CA1146198A - Fuse cutout - Google Patents
Fuse cutoutInfo
- Publication number
- CA1146198A CA1146198A CA000373559A CA373559A CA1146198A CA 1146198 A CA1146198 A CA 1146198A CA 000373559 A CA000373559 A CA 000373559A CA 373559 A CA373559 A CA 373559A CA 1146198 A CA1146198 A CA 1146198A
- Authority
- CA
- Canada
- Prior art keywords
- fuse tube
- cutout
- recoil bar
- convexity
- contact
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Landscapes
- Fuses (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE An improved cutout which accepts a fuse tube of standard length, which is costly to manufacture and which exhibits improved performance, has an offset, rather than a straight, recoil bar. The offset positions the end of the recoil bar closer to the short leg of a J Spring, and positions a hole in the end, through which freely passes a pin interconnecitng the legs of the J, closer to a convexity in the short leg. Operation of the cutout causes a fuse tube, one end of which is in the concavity, to experience random longitudinal and transverse thrust forces. The offset limits the transverse motion of the short J leg and the fuse tube can exper-ience to (a) limit bending forces of the tube and breakage thereof, and (b) prevent the fuse tube disengaging the concavity before the longitudinal thrust thereof subsides. The offset also ensures that longitudinal thrust forces the tube are simul-taneously transferred from the one end of the fuse tube to the recoil bar and from the other end of the tube to a contact assembly opposite from the recoil bar.
Description
.3L~ Case sc- 5153-C
IMPROVED FUSE CUTOUT
BACK(~ROUND OF THE INVENTION
Field of the Invention The present invention relates to an impl~oved fuse cuout and, more partic-ularly, to an improved fuse cutout which is less expensive to manufacture than prior art fuse cutouts, but which exhibits improved operating performance notwith-standing the decrease in expense thereof. The improved fuse cutout of the present invention may be used with a fuse link of the type described and claimed in com-monly-assigned, co-filed Canadian Patent Application, Serial No. 373,563 îiled March 20, 1981 in the name of Riehard J. Sabis. The cutout of this application may also include an improved fuse tube as described and claimed in commonl~-assigned, co-filed Canadian Patent Applieation, Serial No. 373,576 filed March 20, 1981 inthe name of William E. Schm~mk.
Discussion of ~the Prlor Art Fuse cutouts ancl fuse links therefore are well known. A typical fuse ClltOUt includes a~hollow insula~tive fuse tube having conductive ferrules mounted to the opposite ends thereof. Qne ferrule (often called the "exhaust" ferrule) is located at an exhaust end of the fuse tube and usually includes a trunnion casting which inter-fits with a trunn~lon pocket of R first contact Rssembly ~arrled by one end of aporcelain or similar Insulator. The other ferrule is normally held and latched by a second contact assembly carried by the other end of the porcelain insulator so that the fuse tu~e is normally parallel to, but spaced from, the porcelain insulator. The porcelain insulator is mountable to the cross-arm of a utility pole or a similarstructure. The fuse link is located within the fuse tube with its ends respectively electrically continuou& with the ferrules. One point of an electrical circuit is;~` connected to the first contact assembly, while another point of the circuit is con-nected to the second contact assembly. Often, the insulator and the fuse tube are oriented perpendicular to the ground so that the ex~aust ferrule and the first con-, tflct ~assembly are~located~ below the other ferrule and the seeond contact assembly. ~ ~
~ ~
The fuse tuhe may include a high burst strength outer portion -- for exarmple, a fiber-glass-epoxy composite--lined with or containing an ablative arc-extinguishing material, such as horn fiber or bone fiber.
Normal currents flowing through the electrical circuit flow without affecting the fuse link. Should a fault current or other overcurrent, to which the fuse link is designed to respond, occur in the circuit, the fuse link operates as described below. Operation of the fuse link permits the upper ferrule to disengage itself from the upper contact assembly, whereupon the fuse tube rotates down-wardly due to coaction of the trunnion casting and the trunnion pocket. If the fuse link operates properly, current in the circuit is interrupted and the rotation of the fuse tube gives a visual indication that the cutout has operated to protect the circuit.
Typical fuse links include a first terminal and a second terminal, between which there is normally connected a fusible element made of pure silver, silver-tin, or the like. Also connected between the terminals may be a strain wire, for a ~ .
`~ ~ purpose described below. The second terminal is electrically continuous with, and is usually mechanically connected to7 a button assembly7 which is engageable by a . ~
20 porti of the upper ferrule on the fuse tube. The first terminal is eonnecteà to a flexible, stranded length of cableO Surrounding at least a portion of the second ~ ~ :
terminal, the fusible element, the strain wire (if used), the first terminal, and some portion of the flexible stranded cable is a sheath~ The sheath is typically make of a so-called ablative arc-extinguishing material (such as horn fiber) or is a cellulosic 25 material impregnated with an ablative arc-extinguishing material (such as boric acid). Such ablative arc-extinguishing materials are well known and comprise compounds or compositions which, when exposed to the heat of a high~voltage arc,ablate to rapidly evolve large quantities of de-ionizing, turbulent and cooling gases. Typically, the sheath is much shorter than the fuse tube and terminates 30 short of the exhaust end of the fuse tube.
.
The free end of the stranded cable exits the fuse tube from the exhaust end thereoe and has tension or pulling force maintained thereon by a spring-loaded flipper on the trunnion casting. The tension or puUing force exerted on the cable by the flipper attempts to pull the cable and the first terminal out o~` the sheath and 5 out of the fuse tube. The force of the flipper is normally restrained by the strain wire, typical fusible elements not having sufficient mechanical strength to resist this tension or pulling force.
. .
In the operation of typical cutouts, a fault current or other overcurrent 10 results, first, in the melting or vaporization of the fusible element, followed by the ; melting or vaporization of the strain wire. Following such melting or vaporization, a high-voltage arc is established between the first and second terminals within the sheath and the flipper is now free to pull the cable and the first terminal out of the sheath and, ultimately, out of the fuse tube. As the arc 15 forms, the arc-extinguishing materials of the sheath begin to ablate and high quantities of deionizin~, turbulent and cooling gases are evolved. The movement of the irst terminaI under the action of the flipper, and the subsequent rapid movement thereof due to the evolved gases acting thereon as on a piston, results in elongation of the arc. The presence of the de-ionizing, turbulent and cooling gas, 20 plus; arc elongation, may, depending on the level of the fault current or other over-:
current, ultimately result in extinction of the arc and interruption of the current at a subsequent eurrent zero. The loss of the tensis)n on the stranded cable origmally effected by the flipper permits the trunnion casting to experience some initial movement relative to the exhaust ferrule which permits the upper ferrule to dis-Z5 engage itself from the upper contact assembly. This initiates a downward rotationof the fuse tube and its upper ferrule to a so-called "drop out" or "drop down"
;`~ position.
`: :
As noted immediately above, arc elongation within the sheath and the 30 action of the evolved gases rnay extinguish the arc. At very high fault current or overcurrent levels, however, arc elongation and the sheath may not, by themselves~
:, , be suf~icient to achieve this end. Simply stated, at very high fault current levels, : ` :
either the sheath may burst (because of the very high pressure oî the evolved gas) or insufficient gas may be evolved therefrom to quench the high current level arc.
For these reasons, the îuse tube is made of, or is lined with, ablative arc-extin-guishing horn fiber or bone fiber, as noted above~ In the event the sheath bursts, 5 the arc-extinguishing material for the fuse tube interacts with the arc, gas evolved as a result thereof effects arc extinction~ II the sheath does not burst, the arc-extinguishing material of the fuse tube between the end OI the sheath and the exhaust end of the fuse tube is, nevertheless, available for evolving gas, in addition to that evolved from the sheath. The joint action of the two quantities of evolved 10 gas, together with arc elongation, e~tinguish the arc.
Many manufacturers of cutouts and fuse links of the types described above continue to make concerted efforts to decrease the costs of the material and ~; labor thereof, both as a matter of simple, good commercial practice, and in view of lS the fact that certain materials, such as silver, copper, and bronze, continue to experience large price increases. At the same time, manufacturers of cutouts and ;~ fuse links continue ongoing programs to improve the performance of these pro-ducts. A less expensive, improved performance fuse cutout is a primary goal of the present invention.
The upper or second contact assembly usually includes a J~haped spring contact, an end of the long leg of which is mounted for flexing to a rigid recoil bar. The recoil bar extends to a position between the legs of the J. A pin inter-connects the legs of the J for conjoint rnovement. The pin passes through an 25 aperture in a bushing pressed into, and extending beyond, a hole through the recoil bar and is connected to the opposite side of a concavity formed in the J's short leg. The concavity engages and holds an end of the fuse tube, RS described below.
A spring acts between the recoil bar and the concavity to set a "rest"
30 position of the J's short leg (and of the J's long leg~. Upward deflection of the J's short leg is limited by abutment between the opposlte side of the concavity and the bushing.
