly 'after the toggle has been broken;

Figure 'l is a perspective view of the lower line terminal assembly;

Figure 8 is a perspective view of the lower fuse tube terminal and toggle mechanism associated therewith;

Figures 9 through 13 are perspective views showing the parts making up the toggle and fuse link extracting mechanism generally in the relative positions which they occupy when the fuse link has been installed in operative position in the fuse tube;

Figure 14 is a view, in front elevation, of a repeating fuse construction employing the dropout fuse unit shown in Figure 1 as a part thereof;

Figure l5 is a detail sectional view horizontally through one of the insulators, showing in further detail how the insulators are mounted on a support;

Figure 16 is a view, partly in side elevation and partly in section, showing the arrangement of the transfer switch mechanism;

Figure 1'7 is a detail sectional view taken along the line l1--l1 of Figure 16; and

Figure 18 is a detail sectional view taken along the line I8-I8 of Figure 16.

Referring now particularly to Figures 1, 2 and 3 of the drawings, it will be observed that the reference character I designates, generally, a dropout fuse device which is intended for use on electric power distribution circuits operating at voltages ranging upwardly from 2300 volts. Ordinarily, the dropout fuse device I will be employed in connection with a distribution transformer and will be connected between its primary winding and the line. Obviously, other uses may be made of the dropout fuse device I and, accordingly, it will be understood that its use is not limited to the application stated.

The dropout fuse device I comprises a single insulator 2 which may be a hollow porcelain insulator. Intermediate its ends the insulator 2 is provided with a metallic band 3 which is clamped by bolts 4 and 5 to it and to a bracket 3, on which is mounted an upper line terminal,

shown generally at 9, by means of bolts I and II. The upper line terminal 9 includes an upstanding arm I2 having an integrally formed rib I3 to which may be secured a conductor clamp for connecting one of the line conductors thereto.

At its lower end the insulator 2 is provided with a metallic clamp band I4 for supporting a lower line terminal, shown generally at I5, by means of a bolt I6 and screws l1. The lower line terminal I is provided with an integrally formed rib I 8 for receiving a conductor clamp for connecting the other line conductor to the lower line terminal I5.

The upper and lower line terminals 9 and I5 are arranged to be interconnected by a dropout fuse device, shown generally at 2l. The dropout fuse device 2l comprises a fuse tube 22, Figure 3, formed by an outer sleeve 23 of weatherproof material, such as a phenolic condensation product, and an inner liner 24 formed of material such as ber, or paper impregnated with magnesium borate, that is adapted to evolve an arc extinguishing medium due to the heat of an arc drawn incident to the operation of the device.

The fuse tube 22 is provided at its upper end with an upper fuse tube terminal, shown generally at 25. The terminal 25 includes a metallic ferrule 26 that can be secured to the upper end of the fuse tube 22 by transversely extending pins 21. An operating eye 28, Figure l, is integrally formed with the ferrule 26 for receiving the prong of a switch stick for operating the fuse device 2| to the circuit closed position. A cap 29 is threaded on the upper end of the ferrule 26 and it is provided with a generally spherically shaped contact engaging portion 30 for intertting with a correspondingly shaped recess 32 in a sleet hood 33 which forms a part of the upper line terminal 9.

The sleet hood 33 is rockably mounted on a pin 34 which extends through a body portion 35 of the upper line terminal 9 with which the upstanding arm I2 is integrally formed and through which the bolts I9 and Il extend. In order to limit the movement of the sleet hood 33 it is provided with a circular opening 36 in a rear wall 31 thereof through which projects a stop 38 that is integrally formed with the body portion of the upper line terminal 9. It will be observed that the stop 38 limits both the upward and downward rocking lmovements of the sleet hood 33 on the pin 34.

With a. view to shunting the pin connection between the sleet hood 33 and the body portion 35 of the upper line terminal 9, and to provide for biasing the former downwardly, a flexible strip 39 of good conducting material, such as copper, reinforced by a strip 40 of spring metal, is provided. The conducting and spring strips 39 and 40 are secured by rivets 4I, only one of which is shown, to the sleet hood 33. At their other ends the strips 38 and 39 bear against a ridge 42 integrally formed in the body portion 35 of the upper line terminal 9.

Entry of the upper fuse tube terminal 25 into the sleet hood is facilitated and it is guided into position by the outwardly flared sides 43 and the upwardly flared top 44 of the sleet hood 33. Flanges 45, integrally formed with the ferrule 26 and extending laterally therefrom are provided to engage either of the outwardly flared sides 43 for centering the fuse device 2| with respect to the sleet hood 33 so as to insure proper seating of the contact engaging portion 30 in the recess 32 of the sleet hood 33 in the circuit closed position.

The fuse tube 22 is adapted to receive a replaceable fuse link which is shown generally at 46. The fuse link 46 may be of any of the types of universal link now on the market, the particular type shown being that illustrated and described in Ramsey Patent No. 2,144,707.

v In Figure 4 of the drawings, the details of construction of the fuse link 45 are more clearly shown. As there indicated, the fuse link 46 is provided with relatively infusible terminals 41 and 48 which are interconnected by a relatively high strength strain wire 49 and a fusible ele ment 50. The strain wire 49 may be a nickel alloy wire, while the fusible element 50 may be formed of silver. An insulating sleeve 5l is secured to the terminal 41 and projects over the terminal 48, out of which sleeve the terminal 48 is freely movable. The terminal 41 is provided with a threaded portion 52 for receiving a flanged sleeve 53. Underneath the flange of the sleeve 53 there is a washer 54 which is of sufficient diameter to fully cover and properly seat on the upper end of the ferrule 26, as shown in Figure 3 of the drawings. Secured to the terminal 48 is a flexible lead 55 which is of suflicient length to extend out of the lower end of the fuse tube 22 for connection to a lower fuse tube terminal, shown generally at 56, Figure 3. It will now be understood that the fuse link 46 serves to interconnect the upper fuse tube terminal 25 and the lower fuse tube terminal 56. It will also be understood that these fuse tube terminals 25 and 56 are arranged to have contact engagemenu with the upper and lower line terminals 9 and I5, respectively, for interconnecting the line conductors.

