US2305996A - Repeating fuse construction - Google Patents

Description

Dec- 22, 1942- w. o. scHuLTz E-rAL l 2,305,996

REPEATING FUSE CONSTRUCTION Filed May 25, 1940 '3 sheets-sheet 1 Dec. 22, 1942. w. o. scHULTz ET Al. 2,305,996 REPETING' FUSE CONSTRUCTION Filed May 25, 1940 3 Sheets-Sheet 2 A ORNE.

Dec. 22, 1942. w. o. SCHULTZ ET AL 2,305,996

REPEATING FUSE CONSTRUCTION Filed May 25, 1940 3 Sheets-SheerI 3 Patented Dsc. 22, 1942 UNITED STATES PATENT OFFICE 2.305.996 maniac rosa ooNs'rauc'rroN William 0. Schultz, South Milwaukee, and Alwin G. Stcinmayer, Milwaukee, Wis., mignon to Line Material Company, 'South Milwaukee, Wis.,

a corporation oi Delaware Application May z5, 1940, serial No. 337,195 14 claim. (c1. zoo- 126) This invention relates to a repeating fuse construction and is particularly directed to a construction in which a device is provided whichl recloses the circuit after the blowing oi' a fuse and connects a fresh or reserve fuse in vthe circuit, such device being capable of repeating as many times as the device is designed for.

The advantage of this automatic repeating fuse construction is that the device lends itself to transmission service and customers substation service. Frequently in theseservices short-circuits occur due to any one of many causes, such as a tree falling across alpair o1' lines, a pair of lines being whipped together by a wind, a fiashover, a temporary ground, or the branch of a tree which in a violent wind may be blown against the line. Under these and similar conditionsv it frequently happens that the trouble is only temporary and that it either' ceases of itself or the fault is burned out almost immediately.

This invention is designed to provide a device which will take care of conditions such as outlined above, which will electrically disconnect the blown fuse from the line, and after a predetermined brief interval immediately connect a reserve or fresh fuse in the line, such device providing for the successive operation of as many fuses as the device is equipped to handle, and to provide a device of this type in which the time delay interval is obtained by an automatic time delay device.

Further objects are to provide a construction in which the device is well suited for high voltage lines, in which each fuse as it blows drops downwardly and swings outwardly clear of the upper contact to thereby provide maximum spacing at the open portion of the circuit, and in which switch mechanism is provided for connecting the succeeding fuse, the switch mechanism being so constructed that when open a wide spacing is obtained between the contacts of the switch, and in which the switch closes with a quick iinal motion so that arcing even under heavy load conditions is minimized.

This invention provides for the renewal of a blo-wn fuse without interrupting the service, and objects of this invention are to provide a construction which permits the ready removal and refusing of the blown fuse, which permits the ready restoring of such refused fuse, and the automatic disconnecting of the next adjacent auxiliary or reserve fuse Without at any time interrupting the circuit during this restoring operation.

Further objects of this invention are to provide a construction in which no fuse has to be first mechanically moved into place before it is ready to operate upon the blowing of a preceding or iirst fuse, in which the auxiliary or reserve fuses although mechanically in place are never- .theless automatically electrically connected in service in succession as the preceding fuse or fuses blow.

Further objects are to provide a drop-out fuse construction of the repeating fuse type in which the several fuse units are so made that positive contact is maintained between the stationary contact of the housing and the contact carried by the fuse tube, which ultimately moves away from the stationary contact, such positive contact being maintained for an appreciable interval of time to insure complete clearing of the fuse tube prior to the breaking of the contact between one of the fuse tube contacts and one of the contacts carried by the housing, thus guarding against any possibility of arcing at this point.

Further objects are to provide for the quick withdrawal of the fuse link prior to the interruption of the circuit between the stationary contact and one of the contacts of the fuse tube so that the chance of arcing at this point is minimized, and in which means are provided which in addition to the action of gravity afford positive means for moving the fuse tube bodily out of service.