~ 4 ~
The lower or Eirst contact assembly includes a feature--a projection, stud or the like -- normally spaced from a similer feature or surface on the exhaust ferrule. The normal spaeing between these features is substantially the same as the normal spacing between the opposite side of the concavity and the bushing.
When a fuse tube is properly positioned between the contact assemblies, the J's short leg is held away from its rest position against the bias of both the spring and the lon~ leg to firmly engage a contact cap on the upper ferrule of the fuse tube in the concavity~ When the fuse link operates, gases evolved within the fuse tube thrust It against the J's short leg in jet-like Eashion, further compressing the spring and flexing the J's long leg. The fuse tube may also randomly move the ~ ~ pin transversely at this time until the pin engages the walls of the aperture in the `~ bushing. The random, transverse fuse tube movement may b0 viewed as precession of ~the pin between a pair of "pivots," one of which is the pin's connection to the J's short leg, the other of which is the envelope of the points of contact between the pin and the walls of the bushing aperture. This random, transverse fuse tube : ~ :
movement may have~ several deleterious effeets.
,. , First, ideally the features on the first contact assembly and the exhaust 2O ~ ferrule abut at the same time the opposite side of the concavity abuts the bushing.
':
This transfers the forces on the fuse tube simultaneously to the contact assembiies. U the fuse tube moves too far transversely during its thrustmg, these abutting events will not be simultaneous.
~' :
; Z5 ~eeond, icleally the contaet cap ~hould not disenga~e th~ eoncavity until ~. 1 the fusible element of the fuse link completely melts to release the tension in the cable and until the initial thrust of the fuse tube subsides. Release of this tension :~, and subsiding of fuse ;tube thrust permits a limited amolmt of relative movement between the exh~ust ferrule and the trunnion casting a~out a toggle joint there-30 between. This limited movement permits the eontact cap to move out of theconcavity and the fuse tube to fall "open" due to rotation of the trunnion casting in ~:., ~ :: ~ : :
, ~w ~
the trunnion pocket. If the fuse tube moves too far transversely during its thrusting, the contact cap may disengage the concavity too early.
Third, transverse movement of the fuse tube can apply n bending move-5 ment thereon. This bending movement can fracture the fuse tube near the exhaust ferrule.
. .
Any solution to the above problems must take into account that presently availaMe fuse tubes have "standard" lengths, which depend, inter alia, upon the 10 voltage of the circuit to whieh the cutout is connected. Any such solution must not alter the cutout so as to require non~tandard fuse tube lengths.
The present invention, thell, is intended to solve the above--described problems, while achieving the overall goals of improving fuse cutout performance, 15 while at the same time decreAsing its cost~
SUMMARY OP THE INVENTION
According to the present invention, there is provided an improved fuse cutout. The cutout includes a mounting having a first and a second contact 20 assembly. A fuse tube of selected length is to be supported between the contact assernblies. The improve~ cutout includes an improved second contact assembly having certain old elements. The second contact assembly includes a generally J-shaped spring contact. A long leg of the J is attached to a rigid recoil bar, a portion of which extends into the space between the legs of the J. The short leg of 25 the J has a concavity formed therein and a complementary convexity. The con-CRVity selectively receives an end of the fuse tu~e. A pin freely passes through a hole in the extending portion of the recoil bar and is attached to move together as the pin moves through the hole and the long leg flexes out of a rest positon about its point of attachment to the recoil bar. A spring acts between the base of the 30 convexity and the recoil bar to set the rest position of the long leg.
;, ~ - 6 -:
: .
Closure of the cutout by rotating the fuse tube in the first contact assembly inserts the fuse tube end into the concavity so that the legs of the J are deflected against the action of the spring and the flexin~ of the long leg out of its rest position. When the cutout operates, the fuse tube thrusts both against and 5 transverse to the concavity. This thrust applies a bending force to the fuse tube which may fracture as a consequence. The thrust also randomly mQves the J's short leg transverse to the pin until the pin engages the waIls of the hole. Moreover, the thrust further deflects the legs against the action of the sprin8 and the flexing of the long leg.
~- In the improved cutout, an offset is formed in the recoil bar. This offset positions the extending portion of the recoil bar and the hole substantially closer to the short leg and the eonvexity. This closer positioning limits the extent of the random transverse motion of the short leg before the pin enga~es the hole walls.
15 Consequently, the bending force on the fuse tube i9 limited. The offset also positions the convexity closer to the recoil bar to decrease the amount of move-~; ment of the short leg bef~re it engages the recoil bar. This earlier transfers the thrust-caused force to the recoil bar.
;~ 20 Often the fuse tube and the first contact assembly each have a feature or projection which are normally spaced apart. When the legs further deflect due to cutout operation, these features engage. In other aspects of the improved cutout, the distance between the convexity and the recoil bar after cutout closure, but before further leg deflection, is equal to the normal spacing between the features.
,~ I
25 Thus, thrust-caused force on the fuse tube is simultaneously transferred to the first contact assembly and the recoil bar.
The above improvements do not alter the typical spacing between the concavity and the first contact assembly. Thus, fuse tubes of standard length may 30 be usecl in the cutout without alteration.
~ ~ :
y~
In cutouts, it is desirable that the fuse tube end not disengage the con-cavity until the initial thrust of the fuse tube subsides. If the fuse tube moves too far transversely during its thrusting, the fuse tube end may disengage the concavity too early. The offset limits the amount of transverse pin movement and, hence, of 5 transverse fuse tube movement. This prevents too early disengagement of the fuse tube and from the concavity.
DESCRIPTION OF TEIE DRAWINC~
EIGURE 1 is an elevational, prespective view of a fuse cutout according to 10 the prior art;
FIGURE 2 is an enlarged elevational view OI a portion of the cutout of ~IGUlR~ 1 and FI~URE 2a is similar but at a tirne during the operation thereof;
~IGURE 3 is an elev~tional, perspective view of an improved fuse eutout aceording to the present invention;
~.
FIGURES 4a - 4c are enlarged elevational views of portions of the cutout of FIGURE 3; and `
FIGURE S is an enlarged elevational view similar to FIGURE 4a during operation of the cutout of FIGIJRE 3.
_TAILED ES(~RIPTION
~5 Referring first to FIGURE 1, there is shown a fuse cutout 10 according to the prior art. An improved cutout 12 according to the present invention is shown in FIGURES 3-5 and is described later. The same or simllar reference numerals are used for corresponding elements of the cutouts 10 and 12. The improved fuse cutout 12 of the present invention operates in a similar, but improved, manner to that of the prior art fuse cutout 10, and is also less costly.
.
;`. ' ~ 8 -...
The prior art cutout 10 includes an elongated, skirted insulator 24 which has affixed thereto a mounting member. The mounting member 16 permits mounting of the insulator 14 and the use cutout 10 to an upright or a cross-arm of a utility pole (not shown~. The insulator 14 may be rnade of porcelain or similar 5 material.
Afixed to the upper end of the insulator 14 is an upper contact assembly generally designated lû~ Affixed to the lower end of the insulator 14 is a lower contact assembly 2û. The cutout 10 also includes a ~use tube assembly 22 which in 10 the normal or unoperated condition of the cutout 10 may be maintained in the vertical position shown in FIGURE 1, although other orientations may be desirable. Specifically, the fuse tube assembly 22 includes an insulative fuse tube : .:
:~ 24 of a well-known type, which may comprise an epoxy-fiber~lass composite outer ;~; shell lined with horn fiber or bone fiber. nqounted or affixed to the upper end of the 15 fuse tube 24 is an upper ferrule assembly 26, while at the opposite lower or exhaust end of the fuse ~tube 24 is a lower or exhaust ferrule assembly 2#. In the position o~
the fuse~ tube assembly 22 depicted in FIGURE 1, the lower ferrule assembly 28 is held by the lower contact assembly 20, while the upper ferrule assembly 26 is held, and latched against the movement, by the upper contact assembly 18.
IMPROVED FUSE CUTOUT
BACK(~ROUND OF THE INVENTION
Field of the Invention The present invention relates to an impl~oved fuse cuout and, more partic-ularly, to an improved fuse cutout which is less expensive to manufacture than prior art fuse cutouts, but which exhibits improved operating performance notwith-standing the decrease in expense thereof. The improved fuse cutout of the present invention may be used with a fuse link of the type described and claimed in com-monly-assigned, co-filed Canadian Patent Application, Serial No. 373,563 îiled March 20, 1981 in the name of Riehard J. Sabis. The cutout of this application may also include an improved fuse tube as described and claimed in commonl~-assigned, co-filed Canadian Patent Applieation, Serial No. 373,576 filed March 20, 1981 inthe name of William E. Schm~mk.
