US2816979A - High voltage circuit interrupter - Google Patents

Description

s. l. LINDELL HIGH VOLTAGE CIRCUIT INTERRUPTER 3 Sheets-Sheet 1 Filed June 11, 1954 livr/Emol@ .grdflazde BY S. l. LINDELL HIGH VOLTAGE CIRCUIT INTRRUPTER Dec. 17, 1957 Fviled Julie 11, 1954 3 Sheets-Sheet 2 IN VEN TOR. ma l Lzd INVENTOR.

Dec, 17, 1957 s. l. LINDELL HIGH VOLTAGE CIRCUIT INTERRUPTER- Filed June 11, 1954 United States Patent O HIGH VOLTAGE CIRCUIT INTERRUPTER Sigurd I. Lindell, Chicago, Ill., assignor to S & C Electric Company, Chicago, Ill., a corporation of Delaware Application June 11, 1954, Serial No. 436,095

11 Claims. (C1. 200--114) This invention relates, generally, to high voltage circuit interrupters and it has particular relation to dropout fuses for use on circuits ranging from 4 kv., 14.4 kv., 23 kv., 34.5 kv. and upwardly to 115 kv. It constitutes au improvement over the invention disclosed in copending application Serial No. 367,801, led July 14, 1953, and assigned to the assignee of this application, now Patent No. 2,745,923, issued May 15, 1956.

The fuse construction disclosed in this copending application is primarily intended for use on circuits operating at 4 kv. to 14.4 kv. using various makes of fuse links. That fuse construction has suicient interrupting capacity for many installations. However, it is desirable to increase the interrupting capacity of that fuse construction in order to clear circuits where the maximum short circuit current is likely to exceed that for which the prior device was designed.

When the circuit to which the fuse is applied is energized at a voltage above 14.4 kv., the line terminals are correspondingly spaced further apart aud the fuse tube for connecting them is accordingly increased in length. This increase in fuse tube length is not necessarily required for circuit interruption and actually may interfere with optimum current interrupting ability under certain operating conditions. Because of this increase in fuse tube length, difiiculty may be encountered in withdrawing and controlling the exible lead attached to the lower terminal of the fuse link when it blows under predetermined overload conditions. Under severe short circuit conditions the pressure generated in the fuse tube may rupture it due to needless length of the arc beyond the arc length required to withstand the recovery voltage. After circuit interruption, the required disconnect gap must be provided Vand the proper striking distance must be retained in order to maintain safe operating conditions.

Tests have demonstrated that maximum interrupting capacity of a given device of the character disclosed in the above copending application can be increased substantially by reducing the arc length to an optimum length which is less than the length of the fuse tube. When operating at voltages above 14.4 kv. diiculty may be encountered in interrupting low fault currents such `as may occur in a fuse connected in the circuit to the primary winding of a transformer when there is a fault in the circuit connected to its secondary winding. For such higher voltage circuits the arcing time is longer than is the case for -circuits of lower voltage.

Accordingly, among the objects of this invention are: To provide in a dropout fuse of the type that is latched at the top and pivotally mounted at the bottom and there held by a fuse link against unlatching movement for positioning the fuse link, and particularly the portion that blows, remote from the upper end of the fuse tube; to rapidly mechanically withdraw the llexible lead of a fuse link so positioned thereby reducing the arcing time to a `few cycles yand the arc length in the fuse tube;

2,816,979 Patented Dec. 17, 1957 ice to employ a rigid conductor or a spring and cable assembly extending into the fuse tube from its upper terminal to position the fuse link remotely therefrom and to initiate the arc incident to blowing of the fuse link close to the exhaust end of the fuse tube and in conjunction therewith to provide for eiiecting rapid separation of the fuse link terminals and positive movement of one of them out of the exhaust end of the fuse tube in order to achieve etiective interruption of low current arcs; to clamp the 'button head of a replaceable fuse link by rigid conductor means or a stud at a position remote from the upper fuse tube terminal; to distribute electrostatic stress originating from the fuse tube terminals and avoid puncturing of the fuse tube and external ilashover as the result of subjecting it or the external air to voltage greater than they are capable of withstanding; and to provide improved guide means on the upper line terminal for directing the upper end of the fuse tube into engagement with the upper line terminal and `at the same time providing for attachment thereto of a load interrupter tool.