Further objects are to for repeating fuses in provide a construction which the blown fuse may be readily removed by a switch stick and may be readily replaced after refusing by such switch stick without requiring the lineman to handle any portion of the fuse structure while it is' connected to either side of the high tension circuit. Further objects are to provide a repeating fuse construction in which upper and lower stationary contacts are provided for the several fuses, in which the transfer switches for connecting successive fuses are located adjacent closed upper ends of the fuse tubes at a position remote from the open lower ends thereof so that the blast'from the open lower ends is at a zone far removed from the transfer switches and so that there is no chance of the whipping of any remaining portion of the fuse link into accidental damaging contact with another of the fuse devices.

Further objects are to provide a construction in which a simple type of mechanical escapement mechanism is provided for the time delay means, in -which the time delay means is housed and protected from sleet, rain and snow, vand in which o the accompanying drawings, in which:

Figure l1 is a side elevation, with parts sectioned on?, showing one of the fuse umts and the associated transfer switch mechanism, such view corresponding to a section on the line i'i of Figure 2.

Figure 2 is a face view of the device with one of the fuses removed..

Figure 3 is a sectional detail of the upper portion of one of the fuse constructions showing it while a refused fuse unit is being rocked back into place and just before it has been completely rocked back into place.

Figure 4 is a sectional view on the line 4 4 of Figure "1, such view being extended laterally so as to show the gear train more clearly.

Figure 5 is a fragmentary view showing a further form of escapement device.

Referring to the drawings, it will be seen that the repeating fuse construction comprises a rear supporting member i which is provided with a transverse upper channel member 2. This channel member carries a plurality of spaced insulators 3, 4 and 5, three having been shown though any number may be employed depending on the number of fuse units. The lower end of the member I carries an insulator 3 which supports a transversely extending conducting ba 1 to which the lower stationary contacts 3, 3 and Ill are rigidly attached.

The lower stationary contacts are duplicates and comprise the hook-shaped spaced fingers il which preferably have an overhanglng portion I2 and which are provided with brush contacts i3.

'Ihe drop-out fuse units are all of similar construction and comprise in each instance a fuse tube I4 which is provided with a collar i! near its lower end, such collar being provided with a projecting arm i6 adapted to be received by a suitable portion of a switch stick in a well known manner during removal and replacing of the fuse tube. A lever l1 is pivoted at its upper end to the collar II and its lower end is provided with laterally projecting trunnions i3 which removably seat within the hooks ii of the lower stationary contact. The lever I1 is provided with a suitable clamping means as indicated at I3 for clamping the end of the fuse link in place. The upper end of' the fuse tube is provided with an upper contact 2i which terminates in a threaded neck which receives the upper cap 22, such upper cap being provided with an upwardly projecting pin 23 adapted to be received by a latching member hereinafter described.

The upper contact carries an eye 24 which is pivoted at 25 and spring urged to the position shown in Figure 1. This eye is rigidly clamped with a pair of fingers 26 located on opposite sides of the upper contact 2| of the fuse tube so that when the eye is pulled downwardly by a switch stick, it will raise the latch 21 which latter is pivotally carried by the upper stationary contact indicated generally at 23.

All of this construction is similar to that shown in our prior Fatent No. 2,176,227 of October 17, 1939. The upper cap 22 as shown in the prior patent is for the purpose of clamping the upper buttonhead of a fuse link of any suitable type. such for example as that shown in the above mentioned patent, the fuse link preferably having a fusible section as shown in the patent adjacent its upper end and having a flexible leader extending therefrom and clamped by the thumb nut or other clamping means I 3 to the lower lever i1. The upper stationary contact is also provided with a brush contact 2l which bears outwardly against the fiat face 30 of the upper contact 2i of the fuse tube.

The latch 21 is generally channel-shaped and is provided with a cam-shaped upwardly slanting outer end 3i beneath which the pin 23 of the upper contact of the fuse tube rides when the fuse tube is rocked back into service after refusing. The latch is provided with a shouldered portion as shown in Figure 1 which hooks in front of the pin 23 and thus retains the fuse tube against outward dropping motion under normal conditions.