Discussion of ~the Prlor Art Fuse cutouts ancl fuse links therefore are well known. A typical fuse ClltOUt includes a~hollow insula~tive fuse tube having conductive ferrules mounted to the opposite ends thereof. Qne ferrule (often called the "exhaust" ferrule) is located at an exhaust end of the fuse tube and usually includes a trunnion casting which inter-fits with a trunn~lon pocket of R first contact Rssembly ~arrled by one end of aporcelain or similar Insulator. The other ferrule is normally held and latched by a second contact assembly carried by the other end of the porcelain insulator so that the fuse tu~e is normally parallel to, but spaced from, the porcelain insulator. The porcelain insulator is mountable to the cross-arm of a utility pole or a similarstructure. The fuse link is located within the fuse tube with its ends respectively electrically continuou& with the ferrules. One point of an electrical circuit is;~` connected to the first contact assembly, while another point of the circuit is con-nected to the second contact assembly. Often, the insulator and the fuse tube are oriented perpendicular to the ground so that the ex~aust ferrule and the first con-, tflct ~assembly are~located~ below the other ferrule and the seeond contact assembly. ~ ~
~ ~
The fuse tuhe may include a high burst strength outer portion -- for exarmple, a fiber-glass-epoxy composite--lined with or containing an ablative arc-extinguishing material, such as horn fiber or bone fiber.
Normal currents flowing through the electrical circuit flow without affecting the fuse link. Should a fault current or other overcurrent, to which the fuse link is designed to respond, occur in the circuit, the fuse link operates as described below. Operation of the fuse link permits the upper ferrule to disengage itself from the upper contact assembly, whereupon the fuse tube rotates down-wardly due to coaction of the trunnion casting and the trunnion pocket. If the fuse link operates properly, current in the circuit is interrupted and the rotation of the fuse tube gives a visual indication that the cutout has operated to protect the circuit.
Typical fuse links include a first terminal and a second terminal, between which there is normally connected a fusible element made of pure silver, silver-tin, or the like. Also connected between the terminals may be a strain wire, for a ~ .
`~ ~ purpose described below. The second terminal is electrically continuous with, and is usually mechanically connected to7 a button assembly7 which is engageable by a . ~
20 porti of the upper ferrule on the fuse tube. The first terminal is eonnecteà to a flexible, stranded length of cableO Surrounding at least a portion of the second ~ ~ :
terminal, the fusible element, the strain wire (if used), the first terminal, and some portion of the flexible stranded cable is a sheath~ The sheath is typically make of a so-called ablative arc-extinguishing material (such as horn fiber) or is a cellulosic 25 material impregnated with an ablative arc-extinguishing material (such as boric acid). Such ablative arc-extinguishing materials are well known and comprise compounds or compositions which, when exposed to the heat of a high~voltage arc,ablate to rapidly evolve large quantities of de-ionizing, turbulent and cooling gases. Typically, the sheath is much shorter than the fuse tube and terminates 30 short of the exhaust end of the fuse tube.
.
The free end of the stranded cable exits the fuse tube from the exhaust end thereoe and has tension or pulling force maintained thereon by a spring-loaded flipper on the trunnion casting. The tension or puUing force exerted on the cable by the flipper attempts to pull the cable and the first terminal out o~` the sheath and 5 out of the fuse tube. The force of the flipper is normally restrained by the strain wire, typical fusible elements not having sufficient mechanical strength to resist this tension or pulling force.
. .
In the operation of typical cutouts, a fault current or other overcurrent 10 results, first, in the melting or vaporization of the fusible element, followed by the ; melting or vaporization of the strain wire. Following such melting or vaporization, a high-voltage arc is established between the first and second terminals within the sheath and the flipper is now free to pull the cable and the first terminal out of the sheath and, ultimately, out of the fuse tube. As the arc 15 forms, the arc-extinguishing materials of the sheath begin to ablate and high quantities of deionizin~, turbulent and cooling gases are evolved. The movement of the irst terminaI under the action of the flipper, and the subsequent rapid movement thereof due to the evolved gases acting thereon as on a piston, results in elongation of the arc. The presence of the de-ionizing, turbulent and cooling gas, 20 plus; arc elongation, may, depending on the level of the fault current or other over-:
current, ultimately result in extinction of the arc and interruption of the current at a subsequent eurrent zero. The loss of the tensis)n on the stranded cable origmally effected by the flipper permits the trunnion casting to experience some initial movement relative to the exhaust ferrule which permits the upper ferrule to dis-Z5 engage itself from the upper contact assembly. This initiates a downward rotationof the fuse tube and its upper ferrule to a so-called "drop out" or "drop down"
;`~ position.
`: :
As noted immediately above, arc elongation within the sheath and the 30 action of the evolved gases rnay extinguish the arc. At very high fault current or overcurrent levels, however, arc elongation and the sheath may not, by themselves~
:, , be suf~icient to achieve this end. Simply stated, at very high fault current levels, : ` :
either the sheath may burst (because of the very high pressure oî the evolved gas) or insufficient gas may be evolved therefrom to quench the high current level arc.
For these reasons, the îuse tube is made of, or is lined with, ablative arc-extin-guishing horn fiber or bone fiber, as noted above~ In the event the sheath bursts, 5 the arc-extinguishing material for the fuse tube interacts with the arc, gas evolved as a result thereof effects arc extinction~ II the sheath does not burst, the arc-extinguishing material of the fuse tube between the end OI the sheath and the exhaust end of the fuse tube is, nevertheless, available for evolving gas, in addition to that evolved from the sheath. The joint action of the two quantities of evolved 10 gas, together with arc elongation, e~tinguish the arc.
Many manufacturers of cutouts and fuse links of the types described above continue to make concerted efforts to decrease the costs of the material and ~; labor thereof, both as a matter of simple, good commercial practice, and in view of lS the fact that certain materials, such as silver, copper, and bronze, continue to experience large price increases. At the same time, manufacturers of cutouts and ;~ fuse links continue ongoing programs to improve the performance of these pro-ducts. A less expensive, improved performance fuse cutout is a primary goal of the present invention.
The upper or second contact assembly usually includes a J~haped spring contact, an end of the long leg of which is mounted for flexing to a rigid recoil bar. The recoil bar extends to a position between the legs of the J. A pin inter-connects the legs of the J for conjoint rnovement. The pin passes through an 25 aperture in a bushing pressed into, and extending beyond, a hole through the recoil bar and is connected to the opposite side of a concavity formed in the J's short leg. The concavity engages and holds an end of the fuse tube, RS described below.
A spring acts between the recoil bar and the concavity to set a "rest"
30 position of the J's short leg (and of the J's long leg~. Upward deflection of the J's short leg is limited by abutment between the opposlte side of the concavity and the bushing.
~ 4 ~
The lower or Eirst contact assembly includes a feature--a projection, stud or the like -- normally spaced from a similer feature or surface on the exhaust ferrule. The normal spaeing between these features is substantially the same as the normal spacing between the opposite side of the concavity and the bushing.
When a fuse tube is properly positioned between the contact assemblies, the J's short leg is held away from its rest position against the bias of both the spring and the lon~ leg to firmly engage a contact cap on the upper ferrule of the fuse tube in the concavity~ When the fuse link operates, gases evolved within the fuse tube thrust It against the J's short leg in jet-like Eashion, further compressing the spring and flexing the J's long leg. The fuse tube may also randomly move the ~ ~ pin transversely at this time until the pin engages the walls of the aperture in the `~ bushing. The random, transverse fuse tube movement may b0 viewed as precession of ~the pin between a pair of "pivots," one of which is the pin's connection to the J's short leg, the other of which is the envelope of the points of contact between the pin and the walls of the bushing aperture. This random, transverse fuse tube : ~ :
movement may have~ several deleterious effeets.
,. , First, ideally the features on the first contact assembly and the exhaust 2O ~ ferrule abut at the same time the opposite side of the concavity abuts the bushing.
':
This transfers the forces on the fuse tube simultaneously to the contact assembiies. U the fuse tube moves too far transversely during its thrustmg, these abutting events will not be simultaneous.
~' :
; Z5 ~eeond, icleally the contaet cap ~hould not disenga~e th~ eoncavity until ~. 1 the fusible element of the fuse link completely melts to release the tension in the cable and until the initial thrust of the fuse tube subsides. Release of this tension :~, and subsiding of fuse ;tube thrust permits a limited amolmt of relative movement between the exh~ust ferrule and the trunnion casting a~out a toggle joint there-30 between. This limited movement permits the eontact cap to move out of theconcavity and the fuse tube to fall "open" due to rotation of the trunnion casting in ~:., ~ :: ~ : :
, ~w ~
the trunnion pocket. If the fuse tube moves too far transversely during its thrusting, the contact cap may disengage the concavity too early.
Third, transverse movement of the fuse tube can apply n bending move-5 ment thereon. This bending movement can fracture the fuse tube near the exhaust ferrule.
. .
Any solution to the above problems must take into account that presently availaMe fuse tubes have "standard" lengths, which depend, inter alia, upon the 10 voltage of the circuit to whieh the cutout is connected. Any such solution must not alter the cutout so as to require non~tandard fuse tube lengths.