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

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 exemplied in the constructions hereinafter set forth land 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 can be had to the following detailed description, taken together with the accompanying drawings, in which:

Figure l is a view, partly in side elevation and partly in section showing a fuse construction of the type illustrated in the application above referred to modified to achieve higher interrupting capacity and for `application to circuits operating at higher voltages;

Figures 2A and 2B, taken together with the former being placed above the latter, show a longitudinal crosssectional view of the fuse tube and related parts modied in accordance with this invention;

Figure 3 is a bottom plan view of the guide bracket that is employed for insuring that the fuse tube is swung to the closed position and permitting the application of a load interrupter tool;

Figures 4A and 4B, taken together with the former positioned above the latter, show a construction which is a modication of that illustrated in Figures 2A and 2B; and

Figure 5 is a vertical sectional view of the upper portion of a still further modified construction for the fuse tube to adapt it for use with universal button head fuse links or high voltage circuits and to increase its interrupting capacity.

Referring now particularly to Figure 1 of the drawings it will be observed that the reference character 10 designates a channel base at the ends of which insulators 11 and 12 are mounted. It will be understood that the size and number of the insulators 11 and 12 are determined by the voltage of the circuit in which the device herein disclosed is connected and that their spacing apart also is determined by the disconnecting gap and the insulation level associated with the circuit voltage. The insulators 11 and 12 carry upper and lower terminal brackets 13 and 14 in the form of L-shaped members and they, in turn, carry upper and lower line terminals 15 and 16.

The upper line terminal 15 includes an L-shaped terminal pad provided with a split bolt connector 20 for 3 attachment to a line conductor. rl`he terminal pad 19 is secured by a bolt 21 to one arm of the upper terminal bracket 13 and also is secured by this bolt to a recoil bar 22. Clamped between the terminal pad 19 and the recoil bar 22 by the bolt 21 is one end of a top Contact strip 23. A bolt 24 extending through the recoil bar 22 and the horizontal arm of the bracket 13 holds the assembly in predetermined relation to the insulator 11.

The bolt 21 also extends through one arm 25 of an L-shaped metallic bracket 26 which has a depending vertical arm 27 that carries a generally U-shaped bracket, shown more clearly in Figure 3 of the drawings. Here it will be noted that the bottom or central portion 29 of the bracket 2S is secured by rivets 30 to the arm 27. Also the bracket 2S is arranged with the ends 32 of the arms 31 flared outwardly for receiving therebetween an upper fuse tube terminal 33 mounted on the upper end of a fuse tube that is shown, generally7 at 34. The outflared ends 32 serve to guide the upper fuse tube ter minal 33 into the closed position when the fuse tube 34 is swung upwardly from the open circuit position. The combination of the Lshaped bracket 26 and the U- shaped bracket 23 provides a generally Zshaped conducting member with one end portion or arm 25 rigidly secured to the upper line terminal 15, the intermediate portion or arm 27 extending downwardly along the fuse tube 34 and the other end portion or bracket 28 extending outwardly past the upper fuse tube terminal 33. In addition the outflared ends 32 of the arms 31 provide means for receiving one terminal of an auxiliary circuit interrupter such as disclosed in the copending application Ser. No. 412,182, filed February 24, 1954, and assigned to the assignee of this application. As there pointed out the auxiliary circuit interrupter can be positioned to shunt the upper line terminal l and the upper fuse tube terminal 33 for the purpose of permitting them to be separated without arcing when it is ldesired to open the circuit and swing the fuse tube 34 to the open circuit position at a time when load current is llowing.

As pointed out hereinbefore the length of the fuse tube 34 and the spacing of the insulators 11 and 12 depends upon the voltage of the circuit with which the device is intended to operate. For example, if the circuit is to be energized at a voltage of 34.5 kv., the overall length of the fuse tube 34 and the upper fuse tube terminal 33 is of the order of 231/2 inches.