When the fuse blows, the fuse link is ruptured and releases the lever i1 allowing the lower end of the fuse tube to rock downwardlyand outwardly and withdrawing the pin 23 from engagement with the latch and thus allowing the fuse tube to rock outwardly and downwardly at its upper end, as shown in Figure 3. This rocking motion continues until the fuse tube rocks downwardly to an inverted position.

In order to prevent the latch 2 1 from rocking downwardly below a predetermined point when out of engagement with the fuse tube, such latch is provided with a rearwardly projecting tongue 32, see Figure 3, which seats beneath a shoulder formed on the terminal 23.

It is to be noted that al1 of the bottom stationary contacts are electrically connected to the conducting bar 1 and that each of the upper stationary contacts is insulated from every other upper contact under normal conditions. One line wire connects to the upper left-hand terminal in any suitable manner not shown, and the other line wire connects to the conducting bar 1 in any suitable manner not shown. The circuit, therefore, is closed through the left-hand fuse under normal conditions and when this fuse is ruptured, it drops downwardly and outwardly as described hereinabove and thereafter an automatic transfer switch comes into operation which connects the second upper terminal member to the first upper terminal member, as shown in Figure 2. An automatic transfer switch mechanism is provided for all except the last upper terminal member so that as successive fuses blow,

the upper line terminal is connected successively l to the upper terminal members. Obviously as many units may be employed as desired, three having been shown as illustrative.

The automatic transfer switch mechanism comprises a switch arm 33 which carries a switch blade or bar 34. 'I'his switch blade or bar may be freely floating if desired and connects the contact arm 35, electrically connected to the upper terminal of the first fuse, to the contact arm or bar 3B electrically connected to the second upper terminal.

The second upper terminal is provided with a contact arm 31 which is adapted to be connected by the corresponding contact bar 3l of the next transfer switch to the upper contact arm 33 of the third upper contact. Each of these upper the flat face 30 of the upper contact 2| of the corresponding fuse tube. The divergent lips 4I do not engage or grip the fuse tube but mere- `ly act as guides when the fuse tube is being rocked back into place, as shown in Figure 3.

The switch arms are associated with time delay mechanism of the mechanical escapement type. 'Ihe switch arms and the time delay mechanism are identical. Each switch arm is-,provided with a rearwardly projecting extension 42 which is provided with a circular face 43 concentric with the pivot pin 44 about which the switch arm rocks. This extension 42 is also provided with a cam face 45 which extends in any suitable manner, for example, radially outwardly as shown in Figure l.

'I'he switch arm is urged towards switch closed position by means of the spring 46 and the switch arm may be provided with a housing 46' at least partially surrounding the spring 46 as shown in Figure l. It is restrained Ifrom closing motion by the engagement of the portion 4| with the face 38 of the upper contact of the fuse tube. In other words, a portion of thel fuse tube itself engages a part of the switch arm and restrains the switch arm from closing as long as the fuse tube is in service. When the fuse tube drops out of service, either upon overload or when it is manually removed as previously described, the

switch arm closes and connects the next adjacent fuse in service. Obviously when a blown fuse is refused and is rocked back into position, it automatically opens the switch. Opening of the switch does not occur until after the contact 4l of the switch arm engages the upper contact 2| of the fuse tube being rocked back into service and thus there is no break in the service when a refused fuse is rocked back into service position.

The mechanical escapement time delay device may comprise a train of gears, the rst of which 41 is rigidly attached to .a projecting arm or switch restraining member 48, both of which are rigid with the shaft 49 as shown most clearly in Figure 4. The member 48 is in the path of travel of the extension 42' of the switch arm, see Figure 1, so that when the switch arm rocks upwardly when released by the outward dropping of the corresponding fuse tube, it operates the time delay mechanism by driving the shaft 43 through engagement between the members 42 and 48.

Mechanical escapement means are provided for delaying the rotation of the shaft 49, as will switch arm is no longer restrained and thus makes a quick closing stroke, thus avoiding arcing during closing.

