US2175904A - Electric cut-out - Google Patents

Description

G. F. LINCKS ELECTRIC CUT-OUT Filed Dec. ll, 1937 Oct. l0, 1939.

Inventor G eorge `F`. LncKS,

JMA

ttorney Patented Oct. 10, 1939 UNITED STATES PATENT OFFICE ELECTRIC CUT-OUT New York Application December 11, 1937, serial Nc. 179,324

22 Claims.

The present invention relates to electric cutouts and has for an object the provision of an improved fuse cut-out of the automatic circuit reclosing type.

5 Another object of the invention is the provision of a circuit reclosing fuse unit of improved construction and arrangement of parts for use in an electric cut-out.

A still further object of the invention is the l provision of improved mechanism for carrying out the inventions forming the subject matter of United States Letters Patent No. 2,164,994, issued July 4, 1939, in my name, and United States Letters Patent No. 2,165,015, issued July 4, 1939,

l in the name cf L. P. sch1es, both cf which patents are assigned to the assignee of the present invention.

Other objects-and the details of that which I believe to be novel and my invention will become apparent from the following description and the claims appended thereto, taken in conjunction with the accompanying drawing. While my invention may be incorporated in cut-outs of either the open type or the enclosed type, as will become apparent hereinafter, I have chosen as the best means of conveying a complete understanding of all of the features of the invention to illustrate and describe an exemplary embodiment thereof as incorporated in a fuse cut-out of the enclosed type.

In the drawing, Fig. 1 is a sectional view of the exemplary cut-out showing the parts thereof in their normal operative positions; Fig. 2 shows the relative positions of the parts of the cut-out after operation of one of the fuses therein, and Fig. 3 shows the positions of the parts after operation of the final one of the fuses there- Referring to the drawing, I0 indicates an electric cut-out casing of the type commonly employed in non-reclosing fuse cut-out installations. This casing is constructed of porcelain or other suitable insulating material and has an integrally formed electric creepage and gas barrier II provided with a, groove I2 for receiving the innermost fuse holder described hereinafter. A mounting bar I3 is Secured to the rear of the casing for attachment thereof to a suitable supporting structure. Secured to the inner face of the rear wall of the casing respectively on the upper and lower sides of barrier II are line terminal contacts I4 and I5 to which line leads may be secured by screws I4' and I5 respectively. Also secured to the rear wall of the casing adjacent the bottom thereof is a hinge bracket I6 (cl. 20o- 126) having a hinge pin I1. Upper contact I4 has a downwardly pressing contact finger 20 backed by a spring strip 2I and has also a pair of spaced resilient Contact fingers 22, the nearer one of which fingers 22 is shown in the drawing. 5

In accordance with the teachings of the hereinbefore identified patents of myself and of L. P. Sohles, a special form of door 23 is provided for closing the open front of casing I0. This door has a recessed inner side for receiving a fuse l0 holder assembly and circuit reclosing mechanism to be described hereinafter, which assembly and mechanism would project beyond the open front of a cut-out casing, such as the one illustrated, primarily designed for non-reclosing cut-out inl5 stallations and having suflicient depth to accommodate only a single fuse holder. On the outer face of the door is an integrally formed eyelet handle 24 adapted to be engaged for swinging the door, fuse holder assembly, and circuit reclosing 20 mechanism into and out of the normal operative position illustrated in Fig. 1. The inner face 0f the door is formed also with a compartment 25 adjacent the lower edge of the door and the front of this compartment is closed by means of 25 a metal plate 26 bearing against the inner face of the door and secured thereto by means of one or more screws 21. Projecting inwardly from plate 26 substantially at right angles to the door is a fuse holder supporting and guiding arm 30 30 of good conductivity metal, upon the inner end of which is pivotally mounted a spring biased contact arm 3l arranged to bear against contact I5. Arm 30 has a pair of vertically extending bores in the innermost one of which is secured, 35 by means of screw 32, a downwardly depending sleeve 33 of insulating material. A terminal collar 34 is mounted on the lower end of sleeve 33 and fastened thereto by means of a screw 35. This collar has an inwardly projecting arm to 40 which is secured, by means of screws 36 and 39, a hinge element or toggle lever 31 which has a hook-shaped portion 38 arranged to engage hinge pin I1. The upper screw 36 is arranged to provide aV pivotal connection between toggle lever 45 31 and the outwardly projecting arm of collar 34, while screw 39 is adapted to be removed to permit relative movement between the toggle lever and the collar. When screw 39 is in place as illustrated in the drawing, it serves as a lock- 50 ing element to prevent relative movement between the toggle lever andthe collar, and under these conditions door 23, plate 26, arm 30, sleeve 33, collar 34, and lever 31 form a rigid structure arranged to rotate as a unit about hinge pin I1. 55

