US2674673A - High-voltage expulsion type fuse - Google Patents

Description

April 6, 1954 w. H. GILLILAND HIGH-VOLTAGE EXPULSION TYPE FUSE 2 Sheets-Sheet 1 Filed May '7, 1953 INVENTOR WILLIAM H. Gnu LAND ATTORNEYS April 6,1954 w. GILLJLAND 2,674,673

HIGH-VOLTAGE EXPULSI ON TYPE FUSE Filed May 7, 1953 2. Sheets-Sheet 2 WILLIAM H. Guuuwo IV 4 -BY ATrbRNEYs Patented Apr. 6, 1954 UNITED STATES PATENT OFFICE HIGH-VOLTAGE EXPULSION TYPE FUSE William H. Gilliland, Birmingham, Ala., assignor to Usco Power Equipment Corporation, Birmingham, Ala., a corporation of Alabama Application May 7, 1953, Serial No. 353,545

26 Claims. (Cl. 200-127) The present invention relates to high voltage expulsion type fuse assemblies and. in particular to high voltage, transmission line dropout fuse assemblies comprising a pivoted fuse tube latched in engagement with a line terminal and provided with an open end through which a fuse link extends for cooperation with fuse link extractor means for withdrawing a portion of the fuse link from the tube and unlatching the fuse tube when the fuse melts under abnormal current flow. Such assemblies, known as cutouts produce and expel ionized gases from the tube when the fuse melts. These gases are current conducting and in prior fuse assemblies often maintain current flow for undesirable periods after fusion of the link and partial separation of the fuse tube and line contacts causing arcing between the contacts and resulting pitting and burning damage to the contacts themselves.

In high voltage expulsion type fuse assemblies of the prior art, the latch and extractor members are arranged for simultaneous action and in most cases are combined in a single member having a portion covering the end of the fuse tube so that the explosive force of the gases expelled through the end of the tube when the fuse melts is effective to hasten release of the latching means and extraction, of the terminal frag ment of the fused link. To thus hasten the movement of the fuse tube to separate the line and fuse tube contacts which connect the fuse tube to a line terminal increases the objectionable arcing hazard. Since the expelled gases are ionized and current conducting, they also delay complete interruption of the circuit by the fuse while they remain in the immediate vicinity of the end of the tube through which they are expelled. The result is with consequent pitted and burned contacts which, when the fuse has been replaced and the tube is moved again to the circuit closing position, becomes unduly hot under normal load current conditions causing progressive deterioration of the contacts. The deteriorated contacts also become a source of radio interference when the fuse tube is in its closed position.

It is, therefore, an important object of the present invention to provide. a high voltage expulsion type fuse assembly in which means are provided to delay movement of the fuse tube after the fuse melts for a predetermined time interval sufliciently long for the expelled gases from the tube to become adequately dispelled and/or de-ionized so the expelled gas becomes substantially non-conducting before the tube seph in) 2 arates the contacts connecting it with a line terminal.

It is also an important object of the present invention to provide a high voltage expulsion type fuse assembly in which means are provided to positively drive the fuse tube latching means into released condition and to delay the driving engagement with the latching means a sufficient length of time after the fuse melts for the ionized gases expelled from the fuse tube to become adequately dispelled and/or ole-ionized so that the stream of gas becomes substantially non-conducting before the tube separates the contacts connecting it with a line terminal.

It is also an important object of the present invention to provide a high voltage expulsion type fuse assembly in which a fuse tube is held latched with its contacts in engagement with line terminal contacts with means to facilitate the discharge of the arc extinguishing gas from the tube, when the fuse melts, against a latch member to hold said latch member in latch-retaining position under the force of the expelled gases.

It is a further object of the present invention to provide a fuse cutout assembly in which a fuse tube is latched to a line terminal by a latch lever which is normally disengaged with latch driving means so that the latch may be manually operated at will to latch-releasin position without affecting the latch driving means and means responsive to the melting of a fuse in the tube is provided to effect a predetermined delayed engagement of the latch driving means with the latch lever whereby movement of the latch lever to latch-releasing position is effected in timed relation to the melting of the fuse.

It is a further object of the present invention to provide a fuse cutout assembly having a fuse tube latched to a line terminal by a latch lever with means to bias the latch to its latching position whereby undesired forces acting on the fuse tube in a direction normal to the longitudinal axis of the tube are ineffective to releasethe latch lever.