In Figures 1, 2 and 3 of the drawings certain of the details of the lower fuse tube terminal 56 are shown. It will be noted that it comprises a sleeve 51 which may be secured to the lower end of the fuse tube by transverse pins 58. It also includes a toggle and fuse link tensioning and exspring strips 61.

ci these slots.

tracting mechanismthat is shown generally at 66. The mechanism 59 is pivotally mounted, by means o! a pin 66, between the rearwardly projecting ears 6| from the sleeve 51 that are integrally formed therewith. g

The mechanism 59 includes a toggle member 62, Figure 9, through which the pin 66 extends for pivotal mounting between the ears 6|. 'I'he l predetermined tension to the fuse link 46 so that toggle member 62 is also provided with integrally formed outwardly extending trunnions 63 which are arranged to enter and rotate in upwardly opening U-shaped terminal receiving portions 64, Figure 7, in the housing forming the lower line terminal I5. The trunnions 63 serve to pivotally mount the dropout fuse device 2| as a unit, and it is about their axes that the fuse device 2| is rotated to the circuit closed position with the fuse link 46 installed therein.

The toggle member 62 is also provided with a pair of rearwardly extending projections 65 for engagement with contact ngers 66 which are backed up and urged forwardly by means of leaf The contact fingers 66 and leaf springs 61 are secured to the lower line terminal i1 by means of suitable rivets 68.

The toggle member 62 is also provided with a threaded stud 69 around which the flexible lead 55 may be placed and clamped securely to the toggle member 62 -by means of a nut 16.

As will be presently set forth, when the link 46 blows, the dropout fuse device 2|, which is normally latched to the upper line terminal 9 because of the intertting engagement between the spherical portion 30 of the cap 29 and the complementary concave portion 32 in the sleet hood 33, drops to the open circuit position. In order to limit the swing of the dropout fuse device 2| after it is released from latching engagement with the upper line terminal 9, the lower .line terminal i 5, Figure 7, has a generally U- shaped recess il in its lowermost portion the bottom of which is engaged by the sleeve 5! and acts as a stop therefor.

'integrally formed with the toggle member 62 is an eye i3 for receiving the prong of a switch stick. In order to place the dropout fuse device 2i into operative position, the prong of the switch stick is inserted in the eye "i3 and then the fuse device 2i is lifted to such position that the trunf nions 63 are above the U-shaped slots 54 in the lower line terminal l5. The fuse device 2| is then lowered until the trunnions 63 engage the bottom The prong of the switch stick is then removed from the eye 'J3 and is inserted in the eye 28 to swing the fuse device 2| to the circuit closed position, as shown in Figure l.

The relationship of the toggle member 62 with respect to the fuse tube 22 is such that, in the circuit closed position, a locked or over-center toggle arrangement is provided. As shown in Figure 1 of the drawings, in the circuit closed position the pivot axis of the toggle member 62 about the pin 60 is located slightly past a line 14 interconnecting the reaction point 16 at the upper end of the fuse tube 22 and the axes oi the trunnions 63 about which the toggle member it will always be stressed to a certain extent which is independent of any action that is taken on the part of the lineman when the fuse device 2| is re-fused. Also, it is an advantage to be able to connect the fuse link 46 in place in the fuse device 2| so as to interconnect the upper and lower fu'se tube terminals 25 and 56 initially under little or no tension. It is then unnecessary for the lineman, in re-fusing the fuse device 2|, to hold any spring members in stressed condition while he is fastening the free end of the flexible lead 55 in place.

Accordingly, the mechanism 59 has been provided-which not only permits the fuse link 46 to be placed in operative position in the fuse device 2| under little or no tension., but also it permits tensioning of the fuse link 46 in a predetermined amount and further provides for striking the toggle member 62 with a hammer blow in order to release it from the locked toggle position.

Referring now particularly to Figures 9, l1 and 12 of the drawings, it will be observed that the toggle and fuse link tensioning and extracting mechanism 59 comprises essentially three members. One of these members is the toggle member 62, Figure 9, which is pivoted on the ears 6| extending from the sleeve 51 on the lower end of the fuse tube 22 and is also pivoted in the upwardly opening U-shaped slots 64 in the lower line terminal l5. The trunnions 63, which rotatably mount the toggle member 62 on the lower line terminal i1, are apertured to receive a pin 11, Figure l0. On this pin 11 there are positioned a fuse link extracting member 18, Figure il, and an operating member lil, Figure l2. it will be noted that' these members 18 and 'i9 rotate about the same axis as does the toggle member `62 with respect to the lower line terminal i5.

The fuse link extracting member ld is provided with an arm 66 which is long enough to extend slightly past the center or the bore of the inse tube 22, as shown in Figure l, and has a groove 6i in its under surface for receiving the nexible lead 55. When installed, the fuse link d6, with, the flexible iead 55 clamped 'to the toggle member 62 by the clamp nut lil, holds the fuse link extracting member "i6 stationary with respect to the fuse vtube 22, regardless ci its position. lntegrally formed with the arm. 36 is a hub 62 through which the pin 'il extends. A hammer member or arm 63 is integrally formed with the hub 82 or the i'use link extracting member iB and is arranged to strike an anvil member or flange 64 which depends from the underside of the toggle member 62, as shown more clearly in Figure 5 of the drawings. Ji/hen the fuse link 46 blows, the fuse link extracting member 18 is released and, as will be presently apparent, it is urged with considerable force in a clockwise direction, as viewed in Figure 5 of the drawings. This movement of the fuse link extracting member 18 performs two functions. First, it rapidly withdraws the remaining portion of the flexible lead 55 so as to quickly separate the terminal 48, Figure 4, from the terminal 41 and extend the arc therebetween. Next, the hammer portion 83 strikes the anvil or flange 84 of the toggle member 62 with considerable force, and serves to break the toggle joint by causing the toggle member 62 to move in a clockwise direction so that the axis of the pinv 60 moves from the over-center position,

Figure l, past the line 14, where gravity and the downward biasing force applied to the sleet hood 33 are eiective to cause further movement of the fuse device 2| to the open circuit position.