In order to secure the upper end of the door in closed position, there is secured to the inner face of the door adjacent the top thereof an inwardly projecting electrically conductive arm 48 having on its inner end a rounded head portion 4l arranged to be engaged by spring contact ngers 26 and 22 for latching the upper end of the door in closed position. A metallic spring strip is 'fastened on the lower side of arm 46 by means of a rivet 42 or other suitable means and has a pair of contact fingers 43 and 44 extending inwardly and outwardly respectively from the point oi attachment of the spring strip. These Contact iingers 43 and 44 are arranged normally to bear downwardly respectively on the contact caps 45 and 46 on the upper ends of fuse holders 41 and 48 respectively.

Only two fuse holders are employed in the embodiment illustrated, but, as will become apparent hereinafter, the invention may be practiced with more than two fuse holders if desired. Of the pair of fuse holders illustrated, the innermost one, 41, is mounted for longitudinal vertical sliding movement in sleeve 33, while the outermost holder, 48, is mounted for longitudinal vertical sliding movement in the outer bore oi supporting arm 38. Fuse holder 41 is latched in its upper normal operative position by means of an extension 5i] of a fuse link disposed in holder 41 and connected with cap 45, the said extension 56 being passed around a boss 5l on the lower end of hinge element 31 and secured to terminal collar 34 by means of any suitable form 0f clamping means indicated at 52. As will be evident from the drawing, the fuse link in holder 41 normally is electrically isolated from contact I5 due to the insulating sleeve 33 extending between conductive collar 34 and conductive arm 3U. Fuse holder 48 normally is latched in its upper operative position by means of a hook arm 53 which engages the lower end of holder 43 and the mounting of which will become apparent from the ensuing description.

On the lower end oi the plate 26, which as previously described is secured to the inner face of door 23, there are provided two spaced arms 55, the nearer one of which is shown in the drawing, and these arms serve to support a pivot pin 56 upon which is pivotally mounted a fuse terminal 51. This terminal is biased to swing in a counterclockwise direction by means of a helical spring 58 disposed about pivot pin 56. The terminal normally is latched in its position illustrated in Fig. l by securing thereto,

rby means of a winged clamping screw 68, the

end 6l of a fuse link extending out of the lower end of holder 48. The upper end of such fuse link is anchored in the upper end of holder 48 and is electrically connected with contact cap 46. Normally, therefore, the fuse link in holder 48 is electrically connected between contacts i4 and l5, the circuit extending from Contact fingers 26 and 22 through the contact engaging head 4| and arm 46, contact finger 44, cap 46, the fuse link in holder 48, fuse link extension 6l, terminal 51, pivotl pin 56, arms 55, plate 26, fuse holder supporting arm 30, and the spring biased contact arm 3l to lower stationary contact l5.

In order to secure circuit reclosure upon operation of the fuse link in holder 48, there is provided an improved and compact time delayed circuit reclosing mechanism oi the type disclosed in the previously referred to patent of L. P. Sohles. Since the details of this circuit reclosing mechanism are fully set forth in the said Sohles patent, only sulicient of these details will loe described herein to give a proper understanding of the operation of the illustrated cut-out and of the improvements which I have made in certain elements of the Sohles mechanism. On the inner face of plate 26 there is secured by means of screws 62 a guide element 63 which is arranged to support a vertically slidable switch supporting element 64. This switch supporting element is arranged to be biased downwardly by means of a coiled compression spring 65 which bears against the lower face of arm 38 and is reinforced against buckling by means of rod 66. The lower end of element 64 carries a pivot pin 61 upon which is pivotally supported a switching element 68. A helical spring 69 is disposed on pivot pin 61 and arranged to bias the switching element for counterclockwise rotation. The switching element, as described in detail in the said Sohles patent, is substantially U-shaped and has a pair of spaced contact arms 16 arranged to pass on opposite sides of holder 48. Normally switch supporting element 64 and switching element 68 are maintained in raised positions, as illustrated in Fig. 1, by means of a pair of spaced detent fingers 1I, one of which is shown in the drawing. These iingers are carried by the pivotally mounted spring biased terminal 51 and are arranged to engage the lower end of switching element 68, the ngers being held normally in latching position against the action of spring 58 by connection oi fuse link extension 6l with terminal 51, as previously described. Switchng element 68 has a downwardly extending portion 12 arranged to be received between detent fingers 1I and upon the lower end of this extension 12 is mounted the hook arm 53 for latching holder 48 in normal operative position. A shunt strip 13 is connected between terminal 51 and switching element 68 for carrying current to the switching element. Spring 69 tends to effect counterclockwise rotation of contact arms 1li into engagement with contacts 14 on terminal collar 34, as indicated in Fig. 2, but such counterclockwise rotation of the contact arms is prevented when the contact arms are in their raised positions by engagement of the arms with detents 15, one of which may be seen in the drawing, which are mounted on opposite sides of the fuse holder supporting arm 30 and extend downwardly from this arm. In order to delay downward movement of switch supporting element 64 upon release thereof, there is provided a mechanical escapement type timing mechanism of the type described in the previously referred to patent of L. P. Sohles. The gears and inertia arm of this timing mechanism are disposed in compartment 25, as indicated at 16, and this timing mechanism is connected with switch supporting element 64 in a manner to retard the downward movement thereof.