As shown more clearly in Figure 2A of the drawings the upper fuse tube terminal 33 includes a brass ferrule 37 which is secured to the upper end of the fuse tube 34. Formed integrally with the ferrule 37 is an arm 38 which carries eye 39 for receiving a prong of a switch stick or a part of the auxiliary circuit interrupter, previously referred to, for manipulating the fuse tube 34. The ferrule 37 has a threaded head 40 on which a cap 41 is screwed. The cap 41 has a convex head 42 with which latch means, shown generally at 43 in Figure l, cooperates. The latch means 43 forms a part of the upper line terminal and includes a U-shaped top contact 44 the upper end of which is secured by rivets 45 to the forward end of the top contact strip 23. The other end of the contact 44 is provided with a conical seat 46 for overlying the contact head 42 on the cap 41. The conical seat 46 is urged into latching engagement with the convex head 42 when the fuse tube is swung to the closed position shown in Figure 1 by a coil compression spring 47 which is positioned between the underside of the recoil bar 22 and the upper side of the conical seat 46. A contact stud 43 interconnects the upper end of the contact 44 with the lower end where the conical seat 46 is located and it extends through a hollow bushing 49 in the recoil bar 22 that is held in position thereon by a lock nut 50. The details of construction of the upper line terminal 15 are set forth 4 more completely in application Ser. No. 367,801, now Patent No. 2,745,923, issued May 15, 1956, above referred to.

At its lower end the fuse tube 34 is provided with a lower fuse tube terminal as is shown, generally, at 54. This terminal includes a brass ferrule having rearwardly extending arms 56 through which a hinge pin 57 projects for rockably mounting a toggle member 53. The toggle member 58 has oppositely extending trunnions 59 which are positioned in the lower ends of upwardly opening slots 641 in a hinge casting 61 that is secured by bolts 62 and 63 to a horizontal arm of the lower terminal bracket 14. A split bolt connector 64 extends rearwardly from the hinge casting 61 for rcceiving a line conductor. The toggle member 5S has a earn portion 65 against which an auxiliary contact 66 bears, backed up by an auxiliary contact spring 67. The latter biases the toggle member 58 forwardly so that the trunnions 59 interfit with notches 68 at the lower ends of the forward arms of the hinge casting 61 that define the slots 60.

Extending through the trunnions S9 is a shaft 71 on which a flipper 72 is rockably mounted. The flipper 72 is biased by a spring 73 to withdraw a flexible lead 74 which forms a part of a replaceable fuse link, shown generally at "/'5 in Figure 2B of the drawings. The fuse link 75 preferably is constructed as disclosed in Mc- Mahon Patent No. 2,586,171, issued February 19, 1952. However, it will be understood that other fuse links can be employed. For a more complete understanding of the details of construction of the lower fuse tube terminal 54 and how it cooperates with the hinge casting 16 reference can be had to the copending application Ser. No. 367,801, iled July 14, 1953, now Patent No. 2,745,923, issued May 15, 1956, above referred to.

The fuse link 7S includes an upper fuse link terminal 76 which has a threaded stud portion 77. The terminal 76 is connected by a strain wire 78 and a helical fusible element 79 to a lower fuse link terminal Si?. An in sulating sleeve 81, preferably constructed as disclosed in the McMahon patent, is secured to the upper fuse link terminal 76 and extends downwardly over the strain wire 78, helical fusible element 79 and the lower fuse link terminal 80. It will be observed that the flexible lead 74 is secured to the lower fuse link terminal Sti and that it extends downwardly out of the open lower end of the sleeve 81 and out of the open lower end of the fuse tube 34.

As pointed out hereinbefore when the length of the fuse tube 34 is made sufficient for the disconnect distance at any voltage rating from 14.4 kv. up, it is undesirable to place the fuse link 75 at the extreme upper end. If this is done, then it is necessary to increase the length of the liexible lead 74 and difficulty is encountered in controlling and withdrawing such a long length of flexible lead from the fuse tube 34 by the spring operated flipper 72. The arc length is needlessly increased with a corresponding increase in pressure generated when high currents are interrupted. ln accordance with this invention provision is made for positioning the fuse link 75 remote from the upper fuse tube terminal 33 and nearer the lower open end or exhaust end of the fuse tube 34. For this purpose a rigid conductor in the form of a silver plated copper rod 83 can be used. For the 34.5 kv. fuse, the conductor 33 has a length of 5% inches. The conductor S3 has a flanged head 84 which can be clamped between the upper end of the threaded head 4@ and the underside of thc cap 41. The lower end of the conductor 33 is provided with a threaded socket 85 for receiving the threaded stud portion 77 of the upper fuse link terminal 76. This construction then positions the strain wire 73 and the helical fusible element 79 much closer to the lower open end of the fuse tube 34, thereby requiring a corresponding smaller length of tlexible lead 74 to be expelled from the exhaust end of the fuse tube 34 when the fuse link 75 blows and limiting the length of the gas generating arc and the resulting pressure when high currents are interrupted.