The operating member 19 is provided with a pair of spaced-apart apertured ears 86, Figure 12, through which the pin 11 extends. These ears 86 are provided with extensions or shoulder portions 81 which are arranged to engage shoulder portions 88, Figure 7, integrally formed With the housing of the lower line terminal I5 directly underneath the upwardly opening U-shaped slots 64. A web 89, integrally formed with the ears 86, serves to rigidly interconnect them.

It will now be apparent that the fuse link extracting member 18 and the operating member 19 are coaxially mounted within the toggle member 62 and that they are movable relative to each other. With a view to biasing these members for rotation toward each other, a spring 90, Figure 13, is coiled about the ends of the hub 82 of the fuse link extracting member 18. The intermediate portion 9| of the spring 90 is looped about the fuse link extracting member 18 while its ends 92 are hooked over the web 89 interconnecting the ears 86 of the operating member 19. Prior to the installation of the fuse link 46 in operative position in the fuse tube 22, the fuse link extracting member 18 and the operating member 19 are free to rotate together as a unit about the pin 11 relative to the toggle member 62. When the fuse link 46 is installed and the flexible lead 55 is clamped to the toggle member 62 by the clamp nut 10, as shown in Figure 8'of the drawings, then the fuse link extracting member 18 is held stationary with respect to the fuse tube 22, as previously indicated and as shown in Figure l of the drawings, and the spring 90 holds the operating member 19 in engagement therewith. As yet, the spring 9D has not been further stressed, so that the fuse link 46 is installed by the lineman under little or no tension, there being no force tending to turn the fuse link extracting member 18 and tension the fuse link 46.

After the fuse link 46 has been installed in the fuse tube 22 under little or no tension, the fuse device 2! is then ready to be inserted in the lower line terminal I5 in the manner previously described. The fuse tube 22 is then rotated to the circuit closed position. Since the fuse link extracting member 18 is held stationary with respect to the fuse tube 22 by the flexible lead 55 of the fuse link 46, it rotates with the fuse tube. The operating member 19 likewise tends to rotate, but its shoulders 81 promptly engage the shoulders 88 on the lower line terminal l5, and further movement thereof is arrested. Moreover, the fuse link extracting member 18 continues to rotate and, in so doing, stresses further the spring 80 interconnecting the two members. It will be clear that the amount that the spring 90 is further stressed depends entirely upon how far the fuse link extracting member 13 is moved relative to the operating member 19. Since this is determined by the design of the lower line terminal l5 and the position of the shoulders 81 on the operating member 19, it will be obvious that the fuse link 46 will always be tensioned in a predetermined amount. This can be varied by changing the relative positions of the shoulders 81 and 88. However, the lineman has nothing to do with the amount of tension that is applied to the fuse link 46. Nothing is left up to his judgment as to how much tension to apply to it.

Now, when the fuse link 46 blows, the operating member 19 is held stationary and the fuse link extracting member 18 is urged toward it by the spring 90. As previously described, this not only serves to withdraw the remaining portion of the flexible lead 55, but also it serves to break the toggle and initiate the movement of the fuse tube 22 from the circuit closed position.

In Figure 5 of the drawings, the first stage in the movement oi the fuse link extracting member 18 is shown. Here the flexible lead 55 has been withdrawn from the fuse tube 22 and the hammer portion 83 has just engaged the anvil or flange 84 of the toggle member 62. As yet, no movement of the fuse tube 22 has taken place. In this position it will be noted that the fuse link extracting member 18 still has some distance to go before it engages the edge 93 of the web 89 of the operating member 19. This further extent of movement corresponds to additional stress in the spring 90 which is capable of urging the toggle member 62 to the unlocked position, in addition to the force exerted by the hammer blow on the anvil or flange portion 84, resulting from the inertia of the fusel link extracting member 18. In the event that the reaction on the fuse tube 22 due to the expulsion action is such that the impact of the fuse link extracting member 18 is not sufiicient to break the toggle joint, then after the expulsion action has ceased, the additional stress capable of being exerted by the spring 90 is sufficient alone to break the toggle joint.

In Figure 6 of the drawings the toggle member 62 is shown after it has been operated past the center position and into the unlocked position. When the fuse link extracting member 18 engages the edge 93 of the web 89, the spring 99 is not further capable of effecting relative movement between the fuse link extracting member 18 and the operating member 19. As soon as the toggle member 62 is moved past the center position, the pin 60 is lowered so that the fuse tube 22 is not only swung outwardly but also is moved downwardly from underneath the sleet hood 33 and is thereby unlatched therefrom. The upper end of the fuse device 2l then follows along the arc indicated at 94 in its movement to the open circuit position.

Since the shoulders 81 of the operating member 'I9 engage the shoulders 88 on the lower line terminal l5 in a vertical plane, the reaction on the trunnions 63 is in a horizontal plane and they are urged into pressure contact engagement with the inner surfaces of the upwardly opening U-shaped slots 64. Obviously this serves to improve the interconnection between the toggle member 62 and the lower line terminal I5.