Upon operation of the fuse link in fuse holder 48, which fuse link, as previously set forth, is normally connected between contacts I4 and l5, terminal 51 is released to swing outwardly due to the bias of spring 58 and the pressure exerted by downwardly spring biased switching element 68 against detent ngers 1|, which iingers are oi center with respect to the pivotal mounting of terminal 51. This outward movement of terminal 51 causes disengagement of detent fingers 1l from switching element 68 so that switch supporting element 64 and switching element 68 are free to move downwardly under the influence of spring 85 except for the delaying action of timing mechanism 16. After a. predetermined downward movement of element B4, the upper ends of contact arms 18 become disengaged from detents 15. The contact arms are then rotated in a counterclockwise direction into engagement with contacts 14 by 'means of spring 69. Thevcounterclockwise rotation of switching element 68 causes disengagement of hook arm 53 from fuse holder 48 so that this holder may drop downwardly to the position indicated in Fig. 2 wherein the contact cap 46 on the upper end of the holder is disengaged and spaced a considerable distance from contact nger 44. Also, the engagement Yof vcontact arms 10 with contacts 14 eifects reclosure of the circuit through the fuse link in fuse holder 41, the circuit extending from contact fingers 2U and 22 through contact engaging head 4|, arm 40, contact finger 43, contact cap 45, the fuse link in fuse holder 41, fuse link extension 50, terminal collar 34, contacts 14, contact arms 10, shunt strip 13, terminal 51, pivot pin 56, arms 55, plate 26, fuse holder supporting arm 3'0, and the spring biased contact arm 3|, to lower stationary contact I5.

Subsequent to operation of the fuse link in holder 48 and while the fuse link in holder 41 still is intact, the door and fuse holder assembly may be removed for refusing of holder 48. This may be accomplished readily by pulling outwardly on handle 24 to disengage contact engaging head 4I from contact ngers 2|J and 22 and then rotating the assembly about hinge pin I1 to a point where lever 31 may be disengaged from the hinge pin. After removal of the door and fuse holder assembly from casing I0, fuse link extension 50 may be released to permit holder 41 to drop so as to give access to contact cap 46 with the holder 48 in its position shown in Fig. 2. After installation of a new fuselink in holder 48, the circuit reclosing mechanism and fuse holders are reset and the door and fuse holder assembly replaced in casing I0 in the manner described more in detail hereafter.