It is important to proportion properly the wall thickness of the fuse tube 34. As shown in Figure 2B, the fuse tube 34 is made up of a composite tube with the outer layer 88 being formed of a phenolic condensation product while the lining 89 is formed of fibre. The thickness of the outer layer 88 and lining 89 is chosen so that at the voltage of the circuit for which the particular fuse tube 34 is designed, it will be capable of preventing dielectric puncture.

The position of the rigid conductor or rod 83 in the fuse tube 34 is shown by broken lines in Figure 1 of the drawings. It will be noted that its lower end is well below the eye 39 or any metallic part attached to the ferrule 37 and energized at the potential thereof. Thus, as long as the upper fuse tube terminal 33 remains in contact with the energized upper line terminal after the fuse link 75 has blown and the arc has been extinguished, the lines of electrostatic flux will emanate from the lower end of the rod 83 and the likelihood of restriking of the arc or flashover exterior to the fuse tube 34 will be reduced. The fuse tube 34 during this period provides a stationary arcing chamber within which the arc is drawn and extinguished. If the arc is restruck, the same will more likely occur within the fuse tube 34 where it can be more readily extinguished.

lWith a view to limiting the arc length and distributing electrostatic stress applied to the lower fuse tube terminal 54 after the fuse link 75 blows and before the fuse tube 34 drops to the open circuit position, a metallic dielectric stress distribution shield or terminal extension 90 may be located at the lower end of the fuse tube 34. This shield or terminal extension 90 preferably is in the form of a metallic tube and it extends upwardly from the lower open end of the fuse tube 34 so that it is positioned, as Shown in Figure l of the drawings, well above any metallic part that is connected to the lower fuse tube terminal 54. The lower portion 91 extends radially outwardly over the lower end of the fuse tube 34 and there is a turned up end 92 which overlies a reduced portion 93 along the lower edge of the brass ferrule 55. In this manner the metallic dielectric stress distribution shield or terminal extension 90 is permanently connected to the brass ferrule 55 and thus serves to distribute the electrostatic stress applied there* to during the circuit opening operation in fuses of higher voltage rating.

When the fuse link 75 blows as the result of a predetermined overload or short circuit, the flipper 72 no longer is restrained by the ilexible lead 74. It swings downwardly under the influence of the spring 73 and, as described in application Ser. No. 367,801, tiled July 14, 1953, now Patent No. 2,745,923, issued May 15, 1956, withdraws the llexible lead 74 from the exhaust end of the fuse tube 34 and unlocks the toggle mechanism associated with the toggle member 58 which permits the fuse tube 34 to move downwardly and outwardly away from the latch means 43. Since the fuse link 75 is positioned by the conductor 83 away from the upper end of the fuse tube 34, there is a correspondingly lesser length of flexible lead 74 to withdraw than would be the case if it were positioned at the extreme upper end of the fuse tube 34.

As shown in Figures 4A and 4B the fuse link 75 can be positioned in the fuse tube 34 remote from the upper fuse tube terminal 33 and adjacent the exhaust or lower end by employing a spring and cable assembly that is shown, generally, at 96. The spring and cable assembly 96 includes a button head 97 which can be clamped between the threaded head 40 and the underside of the cap 4l. A

coil tension spring 98 and a ilexible conductor 99 serve to interconnect the button head 97 and a threaded iitting 100 into which the stud portion 77 of the fuse link 75 is screwed. In this embodiment of the invention, when the fuse link 75 blows, the flexible lead 74 not only is withdrawn from the lower open end of the fuse tube 34 but also the upper fuse link terminal 76 is withdrawn upwardly into the fuse tube 34. This rapid separation of the fuse link terminals 76 and 80 assists in extinguishing both low current and high current arcs that may be drawn therebetween and there is a minimum of metallic vapor expelled. Otherwise the functioning of the fuse employing the spring and cable assembly 96 is as described for the fuse employing the rigid conductor 83. The early and prompt build up of the arc voltage limits and reduces the direct current component in the fault current. By combining the actions of the spring and cable assembly 96 and of the spring actuated tlipper 72, these improved results are obtained and low and high current arcs are effectively drawn and extinguished with a minimum of circuit disturbance and erosion or damage to the fuse tube 34.