It is a further object of the present invention to provide an expulsion type fuse assembly having a fuse tube carrying a spring-urged extracting lever operable to extract a terminal'portion of a fuse link from the tube when the fuse melts with means to retain the fuse portion captive to the lever against free swinging movement when the terminal portion is whipped from the tube.

Further important objects of the present in- 65 ventlon will appear from the following descrip tion and appended claims when read in conjunction with the accompanying drawings in which:

Figure l is a side elevation of an electric switch provided with a high, voltage expulsion type fuse assembly of one embodiment of our improved opcrating mechanism.

Figure 2 is an enlarged top plan view of the latch lever assembly.

Figure 3 is an enlarged side elevation of the latch lever assembly of Figure 2.

Figure 4 is a top plan view of the fuse-extracting lever used in the preferred embodiment of our improved operating mechanism.

Figure 5 is a side elevation of the fuse-extracting lever of Figure 4.

Figure 6 is a top plan view of a modified form of the fuse-extracting lever.

Figure '7 is a side elevation of the fuse-extracting lever of Figure 6.

Figure 8 is a top plan View of a modified form of the latch lever assembly of our improved operating mechanism.

Figure 9 is a side elevation of the latch lever assembly of Figure 8.

Figure 10 is a fragmentary side elevation of a further modified form to the fuse-extracting lever.

Figure 11 is a perspective view of the stop pin of Figure 10.

With the continued reference to the drawings illustrating several simple and practical embodiments of the invention, similar reference characters are employed to designate corresponding parts through the several views.

Referring particularly to Figure 1, the fuse assembly of this invention is shown mounted in an approximately vertical position on a conventional insulator means I, carrying an upper line terminal 2 and a lower line terminal 3. These terminals support a drop out fuse tube 4, which houses a fuse link 5 of any well known form adapted for conductively connecting the two line terminals. A metal casting 6 is secured on the lower end of the fuse tube and through opposed pivot pins 6a pivotally mounts fuse tube 4 on the lower line terminal 3. The fuse tube is latched at its upper end to the upper line terminal 2 by a latch lever I of novel form to be hereinafter described pivotally mounted on a metal end casting 8 secured to the upper end of the tube. While a keeper of any desired form might be provided the keeper preferably takes the form of a sleet hood 9 pivotally supported on the upper terminal on pivot pin 9a.

The fuse link 5 may be of any conventional construction and is shown in the form of the button-head type in which the fusible portion 5a of the fuse is connected at its lower end to a button head which is engaged by a leaf-spring I0 secured to the casting 6 by means of a thumbscrew I I or other suitable means. The upper end of the fusible portion 5a is connectedto a terminal connector I2 of flexible wire which extends through the upper end of the tube 4 over a fuse-extracting lever I3 adapted to cooperate in a novel manner with latch lever I secured to the metal casting 8 by suitable means such as a thumb-screw I4. The fuse-extracting lever I3 is pivoted on the casting 3 through a pivot pin I5 and is urged by spring means Hi (Fig. 3) so that the extracting lever normally tensions the intact fuse link 5 and is operative to withdraw the connector wire I2 from the fuse when the fusible section 5a melts under abnormal current flow.

It is to be understood that the present invention is equally adapted for use with other conventional types of fuse links including those wherein the fusible portion of the fuse is connected to an upper flexible terminal connector which is turned over the fuse-extracting lever and to a lower flexible link which is extended through the lower end of the tube and is held secured against casting 6 by the thumb-screw I I in well known manner.

The novel latch lever I is pivotally supported between a pair of forwardly and upwardly extending, spaced opposed arms ll of the casting 8 (Fig. 2) by means of a pivot pin I8 on which the latch lever I pivots. The latch lever comprises a broad, upstanding nose I9 integrally connecting a pair of spaced opposed forwardly extending short lever arms 20 and a rearwardly extending and relatively long lever arm 2 I. Arm 2 I, due to its length, acts as a counterweight biasing latch member I to its latching position. The nose I9 of the latch engages the latch-engaging member or keeper 9, while the fuse is in its normal closed position with the fusible portion 5a of the fuse intact and is held against pivotal movement while the fusible portion 5a is intact through a coil spring 22. As clearly seen from Figure 1, keeper 9 is spring-urged by a spring 25, on the upper line terminal engaging a heel portion 26 of the keeper 9, to its normal lower position.