The extension 42 with the faces 45 and 43 constitutes a cam and such member, together with the member 48, constitutes the mechanism whereby the time delay device is driven from the spring or biasing means 46 of the switch.

The shaft 49 is provided with a spring 50 which tends to drive the member 48 in a counterclockwise direction, as viewed in Figure 1, such spring being shown in Figure 4 and constituting restoring means for restoring the time delay mechanism to its initial position when the switch is rocked back to open position. The spring 5D is a considerably lighter spring than the spring 46 and its action is readily overpowered by that of the spring 46 when the switch is released. The

'gear 41 is in mesh with a pinion '5| rigid with a gear 52, such gear and pinion forming a unit and being carried by the shaft 53. The gear 52 meshes with a pinion 54 which is fast to the shaft 55. 'The shaft 55 also rigidly carries a driving gear 56 which meshes with a pinion 51 formed as a unitary structure with a flywheel 58. Either the flywheel 58 or the unit consisting oi.' the pinion 5| and gear 52 may be loose on the shaft 53, or if desired both may be loose on the shaft.

It will be seenthat when the switch is released by the outward dropping of the corresponding fuse unit, that the switch arm tends to move towards closed position and drives the arm 48 of the time delay mechanism in a clockwise direction, thus rotating the flywheel 58. In view of the inertia of the flywheel, it does not immediately come up to full speed but gradually speeds up and thus provides a time delay for the closing of the switch. The switch, therefore, is delayed in its closing stroke until the rounded portion 43 of the arm 42 passes by the arm 48 of the escapement mechanism at which time the switch makes a. quick nal closing stroke.

It is to be noted at this point that instead of having the switch completely released from the time delay mechanism as described, that the increasing speed of the flywheel itself provides for an increasing closing speed of the switch as the switch approaches its final position, but this is not the preferred arrangement. The preferred arrangement is, as stated above, to have the arm 42 pass by the arm 48, see Figui-el, so that the switch will be free of restraint of the time delay mechanism and the final portion of the closing stroke of the switch will be extremely rapid.

Inplace of the flywheel 58 a simple type of fan construction indicated at 59 in Figure 5 may be employed, or if desired other types of mechanical escapement can be used than these shown, two

forms of mechanical escapement however being shown for the purpose of illustration.

It is to be noted from reference to Figure 1 that the upper terminal 28 carries a housing 60 which houses the pivoted portion oi' the switch together with its spring 46 as well as the time delay mechanism and the upper end of the fuse tube. Thishousing projects over the latch 21 and over the brush contacts 29 and over the contact portion 4| of the extension of the switch arm and thus adequately protects these parts from snow, ice and sleet.

It is customary to provide a shielding plate 6| formed integrally with the lower collar I5 to afford limited protection at least for the link I1 and brush contact I 3 and lower portion of the fuse stmcture.

The operation of the apparatus is as follows:

When the first fuse unit blows, the lever l1 is released and allows the lower end of the fuse tube to rock downwardly and outwardly and allows the upper end of the fuse tube to rock downwardly out of engagement with the 'latch 21. .The fuse tube then drops outwardly and swings downwardly below the lower stationary contact.

When thefuse tube has dropped outwardly,

' it' no longer'restrains the extension or arm l! ofthe switch and the switch under the biasing action of its spring 44 moves towards closed position. In so doing. the extension or cam member 42, see Figure 1, drives the time delay mechanism which' causes the first portion at least of the closing stroke of the switch to be relatively slow and thus provides the time delay. Thereafter in the form shown, the rounded portion 42 finally rides past the arm 48 of the time delay mechanism and the switch is then no longer restrained by such time delay mechanism and thus quickly closes,

connecting the electric line through the next fuse unit.

Obviously if the overload continues, the next fuse unit will drop out of circuit and release its transfer switch for connecting the third fuse unit in service. The third fuse unit is not' usually provided with a transfer switch unless a fourth fuse unit is to be added. Obviously as many fuse units as needed could be employed.