In Figure 5 of the drawings the fuse link 75 is shown with a button head 103 which is arranged to bear against a shoulder 104 at the lower end of a metallic sleeve 105. The sleeve 105 has a radial flange 106 at its upper end which overlies the threaded head 40. The lower end of the metallic sleeve 105 is threaded as indicated at 107 into the upper end of the libre lining S9. It is desirable to clamp the button head 103 against the shoulder 104. For this purpose a metallic plug 108 is inserted into the metallic sleeve 105 and bears against the upper end of the button head 103 as shown. The plug 108 has a ilanged head 109 which overlies the radial flange 106 and is clamped thereto by the cap 41. The operation of the fuse employing the construction shown in Figure 5 is the same as previously described for the operation of the fuse shown in Figures 1, 2A. and 2B of the drawings. It will be understood that the metallic sleeve 105 serves the same purpose as the rigid conductor S3 in making it possible to position the fuse link 75 remote from the upper fuse tube terminal 33 and relatively closer to the lower open end of the fuse tube 34. The lower end of the metallic sleeve 105 extends well below any other metallic part connected to the upper fuse tube terminal 33 for limiting the length of the arc drawn in the fuse tube 34 and to provide a conductor energized at the potential of the upper terminal for distributing electrostatic stress applied to the intermediate section of the fuse tube 34, as described previously, after the fuse link 75 has blown and the arc is being extinguished.

In the various embodiments of the invention, when a relatively low fault current is interrupted and maximum recovery voltage is encountered as in the interruption of current flow to the primary winding of a step down transformer on the occurrence of a secondary fault, after the fuse link 75 has blown and the arc has been extinguished and before the lower fuse link terminal 80 has been moved to a position below any energized metallic part connected to the low fuse tube terminal 54, the fuse link terminal 80 acts to distribute the electrostatic stress in the same manner that this stress is distributed by the shield of terminal extension 90. The reason for this is that the terminal 80 is connected by the llexible lead 74 to the lower fuse tube terminal 54 and thus is energized at its potential.

Through the use of this invention it is possible not only to increase substantially the interrupting capacity of the dropout fuse construction designed for operation at voltages in the 4 kv. to 14.4 kv. range but also it is possible to employ this dropout fuse construction on circuits energized at higher voltages, such as 23 kv., 34.5 kv. and kv., particularly when the fuse link 75 is constructed as disclosed in the McMahon patent, without being limited by the necessity of employing a longer fuse tube to take care of the increased spacing required by the higher voltage level. The are length is reduced, the arcing time is 7 reduced, the pressure incident to the evolution of arc extinguishing material is minimized, and the resulting electrostatic stress is so distributed as to require that any restriking that may occur will take place within the fuse tube 34.

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

What is claimed as new is:

l. A device for interrupting a high voltage electric power circuit on the blowing of a replaceable fuse link comprising, in combination, upper and lower line terminal members and means mounting the same in insulated spaced relation, a fuse tube for receiving the fuse link and having fuse tube terminals at its ends for connection to said line terminals, latch means on said upper line terminal cooperating with the upper fuse tube terminal to hold said fuse tube in the closed position, mounting means on the lower fuse tube terminal pivotally supporting the same on said lower line terminal and arranged to be restrained by the fuse link as long as it remains intact to hold said fuse tube in the closed position and to permit it to move downwardly and away from said latch means on blowing of the fuse link, conductor means connected to said upper fuse tube terminal and extending downwardly therefrom into said fuse tube for a distance several times the diameter thereof and below the lowermost part of said upper fuse tube terminal for detachable connection at its lower end to the upper end of the fuse link to position the portion thereof that is ruptured on blowing remote from the upper end of said fuse tube and relatively closer to its lower end, and conductor means permanently connected to said lower fuse tube terminal and extending upwardly therefrom into said fuse tube for a distance several times the diameter 'thereof and above the uppermost part of said lower fuse tube terminal and any metallic part connected thereto for distributing electrostatic stress after blowing 0f the fuse link and before said upper fuse tube terminal disengages said upper line terminal.