The fuse-extracting lever I3 is adapted for novel cooperation with latching lever 1 through a depending arm 21 having a side extension or pin 28 spaced from and extending under the free end of arm 2| of the latch lever I. When fuse link 5 is intact and fuse-extracting lever I3 is in its normal fuse-tensioning position, with fuse tube 4 in open position, the rear end of the latch lever can be manually oscillated through an arc to released position for there is no positive connection between pin 28 and. the latch lever. In other words latch lever 1 is independent of the spring means I6 which normally bias the fuse extracting lever I3 to tension the fuse 5. However, when the fuse tube 4 is pushed home to its normal circuit-closing position with the nose I9 of the latch I in holding engagement with the latch-engaging member 9, the latch is held against disengagement from the latch-engaging member 9 under the influence of forces acting thereon parallel to the fuse tube 4 by means of spring 22 and the counterweight effect of long arm 2|.

When the fuse is installed in service there may be many reasons, such as gales, vibration, temperature changes, and so on imparting forces parallel to the tube and tending to disengage the latch. The hold means just described is wholly adequate to meet these forces and hold the latch securely.

With the fuse tube 4 in its normal circuitclosing position blowing of the fuse releases the fuse-extracting lever I3 which then swings under influence of spring I6 in a clockwise direction to pull the link I2 out of the tube. As the fuseextracting lever swings, depending arm 2'! also swings in a clockwise direction and the side of pin 28 engages lever 2| of latch member 1 to positively drive the latch to released position freeing the tube which then swings downwardly in a clockwise direction to finally hang from the lower terminal 3.

Means are employed to assist gravity in swinging the released tube 4 away from its closed position. These include leaf spring contact 32 secured to upper terminal 2 and pressing against a bent contact arm 33 extending forwardly from the casting a and a similar leaf spring contact 324 secured to lower terminal 3 and pressing against curved contact arm 33a extending forwardly from the casting B.

In the preferred embodiments of this invention, the fuse-extracting lever I 3 has a forwardly extending integral portion 34 approximating the form of the letter C. In the normal fusetensioning position of fuse-extractor lever [3 the Wall defining the C sits on the upper end sur face of the fuse tube 4 leaving the upper end of the tube bore unimpeded for the free flow of gas around the connector terminal i2 and from the tube when the fuse blows. This is best shown in Figure 2, and insures the withdrawal of. the fuse link terminal connector l2 under influence of the extractor spring only with the result that the arc is drawn and extinguished within the protective tube by the gases produced therein, further assures that the gases do not expulsively eject the terminal connector l2 from proper engagement with the extractor lever !3 before the arc can be effectively extinguished, and finally assures that the ionized gases may be most quickly cleared from the tube and that the path swept out by the terminal connector is determined by swinging of the terminal connector about the foremost portion of the c shaped end. This tends to shorten the free length of the terminal connector thereby preventing a restrike of the terminal connector on the lower casting 6 resulting in a reestablishment of the circuit momentarily before the fuse tube has moved sufficiently to avoid reestablishment of the circuit through the ionized gases surrounding the upper terminal members.

In a modified form of the fuse-extracting lever 13, shown in Figures 4 and 5, the forward end of the lever rests on one side of the end of the tube 4, does not encircle the bore of the tube and no part of the lever swings across the longitudinal axis of the bore of the tube or the path of ejected gases. In this modified form of the fuse-extracting lever, an upstanding bridge 35 is provided at the forward end of the lever so that, as the fuse link [2 is whipped upwardly by the fuse-extracting lever, the path swept out by the terminal connector l2 will be largely determined by the swinging of the terminal connector about the bridge 35. This structure assures the link being held captive by the extracting lever. The function of the bridge having been disclosed, it is apparent that equivalent means may be employed, and such equivalent means may take the form of a pair of vertically spaced and overlapping arms 35' as shown in Figures 6 and 7. This form of the invention equally effective in assuring rapid dissipation of the gases generated upon fusing of the link and preventing restrikes and has the added advantage, since it has no portion of the extractor lever passing through the path of 6. service without disturbing extracting lever 13 or fuse link 5 and in spite of icing of the hood since the protected latching lever pivot is less likely to be heavily iced and the long lever arm 2| is efiective to amplify the manual opening force to break any ice that may form on pivot pin I 8. However, opening and closing of the fuse tube may be effected equally well by the conventional method of engaging the hood and raising it against resistance of spring 25, if desired.