The present invention, thell, is intended to solve the above--described problems, while achieving the overall goals of improving fuse cutout performance, 15 while at the same time decreAsing its cost~
SUMMARY OP THE INVENTION
According to the present invention, there is provided an improved fuse cutout. The cutout includes a mounting having a first and a second contact 20 assembly. A fuse tube of selected length is to be supported between the contact assernblies. The improve~ cutout includes an improved second contact assembly having certain old elements. The second contact assembly includes a generally J-shaped spring contact. A long leg of the J is attached to a rigid recoil bar, a portion of which extends into the space between the legs of the J. The short leg of 25 the J has a concavity formed therein and a complementary convexity. The con-CRVity selectively receives an end of the fuse tu~e. A pin freely passes through a hole in the extending portion of the recoil bar and is attached to move together as the pin moves through the hole and the long leg flexes out of a rest positon about its point of attachment to the recoil bar. A spring acts between the base of the 30 convexity and the recoil bar to set the rest position of the long leg.
;, ~ - 6 -:
: .
Closure of the cutout by rotating the fuse tube in the first contact assembly inserts the fuse tube end into the concavity so that the legs of the J are deflected against the action of the spring and the flexin~ of the long leg out of its rest position. When the cutout operates, the fuse tube thrusts both against and 5 transverse to the concavity. This thrust applies a bending force to the fuse tube which may fracture as a consequence. The thrust also randomly mQves the J's short leg transverse to the pin until the pin engages the waIls of the hole. Moreover, the thrust further deflects the legs against the action of the sprin8 and the flexing of the long leg.
~- In the improved cutout, an offset is formed in the recoil bar. This offset positions the extending portion of the recoil bar and the hole substantially closer to the short leg and the eonvexity. This closer positioning limits the extent of the random transverse motion of the short leg before the pin enga~es the hole walls.
15 Consequently, the bending force on the fuse tube i9 limited. The offset also positions the convexity closer to the recoil bar to decrease the amount of move-~; ment of the short leg bef~re it engages the recoil bar. This earlier transfers the thrust-caused force to the recoil bar.
;~ 20 Often the fuse tube and the first contact assembly each have a feature or projection which are normally spaced apart. When the legs further deflect due to cutout operation, these features engage. In other aspects of the improved cutout, the distance between the convexity and the recoil bar after cutout closure, but before further leg deflection, is equal to the normal spacing between the features.
,~ I
25 Thus, thrust-caused force on the fuse tube is simultaneously transferred to the first contact assembly and the recoil bar.
The above improvements do not alter the typical spacing between the concavity and the first contact assembly. Thus, fuse tubes of standard length may 30 be usecl in the cutout without alteration.
~ ~ :
y~
In cutouts, it is desirable that the fuse tube end not disengage the con-cavity until the initial thrust of the fuse tube subsides. If the fuse tube moves too far transversely during its thrusting, the fuse tube end may disengage the concavity too early. The offset limits the amount of transverse pin movement and, hence, of 5 transverse fuse tube movement. This prevents too early disengagement of the fuse tube and from the concavity.
DESCRIPTION OF TEIE DRAWINC~
EIGURE 1 is an elevational, prespective view of a fuse cutout according to 10 the prior art;
FIGURE 2 is an enlarged elevational view OI a portion of the cutout of ~IGUlR~ 1 and FI~URE 2a is similar but at a tirne during the operation thereof;
~IGURE 3 is an elev~tional, perspective view of an improved fuse eutout aceording to the present invention;
~.
FIGURES 4a - 4c are enlarged elevational views of portions of the cutout of FIGURE 3; and `
FIGURE S is an enlarged elevational view similar to FIGURE 4a during operation of the cutout of FIGIJRE 3.
_TAILED ES(~RIPTION
~5 Referring first to FIGURE 1, there is shown a fuse cutout 10 according to the prior art. An improved cutout 12 according to the present invention is shown in FIGURES 3-5 and is described later. The same or simllar reference numerals are used for corresponding elements of the cutouts 10 and 12. The improved fuse cutout 12 of the present invention operates in a similar, but improved, manner to that of the prior art fuse cutout 10, and is also less costly.
.
;`. ' ~ 8 -...
The prior art cutout 10 includes an elongated, skirted insulator 24 which has affixed thereto a mounting member. The mounting member 16 permits mounting of the insulator 14 and the use cutout 10 to an upright or a cross-arm of a utility pole (not shown~. The insulator 14 may be rnade of porcelain or similar 5 material.
Afixed to the upper end of the insulator 14 is an upper contact assembly generally designated lû~ Affixed to the lower end of the insulator 14 is a lower contact assembly 2û. The cutout 10 also includes a ~use tube assembly 22 which in 10 the normal or unoperated condition of the cutout 10 may be maintained in the vertical position shown in FIGURE 1, although other orientations may be desirable. Specifically, the fuse tube assembly 22 includes an insulative fuse tube : .:
:~ 24 of a well-known type, which may comprise an epoxy-fiber~lass composite outer ;~; shell lined with horn fiber or bone fiber. nqounted or affixed to the upper end of the 15 fuse tube 24 is an upper ferrule assembly 26, while at the opposite lower or exhaust end of the fuse ~tube 24 is a lower or exhaust ferrule assembly 2#. In the position o~
the fuse~ tube assembly 22 depicted in FIGURE 1, the lower ferrule assembly 28 is held by the lower contact assembly 20, while the upper ferrule assembly 26 is held, and latched against the movement, by the upper contact assembly 18.
2 0 The upper contact assembly 18 includes a suppcrt bar 30 bent at the 90 angle shown and a straight recoil bar 32 which runs generally parallel to a portion of the support bar 30. The bars 30 and 32 are connected together and spaced apart by a rivet or stud 34. Near the rivet or stud 34, the two bars 30 and 32 are mounted ZS by a nut and bolt cornbination 36 to a mount 38, which is attached to the top of the insulator 14. Also held by the nut and bolt 36 is a connector 4û, such as a parallel groove connector. The connector 40 facilitates the connection to the upper contact assembly 18 of one cable or conductor of a high-voltage circuit.
,, ~
The upper contact assembly 18 also includes a generally J~;haped spring contact 42. The long leg ;of the spring contact 42 is attached, as shown in FIGURE
~, 1, to the upper surface of the recoil bar 32 in the vicinity of the nut and bolt 36.
_ ~ _ ;:: : : :
,. . . .
The J curves out, down and back into a short leg, so that thc recoil bar 32 is positioned between the le~s of the contact 42. Formed in the short leg of the spring contact 42 is an indentation or concavity 42a. A stud or rod 43 freely passes through an aperture 44 (not numbered in FIGIJRE 1; see FIGURRS 2 and ~a) through a bushing 45 pressed into a hole (not numbered) through the end of the recoil bar 32 and is firmly attached between the legs of the spring contact 42. Preferably, the stud or rod 42 is attached to the short leg of the spring contact 42 so that its axis is coaxial with the axis of the inclentation or concavity 42a formed in the short leg, both axes being labeled A in FIGURE 2. Thus, although the spring contact 42 may - lO flex near the nut and bolt 36, the legs (interconnected by the stud or rod 43) are constrained to move together. The bushing 45 extends both above the recoil bar 32, as shown at 45a, ~nd below the recoil bar 32, as shown at 45b.
.
Acting between the lower surface of the recoil bar 32 flnd a washer 4fi at ~`~ 15 the top of the convexity 42b formed in the short leg of the spring contact 42 , :
complementarily with the indentation or concavity 42a is a backup spring 47 which sets a rest position for the legs of the spring aontact 42. The upper turns of the backup spring 47 surround the extending portion 45b of the bushing 45.
zo The downwardly bent portion of the support bar 30 may have mounted ~ . .
thereto attachmeIll hooks a~.
: .
The upper ferrule assembly includes a cast ferrule 50, which is attached or mounted to the upper end of the fuse tube 24. The ferrule 50 may include a z5 threaded portion (not shown) onto which may be threaded a contact cap 52. The contact cap 52 is configured so as to fit into and be held by the indentation or concavity 42a formed in the short leg of the spring contact 42 when the fuse tube assembly 22 is in the position shown in FIC~IJRES 1 and 2. The ferrule 50 may a]so include a pull ring 54. The pull ring 54 may be engaged by a hot stick or switch 30 stick to move the upper ferrule assembly 2~ away from the upper contact assembly 18 while the lower ferrule assembly 28 rotates in the lower contact assembly 20, as described below. In view of the nature oi high voltage circuits, this opening ,, , : :
movement of the fuse tube assembly 22 must be effected while the circuit connected to the cutout 10 is de-energized or else an arc will form between the upper ferrule assembly 26 and the upper contact assembly 18. The fuse tube assembly 22 may also be opened by initially attachirlg between the attachment 5 hooks 48 and the pull ring 54 a portable load-break tool. Such a portable load-break tool permits the fuse tube assembly 22 to be opened with the circuit energized, momentarily having transferred thereto the flow of current in the circuit 10 and interrupting such current internally thereof.