Assume that the first fuse unit has blown and dropped outwardly and downwardly and the transfer switch has functioned to connect the next fuse unit in service. The blown fuse unit is readily detached from the hooks H by means of a switch stick engaging the portion Il of the fuse tube, see Figure 1. The fuse tube is lifted down from position, is refused, is replaced,A and is rocked back into service, the switch stick, after having positioned the fuse tube in place being detached from the member Il and. hooked into the eyelet 24. Thereafter the refused tube is rocked back into position by means of a switch stick. It engages the contact portion 4I of the extension 39 of the switch arm, see Figure 1, and rocks the switch arm back to open position as shown. This backward rocking of the switch arm to open position does not drive the time delay mechanism and consequently no strain is imposed on the time delay mechanism, although the refused fuse unit may be rocked back into position in avery rapid manner. Obviously as the extension or cam member 42 of the switch arm is rocked in a clockwise direction from the position shown in Figure 3 to the position shown in Figure 2, the time delay mechanism will be automatically returned by means of its restoring spring 50, see Figure 4, and will ultimately come to rest with the arm 42 thereof in engagement with the face 45 of the extension 42 of the switch arm.

It is obvious that when the refused unit is rocked back into place, that it does not open the. circuit for its upper contact 2l is in engagement with the contact portion 4I of the extension 29 of the switch arm before the switch arm starts to move away from its closed position. In its final position the upper contact 2| of the fuse tube engages the brush contact 2l of the upper stationary terminal member and the fuse tube is temporarily locked in position. 1

It is obvious that any of the fuse units may be removed from service position by pulling downwardly and outwardly on the eyelet 24 by means of a'switch stick. When this is done, the arms 2C raise the latch 21 and release the upper end of the fuse tube, allowing the fuse tube to be rocked outwardly without breaking the fuse link.

It is obvious that if the nrst or second fuse tubes were detached manually as described, that the corresponding ,transfer switch would ultimately close to connect the next succeeding fuse in service.

It is to be understood that the flywheel Il, see Figure 4. or fan I8, see Figure 5, may be housed and protected from the weather in any suitable manner. For instance, the housing I0 may have a cap 02 secured in place in any suitable manner to a cylindrical or other shaped extension l2 of the housing l0.

It is also clear from an examination of Figure A, that the housing i0 may have an inturned front portion 20' whose inner end is spaced from the opposite wall of the housing to provide a space through which the switch arm 32 can project, as shown in Figure l.

It will be seen that a simple type of repeating dropout fuse device has been provided in which mechanical escapement time delay means is employed for delaying the connecting of the next succeeding fuse unit in service. It will also be seen that the switch is released by the outward vdropping of the fuse tube of the corresponding fuse unit but that a portion at least of the closing stroke of the switch is retarded by the time delay means.

It will be seen further that a very simple type of mechanical time delay means may be employed and that this time delay means is wholly automatic in its operation, restraining the switch during a portion at least of the closing motion of the switch and providing for the sudden release of the switch during the final portion of its closing stroke and also being unstressed during the opening stroke of the switch due to the rocking of the refused unit back into service or operative position, the time delay means itself being provided with restoring means for restoring it to its initial position.

i Although this invention has been described in considerable detail, it is to be understood that such description is intended as illustrative rather than limiting, as the invention may be variously embodied and is to be interpreted as claimed.

We claim:

1. An automatic repeating fuse construction comprising a first fuse unit and a second fuse unit, each of said fuse units including a fuse tube having a discharge opening at one end, each of said fuse units being normally held in operative position, means for releasing said first fuse unit upon blowing of said first fuse unit, an electric line normally connected through said irst fuse unit, normally open switch means permanently biased towards closed position and located at a point remote from the open end of said first fuse unit for connecting said electric line through said second fuse unit upon blowing of said nrst fuse unit, and time delay means including a mechanically rotated member operatively connected to and rotated by said switch means a pluraiity of times when said switch means is moving towards closed position for a portion only of the closing stroke of said switch and being operatively free of said switch for the final portion of the closing stroke4 of said switch.