The spring means 22 about pivot pin I8 is preferably designed to have a force just sufficient to urge the nose 33 of the latch upwardly against the probable forces, already mentioned, which tend to push the nose towards the latch-releasing position. The upward thrust of theextractor lever spring means i 5 can be conveniently ample because, when the side pin 28 is required to move the latch member 1 to the latch-releasing position under the urging of the spring means IE, it has the mechanical advantage before mentioned due to the relatively long lever arm 2| In a further modification of this invention shown in Figures 8 and 9, a sleet hood M is pivoted at i5 on the upper line terminal 2 and is limited in its movement in an upward direction by a stop member ie on the line terminal. The hood carries a keeper 4?, which is engageable by a latch 4% as indicated at 29. A leaf spring 5ilon the upper line terminal 2 engages the keeper ll to normally urge the sleet hood upwardly against the stop 46.

The latch 48 is pivoted on a pivot pin 5| and straddles spaced opposed upstanding arms 52 of a casting 53 on the upper end of the fuse tube it and is normally spring urged into engagement with the keeper s: by a coiled spring 54 disposed about the pivot pin 5!. The latch extends rearwardly of the pivotal point as a relatively long arm 55 and forwardly as a relatively short arm 55a which carries a stop member 56 arranged to engage a flat 56a on the casting 53 to limit downward movement of the short arm.

Means are provided to move the long arm downwardly about the pivot pin 5! to release the latch in response to the blowing of a fuse in the fuse tube i and to effect the releasing of the latch in predetermined timed relation to the blowing of the fuse. These means, as in the former embodiment, comprise an ejector lever 5'1 pivoted at 58 on the casting 53 and normally spring urged in a clockwise direction by spring means 59 and a side extension or pin 66 to engage the arm 55 to drive it into releasing position. A fuse link 5 connected to the fusible portion 5a of a fuse in the fuse tube is placed over the ejector lever 51 and is secured to the casting 53 by a thumb screw til or other suitable means so that the ejector lever normally tensions the fuse link while the fuse is intact. usual lever 5! is arranged to swing clockwise and withdraw the link when the fuse blows.

The upper end of the fuse tube is open to facilitate the movement of gas expelled from the fuse tube when the fuse melts, and the sleet hood M is disposed extending across the open end of the tube in spaced opposed relation thereto and in the path of the expelled gases as they pass upwardly and outwardly and away from the assembl and the impact of the gases on the sleet hood is in a direction to move the sleet hood into latch retaining disposition.

The side pin 6i! is variously placed on the link ejector lever 5'! to predetermine at will the time between the blowing of the fuse and the releasing of the latch 48 through driving engagement of the pin 60 with the arm 55. The engaged surface of the arm 55 may also be varied by notching to various degrees or similar methods to predetermine the length of the free path travelled by the pin 60 as it moves from its position of rest while the fuse is intact to its engaging position on the lever 51 when the fuse blows.

Various other means of securing the pin or side extension 60 to the ejector lever 51 may be adopted and various means for varying the contour of the engaged surface of the lever 51 may be adopted to embody the concept.

The hood 44 is provided at its upper free end with an upwardly curved terminer 62 to be engaged by a hook-stick in the hands of a lineman so that the hood can be moved downwardly to release the keeper 41 from the latch 48 when it is desired that the fuse tube 4 be released while the fuse is still intact. The hood 44 may be provided with depending side wings or aprons 63 in protecting relation to leaf spring 50, to protect it against sleet.

A modification of ejector lever 51 is shown in Figure 10. As there shown ejector lever 51a is provided with a series of spaced openings 85 centered along an are drawn with the axis of the opening for pivot pin 15. These openings 6-5 removably receive a pin 61 which may be utilized for varying the length of the free path travelled by the pin 61. It will thus be appreciated that a selectively variable time delay may be provided by a service man in the field without the need of replacing the extractor lever if a lever such as lever 51a is provided.

In all forms of the invention a predetermined time delay between the blowing of the fuse and the releasing of the fuse tube is effectively pro vided by determining the length of the free travel of the latch driving member from its point of rest while the fuse is intact to its point of engagement with the latch when the fuse blows.