In case the rupture of the fuse link in fuse holder 48 is due to a temporary fault, it is desirable that some time delay be afforded before reclosure of the circuit through the fuse link in fuse holder 41 so that the fault current may be completely interrupted in fuse holder 48. Otherwise, the fuse links in both of the fuse holders would operate on a single temporary fault which required an appreciable time to clear after rupture of the fuse link in holder 48. Also, the time delay has a distinct `advantage in that it makes possible to closer coordination between fuse links connected in series at sectionalizing points and fuse links connected in series with induction type relays. The desired time delay in the circuit reclosure is provided, as previously set forth, by the timing mechanism 16. In order that the amount of time delay may be adjusted as desired in accordance withconditions encountered, I provide means for adjustment of the extent to which element 64 must move downwardly before contact arms 10 are released from detents 15. To this end, detent fingers 1| are provided with elongated slots 8D for receiving the screws 8| by which the ngers are secured to terminal 51, so that the fingers may be adjusted vertically. With screws 8| at the lower ends of slots 80, as indicated in the drawing, the detent fingers serve to hold contact arms 10 in their extreme uppermost positions so that a greater downward movement thereof will be required to release the contact arms from detents 15, thus providing a longer time delay. If detent fingers 1| are moved downward so that screws 8| are in the upper ends of slots 80, contact arms 10 normally will be latched in a lower position so that less downward `movement thereof will be required to release the contact arms from detents 15 and thus a shorter time delay will be provided. With fingers 1I in their lowermost positions, fuse holder 48 also is maintained in a lowered position by hook arm 53. Upper spring contact finger 44 may be given such form and tension that it will maintain contact with contact cap 46 notwithstanding the lowered position of holder `48. A further time delay adjustment is provided in that detents 15 have elongated slots 82 for receiving screws 83 by which the detents are secured to supporting arm 30. With screws 83 in the upper end of slots 82, as illustrated, detents 15 are maintained in their lowermost positions so that a greater downward movement of contact arms 10 is required for release of the contact arms from the detents. By adjusting the detents 15 upwardly, less downward movement of the contact arms will be required and thus less time delay will be secured. Hence, by vertical adjustment, both of detent fingers 1i and detents 15 a relatively wide range of adjustment of the time delay of circuit reclosure is made possible.

In order to insure against reclosure of the circuit through the fuse link in holder 41 due to arc-over between the lower ends of holders 41 and 48 upon discharge of arc gases from holder 48, holder 48 is made longer than holder 41 and is arranged to project substantially below the ditional time allows for cooling of the gases, so

that they are less conducting, and for proper clearing of a temporary fault current in holder 48 and proper reclosure of the circuit by means of the time delayed circuit reclosing mechanism.

Also, in accordance with the teachings of the l said patent of R. S. Bennett, a barrier plate 85, preferably of insulation material, is disposed on top of fuse holder supporting arm 30 just beneath the barrier of casing IIJ. This barrier plate 'has an opening through which the fuse holders pass and extends transversely of the fuse holders into close proximity with the walls of casing I0 and door 23, so as to supplement the action of barrier |I and effect substantially complete iso- .f `lation from each other of the spaces around contacts I4 and I5. Thus, arc gases discharged from the lower ends of holders 41 and 48 are greatly retarded, if not entirely prevented, from rising into the upper portion of the cut-out housif ing around contact I4 so as to bridge the terminals of the cut-out.

After reclosure of the circuit through the fuse link in holder 41 by means of Contact arms 10, as previously described-` and in case of continuing or recurring fault, the fuse link in holder 41 will rupture, thereby to cause fuse link extension 50 to release holder 41 so that this holder may drop to its position indicated in Fig. 3 wherein contact cap 45 is `disengaged-and electricallysolated from contact finger 43 and wherein the downward projection of holder 41 gives clear indication or operation of the last of the fuse links. If, in the installation of the door and fuse holder assembly in casing Il), the locking screw 39 is left out of the supporting hinge means comprised of toggle lever 31 and the inwardly projecting arm of collar 313, rupture of the fuse link in holder 41 also will cause release or" the toggle lever by fuse link extension 5l) so that the toggle mechanism may collapse in the well known manner. This permits the door and fuse holder assembly as a unit to drop downwardly and then swing outwardly and downwardly to complete dropped-out positionin the manner described in detail in the previously referred to patent of L. P. Sohles. With the assembly in complete dropped-out position, an additional clearly observable indication is given of operation of all of the fuse links.

Subsequent to operation of the fuse links in both of the fuse holders, or to operation of the fuse link in holder d1 after previous operation of the fuse link in holder 48, door 23 and the fuse holder vassembly supported thereby may be removed rom casing lil in the manner previously described in connection with removal of the door and fuse holder assembly after operation of only the rst fuse link. Replacement of the ruptured fuse links in the fuse holders by new fuse links may be accomplished readily when the fuse holders are in the positions illustrated in Fig. 3, relative to the door, wherein contact caps 45 and i6 are easily accessible. the new fuse links and replacement of caps d5 and 4G, holder 41 is moved upwardly until cap i5 engages and tensions spring contact nger 43. Then fuse holder 1 is latched in its operative position by clamping the fuse link extension 5U to terminal collar E54. Also, holder 4B is moved upwardly into its operative position wherein its contact cap 45 engages and tensions contact fmger 44. Holder Q8 then is latched in operative position by rotation of switching element 68 into parallel relationship with switch supporting element @d and movement of the switching element and supporting element upwardly against compression spring 65 until hook arm 53 engages the lower end of holder 48. Contact arms 1G are then held in open circuit position relative to terminal contacts 1d by detents 15, and switching element 58 is latched in its raised position by swinging terminal 51 toward holder 118 until detent fingers 1l engage the lower end of the switching element in the manner previously described. The terminal element is latched by securing thereto the portion 6I of the fuse link extending out of the lower end of holder 48. The parts of the circuit reclosing fuse unit are then in their positions illustrated in Fig. l and the unit may be installed in the cut-out casing by engaging hinge element 31 with hinge pin l1 and rotating the unit upwardly until contact engaging head il is latched by means of spring contact fingers 22 and spring backed contact finger 2li.