2. A device for interrupting a high voltage electric power circuit on the blowing of a replaceable fuse link comprising, in combination, upper and lower line terminal members and means mounting the same in insulated spaced relation, a fuse tube for receiving the fuse link and having fuse tube terminals at its lo\ er ends for connection to said line terminals, latch means on said upper line terminal cooperating with the upper fuse tube terminal to hold said fuse tube in the closed position, mounting means on the lower fuse tube terminal pivotally supporting the same on said lower line terminal including a flipper biased away from the lower end of said fuse tube and arranged to be restrained by the fuse link as long as it remains intact to hold said fuse tube in the closed position and to permit it to move downwardly and away from said latch means on blowing of the fuse link whereupon Said flipper withdraws the remaining portion of the fuse link from said lower end of said fuse tube, conductor means connected to said upper fuse tube terminal and extending downwardly therefrom into said fuse tube for a distance several times the diameter thereof and below the lowermost part of said upper fuse tube terminal for detachable connection at its lower end to the upper end of the fuse link to position the portion thereof that is ruptured on blowing remote from the upper end of said fuse tube and relatively closer to its lower end, and conductor means permanently connected to said lower fuse tube terminal and extending upwardly therefrom into said fuse tube for a distance several times the diameter thereof and above the uppermost part of said lower fuse tube terminal and any metallic part connected thereto for distributing .electrostatic stress after blowing of the fuse link 8 and before said upper fuse tube terminal disengages said upper line terminal.

3. A device for interrupting a high voltage electric power circuit on the blowing of a replaceable fuse link comprising, in combination, upper and lower line terminal members and means mounting the same in insulated spaced relation, a fuse tube for receiving the fuse link and having fuse tube terminals at its ends for connection to said line terminals, latch means on said upper line terminal cooper ting with the upper fuse tube terminal to hold said fuse tube in the closed position, mounting means on the lower fuse tube terminal pivotally supporting the same on said lower line terminal including a flipper biased away from the lower end of said fuse tube and arranged to be restrained by the fuse link as long as it remains intact to hold said fuse tube in the closed position and to permit it to move downwardly and away from said latch means on blowing of the fuse link whereupon said flipper withdraws the remaining portion of the fuse link from said lower end of said fuse tube, a rod-lite conductor connected to said upper fuse tube terminal and extending downwardly therefrom into said fuse tube for a distance several times the diameter thereof and below the lowermost part of said upper fuse tube terminal for etachable connection at its lower end to the upper end of the fuse link to position the portion thereof that is ruptured on blowing remote from the upper end of said fuse tube and relatively closer to its lower end, and conductor means permanently connected to said lower fuse tube terminal and extending upwardly therefrom into said fuse tube for a distance several times the diameter thereof and above the uppermost part of said lower fuse tube terminal and any metallic part connected thereto for distributing electrostatic stress after blowing of the fuse link and before said upper fuse tube terminal disengages said upper line terminal.

4. A device for interrupting a high voltage electric power circuit comprising, in combination, upper and lower line terminals and means mounting the same in insulated spaced relation, a fuse tube having terminals at its ends for connection to said line terminals with its lower end open and its upper end closed by the upper fuse tube terminal, latch means on said upper line terminal cooperating with said upper fuse tube terminal to hold said fuse tube in the closed position, mounting means on the lower fuse tube terminal pivotally supporting the fuse tube on said lower line terminal including a flipper biased away from the lower end of said fuse tube and holding said fuse tube in closed position and arranged to permit it to move downwardly and away from said latch means and to swing to open position, conductor means connected to said upper' fuse tube terminal and extending downwardly therefrom into said fuse tube, a replaceable fuse link having relatively infusible upper and lower terminals and a flexible lead the upper end of said lower fuse link terminal being located above the uppermost part of said lower fuse tube terminal and said llexible lead being connected thereto and extending out of the lower end of said fuse tube, said fuse tube providing an arcing chamber stationary relative to said fuse link, and means interconnectinfy said flipper and said other end of said flexible lead whereby the former is restrained by the latter as long as said fuse link remains intact and said flexible lead is withdrawn by said flipper when said fuse link blows, said upper fuse link terminal being detacbably connected to thc lower end of said conductor means in said relatively stationary arcing chamber in such position that the distance between its lower end and said lower fuse tube terminal is substantially less than the length of the bore of said fuse tube.

5. The invention as set forth in claim 4 wherein the conductor means connected to the upper fuse tube terminal is a rod-like conductor.

6. The invention as set forth in claim 4 wherein the conductor means connected to the upper fuse tube tcrminal is a spring and cable assembly which withdraws the upper fuse link terminal into the fuse tube when the fuse link blows.