This arrangement of the shoulders 81 and 88 also permits a slight longitudinal movement of the fuse device 2| in the slots 64. The upward movement in the slots 64 is opposed by the downward biasing action applied to the sleet hood 33. This provides a shock absorber action to the recoil of the fuse tube 22 when the fuse link 46 blows. That is, when the fuse link 46 blows there is a tendency for the fuse tube 22 to move upwardly. Under short circuit conditions this recoil force may be relatively great. Rather than to rigidly hold the fuse tube 22 in place, it is preferable to provide the shock absorber action just described in order to permit some movement of the fuse tube 22 to 'more readily overcome the recoil and prevent the fuse tube 22 from being torn loose from its supports.

The upward movement of the fuse tube 22 is limited by flanges 96, Figures 1, 2 and 7, which extend inwardly from opposite sides of the housing of the lower line terminal I5 and project into the path of shoulders 91, Figures 8 and 9, on the toggle member 62. Thus, the fuse tube 22 is permitted to move upwardly due to the recoil resulting from the blowing of the fuse link 45 until the shoulders 91 engage the flanges 96.

The movement of the contact fingers 66 outwardly is limited by flanges 08, Figures 2 and '1. The anges 98 are formed integrally with the housing of the lower line terminal I5 so that they project into the paths of the contact lingers 06 as they are urged outwardly by the leaf springs It will be observed that the upper portion of the lower line terminal I5, Figure 7, has a downwardly curved roof portion 99 which serves to protect the mechanism therein, and the parts associated with the lower fuse tube terminal 56, from the weather and particularly from the entrance of snow and sleet. The roof portion 99 is formed to provide a groove |00 through which the upper portion of the eye 13 on the toggle member 62 moves when the fuse tube 22 is moved to the circuit closed position. This serves to guide the upper fuse tube terminal 25 into the sleet hood 33.

If desired, the toggle member 62 may be locked against rotation with respect to the ears 6I of the ferrule 51. In such case, a non-dropout fuse construction would be provided. However, the fuse link 46 would be inserted as described hereinbefore and connected in place under little or no tension. When the fuse tube 22 would be rotated to the closed circuit position, the fuse link 46 would be tensioned as before. However, when theV fuse link 4S subsequently blows, the fuse link extracting member 18 would perform a single function only, namely, it would Withdraw the remaining portion of the lexible lead 55. In some instances, where a non-dropout fuse device is desired, such an arrangement can be employed.

While the upwardly opening U-shaped slots 64 have been shown as being formed in the lower line terminal I1 itself, it will be apparent that these slots could be mounted on a separate support member if desired. Thus, there may be upper and lower line terminals and a support member in which the drop-out fuse device 2| is rotatably mounted.

It will now be apparent that the present invention employs the resilient action of the upper contact member to provide contact pressure, resilient recoil on short circuit operation and latching action. However, the design is such that the tension imposed on the fuse link is substantially independent of this pressure. The linkage is normally on dead center. No shock is transmitted to the fuse link from the upper contact member on operation to the closed circuit position. The tension imposed on the fuse link is not dependent on close adjustment of the spacing of the line terminals.

The fuse link extracting member or rotary flipper extracts the flexible lead or cable from Since the toggle latch is not broken while the flexible lead or cable is being extracted and the arc drawn and extinguished in the fuse tube, the fuse tube remains in place and no arcing occurs at the upper contact member. This operation takes place because the action of the ilipper or fuse link extracting member initially is independent of the toggle.

On the continued movement of the fuse link extracting member or flipper its kinetic energy is utilized to break the toggle latch in a second stage of operation. This unlatches the tube and permits the dropout action to take place. The impact of the flipper is useful in breaking a frozen or sleet covered mechanism as will be readily apparent.

In the case of a heavy fault current the reaction of the tube prevents breaking of the toggle by the impact of the flipper. The toggle is finally broken after the current has been interrupted and the gas pressure has subsided by the cornl tinued rotation of the flipper as driven by its spring.

As indicated provision'is made to permit a sliding recoil of the fuse tube in cooperation with the biased sleet hood. This motion must be lim-` ited because of the guiding cam surfaces on the lower contact member. The resilient motion of the sleet hood is limited to prevent parting and arcing at the upper contact member when heavy currents are interrupted. It is desirable to back the tube by a ilnal stop on the upper contact member in order to avoid placing the tube assembly in longitudinal tension which might unduly stress the tube and the ferrule joints.

The dropout fuse device I, shown in Figure 1 of the drawings and described hereinbefore, can be employed as a part of a repeating fuse construction. In such a construction two or more of the dropout fuse devices are provided, with one of them normally connected in the circuit. When this fuse device blows it is automatically operated to the open circuit position as described, and in so doing it effects the operation of a transfer switch which connects the next fuse device in the circuit. Ordinarily, each of the fuse devices that is employed is of the dropout type'. However, if desired, the last fuse device need not be of this type.

Two or more fuse devices may be employed in a repeating fuse construction. In Figure 14 of the drawings, three dropout fuse devices of the type shown at I in Figure 1 of the drawings have been shown as assembled in a repeating fuse construction. If desired, only two of the dropout fuse devices may be employed or more than three can be used, as will be readily understood.

The three dropout fuse devices I are arranged to be mounted commonly on a suitable support member such as a channel member |02 having spaced apertures |03 to permit mounting of the same on a suitable support structure. Each of the insulators 2 of the dropout fuse devices I is provided with the clamp band 3, as previously described. However, the bracket 6 is omitted and instead two L-shaped brackets |04 are substituted therefor. These brackets |04 are secured to the clamp band 3 by the bolts 4 and 5, as shown in Figure 1510i the drawings. Also, as shown in this figure, the outturned ends of the brackets |04 are secured to the channel |02 by suitable bolts |05.

The upper line terminals 9 are commonly connected together by a connector strap |06 of good conducting material such as copper. The strap |06 is secured to each of the line terminals by means of a suitable connector I 01 which fits over the ribs I3. One line conductor is connected to one of the connectors |01 so that the upper line terminals 9 are commonly connected thereto. The other line conductor is connected to the lower line terminal I5 of the left hand fuse device as previously described.