It is well understood that at some points in a transmission system the duty on the fuse is severe when it has to clear a short-circuit on a line having good regulation, while at other points the duty on the fuse is not severe when it has to clear a short-circuit on a line having poor regulation. The fuse assembly of the present invention provides means whereby various operating conditions can be met for it can be adjusted at will to ensure extraction. of the fuse link and expulsion of the ionized gases and extinguishment of the arc drawn within the fuse tube before the fuse tube is released from the line terminal. It is thus possible to delay the releasing of the fuse tube from the line terminal to avoid drawing of an are between the fuse tube and the line terminal through the ionized gases in the tube and adjacent the upper end of the fuse tube and the line terminal. Thus pitting of the upper contact surfaces is readily preventable. It is well understood that pitting of the contact surfaces results in poor contact-making ability heating of the contacts under load and makes possible the welding together of contacting surfaces under severe load conditions. Pitting of the lower contact under arcing conditions when the upper end of the fuse tube is released of course, avoided since the arc does not extend out of the lower end of the tube to the lower contact.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristic thereof. The present embodiments are therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

1. An expulsion type fuse assembly comprising a pair of spaced line terminals, a fuse tube hinged on one of said terminals, a first pivot means on said tube, a lever pivoted on said first pivot means, spring means biasing said lever for movement in one direction of movement, a fuse link in said tube in engagement with said lever and arranged to restrain said lever against movement in said one direction while said fuse link is intact and to release said lever for movement in said one direction when said fuse link ruptures under abnormal current flow, a latchengaging member on the other of said line terminals, a second pivot means on said tube, a latch pivoted on said second pivot means, means acting about said second pivot means normally biasing said latch toward latching engagement with said latch-engaging member, and normally inactive driving means movable with said lever to drive said latch into latch-released relation to said latch-engaging member upon predetermined movement of said lever in said one direction of movement.

2. An expulsion type fuse assembly comprising a pair of spaced line terminals, a fuse tube hinged on one of said line terminals, a first pivot means on said tube. a lever pivoted on said first pivot means, spring means biasing said lever for movement in one direction of movement, a fuse link in said tube in engagement with said lever and arranged to restrain said lever against movement in said one direction while said fuse link is intact and to release said lever for movement in said one direction when said fuse link rup-' tures under abnormal current flow, a second pivot means on said tube, a latch pivoted on said second pivot means, a latch-engaging member on said other line terminal, means normally biasing said latch into latching engagement with said latch-engaging member, and means on said lever adapted to engage said latch to drive it to latch-released relation with respect to said latchengaging member upon predetermined movement of said lever in said one direction.

3. An expulsion type fuse assembly comprising a pair of spaced line terminals, a fuse tube hinged on one of said line terminals, a first pivot means on said tube, a lever pivoted on said first pivot means, spring means normally biasing said lever for movement in one direction of movement, a fuse link in said tube in engagement with said lever and arranged to restrain said lever against movement in said one direction .of movement while said fuse link is intact and to release said lever for movement in said one direction when said fuse link ruptures under abnormal current flow, a latch-engaging member on the other of said line terminals, a second pivot means on said tube. a latch pivoted on said second pivot means and adapted to be manually operable at will into released relation to said latch-engaging member, means normally biasing said latch into latchengaged relation with said latch-engaging member and means activated upon movement of said lever in said one direction of movement to drive said latch to latch-released relation with respect to said latch-engaging member.

4. An expulsion type fuse assembly comprising a pair of spaced line terminals, a fuse tube hinged on one of said line terminals, a first pivot means on said tube, a lever pivoted on said first pivot means, spring means normally biasing said lever for movement in one direction of movement, a fuse link in said tube having a portion thereof in overlying engagement with a portion of said lever to restrain said lever while said fuse link is intact and to release said lever for movement in said one direction of movement when said fuse link ruptures under abnormal current flow, fuseretaining means on said lever extending about the bore of said tube and about said fuse link, a second pivot means on said tube, a latch pivoted on said second pivot means, a latch-engaging member on the other terminal, means normally biasing said latch into latched relation with said latch-engaging member and means cooperable with said lever arranged to drive said latch into released relation with respect to said latchengaging member upon movement of said lever in its one direction of movement.