The lower contact assembly 20 includes a support member 56 attaehed to a mount 58 by a nut and bolt combination 60. The support mernber 56 may also carry a connector 62, such as a parallel groove~connector. The connector 62 facili-tates the connection to the lower contact assembly 20 of another cable or conductor of the high-voltage circuit in which the fuse cutout 10 is to be used. It 15 ~ should be noted that the connectors 40 and 62 may both take the form of that described and claimed in commonly-assigned Canadian Patent Application, Serial No~ 354,387 filed July 28, 1980 in the name of Hiram Jackson.
Formed in the sMpport member 56 are trunnion pockets 64. The trunnion Z0 pockets 64 are designed to hold outwardly extending portions 66 of a trunnion casting 6a which is pivotally mounted at a toggle joint 70 to a cast ferrule 72 which is attached or mounted to the lower or exhaust end of the fuse tube 24. As here-inafter described, the trunnion casting 68 and the cast ferrule 72 are normally rigidly held in the relative position depicted in EIGUR~ 1. In this normal relative position of the trunnion casting 68 and the ferrule 72, the contact cap 52 may be engaged by and held in the concavity 41a formed in the short leg of the spring contact 42 to maintain the fuse tube assembly 22 in the position depicted in FIGURE 1. Also, as described in more detail below, when a fuse link within the fus0 tube 24 operates, the trunnion casting 68 and the ferrule 72 are no longer so rigidly held~ and the ferrule 72 may rotate downwardly relative to the trunnion casting 68 about the toggle joint 70. This movement of the ferrule 72 permits the contact cap 52 to disengage the spring contact 42, following which the entire fuse ;
tube assembly 22 rotates about the lower contact assembly 20 via rotfltion of the extending portions 66 in the trunnion pockets 64.
Rotatably mounted to the trunnion casting 68 is a flipper 74. A spring 75 5 mounted between the trunnion casting 68 and the flipper 74 biases the flipper 74 away from the lower or exhaust end of the fuse tube 24.
The trunnion casting 68 includes shoulders 76 or other features. The support member 56 also includes features, such as shoulders 78, normally spaced 10 from the shoulders 76 when the extending portions ~6 of the trunnion casting 68 are :;
seated in their respective trlmnion pockets 64. The normal spacing between the shoulders 76 and 78 is about equal to the normal spacing between the washer 46 and the extending portion 45b of the bushing 45. It should be noted that the pin 42 is free to move transversely (or to precess) between its attQchment to the convexit~
15 42b and its engagement with the walls of the aperture 44 through the bushing 45, as shown in FIGURE 2a.
To use the fuse cutout lO, the fuse tube assembly 22 is first "armed" with a fuse link. Suffice it here to say that the contact cap 52 is removed and the fuse zo link is inserted into the interior of the fuse tube 24 from the upper end thereof. A
portion of the fuse link abuts a shoulder ~not shown) at the top of the ferrule 50 following which the contact cap 52 is threaded back onto the ferrule 50. A flexible stranded cable 80 forming a part of the fuse link exits an exhaust opening in the lower or exhaust end of the -fuse tube 24. The flipper 74 is manually rotated against 25 the action of the spring 74 to position it ad~jacent the exhaust opening following which the cable 80 is laid into a channel formed in the flipper 74. Following this, the cable ~0 is wr~pped around a flanged bolt (not shown) which is threaded into the trunnion casting 68. Following tightening of the flanged bolt to hold the cable 80, the flipper 74 is maintained against the bias of the spring 75 in the position shown 30 in FIGURE 1, whereat there is a constant tension force applied to the cable 80 and, accordingl~, to the fuse link within the fuse tube 24. It is this connection of the cable 80 to the trunnion casting 68 by the flanged bolt and the action of the spring 75 on the flipper 74 which normally holds the trunnion casting~ 68 and the ferrule 72 in the position depicted in FIGURE 1 relative to the tog~le 30int ~0.
Fo110wing operation of a fuse link within the fuse tube 249 the flipper 74 is 5 able to move the cable 80 downwardly within the fuse tube 24. The release of the tension force applied to the ~ablc 80 by the flipper 74 permits relative movement of the ferrule 72 and the trunnion casting 68 about the toggle JOint 70 to p~rmit separation of the contact cap 52 from the spring contact 42.
I0 Ideally, the relative movement of the ferrule 72 and the trunnion casting 68 occurs after tension in the cable 80 is released and after an initial upward thrust of the fuse tube 24 subsides~ As set forth more fully in the above-noted application of Sabis, Serial No. 373,563 filed March 2û, 198 l, when a fusible element (not shown) of the fuse link within the fuse tube 24 melts, there follows the rapid 15 evolution of arc-extinguishing gas within the fuse tube 24. This ~volved gas exits the exhaust opening of the fuse tube 24 at a very rapid rate, thrusting the fuse tube 24 upwardly in Jet-like fashion. Before the cutout ln is closed ~ i.e., before the fuse tube assembly 22 is rotated, by rotating the extensions 66 of the trunnion casting 68 in the trunnion pockets 64 of the support member 56, until the conta~t 20 cap~ 52 engages the concavity 42a--the spring 47 and the long leg of the contact 42 set a rest position for the legs of such contact 42. In this rest positis)n, the con-vexity 42b and the washer 46 are spaced from the portion 45b OI the hushing 45.
After the cutout 10 is closed, the contact cap 52 deflects the short leg of the J 42 (and also, flexes the long leg) upwardly against the spring bias of the spring 47 and 25 of the long leg to decrease the spacing between the washer 46 and the bushing portion 45 to equal the spacing between the shoulders 76 and 78. This situation obtains until the fuse link within the fuse tube 24 operates in response to a fault current.
:
; ~ 30 When the fuse link operates, the tension on the cable 80 is released at the sam~e time the fuse tube 24 thrusts up. Ideally, such thrust occurs while the fuse ; ~ ~ tube 24, the pin 42, and the aperture 44 remain coaxial. If such coaxial relation ~ ~ - 1 3 ~ ~ ,''~.``
obtains, the relative movernent of the ferrule 72 and the trunnion casting 68 about the toggle joint 70 does not immediately occur--though it is able to occur because of the release of tension in the cable 80 ~ due to the thrust of the fuse tube 24.
This thrust, therefore, results in simultaneous engagement of the shoulders 76 and 5 78 at one end of the fuse tube 24 and of the washer 46 and the bllshing portion 45b at the other end of the fuse tube 24. These simultaneous engagements transfer the thrust forces on the fuse tube assembly 22 more or less equally to the contact assemblies 18 and 20 until the thrust subsides. As the thrust subsides and the fuse tube assembly 22 begins to move back down under the action of the spring 47 and 10 the long leg of the J 42~ (1) the shoulclers 76 and 78, and the washer 46 and the bushin~ portion 45b separate, and (2) the aforedescribed relative movement of the ferrule 72 and the trunnion casting 68 occurs. This relative movement perrnits the contact cap 52 to disengage the concavity 42a and the fuse tube assembly 22 to ;~rotate to a "drop out" position via rotation of the extensions 66 in the trunnion 15 pockets 64. All of the above is "timed" so that rotation of the assembly 22 is initiated as or after the fuse link has interrupted current in the circuit.
:
Randomj deleterious deviations from the ideal operation of the cutout 10 have been detected. Specifically and referring to ~I~;UPcE 2a, during thrusting of 20 the fuse tube 249 the tube 24 has been observed to move transversely, which may cause transverse movement or precession of the pin 43 between the convexity 42b and the aperture 44 in the bushing 45, as shown by the angle B between the axis A
of the pin 42 and the a2ds C of the aperture. Several improper results may flow from these transverse movements. First, transverse movement of the fuse tube 24 2~ has been observed to result in the application of a bending force to the fuse tube 24. This bending force at times fractures the f~lse tube 24, usually in the vicinity of its attachment to the ferrule 72. Second, if the transverse movement of the fuse tube 24 is too severe, the shoulders 76 and Y8 and the washer 46 and the bushing portion 45b do not abut simultaneously. This has been observed to exacerbate both ;~
30 the effect of the bending forces on the fuse tube 4~ and the number and severity of fractures thereof. Third~ if the transverse movement of the fuse tube 24 is too severe, the contact cap 52 mfly begin to dlsengage the concavity 42a before the " .
:
thrust of the fuse tube 24 subsides. Such disengagement may occur before the fuse link has interrupted current and result in arcing between the contact cap 52 and the spring contact 42, thus defeating the very reason for inclusion of the cutout 10 in the cireuit. Fourth, as noted earlier, the bushing 45 is pressed into a hole in the 5 recoil bar 32. II this pressing operation is not carried Ollt precisely enough so that the normal shoulder-shoulder 76-78 spacing equals the normal washer-bushing 46-45b spacing9 the second and third improper results, immediately above, may be worsened.