From the foregoing description, it will be apparent that I have provided a circuit reclosing apparatus having an improved and compact construction and arrangement of parts and which may be furnished to electric operating companies and the like in the form of a single unit embodying a plurality oi fuse holders, circuit reclosing mechanism, and time delay mechanism with the necessary connections and means for removably mounting the unit on a cut-out supporting structure of standard design. Such a unit has, among After installation of others, the advantages that it may be used as a replacement for similar units or may be made interchangeable with fuse units of the non-reclosing type so that, without modication of the cut-out supporting structure and stationary contacts carried thereby, an electric cut-out of the non-reclosing type may be converted readily to one of the reclosing type, or vice versa, without the necessity for removal of the cut-out supporting structure from the line pole or the like upon which the supporting structure is mounted in the field.

It will be apparent also to one skilled in the art that my present invention in its broader aspects is not limited to the particular details of the exemplary cut-out illustrated. For example, by simple modifications well within the range of mechanical skill, the illustrated reclosing fuse unit may be adapted for use also in cut-outs of the open type.

lVhat I claim as new and desire to secure by Letters Patent of the United States, is:

l. In an electric cut-out, an insulating support, a pair of terminals carried thereby, a fuse assembly removably mounted on said support and including a plurality of fuse holders and common supporting means therefor arranged to provide for bodily longitudinal movement of the holders relative to said terminals, means for normally latching said holders in operative positions, means for connecting a fuse link in one of said holders between said terminals and means operative responsively to operation of the fuse link in said one holder for completing an electric connection of a fuse link in the other of said holders between said contacts, said latching means being operative to release each of said holders upon operation of the fuse link therein for bodily movement of the holder to a position isolated electrically from at least one of said terminals.

2, In an electric cut-out, the combination with an insulating support having spaced terminals, or" a circuit reclosing fuse unit comprising a plurality of fuse holders, a common supporting structure for-said holders arranged to guide the holders for bodily movement relative to the supporting structure, means for latching the holders against bodily movement and in normal operative positions, said latching means being arranged to release each of said holders for bodily movement upon operation of a fuse link therein, means for mounting said supporting structure and holders on said insulating support with the holders disposed for successive connection of fuse links in the respective holders between said terminals, means for connecting a fuse link in one of said holders between said terminals, and circuit reclosing mechanism carried by said supporting structure operative responsively to operation of a fuse link in said one holder for completing an electric connection of a fuse link in another of said holders between said contacts, each ol said holders upon release thereof by said latching means being lmovable bodily to a position wherein the holder is electrically isolated from at least one of said terminals.

3. In a circuit reclosing fuse unit for installation on an electric cut-out support of the type having a pair of spaced terminal contacts, a plurality of fuse holders and common supporting means therefor arranged for bodily longitudinal movement of the holders relative to said supporting means, means for latching said holders against such movement and in normal operative positions, means for mounting said supporting means and holders on a cut-out support of the above said type, means for connecting a fuse link in one of said holders between the stationary contacts of the cut-out support, and circuit reclosing mechanism operative for completing an electric connection of a fuse link in another of said holders between the stationary contacts of the cut-out support upon rupture of the fuse link in said one holder, said latching means being operative to release each of said holders upon rupture of the fuse link therein for bodily movement of the holder.