5. An expulsion type fuse assembly comprising a pair of spaced line terminals, a fuse tube hinged on one of said line terminals, a first pivot means on said tube, a bell-crank pivoted on said first pivot means, spring means biasing said bell-crank for movement in one direction of movement, a fuse link in said tube having a portion thereof disposed about said bell-crank and arranged to retain said bell-crank against movement in said one direction of movement while said fuse link is intact and to release said bell-crank for movement in its one direction of movement when said fuse link ruptures under abnormal current flow, fuse retaining means on one arm of said bell-crank adapted to hold said fuse link captive to said bell-crank when said fuse ruptures, a second pivot means on said tube, a latch pivoted on said second pivot means, spring means normally biasing said latch into latching engagement with the other line terminal, and means on the other arm of said bellcrank engageable with said latch upon rupture of said fuse link to drive said latch to released relation with respect to said other line terminal upon movement of said bell-crank in its one direction of movement.

6. An expulsion type fuse assembly comprising a pair of spaced line terminals, a fuse tube hinged on one of said line terminals, a first pivot means on said tube, a lever pivoted on said first pivot means, spring means normally biasing said lever for movement in one direction of movement, a fuse link in said tube and arranged engaging said lever to restrain said lever against movement in said one direction of movement while said fuse link is intact and to release said lever when said fuse link ruptures under abnormal current now, a latch-engaging member on the other line terminal, a second pivot means on said tube positioned at one side of and a short distance above an end of said tube, a latch pivoted on said second pivot means in underhung relation to said pivot means, and having a portion in engagement with said latch-engagin member, means to oppose forces parallel to the longitudinal axis of said tube and tending to unlatch said latch from said latchengaging member comprising biasing means acting on said latch about said second pivot means, and means movable with said lever arranged to engage said latch and to drive it to released relation with respect to said latch-engaging member upon movement of said lever in its said one direction of movement.

7. An expulsion type fuse assembly comprising two spaced line terminals, a fuse tube hinged at one end on one of said line terminals, a latchengaging member on the other of said line terminals, a first pivot means on the other end of said tube, a latch pivoted on said first pivot means and adapted for latching engagement with said latchengaging member, spring means normally biasing said latch to latch-engaging position, a second pivot means on said other end of said tube, a lever pivoted on said second pivot means and having a portion adapted upon movement in one direction to engage said latch and drive said latch into latch-releasing position, spring means normally biasing said lever for movement in said one direction of movement, and a fuse link in said tube engaging said lever to restrain said lever against movement in said one direction of movement while said fuse is intact and to release said lever when said fuse link melts under abnormal current flow.

8. An expulsion type fuse assembly comprising two spaced terminals, a fuse tube hinged at one end on one of said terminals, a latch-engaging member on the other of said line terminals, a first pivot means on the other end of said tube, a latch pivoted on said pivot means and adapted for latching engagement with said latch-engaging member, a second pivot means on the other end of said tube, a lever pivoted on second pivot means, spring means normally biasing said lever for movement in one direction of movement, a fuse link in said tube having a portion thereof in overlying engagement with said lever and arranged to restrain said lever against movement in said one direction of movement while said fuse link is intact and to release said lever when said fuse link is ruptured by abnormal current flow, stop means on said lever extending in surrounding relation to the fuse link to retain the fuse link captive to said lever when the ruptured fuse link is expelled from said fuse tube, said lever being adapted to cooperably engage said latch when said fuse ruptures to move said latch to latchreleased relation With respect to said latch-engaging member upon movement of said lever in said one direction of movement.

9. In an expulsion type fuse assembly which includes a line terminal and a latch-engaging member on said line terminal, a fuse tube, a first pivot means on said tube, a latch pivoted on said pivot means and rotatable in one direction to engage said latch-engaging member and rotatable in an opposite direction to released relation to said latch-engaging member, a second pivot means on said tube, a lever pivoted on said second pivot means, spring means normally biasing said lever for movement in one direction of movement, a fuse link in said tube having a portion disposed on said lever and arranged to restrain said lever against movement in said one direction of movement while said fuse link is intact and ,to release said lever when said fuse link is ruptured by abnormal current flow, fuse retaining means on said lever extending around said fuse link on said lever, and means on said lever cooperatively engageable with said latch to rotate said latch in said opposite direction of movement upon movement of said lever in said one direction of movement.