The above deviations from ideal cutout operation are ameliorated or eliminated by the improved cutout 12 of the present invention. As noted earlier, elements of the improved cutout 12, which are the same as or similar to corre-sponding elements of the prior art cutout 10, are designated by the same or similar reference numerals.
Improvements present in the cutout 12, as depicted in FIGURE 3, primarily center around improvements in the second or upper contact assembly 18.
; ~ Specifically, as can be seen from FIGURE 3, the recoil bar 32' is similar to the recoil bar 32 of the cutout 10, except that the recoil bar 32' has heen formed to 20 have an offset therein substantially as shown at 100. This offset 100 positions the ~; free end of the recoil bar 32' closer to the convexity 42b in the spring contact 42 ; ~ which remains essentially unchanged from that depicted in FIGURE 1. The recoil bar 32' also includes near its free end a hole or aperture 102 therethrough (FIGURES 4a and 5). Surrounding the hole or aperture 102 on the underside of the 25 recoil bar 32' is a circulflr raised shoulder 104 (FIGURR 4a) which is coaxial with the hole 102. The spring 47' acts between the recoil bar 32' and the convexity 42b and surrounds both the base of the convexity 42b and the shoulder 104. A pin 43' passes freely through the hole or aperture 102 and is connected (simi]ar to the pin 43) between the legs of the J~haped spring contact 42. The pin 43' includes a stop 30 shoulder 108 ~ormed generally centrally of the pin 42'.
~, 6~
:
The construction depicted in ~IGUlRES 3, 4a and 5 achieves two ends.
First, as described in more detail below, this construction improves the operation of the cutout 12 over that of the cutout 10 and, specifically, ameliorates or eliminates the above-described deviations from ideal cutout operation. Second, the con-5 struction illustrated in FIGURES 3, 4a and 5 decreases the material costs of thecutout 12 over that of the cutout 10.
A ma~erial cost decrease of the cutout 12 over that of the cutout tO is achieved by the elimination of the bushing 45 illustrated in FIGUR~S 1, 2 and 2a, lO decrease in the number of turns present in the spring 47, and elimination of the washer 46. The cost decrease achieved by these s~hanges is only partially offset by the fact that the recoil bar 32' must be formed to have the offset 100 and to contain the raised shoulder 104. If convenient, both the offset 100 and the raised shoulder 104 may be formed in a single stamping, pressing or dieing operation.
` 15 The elimination of the deviations from ideal cutout operation described with reference to the cutout 10 of FIGUR~ 2a is achieved as follows. Referring to FIGURES 4a and 5, the o-ffset 10 positions the free end of the reeoil bar 327 closer to the convexity 42b. This closeness decreases the amount of transverse movement20 of precession that can be experienced by the pin 43', as shown by the angle B' between the axis A' of the pin 43' and the axis C' of the hole 1û2 in FIGURE 5;
B' cB. Viewing the engagement of the pin 43' with the walls of the hole 102 and the pinis attachment to the convexity 42b as the points between which the pin 43' may move or precess, this decrease in the precessable portion of the pin 43' limits the 25 amount of transverse movement which can be experienced by the fuse tube 24 during cutout operation and thereby limits the bending force experienced by the fuse tube 24 to limit or prevent fracturing thereof in the vicinity of the ferrule 72. Also, noting that the distance between the convexity 42b and the bottom of the offset recoil bar 32' with the fuse tube assembly 22 in the closed position, 30 illustrated in FIGURE 3 and 4a, is equal to the norma] spacing between the shoulders 76 and 78, the spacing betureen the recoil bar 32' and the convexity 42b may be more accurately controlled than was the spacing between the pressed in ' ~ '' ' , :
. ~ . .
:: - . :
bushing 45 and the washer 46. This more close control over the above-mentioned spacing ensures that during the upward thrust of the fuse tube 24 during operation of the cutout tû, the convexity 42b abuts the recoil bar 321 at the same time the shoulders 76 and 78 engage. This ensures that forces on the fuse tube 24 caused by 5 the thrust thereof are equally and simultaneously transferred to the contaet assemblies 18 and 20 during operation of the cutout 2. As a consequence of this, and as a consequence of the fact that the pin 43' can precess a more limited amount that can the pin ~13 o~ FIGUl~E 1, both too early opening of the fuse tube assembly 22 and exacerbation of the effect of ~he bending forces on the filse tube 24 are 10 limited or eliminated.
Thus, by the simple expedients of e]iminating the bushing 45 and the washer 46, and forming the recoil bar 32', the operation of the cutout 12 has been observed to be gre~tly improved over that of the cutout 10 illustrated in FIGURE
15 1. Fractures OI the fuse tube 24 in the vicinity of the ferrule 72 are all ~ut eIiminated, as is too early opening of the fuse tube assembly 22. The limitation of the amount of transverse movement of the fuse tube 24 and precession of the pin 43' effected by the improvement in the upper contact structure l 8 are illustrated in FIGUR~ 5 which is similar to, but represents an improvement over FIGURE 2a.
Another improvement in the eutout 12 over that of the cutout 10, but which does not form the subject matter of the present invention, is illustrated by the depiction of the lower contact assembly 20', as shown in FIGURES 3, 4b, and 4c. Specifically, it will be noted from these FI~URES that the metal content of 2 5 the support member 56 has been decreased significantly so that the reference numeral 56' is used to indicate the support member of the cutout 12.
~' .
It should be noted that the above-described improvements in the cutout 12 do not affect the normal or rest spacings between the concavity 42a and the trun-30 nion pockets 649 That is to say, the general contour and location of the springeontact member 42 has not been altered b~ the above improvements. As a conse-:. , quence, fuse tube assemblies 22 viewed as "standard" that is, having "standard' : ~ :
lengths--may be used with the improved cutout 12 similar to their use in the prior art cutout tû. Accordingly, eomplete interchangeabi]ity between the fuse tube assemblies 2? used in either cutout 10 or 12 is achieved. This ability to continue to use fuse tube assemblies 22 of standard lengths is obviously important. One 5 solution to the problems of the prior art cutout 10, which was arrived at prior to the derivation ot the present invention, involved permitting the recoil bar 32 of FIGURE 1 to remain as depicted in that FI(3UR~ and to simply change the contour of the spring contact member 42 to move the short leg thereof closer to the recoil bar 32. Note that while this chan~e in the spring contact member 42 might have 10 the effect of shortening the available length of the pin 42 for precession or random transverse movement, it also changes the distance between the concavity 42a and the trunnion pockets 64. Thus, if this interrnediate improvement were to be :~ .
effected, either fuse tube assemblies 22 of non-standard length would be necessary, I
, : ~
thus eliminating interchangeability, or the contour and configuration of the lower 15 contact assembly 20 vvould have to be altered, especially in the vicinity of the trunnion pockets 64 to permit continued use of the standard length fuse tube assemblies 22. Thus, the improvement represented by the cutout 12 involves material savings, improved operation, and the ability to continue to use standard ~; lengths of ~se tube assemblies 22. It also represents a distinct improvement over 20 any proposed solution ~hat involves alteration of the contour and location of either : ::
the spring contact member 42 or the first contact assembly 20 or both.
The above described embodiments of the present invention are simply illustrative of the principles thereof. Various other modifications and changes may ,, 25 be devised by those skilled in the art which embody the principles of this invention, yet fall within the spirit and the scope thereof.
.
.
i .
,, ~
The upper contact assembly 18 also includes a generally J~;haped spring contact 42. The long leg ;of the spring contact 42 is attached, as shown in FIGURE
~, 1, to the upper surface of the recoil bar 32 in the vicinity of the nut and bolt 36.
_ ~ _ ;:: : : :
,. . . .
The J curves out, down and back into a short leg, so that thc recoil bar 32 is positioned between the le~s of the contact 42. Formed in the short leg of the spring contact 42 is an indentation or concavity 42a. A stud or rod 43 freely passes through an aperture 44 (not numbered in FIGIJRE 1; see FIGURRS 2 and ~a) through a bushing 45 pressed into a hole (not numbered) through the end of the recoil bar 32 and is firmly attached between the legs of the spring contact 42. Preferably, the stud or rod 42 is attached to the short leg of the spring contact 42 so that its axis is coaxial with the axis of the inclentation or concavity 42a formed in the short leg, both axes being labeled A in FIGURE 2. Thus, although the spring contact 42 may - lO flex near the nut and bolt 36, the legs (interconnected by the stud or rod 43) are constrained to move together. The bushing 45 extends both above the recoil bar 32, as shown at 45a, ~nd below the recoil bar 32, as shown at 45b.
.