The strap |06 not only serves to interconnect the upper line terminals II but also it serves to mechanically tie the dropout fuse devices I together in order to more rigidly mount the same.

With a view to connecting the next dropout fuse device into the circuit when the preceding fuse device blows, transfer switches, shown generally at |08, are provided. It will be noted that a transfer switch assembly is provided between the rst and second fuse devices and between the second and third fuse devices.

Each of the transfer switch assemblies |08 comprises a switch arm or switch blade |09 that is rotatably mounted on a stud I I coaxially with the associated fuse tube 22. That is, each of the studs |i0 is coaxial with the trunnions 63, Figure 1, so that each fuse tube 22 and its associated switch arm or blade |09 rotate about a common axis. The stud I I0 is carried by a bracket III which may be secured by suitable screws to one side of the housing forming the lower line terminal I 5. Each switch arm or blade |09 is -provided with an extension or contact arm 2 for movement into and out of contact engagement with a stationary contact assembly, shown generally at II3. The stationary contact assembly ||3 is carried by a. bracket Ill that is secured by means of suitable screws to the housing forming a part of the lower line terminal |5 of the next fuse device.

With a view to operating the switch arm or blade |09 to the circuit closed position when the rst fuse device blows, an arm ||5 is provided thereon which extends into the path of the fuse tube 22 in its movement to the open circuit position. As shown in Figure 14 of the drawings, the left-hand dropout fuse device I has been operated to the open circuit position. In so doing it has picked up the arm ||5 and moved the switch arm or blade |09 so that the contact arm ||2 carried thereby engages the stationary contact assembly I |3, thereby connecting the center fuse device into the circuit.

When the blown fuse link in the fuse device which has operated has been replaced and the fuse device restored to service, the transfer switch should be operated in a reverse manner in order to disconnect the next fuse device from the circuit. This is accomplished automatically by the provision of an arm IIS on the other end of the switch arm or blade |09 also in the path of movement of the fuse tube 22. When the fuse tube 22 is operated to the circuit closed position, it engages the arm ||6 and carries with it the switch arm or switch blade |09. As a result, the contact engaging member ||2 is moved out of engagement with the stationary contact assembly I| 3.

As shown in Figure 16 of the drawings, the switch arm or blade |09 is provided with an eye IIl to permit operation by means of a switch stick. When the prong of the switch stick is inserted in the eye II'I, the switch arm or blade |09 can be moved, provided such movement is not prevented by the fuse tube associated therewith.

As illustrated in Figure 17 of the drawings, the

contact arm ||2 of the switch arm or blade |09 is provided with a generally cylindrical contact engaging portion |I8 for intertting between the inturncd ends II9 of a generally U-shaped bifurcated straplike contact member |20. The ends ||9 are urged inwardly by means of a generally U-shaped spring member |2I. Portions of the contact member |20 are ared outwardly as indicated at |22 in order to facilitate the entry of the contact engaging member |I8. The contact member |20 and its associated spring I2| are mounted in a downwardly opening housing |23 by means of screws |24 which project therethrough and through a suitable plate |25 that is secured to the members |20 and |2| by means of a rivet |26.

It is desirable that the switch arm or blade |09 remain in any position to which it is operated. This is accomplished by mounting it on the stud I I0 in such manner as to provide a predetermined amount of friction therebetween. As shown in Figure 18 of the drawings, the stud ||0 may be knurled at one end and secured in the bracket III by a press fit. The knurling is indicated at |28. The stud 0 is provided with a flanged portion having a generally conical suriace |29 for engagement by a correspondingly shaped surface -on the switch arm or blade |09. These conical surfaces arc urged into mutual engagement by means of a coil compression spring |30 which surrounds the stud I l0, as shown, and is held in position by means of a' washer |3I that is restrained by a nut |33. The nut |33 is provided with a conical surface |34 for engaging a correspondingly shaped surface on the washer |3I. This construction not only provides a definite frictional force for holding the switch arm or blade |09 in any position to which it may be operated, but also it permits adjustment of the friction by Ichanging the position of the nut, |33, as will be readily understood.

Since certain further changes can be made in the foregoing constructions, and different embodiments of t-he invention can be made without departing from the scope thereof, it is intended that all matter shown in the accompanying -drawings or described hereinbefore shall be interpreted as illustrative and not in a limiting sense.

What is claimed as new is:

l. A circuit interrupter comprising, in combination, a fuse tube adapted to receive a fuse link, means for tensioning the fuse link, means for holding the fuse link in operative relation to the link tensioning means with little or no application of tension to the fuse link, and means for stressing said link tensioning means to tension the fuse link.

2. A circuit interrupter comprising, in combination, a fuse tube adapted to receive a fuse link, link tensioning means movable through a predetermined extent for tensioning the fuse link, means for holding the fuse link in operative relation to said link tensioning means with little' or no tension being applied to the fuse link, and means for moving said link tensioning means through said predetermined extent to apply a predetermined tension to the fuse link.

3. A circuit interrupter comprising, in combination, terminal members and means for mounting the same in insulated spaced relation, a fuse tube having terminals for contact engagement with saidterminal members in the circuit closed position and adapted to receive a fuse link for interconnecting said terminals. means for pivotally supporting said fuse tube. means for tensioning the fuse link, means for holding the fuse link in operative relation tothe link tensioning means with little or no application of tension to the fuse link, and means operative on movement of said fuse tube to the circuit closed position for stressing said link tensioning means to tension the fuse link.