10. An elongated fuse tube having a first metallic terminal at one end and having a second metallic terminal at its other end, a fuse link in said fuse tube conductively connecting said first and said second terminals and being removably secured thereto, pivot means on said second terminal, a fuse-extracting lever pivoted on said pivot means, spring means normally biasing said lever for movement in one direction of movement, said fuse link having a portion overlying said lever and arranged to restrain said lever against movement in said one direction of movement and to be tensioned by said lever while said fuse link is intact and to release said lever for movement in said one direction of movement when said fuse link becomes ruptured by abnormal current flow, and fuse link retaining means on said lever having a portion thereof in projected normal relation to the bore of said fuse tube to retain the fuse link captive to said lever when the ruptured fuse link moves out of the tube.

11. An expulsion type fuse assembly comprising a pair of spaced line terminals, an elongated fuse tube having a first metallic terminal engaging one of said line terminals and a second metallic terminal engaging the other of said line terminals, a fuse link in said tube conductively connecting said first an said second metallic terminals and being removably secured thereto, pivot means on said first metallic terminal, a fuse-extracting lever pivoted on said pivot means, spring means normally biasing said lever for movement in one direction of movement, said fuse link having a portion overlying said lever and arranged to restrain said lever against movement in said one direction of movement and to be tensioned by said lever whil said fuse link is intact and to release said lever for movement in said one direction of movement when said fuse link becomes ruptured, and fuse retaining means on said lever having a portion thereof in projected normal relation to the bore of said fuse tube and adapted to retain said fuse link captive in relation to said lever when the ruptured fuse link moves out of the tube.

12. An expulsion type fuse assembly comprising a pair of spaced insulated line terminals, a fuse tube pivoted on one of said line terminals, a latch engaging member on the other of said line terminals, a latch on said tube engaging said latch engaging member, a fuse link in said tube conductively connecting said line terminals, means on said tube held restrained by said fuse while fuse is intact and arranged for uni-directional movement, in response to the fusing of said fuse link into driving engagement with said latch and move it in one direction, and means to predetermine the extent of uni-directional movement of said means before engagement of said means with said latch whereby a time delay is provided to assure clearance of the gas evolved in said fuse tube before movement of said latch in said one direction is effected.

13. A fuse tube assembly for use as a drop out fuse cutout comprising a fuse tube; a line terminal contact casting at one end having pivot mounting means thereon; a line terminal contact casting at the other end having a first pivot means and a second pivot means formed thereon in transversely spaced relation to the axis of the tube; a latch pivotally supported by said first pivot means and having a relatively long arm extending generally transversely from said first pivot means past the axis of said tube and terminating in spaced relation to said second pivot means; a fuse link extractor lever pivotally supported by said second pivot means and having a fuse link extracting arm an an 'angularly re lated latch release arm; spring means biasing said fuse link extractor lever toward its fuse link extracting position; a fuse link in said fuse'tube conductively connecting said terminal contact castings and engaging said fuse link extracting arm to restrain said fuse link extractor lever against movement under influence of said spring and retain said latch release arm in spaced relation to said long arm of said latch so long as said fuse link is intact and adapted upon fusing of said fuse link to release extracting lever whereby said latch release arm moves under influence of said spring means into engagement with said long arm of said latch and thereafter drives said latch to released position. i'

14. The combination defined in claim 13 wherein said latch release arm includes means for predetermining the extent of its free movement before engagement with said latch whereby a predetermined time delay occurs between fusing of the fuse link and release of said latch to permit effective dissipation of the ionized gases formed in said tube upon fusion of said fuse link.

15. The combination defined in claim 14 wherein said fuse link extracting arm is formed to at least partially surround said fuse link in normal closed circuit condition of said fuse While leaving the bore of the tube at the adjacent end of the tube fully open to thereby assure free flow and rapid dissipation of the tube gases from said end and extraction of said fuse link under influence of said spring means alone.

16. The combination defined in claim 14 together with spring means acting on the latch to resiliently lock the latch against pivotal release movement in the normal non-fused condition of said fuse tube assembly. i

17. An expulsion type fuse assembly comprising an upper line terminal and a lower line terminal in spaced and insulated relation to said upper line terminal, a fuse tube pivotall mounted on said lower line terminal, a fuse in said tube conductively connecting said upper and said lower line terminals, latch means normally retaining the upper end of said fuse tube in engaged relation with said upper line terminal, and time dela means held ineffective by said fuse while said fuse is intact arranged effective to drivingly release said latch means and to thereby release said fuse tube from engagement with said upper line terminal after a predetermined time interval following the melting of said fuse.