2. An automatic repeating fuse construction comprising a first fuse unit and a second fuse unit, each of said fuse units including a fuse tube having a discharge opening at the bottom. each of said fuse units being normally held in operative position, means for releasing said first fuse unit upon blowing of said first fuse unit, an electricline normally connected through said first fuse unit, normally open switch means permanently biased towards closed position and located atapoint adjacentjhgllpler end of said repeating fuse construction for-connecting said electric line through said second fuse unit upon blowing of said first fuse unit, and time delay means including a mechanically rotated member operatively connected to and rotated by said switch mean's a plurality of times when said switch means is moving towards closed position' for a portion only of the closing stroke of said switch and being operatively free of said switch for the final portion of the closing stroke of said switch.

3. An automatic repeating fuse construction comprising a first fuse unit and a second fuse unit, each of saidfuse units being normally held in operative position, an electric line normally connected through said first fuse unit,normally open transfer switch means for transferring the electric circuit to the second fuse unit upon blowing of said first fuse unit, and mechanical escapement time delay means operatively connected to said switch means and including a, revoluble member rotated a plurality of times when said switch means is moving towards closed position, said switch means being restrained from closing motion by said first fuse unit until said first fuse unit has blown and being released by said first fuse unit upon blowing thereof, said mechanical escapement time delay mechanism controlling said switch means and said switch means having a closing stroke, the first portion of which being retarded by the mechanical esv of the closing stroke of capement time delay means and the last por- Ition being free of 4. An automatic said time delay means. repeating fuse construction comprising a first fuse unit and a secondffuse unit, each of said fuse units being normally held in operative position, an electric line normally connected through said first fuse unit, normally open transfer switch means for transferring the electric circuit to the second fuse unit upon blowing of said first fuse unit, and mechanical escapement time delay means operatively connected to said switch means, said switch means being restrained from closing motion by said first fuse unit until said first fuse unit has blown and being released by said first fuse unit upon blowing thereof, said mechanical escapement time delay mechanism controlling said switch means, the first portion atleast of the closing motion of said switch means being retarded by the mechanical escapement time delay means, said switch means being operatively free from the retarding action of.' said mechanical escapement time delay means during the latter part of the stroke of said switch means and making a quick final closing motion during said latter part of the closing stroke of said switch means.

5. An automatic repeating fuse construction comprising a first fuse unit and a second fuse unit, an electric line normally connected through said first fuse unit, switch means for connecting said electric line through said second fuse unit upon blowing of said first fuse unit, biasing means biasing said switch means towards closed position, said switch means being normally held in open position by said first fuse unit and being released upon blowing of said first fuse unit, and mechanical escapement means driven .by the vclosing stroke of said S biasing means of said switch means and delaying the closing motion of said switch means when said switch means is released, said escapement means having self-restoring means.

6. An automatic repeating fuse construction comprising a. first fuse unit and a second fuse unit, an electric liiie normally connected through said first fuse unit, switch means for connecting said electric line through said second fuse unit upon blowing of said first fuse unit, biasing means biasing said switch means towards closed position, said switch means being normally restrained by said first fuse unit and being released upon blowing of said first fuse unit, and mechanical escapement time delay means driven by said biasing means when said switch means is released and including a rotary member whose rotation lis retarded, said mechanical escapement means being operatively free of said switch during the final portion of the closing stroke of said switch.

7. An automatic repeating fuse construction comprising a first fuse unit and a second fuse unit, an electric line normally connected through id first fuse unit, switch means for connecting said electric line through said second fuse unit upon blowing of said first fuse unit, biasing means biasing said switch means towards closed position, said switch means being normally restrained by said first fuse unit and being released upon blowing of said first fuse unit, and time delay means for retarding a portion at least said switch means, said time delay means comprising a rotary member and a gear train interposed between said rotary member and said switch means, said gear train being driven from said switch means and driving said rotary member, said time delay means having self-restoring means. I 8. An automatic repeating fuse construction comprising a first fuse unit and a second fuse unit, an electric line normally connected through said first fuse unit, switch means for connecting. said electric line through said second fuse unit upon blowing of said first fuse unit, biasing means biasing said switch means towards closed position, said switch means being normally restrained by said rst fuse unit and being released upon blowing of said first fuse unit, and time delay means for delaying a portion of the closing stroke of said switch means, said time delay switch means, said switch delay means during the final portion of the closing stroke of said switch.