Acting between the lower surface of the recoil bar 32 flnd a washer 4fi at ~`~ 15 the top of the convexity 42b formed in the short leg of the spring contact 42 , :
complementarily with the indentation or concavity 42a is a backup spring 47 which sets a rest position for the legs of the spring aontact 42. The upper turns of the backup spring 47 surround the extending portion 45b of the bushing 45.
zo The downwardly bent portion of the support bar 30 may have mounted ~ . .
thereto attachmeIll hooks a~.
: .
The upper ferrule assembly includes a cast ferrule 50, which is attached or mounted to the upper end of the fuse tube 24. The ferrule 50 may include a z5 threaded portion (not shown) onto which may be threaded a contact cap 52. The contact cap 52 is configured so as to fit into and be held by the indentation or concavity 42a formed in the short leg of the spring contact 42 when the fuse tube assembly 22 is in the position shown in FIC~IJRES 1 and 2. The ferrule 50 may a]so include a pull ring 54. The pull ring 54 may be engaged by a hot stick or switch 30 stick to move the upper ferrule assembly 2~ away from the upper contact assembly 18 while the lower ferrule assembly 28 rotates in the lower contact assembly 20, as described below. In view of the nature oi high voltage circuits, this opening ,, , : :
movement of the fuse tube assembly 22 must be effected while the circuit connected to the cutout 10 is de-energized or else an arc will form between the upper ferrule assembly 26 and the upper contact assembly 18. The fuse tube assembly 22 may also be opened by initially attachirlg between the attachment 5 hooks 48 and the pull ring 54 a portable load-break tool. Such a portable load-break tool permits the fuse tube assembly 22 to be opened with the circuit energized, momentarily having transferred thereto the flow of current in the circuit 10 and interrupting such current internally thereof.
The lower contact assembly 20 includes a support member 56 attaehed to a mount 58 by a nut and bolt combination 60. The support mernber 56 may also carry a connector 62, such as a parallel groove~connector. The connector 62 facili-tates the connection to the lower contact assembly 20 of another cable or conductor of the high-voltage circuit in which the fuse cutout 10 is to be used. It 15 ~ should be noted that the connectors 40 and 62 may both take the form of that described and claimed in commonly-assigned Canadian Patent Application, Serial No~ 354,387 filed July 28, 1980 in the name of Hiram Jackson.
Formed in the sMpport member 56 are trunnion pockets 64. The trunnion Z0 pockets 64 are designed to hold outwardly extending portions 66 of a trunnion casting 6a which is pivotally mounted at a toggle joint 70 to a cast ferrule 72 which is attached or mounted to the lower or exhaust end of the fuse tube 24. As here-inafter described, the trunnion casting 68 and the cast ferrule 72 are normally rigidly held in the relative position depicted in EIGUR~ 1. In this normal relative position of the trunnion casting 68 and the ferrule 72, the contact cap 52 may be engaged by and held in the concavity 41a formed in the short leg of the spring contact 42 to maintain the fuse tube assembly 22 in the position depicted in FIGURE 1. Also, as described in more detail below, when a fuse link within the fus0 tube 24 operates, the trunnion casting 68 and the ferrule 72 are no longer so rigidly held~ and the ferrule 72 may rotate downwardly relative to the trunnion casting 68 about the toggle joint 70. This movement of the ferrule 72 permits the contact cap 52 to disengage the spring contact 42, following which the entire fuse ;
tube assembly 22 rotates about the lower contact assembly 20 via rotfltion of the extending portions 66 in the trunnion pockets 64.
Rotatably mounted to the trunnion casting 68 is a flipper 74. A spring 75 5 mounted between the trunnion casting 68 and the flipper 74 biases the flipper 74 away from the lower or exhaust end of the fuse tube 24.
The trunnion casting 68 includes shoulders 76 or other features. The support member 56 also includes features, such as shoulders 78, normally spaced 10 from the shoulders 76 when the extending portions ~6 of the trunnion casting 68 are :;
seated in their respective trlmnion pockets 64. The normal spacing between the shoulders 76 and 78 is about equal to the normal spacing between the washer 46 and the extending portion 45b of the bushing 45. It should be noted that the pin 42 is free to move transversely (or to precess) between its attQchment to the convexit~
15 42b and its engagement with the walls of the aperture 44 through the bushing 45, as shown in FIGURE 2a.
To use the fuse cutout lO, the fuse tube assembly 22 is first "armed" with a fuse link. Suffice it here to say that the contact cap 52 is removed and the fuse zo link is inserted into the interior of the fuse tube 24 from the upper end thereof. A
portion of the fuse link abuts a shoulder ~not shown) at the top of the ferrule 50 following which the contact cap 52 is threaded back onto the ferrule 50. A flexible stranded cable 80 forming a part of the fuse link exits an exhaust opening in the lower or exhaust end of the -fuse tube 24. The flipper 74 is manually rotated against 25 the action of the spring 74 to position it ad~jacent the exhaust opening following which the cable 80 is laid into a channel formed in the flipper 74. Following this, the cable ~0 is wr~pped around a flanged bolt (not shown) which is threaded into the trunnion casting 68. Following tightening of the flanged bolt to hold the cable 80, the flipper 74 is maintained against the bias of the spring 75 in the position shown 30 in FIGURE 1, whereat there is a constant tension force applied to the cable 80 and, accordingl~, to the fuse link within the fuse tube 24. It is this connection of the cable 80 to the trunnion casting 68 by the flanged bolt and the action of the spring 75 on the flipper 74 which normally holds the trunnion casting~ 68 and the ferrule 72 in the position depicted in FIGURE 1 relative to the tog~le 30int ~0.
Fo110wing operation of a fuse link within the fuse tube 249 the flipper 74 is 5 able to move the cable 80 downwardly within the fuse tube 24. The release of the tension force applied to the ~ablc 80 by the flipper 74 permits relative movement of the ferrule 72 and the trunnion casting 68 about the toggle JOint 70 to p~rmit separation of the contact cap 52 from the spring contact 42.
I0 Ideally, the relative movement of the ferrule 72 and the trunnion casting 68 occurs after tension in the cable 80 is released and after an initial upward thrust of the fuse tube 24 subsides~ As set forth more fully in the above-noted application of Sabis, Serial No. 373,563 filed March 2û, 198 l, when a fusible element (not shown) of the fuse link within the fuse tube 24 melts, there follows the rapid 15 evolution of arc-extinguishing gas within the fuse tube 24. This ~volved gas exits the exhaust opening of the fuse tube 24 at a very rapid rate, thrusting the fuse tube 24 upwardly in Jet-like fashion. Before the cutout ln is closed ~ i.e., before the fuse tube assembly 22 is rotated, by rotating the extensions 66 of the trunnion casting 68 in the trunnion pockets 64 of the support member 56, until the conta~t 20 cap~ 52 engages the concavity 42a--the spring 47 and the long leg of the contact 42 set a rest position for the legs of such contact 42. In this rest positis)n, the con-vexity 42b and the washer 46 are spaced from the portion 45b OI the hushing 45.
After the cutout 10 is closed, the contact cap 52 deflects the short leg of the J 42 (and also, flexes the long leg) upwardly against the spring bias of the spring 47 and 25 of the long leg to decrease the spacing between the washer 46 and the bushing portion 45 to equal the spacing between the shoulders 76 and 78. This situation obtains until the fuse link within the fuse tube 24 operates in response to a fault current.
:
; ~ 30 When the fuse link operates, the tension on the cable 80 is released at the sam~e time the fuse tube 24 thrusts up. Ideally, such thrust occurs while the fuse ; ~ ~ tube 24, the pin 42, and the aperture 44 remain coaxial. If such coaxial relation ~ ~ - 1 3 ~ ~ ,''~.``
obtains, the relative movernent of the ferrule 72 and the trunnion casting 68 about the toggle joint 70 does not immediately occur--though it is able to occur because of the release of tension in the cable 80 ~ due to the thrust of the fuse tube 24.
This thrust, therefore, results in simultaneous engagement of the shoulders 76 and 5 78 at one end of the fuse tube 24 and of the washer 46 and the bllshing portion 45b at the other end of the fuse tube 24. These simultaneous engagements transfer the thrust forces on the fuse tube assembly 22 more or less equally to the contact assemblies 18 and 20 until the thrust subsides. As the thrust subsides and the fuse tube assembly 22 begins to move back down under the action of the spring 47 and 10 the long leg of the J 42~ (1) the shoulclers 76 and 78, and the washer 46 and the bushin~ portion 45b separate, and (2) the aforedescribed relative movement of the ferrule 72 and the trunnion casting 68 occurs. This relative movement perrnits the contact cap 52 to disengage the concavity 42a and the fuse tube assembly 22 to ;~rotate to a "drop out" position via rotation of the extensions 66 in the trunnion 15 pockets 64. All of the above is "timed" so that rotation of the assembly 22 is initiated as or after the fuse link has interrupted current in the circuit.