18. The combination defined in claim 17, wherein the time delay means comprise a fuse ejector lever, spring means normally urging said ejector lever for one direction of movement, a link connected to said fuse and arranged normally restraining said ejector lever while said fuse is intact, and means on said ejector lever movable into driving relation with said latch means upon a predetermined movement of said ejector lever in said one direction of movement after said fuse melts. I

19. In an expulsion type fuse assembly, a line terminal, a member pivoted on said line terminal, a keeper on said member, spring means on said line terminal and engaging said member to normally urge said member in one direction of movement, abutment means on said line terminal normally limiting movement of said member in said one direction of movement, a fuse tube, a

latch on said fuse tube in latching engagement with said keeper, means normally urging said 13 latch against said keeper in a direction opposite said one direction of movement of said member, a fuse in said fuse tube, and means cooperably engaging said fuse and adapted to effect an ejection of said fuse and movement of said latch in an opposite direction of movement to effect release of said fuse tube upon fusing of said fuse.

20. In an expulsion type fuse assembly, a fuse tube, a line terminal, a lever pivoted at one end thereof on said line terminal and extending across an end of said tube in spaced opposed relation thereto, a latch on said tube in latching engagement with said lever, a fuse in said tube in conductive connection with said line terminal and extending through an open end of said tube, said lever being arranged movable in one direction of movement in latch engaging disposition under the influence of gases expelled from said tube when said fuse melts, and said lever being movable, at will, in an opposite direction of movement to release said latch.

21. In an expulsion type fuse assembly, a fuse tube, a line terminal, a lever pivoted at one end thereof on said line terminal and extending across an end of said tube in spaced opposed relation thereto, a latch on said tube in latching engagement with said lever, a fuse in said tube and extending through an open end of said tube, said lever being arranged movable in one direction of movement in latch engaging disposition under the influence of gases expelled from said tube when said fuse melts, and means connected to said fuse and responsive to the melting of said fuse arranged operable to move said latch to latch released position in delayed time relation to the melting of said fuse.

22. In an expulsion type fuse assembly, a line terminal, a fuse tube, a fuse in said tube, latching means retaining said tube in latched relation to said line terminal, said latching means including a member responsive to gas expelled from said tube when said fuse melts for movement into latch-maintaining position, and means connected to said fuse and responsive to the melting of said fuse arranged operable to move said latching means to latch-released position in delayed time relation to the melting of said fuse.

23. In an expulsion type fuse assembly, a line terminal, a fuse tube, a latch-engaging member on said line terminal, pivot means on said tube at the upper end thereof, a latch pivoted on said pivot means and in underhung relation to said pivot means, said latch comprising a relatively long arm extending in one direction and disposed below the upper end of said tube, and a relatively short arm extending in an opposite direction and disposed below the upper end of said tube and having an upstanding member thereon in engagement with said latch-engaging member, and spring means. engaging said upstanding member and urging it into engaged relation with said latch-engaging member.

24. In an expulsion type fuse assembly, a line terminal, a fuse tube having a fusible element therein, a hood pivoted on said terminal and extending over an end of said tube and in spaced opposed relation thereto, a keeper on said hood, spring means on said terminal urging said hood in one direction of movement away from said end of said tube, a latch on said tube in latching engagement with said keeper, said hood being movable at will in an opposite direction of movement to release said latch from said keeper and in said one direction of movement under influence of expelled gases issuing from said tube upon fusing of said fusible element to delay release of said latch.

25. In an expulsion tube fuse assembly, a line terminal, a keeper on said terminal, a fuse tube, a fuse in said tube, a latch on said fuse tube in overlying latching engagement with said keeper, means on said tube movable to engage said latch to effect lifting of said latch out of engagement with said keeper, said means being connected to said fuse and being normally restrained thereby while said fuse is intact and being movable when said fuse melts to engage said latch.

26. In an expulsion type fuse assembly, a line terminal, a keeper on said terminal, a fuse tube, a fuse in said tube, a pivot on said tube, a latch on said pivot and having one portion thereof extending from said pivot and overlying said keeper in engaged latching relation and having another portion extending from said pivot in an opposite direction, means to release said latch in response to melting of said fuse, said means comprising a member on said tube movable to depress said another portion of said latch and being normally held inactive by said fuse while said fuse is intact.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,323,213 Garrison, Jr. June 29, 1943 2,574,401 Lesher Nov. 6, 1951

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