7. The invention as set forth in claim 4 wherein the flipper is biased by a spring individual thereto.

8. A device for interrupting a high voltage electric power circuit on the blowing of a replaceable fuse link comprising, in combination, upper and lower line terminal members and means mounting the same in insulated spaced relation, a fuse tube for receiving the fuse link and having fuse tube terminals at its ends for connection to said line terminals, latch means on said upper line terminal cooperating with the upper fuse tube terminal to hold said fuse tube in the closed position, mounting means on the lower fuse tube terminal pivotally supporting the same on said lower line terminal including a flipper biased away from the lower end of said fuse tube, means for interconnecting said flipper and the fuse link whereby the former is restrained by the latter as long as it remains intact to hold said fuse tube in the closed position and to permit it to move downwardly and away from said latch means on blowing of the fuse link whereupon said ipper withdraws the remaining portion of the fuse link from said lower end of said fuse tube, said fuse tube providing an arcing chamber stationary relative to said fuse link, and a spring and cable assembly connected to said upper fuse tube terminal and extending downwardly therefrom into said fuse tube for a distance several times the diameter thereof and below the lowermost part of said upper fuse tube terminal for detachable connection at its lower end to the upper end of the fuse link in said relatively stationary arcing chamber to position the portion thereof that is ruptured on blowing remote from the upper end of said fuse tube and relatively closer to its lower end and for withdrawing the upper portion of the fuse link into said fuse tube when the fuse link blows.

9. The invention as set forth in claim 4 wherein the conductor means connected to the upper fuse tube terminal is a metallic sleeve having a radially inwardly extending shoulder at its lower end for receiving the button head of a fuse link.

10. The invention as set forth in claim 4 wherein the conductor means connected to the upper fuse tube terminal is a metallic sleeve having a radially inwardly extending shoulder at its lower end for receiving the button head of a fuse link, and a metallic plug extends into said metallic sleeve for bearing against the upper surface of said button head to clamp the same against said shoulder.

11. A high voltage circuit interrupter comprising, in combination, upper and lower line terminal members and means mounting the same in insulated spaced relation, a fuse tube having fuse tube terminals at its ends for connection to said line terminals, latch means on said upper line terminal cooperating with the upper fuse tube terminal to hold said fuse tube in the closed position, mounting means on the lower fuse tube terminal pivotally supporting the same on said lower line terminal and arranged to be restrained by a fuse link to hold said fuse tube in the closed position and to permit it to move downwardly and away from said latch means on blowing of the fuse link, conductor means connected to said upper fuse tube terminal and extending downwardly therefrom into said fuse tube for a distance several times the diameter thereof and below the lowermost part of said upper fuse tube terminal, a replaceable fuse link including upper and lower fuse link terminals interconnected by fusible means with the upper fuse link terminal connected to the lower end of said conductor means and the lower fuse link terminal connected by a exible conductor to said lower fuse tube terminal, said upper and lower fuse link terminals being disposed respectively below and above any other energized conducting part connected to said upper and lower fuse tube terminals whereby on blowing of said fusible means and extinction of the arc between said fuse link terminals the resulting electrostatic stress distribution is such as to require any restriking of the arc to occur within said fuse tube, and conductor means permanently connected to said lower fuse tube terminal and extending upwardly therefrom into said fuse tube for a distance several times the diameter thereof and above the uppermost part of said lower fuse tube terminal for distributing electrostatic stress after blowing of said fuse link and withdrawal of said lower fuse link terminal to a position below the upper end of said conductor means and before said upper fuse tube terminal disengages said upper line terminal.

References Cited in the file of this patent UNITED STATES PATENTS Re. 22,805 Schultz et al Oct. 15, 1946 2,247,701 Ramsey July 1, 1941 2,247,702 Ramsey July 1, 1941 2,272,717 Ludwig et al Feb. 10, 1942 2,331,843 Nelson et al Oct. 12, 1943 2,390,670 Steinmayer Dec. 11, 1945 2,398,469 Schultz et al Apr. 16, 1946 2,485,076 Timerman Oct. 18, 1949 2,521,155 Earle et al Sept. 5, 1950 2,549,635 Pittman Apr. 17, 1951 2,567,236 Rawlins et a1 Sept. 11, 1951 2,655,576 Milne et al. Oct. 13, 1953 2,672,539 Steinmayer Mar. 16, 1954 2,677,738 Schneider May 4, 1954 2,695,350 Schultz Nov. 23, 1954 fL709,736 Schneider May 31, 1955

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