4. In an electric cut-out, a first stationary contact device, a second stationary contact device, a fuse assembly including a pair of fuse holders each having a terminal for connection with one end of a fuse link therein, supporting means for said holders arranged for bodily longitudinal movement of the holders relative to said contact devices, means for maintaining said holders in normal operative positions with said fuse holder terminals engaging said first contact device, said maintaining means being operative upon rupture of a fuse link in each of the holders to release the holder for bodily movement, means for connecting the other end of a fuse link on one oi said holders with said second contact device, and circuit reclosing mechanism operative upon rupture of a fuse link in said one holder for completing an electric connection between said second contact device and the other end of a fuse link in the other of said holders, each of said holders upon release thereof by said maintaining means being movable longitudinally to disengage its corresponding terminal from said rst Contact arranged for connection with one end of a fuse link in the holder and for engagement normally with said contact device and said fuse holder supporting means being arranged for bodily longitudinal movement of the holders for disengagement of said terminals from said contact device, latching means for normally preventing such movement of the holders, means for connecting the other end of a fuse link in one of said holders with the other of said spaced contact terminals and means operative upon rupture of the fuse link in said one holder for completing an electric connection between said other terminal and the other end of a fuse link in the other of said holders, said latching means being operative to release each of said holders upon rupture of the -fuse link therein.

6. A circuit reclosing fuse unit comprising a plurality of fuse holders each having a terminal for connection with one end of a` fuse link therein, a supporting structure for said holders arranged to provide for bodily movement of the holders relative to the supporting structure, means for mounting said supporting structure and holders on an electric cut-out support having an upper and a lower stationary contact, an upper and a lower contact -engaging device carried by said supporting structure for engagement respectively with the upper and lower stationary contact of a cut-out support, latching means for maintaining said holders in operative positions with their said terminals engaging said upper contact engaging device, said latching means being arranged to release each of said holders for bodily movement thereof upon operation of a fuse link therein, means for connecting the other end of a fuse; link in one of said holders with said lower contact engaging device and means operative responsively to operation of a fuse link in said one holder for completing an electric connection between said lower contact engaging device and the other end of a fuse link in another of said holders, each off said holders upon release thereof by said latching means being movable bodily to disengage its corresponding terminal from said upper contact engaging device.

'7. In an electric cut-out of the circuit reclosing type, a housing including a casing having an open side and a door mounted for closing said open side, spaced stationary terminals in said housing, a plurality of fuse holders, means including said door for supporting said holders in said housing and arranged for bodily longitudinal movement of the holders relative to said terminals, means for latching said holders in normal operative positions and arranged to release each of said holders for bodily movement upon rupture of a fuse link therein, and means for successively connecting fuse links in the respective holders between said terminals, each of said holders upon release thereof by said latching means being movable longitudinally to a position wherein the holder is disconnected from at least one of said terminals.

8. In an electric cut-out, a housing comprising a casing having an open side and a door removably mounted for closing said open side, a pair of terminal contacts mounted in said casing, a contact device carried by said door and arranged to engage one of said terminal contacts, a fuse assembly in said housing and including a pair of fuse holders with common supporting means therefor, said supporting means providing for bodily longitudinal movement of said holders relative to said contact device, each of said holders having a terminal for connection with' one end of a fuse link in the holder, means for latching said holders in normal operative positions with said terminals engaging said contact device, means for connecting the other end of a fuse link in one of said holders with the other of said terminal contacts and circuit reclosing mechanism operative upon rupture of the fuse link in said one holder for completing an electric connection between said other terminal contact and the other end of a fuse link in said other holder, said latching means being operative to release each of said holders upon operation of the fuse link therein for longitudinal movement of the holder to disengage its corresponding terminal from said contact device.

9. In an electric cut-out of the circuit reclosing type, a housing comprising a casing and a dooi` removably mounted for closing an open side of the casing, spaced terminals mounted in the casing, a plurality of fuse holders, means mounted on the inner side of said door for supporting said holders in said housing, said holders being bodily longitudinally movable relative to said terminals, means for latching said holders in normal operative positions, and means for successively connecting fuse links in the respective holders between said terminals, said latching means being operative upon rupture of a fuse link in each of said holders to release the holder for longitudinal movement thereoi:` to a position electrically isolated from at least one of said terminals.

10. In an electric cut-out of the circuit reclosing type, a housing comprising a casing having an open iront and a door removably mounted for closing said open front, spaced terminals mounted in the casing, a plurality of fuse holders, supporting means for said holders including a guide member attached to and projecting inwardly from the inner side of said door, said member being arranged to maintain the holders with their axes lying substantially in a plane normal to the irear wall of said casing and to provide for bodily longitudinal movement of the holders relative to said terminals, means for latching the holders in normal operative positions, and means for successively connecting use links in the respective holders between said terminals, said latching means being operative to release each of said holders upon rupture of a fuse link therein for longitudinal movement of the holder to a position electrically isolated from at least one of said terminals.