4. A circuit interrupter comprising, in combination, terminal members and means for mounting the same in insulated spaced relation, a, fuse tube having terminals for contact engagement with said terminal members in the circuit closed position and adapted to receive a fuse link for interconnecting said terminals, means for pivotally supporting said fuse tube, link tensioning means movable through a predetermined extent for .tensioning the fuse link, means for holding the fuse link in operative relation to said link tensioning means with little or no tension bein-g applied to the fuse link, and means loperative on pivotal movement of said fuse tube to the circuit closed position for moving said link tensioning means through said predetermined extent to apply a predetermined tension to the fuse link.

5. A circuit interrupter comprising, in cornbination, a fuse tube adapted to receive a iuse link, a pair of vrelatively movable members carried by said fuse tube and biased for movement toward each other, means for holding t-he fuse link in operative relation to one of said movable members under little or no tension, and means for relatively moving said movable members apart for placing the same under stress and tensioning the fuse link.

6. A circuit interrupter comprising, in combination, terminal members and means for mounting the same in insulated spaced relation, a fuse tube having terminals for contact engagement with said terminal members in the circuit closed position and adapted to receive a fuse link for interconnecting said terminals, means for pivotally supporting said inse tube, a pair of relatively movable members carried by said fuse tube and biased for movement toward each other, means for holding the fuse link in operative relation to one of said movable members under little or no tension, and means operative on pivotal movement of said fuse tube to the circuit closed position for relatively moving said movable members apart to place the same under stress and thereby tension the fuse link.

'7. A circuit interrupter comprising, in combination, a fuse tube adapted to receive a fuse link, a pair of members coaxially pivotally mounted on said fuse tube over which the fuse link is disposed to be placed, spring means biasing said members toward each other, means for holding the fuse link in operative relation to one of said members under little or no tension, and means for relatively movingsaid members apart to stress said spring means and thereby tension the fuse link.

8. A circuit interrupter comprising, in combination, terminal members and means for mounting the same in insulated spaced relation, a fuse tube having terminals for contact engagement with said terminal members in the circuit closed position and adapted to receive a fuse link for interconnecting said terminals, means for pivotally supporting said fuse tube, a pair of members coaxially pivotally mounted on said fuse tube over which the fuse link is disposed to be placed, spring means biasing said members toward each other, means for holding the fuse link in operative relation to one of said members under little or no tension, and means operative on pivotal movement of said fuse tube to the circuit closed position for relatively moving said members apart to cock said spring means and thereby tension the fuse link.

9. A circuit interrupter comprising, in combination, upper and lower line terminals and means for mounting the same in insulated spaced relation, latch means associated with said upper line terminal, support means associatedwith said lower line terminal, a fuse tube having terminals at its ends for engaging said line terminals and adapted to receive a fuse link for interconnecting the fuse tube terminals, toggle means pivoted on said support means and on said fuse tube and adapted to be held rigid therewith as long as the fuse link remains intact and swingable therewith to the circuit closed position where said fuse tube is held by said latch means, and means restrained by the fuse link and released on blowing of the same for striking said toggle means to insure breaking of the toggle and disengagement of said fuse tube from said latch means.

10. A circuit interrupter comprising, in combination, upper and lower line terminals and means for mounting the same in insulated spaced relation, latch means associated with said upper line terminal, support means associated with said lower line terminal, a fuse tube having terminals at its ends for engaging said line terminals and adapted to receive a fuse link for interconnecting the fuse tube terminals, toggle means pivoted on said support means and on said fuse tube and adapted to be held rigid therewith as long as the fuse link remains intact and swingable therewith to the circuit closed position where said fuse tube is held by. said latch means which exerts a downward thrust thereon, the locations of the two pivot axes o said toggle means in the circuit closed position with respect to the direction of downward thrust of said latch means being such that the toggle means is slightly over-center or locked, and'means restrained by the fuse link and released on blowing of the same for impacting said toggle means to move the same from the over-center or locked position and lower said :fuse tube out oi engagement with said latch means.

ll. A circuit interrupter comprising, in combination, upper and lower line terminals and means for mounting the same in insulated spaced relation, latch means associated with said upper line terminal, support means associated with said lower line terminal, a fuse tube having terminals at its ends for engaging said line terminals and adapted to receive a fuse link for interconnecting the fuse tube terminals, a toggle member pivoted on said support means and on said fuse tube and adapted to be held rigid therewith as long as the fuse link remains intact and swingable therewith to the circuit closed position where said fuse tube is held by said latch means, an

/ operating member and a fuse link extracting member pivotally mounted on said toggle member and biased toward each other by spring means, said fuse link extracting member being initially operatively associated with the fuse link and applying thereto little or no tension, and means for arresting movement of said operating member while said fuse tube is being moved to the circuit closed position and said fuse link extracting member is held by the fuse link substantially stationary with respect to said fuse tube whereby said spring means is stressed and the fuse link is tensioned in an amount depending upon the relative movement apart of said fuse link extracting and operating members during' the circuit closing operation, said fuse link extracting member being released on blowing of the fuse link and withdrawing a portion of the same from said fuse tube and impacting said toggle member to insure breaking of the toggle and disengagement of said fuse tube from said latch means.

12. A circuit interrupter comprising, in coinbination, terminal members and means for mounting the same in insulated spaced relation, a fuse tube having terminals for contact engagement with said terminal members in the circuit closed position and adapted to receive a fuse link for interconnecting said terminals, means for pivotally supporting said fuse tube, a fuse link extracting member and an operating member ccaxially pivotally mounted on said fuse tube about its pivotal axis, spring means biasing said members towardeach other, means for holding the fuse link in operative relation to said fuse link extracting member under little or no tension, and means for arresting the movement of said operating member on movement of said'fuse tube to the circuit closed position whereby said spring means is stressed and the fuse link is tensioned in an amount depending upon the relative movement apart of said fuse link extracting and operating members during the circuit closing operation.