9. An automatic repeating fuse construction comprising a first fuse unit and a second fuse unit, an electric line normally connected through said first fuse unit, switch means for connecting said electric line through said second fuse unit upon blowing of said first fuse unit, biasing means biasing said switch means towards closed position, said switch means being normally restrained by said Iirst fuse unit and being released upon blowing of said first fuse unit, and time delay means for delaying a portion of the switch means, said time delay means including a fan driven from said switch means, said switch being free of said time delay means during the final portion of the closing stroke of said switch.

10. An automatic repeating fuse construction comprising a first fuse unit and a second fuse unit, each of said fuse units including a fuse tube normally held in operative position, means unit. and mechanical time delay means delaying a part o! the clodng stroke o! said switch means, said mechanical time delay means including a rotary member driven from said switch means. said switch being free of said time delay means during the iinal portion of the closing stroke of said switch.

11. An automatic repeating fuse construction comprising a ilrst fuse unit and a second fuse unit, each of said fuse units including a iuse tube normally held in operative pomtion. means for releasing the fuse tube oi' said first fuse unit upon blowing ot said iirst Iuseunit, an electric line normally connected through said iirst fuse unit, normally open switch means permanently biased towards closed position and having an arm normally in engagement with said nrst fuse unit and being restrained againstclosing motion by said ilrst fuse unit and being released when the fuse tube of said ilrst fuse unit drops out of operative position upon blowing oi! said iirst fuso unit, and mechanical time delay means delaying a part of the closing stroke 'of said switch means and being inoperatively related to said switch during the ilnal portion 'of the closing stroke of said switch, said mechanical time delay means including a rotary member driven by said switch means l2. An automatic repeating fuse construction comprising a ilrst fuse` unit and a second fuse unit, each of said fuse units including a fuse tube having a discharge opening at the bottom. each of said fuse units being normally held in operative position, means for releasing said ilrst fuse unit upon blowing oi' said first fuse unit to allow said first fuse unit to drop out ot operative position, an electric line normally connected through said iirst fuse unit, normally open switch means normally biased towards closed position and located adjacent the upper end of said ilrst fuse unit for connecting said electric line through said second fuse unit'upon blowing of said ilrst fuse unit, mechanical escapement time delay means including a. rotary member for delaying a portion o! the closing stroke oiv said switch means; and means operatively connecting said time delay means and said switch means during a portion of the closing stroke ot said switch means to drive said rotary member from said switch means and inoperatively relating said switch means to said time delay means during the ilnal portion of the closing stroke of said switch means.

=13.An automatic repeating fuse construction comprising a ilrst fuse unit and a second fuse unit. an electric line normally connected through said iirst fuse unit, switch means for connecting said electric line through said second i'use unit upon blowing of said ilrst fuse unit, biasing means biasing said switch means towards ,closed position, said switch means being normally restrained by said rst fuse unit and being released upon blowing of said first fuse unit, and time delay m'eans, said time delay means including restraining means for preventing immediate closing of said switch means after blowing of said rst fuse unit and a rotary member for controlling the motion of said restraining means, said time delay means having self-restoring means for returning said time delay means .to its original position when said switch is moved to open position.

'14. An automatic repeating fuse construction comprising a first fuse unit and a second fuse unit, an electric line normally connected through said first fuse unit, switch means for connecting said electric line through said second Iuse unit upon blowing of said iirst fuse unit, biasing means biasing said switch means towards closed position, said switch means being normally held in open position by said iirst fuse unit and being released upon blowing of said first fuse unit, me-

chanical escapement means driven by the biasing means of said switch means and delaying the closing motion of said switch means when said switch means is released, and biasing means for returning said mechanical escapement means to its original position when said switch means is moved to open position.

WILLIAM O. SCHULTZ. ALWI'N G. STEINMAYER.

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