11. An automatic circuit reclosing fuse unit adapted for removable installation in an electric cut-out casing and comprising a door adapted to close an open side of an electric cut-out casing, a rst and a second contact device arranged respectively to connect with a pair of stationary terminals in an electric cut-out casing, a fuse assembly including a plurality of fuse holders and means for supporting the holders on the inner side of said door, each of said holders having a terminal normally engaging said rst contact device and arranged to connect with one end of a fuse link in the holder, said supporting means being arranged for bodily longitudinal movement of the holders to disengage said terminals from said first contact device, means for latching said holders in their normal operative positions, and means for successively electrically connecting the other ends of fuse links in the respective holders with said second contact device, said latching means being arranged to release each of said holders for longitudinal movement upon rupture of a fuse link therein.

12. In an electric cut-out, an insulating support having spaced stationary terminals, a fuse assembly including a pair of fuse holders and aY against sliding and in normal operative positions,V

a terminal contact carried by said supporting structure and insulated from said element, means for normally electrically connecting a fuse link in one of said holders between the other of said stationary terminals and said element, means for normally electrically connecting a fuse link in the other of said holders between said other stationary terminal and said insulated contact, and circuit reclosing switching means operative upon rupture of a fuse link in said one holder for completing an electric connection between said insulated contact and said element, said latching means being operative to release each of said holders upon rupture of a fuse link therein for longitudinal sliding of the fuse holder to effect electrical isolation thereof from at least one of said stationary terminals.

13. In an electric cut-out, an insulating support having spaced stationary terminals, a pair of fuse holders, a common supporting structure for said holders including an electrically conductive element having means for receiving and slidably guiding said holders and an insulating member rigidly attached to said element and having mounted thereon in insulated spaced relation to said element a contact terminal and means for mounting said supporting structure on said insulating support, said element having means arranged to connect electrically with one of said stationary terminals, latching means normally restraining said holders from sliding relative to said element and in operative positions, means for connecting a fuse link in one of said holders between said element and the other of said stationary terminals, means for connecting a fuse link in the other of said holders between said contact terminal and said other stationary terminal, and circuit reclosing mechanism carried by said supporting structure and operative upon rupture of a fuse link in said one holder for completing an electric connection between said contact terminal and said element thereby to reclose a circuit througlr the fuse link in said other holder, said latching means being operative to release each of said holders for longitudinal sliding upon rupture of the fuse link therein.

14. In an electric cut-out, the combination with an insulating support having a hinge bracket and an upper and a lower terminal contact, of a circuit reclosing fuse unit including a pair of fuse holders, an electrically conductive member having means receiving and guiding said holders for substantially vertical longitudinal movement relative to said terminal contacts, an insulating sleeve attached at one end to said member and extending in, surrounding relation to one of said holders, a terminal collar mounted on the other end of said sleeve and having attached thereto a hinge element for engagement with said hinge bracket, means for latching said holders against sliding and for maintaining the holders in normal operative positions, means for connecting the upper ends of fuse links in said holders with said upper contact, means for connecting said member with said lower contact, means for connecting the lower endV of a fuse link in said one holder with said collar, means for connecting the lower end of a fuse link in the other of the holders with said member, and circuit reclosing mechanism operative responsively to operation of a fuse link in said other holder for completing an electric connection between said member and said collar, said fuse holders upon rupture of fuse links therein being released by said latching means and movable downwardly to positions electrically isolated from said upper contact.

l5. In an electric cut-out, an insulating support, spaced terminals carried thereby, a fuse assembly including a pair of fuse holders and common supporting means therefor, means including a toggle lever hingedly mounted at one end on said support and pivotally connected at the other end with said assembly for supporting said assembly on said support removably in normal operative position relative to said terminals, said lever being held normally in fixed relation to said assembly, one of said holders being supported for bodily longitudinal movement relative to said supporting means and out of its normal operative position, means for restraining said one holder against longitudinal movement and in normal operative position, said restraining means being operative to release said one holder upon rupture of a fuse link therein, means for connecting a fuse link in said one holder between said terminals, and means operative responsively to rupture of a fuse link in said one holder for completing a connection of a fuse link in the other of said holders between said terminals, said toggle lever being releasable by operation of a fuse link in said other holder to provide for movement of said assembly as a unit from its said normal operative position.