13. A circuit interrupter comprising, .in combination, upper and lower terminals and means for mounting the same in insulated spaced relation, a fuse tube having terminals at its ends for contact engagement with said upper and lower terminals and adapted to receive a fuse link for interconnecting the fuse tube terminals, means pivotally mounting said fuse tube on said lower terminal, a fuse link extracting member and an operating member coaxially pivotally mounted on said fuse tube about its pivotal axis on said lower terminal, spring means biasing said members toward each other, means for holding thefuse link in operative relation to said fuse link extracting member` initially under little or no tension, and means on said lower terminal for arresting the movement of said operating member while said fuse tube is being moved to the circuit closed position and said fuse link extracting member remains substantially stationary with respect to said fuse tube whereby said spring means is stressed and the fuse link is tensioned 'in an amount depending upon the relative movement apart of said fuse link extracting and operating members during the circuit closing operation, said fuse link extracting member being released on blowing of the fuse link and withdrawing a portion of the same from said fuse tube in its movement under the iniiuence'of said spring means toward said operating member.

14. A circuit interrupter comprising, in combination, upper and lower line terminals and means for mounting the same in insulated spaced relation, a fuse tube having upper and lower terminals at its ends for contact engagement with said line terminalsl and adapted to receive a -fuse link for interconnecting the fuse tube terminals, a toggle member pivotally mounted on said fuse tube at its lower end and also pivotally mounted on said lower line terminal, a fuse link extracting member and an operating member pivotally mounted on said toggle member, spring means biasing said fuse link extracting and operating members toward each other, means on said toggle member for holding the fuse link in operative relation to said fuse link extracting member initially under little or no tension, and stop means on said lower line terminal for arresting movement of said operating member while said fuse tube is being moved to the circuit closed position and said fuse link extracting member is held by the fuse link substantially stationary with respect to said fuse tube whereby said spring means is stressed and the fuse link is tensioned in an amount depending upon the relative movement apart of said fuse link extracting and operating members during the circuit closing operation, said fuse link extracting member being released on blowing of the fuse link and withdrawing a portion of the same from said fuse tube in its movement under the iniiuence of said springmeans toward said operating member.

l5. A circuit interruptor comprising, in combination, upper and lower line Vterminals and means lfor mounting the same in insulated spaced relation, latch means associated with said upper line terminal, -a fuse tube having terminals at its ends for engaging said line terminals and adapted to receive a fuse link for interconnecting the fuse tube terminals, a toggle member pivotally mounted on said lower line terminal and pivotally connected to said fuse tube and adapted to be held rigid therewith as long as the fuse link remains intact and swingable therewith to the circuit closed position where said fuse tube is held by said latch means, and means carried lby said fuse tube for tensioning the fuse link as a result of movement of'said fuse tube to the circuit closed position, the tension imposed onfuse tube terminal -to said lower line terminal to provide pressure contact engagement therebe' tween.

18. A circuit interrupter comprising, in combination, upper and lower line terminals and means for mounting the same in insulated spaced relation, latch means associated with said upper line terminal, a iuse tube having terminals .at its ends for engaging said line terminals and adapted to receive a fuse link for interconnecting the fuse tube terminals, said lower line terminal having generally U-shaped upwardly opening terminal receiving means, a toggle member pivotally and detachablymounted in said terminal receiving means and pivotally-connected to said fuse tube and adapted to be held rigid therewith as long as the fuse link remains intact and swingable therewith to the circuit closed position where said fuse tube is held by said latch means, and means carried by said fuse tube for tensioning the fuse link as a result of movement of said fuse tube to the circuit closed position, the tension imposed on the fuse link being transmitted through said toggle member to the inner surface of said U-shaped terminal receiving means to provide pressure contact engagement therebetween.

17. A circuit interrupter comprising, in combination, a pair oi line terminals and means i'or mounting the same in insulated spaced relation, a fuse tube having terminals at its ends for engaging said line terminals and adapted to receive a fuse link for interconnecting the fuse tube terminals, a pair of relatively movable members carried by said fuse tube and biased for movement toward each other, means for holding the fuse link in operative relation to one of said movable members under little or no tension, means for pivotally mounting said fuse tube relative to said line terminals, and means cooperating with the other of said pair of relatively movable members for arresting movement of the same while said fuse tube is being swung into circuit closed position whereby the fuse link is tensloned.

18. A circuit interrupter comprising, in combination, upper and lower line terminals and means for mounting the same in insulated spaced relation, a fuse tube having terminals at its ends for engaging said line terminals and adapted to 'receive a fuse link for interconnecting the fuse tube terminals, said lower line terminal having a pair of generally U-shaped upwardly opening terminal receiving portions, a toggle member having a pair of trunnions for positioning in said terminal receiving portions and pivotally connected to said fuse tubev and adapted to be held rigid therewith by the fuse link being connected thereto, an operating member and a fuse link extracting member pivotally mounted on said toggle member, spring means biasing said operating and extracting members toward each other, said fuse link extracting member being initially operatively associated with the vfuse link and applying thereto little or no tension, and stop means on said lower line terminal positioned in the path of said operating member for arresting movement of the same while said fuse tube is being moved to the circuit closed position and said fuse link extracting member is held stationary with respect to said fuse tube whereby said spring means is stressed and the fuse link is tensioned, the stress of said spring means being transmitted through said trunnions to the inner surfaces of said U-shaped terminal receiving portions to provide pressure contact engagement therebetween.

19. A circuit interrupter comprising, in combination, upper and lower line terminals and means for mounting the same in insulated spaced relation, latch means associated with said upper line terminal, a fuse tube having terminals at its ends for engaging said line terminals and adapted to receive a fuse link for interconnecting the fuse tube terminals, said lower line terminal having generally U-shaped' upwardly opening terminal receiving means, a toggle member pivotally and detachably mounted in said terminal receiving means and pivotally connected to said fuse tube and adapted to be held rigid therewith as long aS the fuse link remains intact and swingable therewith to the circuit closed position where said fuse tube is held by said latch means, means carried '60 by'said fuse tube for tensioning the fuse link vas a result of movement of said fuse tube to the circuit closed position, the tension imposed on the fuse link being transmitted through said toggle member to the inner surface of said U-shaped terminal receiving means to provide pressure Contact engagement therebetween, resilient means cooperating with said upper line terminal and urging said fuse tube downwardly, the recoil of said fuse tube on blowing or the fuse link therein causing the fuse tube to move upwardly against the biasing force of said resilient means'thereby providing a shock absorber action, and means limiting the upward movement of said fuse tube due to said recoil.