16. In an electric cut-out of the circuit reclosing type, a pair of stationary terminals, a fuse holder supported normally for connection of a fuse link therein between said terminals and arranged for bodily longitudinal movement relative to the terminals, circuit reclosing mechanism including a switching element normally disposed in open circuit position, detent means carried by said switching element operative to latch said holder in normal connected position when said element is in open circuit position and operative to release said holder upon movement of said element toward closed circuit position, and means operative upon rupture of a fuse link in said holder for effecting movement of said element to closed circuit position, said holder upon release thereof by said detent means being longitudinally movable to a position electrically isolated from one of said terminals.

17. In an electric cut-out, the combination with a pair of stationary terminals and a fuse holder supported normally for connection of a fuse link therein between said contacts and arranged for bodily longitudinal movement relative to the terminals, of circuit reclosing mechanism including a member guided for movement in a direction substantially parallel with said holder, a. switch element movably mounted on said member and spring biased to closed position, a detent mounted for hol-ding said element in open position When, said member is in a rst position, means carried, by said element operative to restrain said holder in connected position when, said member is in its said first position and said element in its said open position, means for latching said member in its said rst position and arranged to release said member upon operation of a fuse link in the holder, means operative upon release of said member for effecting movement thereof toward a second position to release said element from said detent, said element upon release being movable toward closed position so as to cause release of said holder by said restraining means, and timing mechanism connected for delaying movement of said member toward its said second position.

18. In combination, a switch supporting member, a switching element movably mounted thereon and spring biased to a circuit controlling position, a detent mounted for holding said element in another position when said member is in a first position, releasable latching means for holding said member in its said first position, means operative upon release of said latching means for effecting movement of said member toward a second position to disengage said switching element from said detent, and timing mechanism connected for delaying movement of said member toward its said second position, said detent being adjustably mounted for movement substantially in the direction of movement of said member so as to provide for adjustment of the movement of said member required to effect release of said element from the detent.

19. In combination, a switch supporting member, a switching element movably mounted thereon and spring biased to a circuit controlling position, a rst detent mounted for holding said element in another position when said member is in a rst position., releasable latching means including a second detent arranged to restrain said member in its said rst position, means operative upon release of said member for effecting movement of said member toward a second position to disengage said switching element from said rst detent, and timing mechanism connected for delaying movement of said member toward its said second position, said second detent being adjustably mounted for movement substantially in the direction of movement of said member so as to provide for adjustment of the said rst position of said member and thereby the amount of movement of said member required to effect release of said element from` said rst detent.

20. In an electric cut-out of the circuit reclosing type, the combination with a pair of stationary terminals and a fuse holder normally supported for connection of a fuse link therein between said terminals, of circuit reclosing mech-- anism including a movably mounted switch supporting member, a switching element movably mounted on said member and biased to closed position, a rst detent mounted for holding said element in open position when said member is in a nrst position, a movably mounted terminal having a second detent operative releasably to restrain said member in its said first position, said second detent being held in its restraining position by connection of a fuse link in said holder with said movably mounted terminal, said second detent being adjustably supported on said terminal for movement substantially in the direction of movement of said member so as to provide for adjustment of the said rst position of said member, and means operative upon release of said member by said second detent for effecting movement of said member toward a second position to disengage said switching element from said rst detent.

21. In an electric cut-out of the circuit reclosing type, a support having spaced terminals, a fuse assembly removably mounted on said support and including a fuse holder having a fuse link electrically connected between said terminals and a supporting structure for said holder, and circuit reclosing means carried by said structure, which means includes a movable mounted switch supporting member, a switching element movably mounted on said member and biased toward a circuit closing position, a iirst detent operativey to maintain said element in an open circuit position when said member is in a normal position, means tending to eiect movement of said member to a second position to cause release of said elemerit from said rst detent, and means latching said member in its said normal position including a terminal element mounted on and movable relative to said structure and having a second detent operative to latch said member in its said normal position, said terminal element being biased to a position to cause said second detent to release said member and said second detent being held in iatching position by mechanical connection of the fuse link in said holder with said terminal element.

22. In an electric cut-out of the circuit reclosing type, a casing having spaced terminals, a fuse assembly removably mounted in said casing and including a fuse holder and a unitary structure for supporting said holder with a fuse link therein connected between said terminals, said structure including a door for closing an open side of tlie casing, means arranged to hold said structure substantially Xed in normal position with said door in closed position during fuse operation, a frise terminal element carried by and movable relative to said structure, circuit reclosing mechanism carried by said structure and including a switching element biased for movement 10 to a circuit controlling position, and means nor-

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