20. A circuit interrupter comprising, in combination, upper and lower line terminals and means for mounting the same in insulated spaced relation, a fuse tube having terminals at its ends for engaging said line terminals and adapted to receive a fuse link for interconnecting the fuse tube terminals, said lower line terminal having a pair of generally U-shaped upwardly opening terminal receiving portions, a toggle member having a pair of trunnions for positioning in said terminal receiving portions and pivotally connected to said fuse tube and adapted to be held rigid therewith by the fuse link being connected thereto, an operating member and a fuse link extracting member pivotally mounted on said toggle member, spring means biasing said operating and extracting members toward each other, said fuse link extracting member being initially operatively associated with the fuse link and applying thereto little or no tension, stop means on said lower line terminal positioned in the path of said operating member for arresting movement of the same while said fuse tube is being moved to the circuit closed position and said fuse link extracting member is held stationary with respect to said fuse tube whereby said spring means is stressed and the fuse link is tensioned, the stress of said spring means being transmitted through said trunnions to the inner surfaces of said U-shaped terminal receiving portions to provide pressure Contact engagement therebetween, resilient means cooperating with said upper line terminal and urging said fuse tube downwardly, the recoil of said fuse tube on blowing of the fuse link therein causing the fuse tube to move upwardly against the biasing force of said resilient means thereby providing a shock absorber action, and means limiting the upward movement of said fuse tube due'to said recoil. i

21. A circuit interrupter comprising, in combination, upper and lower line terminals and means for mounting the same in insulated spaced relation, a fuse tube having upper and lower a toggle member pivotally mounted on said fuse said lower line terminal for arresting movementr of said operating member while said fuse tube is being moved to the circuit closed position and said fuse link extracting member is held by the fuse link substantially stationary with respect to said fuse tube whereby said spring means is stressed and the fuse link is tensioned in an amount depending upon the relative movement apart of said fuse link extracting and operating members during the circuit closing operation, said fuse link extracting member being released on blowing of the fuse link and withdrawing a portion of the same from said fuse tube in its movement under the influence of said spring means toward said operating member, and means on said toggle member in the path of said fuse link extracting member and adapted to be struck thereby when it is released on blowing of the fuse link prior to engagement with said operating member for breaking the toggle by positively initiating rotation of said toggle member.

22. A circuit interrupter comprising, in oombination, upper and lower line terminals and means for mounting the same in insulated spaced relation, a fuse tube having terminals at its ends for engaging said line terminals and adapted'to receive a fuse link for interconnecting the fuse tube terminals, said lower line terminal having a pair of generally U-shaped upwardly opening terminal receiving portions, a toggle member having a pair of trunnions for positioning in said terminal receiving portions and pvotally connected to said fuse tube and adapted to be held rigid therewith by the fuse link being connected thereto, an operating member and a fuse link extracting member pivotaliy mounted on said toggle member, spring means biasing said operating and extracting members toward each other, said fuse link extracting member being initially operatively associated with the fuse link and applying thereto little or no tension, and stop means on said lower line terminal located in the path of said operating member in such position as to arrest movement of the same while said fuse tube is being moved to the circuit closed position and said fuse link extracting member is heid stationary with respect to said fuse tube so that the reaction to the stressing of said spring means resulting from the movement apart of said operating and extracting members is transmitted through said trunnions in a substantially horizontal plane against the rear inner surfaces of said U-shaped terminal receiving portions. v

23. A circuit interrupter comprising, in combination, upper and lower line terminals and means for mounting the same in insulated spaced'relation, a fuse device for interconnecting said terminals and means for pivotally mounting the same at its lower end, a sleet hood pivotally mounted on said upper line terminal and arranged to latch said fuse device in circuit closed position, a flange depending from said sleet hood having an aperture, and a stop extending from said upper terminal into said aperture for limiting the up and down movement of said sleet hood.

SIGURD I. LINDELL. ANTHONY VAN RYAN.

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2493432 *Dec 7, 1944Jan 3, 1950Joslyn Mfg And Supply CompanyFused cutout
US2519078 *Nov 6, 1943Aug 15, 1950Mcgraw Electric CoFuse construction
US2553098 *Oct 29, 1948May 15, 1951S & C Electric CoDropout fuse construction
US2574400 *Aug 1, 1947Nov 6, 1951Gen ElectricElectric switch
US2745923 *Jul 14, 1953May 15, 1956S & C Electric CoFuse construction
US2843704 *Mar 9, 1955Jul 15, 1958Ite Circuit Breaker LtdLoad break cut-out
US2862080 *Nov 19, 1956Nov 25, 1958Joslyn Mfg & Supply CoFused cutout with knee joint
US3002070 *Sep 1, 1960Sep 26, 1961Mc Graw Edison CoFuse cutout
US3447114 *Aug 24, 1967May 27, 1969Westinghouse Electric CorpDropout fuse structure
US3501731 *Aug 24, 1967Mar 17, 1970Westinghouse Electric CorpHigh voltage circuit interrupter
US4326184 *Aug 4, 1980Apr 20, 1982Kearney-National Inc.Electric cutout
Classifications
U.S. Classification337/176, 337/180
International ClassificationH01H31/12, H01H31/00
Cooperative ClassificationH01H31/127
European ClassificationH01H31/12B2