:
Randomj deleterious deviations from the ideal operation of the cutout 10 have been detected. Specifically and referring to ~I~;UPcE 2a, during thrusting of 20 the fuse tube 249 the tube 24 has been observed to move transversely, which may cause transverse movement or precession of the pin 43 between the convexity 42b and the aperture 44 in the bushing 45, as shown by the angle B between the axis A
of the pin 42 and the a2ds C of the aperture. Several improper results may flow from these transverse movements. First, transverse movement of the fuse tube 24 2~ has been observed to result in the application of a bending force to the fuse tube 24. This bending force at times fractures the f~lse tube 24, usually in the vicinity of its attachment to the ferrule 72. Second, if the transverse movement of the fuse tube 24 is too severe, the shoulders 76 and Y8 and the washer 46 and the bushing portion 45b do not abut simultaneously. This has been observed to exacerbate both ;~
30 the effect of the bending forces on the fuse tube 4~ and the number and severity of fractures thereof. Third~ if the transverse movement of the fuse tube 24 is too severe, the contact cap 52 mfly begin to dlsengage the concavity 42a before the " .
:
thrust of the fuse tube 24 subsides. Such disengagement may occur before the fuse link has interrupted current and result in arcing between the contact cap 52 and the spring contact 42, thus defeating the very reason for inclusion of the cutout 10 in the cireuit. Fourth, as noted earlier, the bushing 45 is pressed into a hole in the 5 recoil bar 32. II this pressing operation is not carried Ollt precisely enough so that the normal shoulder-shoulder 76-78 spacing equals the normal washer-bushing 46-45b spacing9 the second and third improper results, immediately above, may be worsened.
The above deviations from ideal cutout operation are ameliorated or eliminated by the improved cutout 12 of the present invention. As noted earlier, elements of the improved cutout 12, which are the same as or similar to corre-sponding elements of the prior art cutout 10, are designated by the same or similar reference numerals.
Improvements present in the cutout 12, as depicted in FIGURE 3, primarily center around improvements in the second or upper contact assembly 18.
; ~ Specifically, as can be seen from FIGURE 3, the recoil bar 32' is similar to the recoil bar 32 of the cutout 10, except that the recoil bar 32' has heen formed to 20 have an offset therein substantially as shown at 100. This offset 100 positions the ~; free end of the recoil bar 32' closer to the convexity 42b in the spring contact 42 ; ~ which remains essentially unchanged from that depicted in FIGURE 1. The recoil bar 32' also includes near its free end a hole or aperture 102 therethrough (FIGURES 4a and 5). Surrounding the hole or aperture 102 on the underside of the 25 recoil bar 32' is a circulflr raised shoulder 104 (FIGURR 4a) which is coaxial with the hole 102. The spring 47' acts between the recoil bar 32' and the convexity 42b and surrounds both the base of the convexity 42b and the shoulder 104. A pin 43' passes freely through the hole or aperture 102 and is connected (simi]ar to the pin 43) between the legs of the J~haped spring contact 42. The pin 43' includes a stop 30 shoulder 108 ~ormed generally centrally of the pin 42'.
~, 6~
:
The construction depicted in ~IGUlRES 3, 4a and 5 achieves two ends.
First, as described in more detail below, this construction improves the operation of the cutout 12 over that of the cutout 10 and, specifically, ameliorates or eliminates the above-described deviations from ideal cutout operation. Second, the con-5 struction illustrated in FIGURES 3, 4a and 5 decreases the material costs of thecutout 12 over that of the cutout 10.
A ma~erial cost decrease of the cutout 12 over that of the cutout tO is achieved by the elimination of the bushing 45 illustrated in FIGUR~S 1, 2 and 2a, lO decrease in the number of turns present in the spring 47, and elimination of the washer 46. The cost decrease achieved by these s~hanges is only partially offset by the fact that the recoil bar 32' must be formed to have the offset 100 and to contain the raised shoulder 104. If convenient, both the offset 100 and the raised shoulder 104 may be formed in a single stamping, pressing or dieing operation.
` 15 The elimination of the deviations from ideal cutout operation described with reference to the cutout 10 of FIGUR~ 2a is achieved as follows. Referring to FIGURES 4a and 5, the o-ffset 10 positions the free end of the reeoil bar 327 closer to the convexity 42b. This closeness decreases the amount of transverse movement20 of precession that can be experienced by the pin 43', as shown by the angle B' between the axis A' of the pin 43' and the axis C' of the hole 1û2 in FIGURE 5;
B' cB. Viewing the engagement of the pin 43' with the walls of the hole 102 and the pinis attachment to the convexity 42b as the points between which the pin 43' may move or precess, this decrease in the precessable portion of the pin 43' limits the 25 amount of transverse movement which can be experienced by the fuse tube 24 during cutout operation and thereby limits the bending force experienced by the fuse tube 24 to limit or prevent fracturing thereof in the vicinity of the ferrule 72. Also, noting that the distance between the convexity 42b and the bottom of the offset recoil bar 32' with the fuse tube assembly 22 in the closed position, 30 illustrated in FIGURE 3 and 4a, is equal to the norma] spacing between the shoulders 76 and 78, the spacing betureen the recoil bar 32' and the convexity 42b may be more accurately controlled than was the spacing between the pressed in ' ~ '' ' , :
. ~ . .
:: - . :
bushing 45 and the washer 46. This more close control over the above-mentioned spacing ensures that during the upward thrust of the fuse tube 24 during operation of the cutout tû, the convexity 42b abuts the recoil bar 321 at the same time the shoulders 76 and 78 engage. This ensures that forces on the fuse tube 24 caused by 5 the thrust thereof are equally and simultaneously transferred to the contaet assemblies 18 and 20 during operation of the cutout 2. As a consequence of this, and as a consequence of the fact that the pin 43' can precess a more limited amount that can the pin ~13 o~ FIGUl~E 1, both too early opening of the fuse tube assembly 22 and exacerbation of the effect of ~he bending forces on the filse tube 24 are 10 limited or eliminated.
Thus, by the simple expedients of e]iminating the bushing 45 and the washer 46, and forming the recoil bar 32', the operation of the cutout 12 has been observed to be gre~tly improved over that of the cutout 10 illustrated in FIGURE
15 1. Fractures OI the fuse tube 24 in the vicinity of the ferrule 72 are all ~ut eIiminated, as is too early opening of the fuse tube assembly 22. The limitation of the amount of transverse movement of the fuse tube 24 and precession of the pin 43' effected by the improvement in the upper contact structure l 8 are illustrated in FIGUR~ 5 which is similar to, but represents an improvement over FIGURE 2a.
Another improvement in the eutout 12 over that of the cutout 10, but which does not form the subject matter of the present invention, is illustrated by the depiction of the lower contact assembly 20', as shown in FIGURES 3, 4b, and 4c. Specifically, it will be noted from these FI~URES that the metal content of 2 5 the support member 56 has been decreased significantly so that the reference numeral 56' is used to indicate the support member of the cutout 12.
~' .
It should be noted that the above-described improvements in the cutout 12 do not affect the normal or rest spacings between the concavity 42a and the trun-30 nion pockets 649 That is to say, the general contour and location of the springeontact member 42 has not been altered b~ the above improvements. As a conse-:. , quence, fuse tube assemblies 22 viewed as "standard" that is, having "standard' : ~ :
lengths--may be used with the improved cutout 12 similar to their use in the prior art cutout tû. Accordingly, eomplete interchangeabi]ity between the fuse tube assemblies 2? used in either cutout 10 or 12 is achieved. This ability to continue to use fuse tube assemblies 22 of standard lengths is obviously important. One 5 solution to the problems of the prior art cutout 10, which was arrived at prior to the derivation ot the present invention, involved permitting the recoil bar 32 of FIGURE 1 to remain as depicted in that FI(3UR~ and to simply change the contour of the spring contact member 42 to move the short leg thereof closer to the recoil bar 32. Note that while this chan~e in the spring contact member 42 might have 10 the effect of shortening the available length of the pin 42 for precession or random transverse movement, it also changes the distance between the concavity 42a and the trunnion pockets 64. Thus, if this interrnediate improvement were to be :~ .
effected, either fuse tube assemblies 22 of non-standard length would be necessary, I
, : ~
thus eliminating interchangeability, or the contour and configuration of the lower 15 contact assembly 20 vvould have to be altered, especially in the vicinity of the trunnion pockets 64 to permit continued use of the standard length fuse tube assemblies 22. Thus, the improvement represented by the cutout 12 involves material savings, improved operation, and the ability to continue to use standard ~; lengths of ~se tube assemblies 22. It also represents a distinct improvement over 20 any proposed solution ~hat involves alteration of the contour and location of either : ::
the spring contact member 42 or the first contact assembly 20 or both.
The above described embodiments of the present invention are simply illustrative of the principles thereof. Various other modifications and changes may ,, 25 be devised by those skilled in the art which embody the principles of this invention, yet fall within the spirit and the scope thereof.
.
.
i .
Claims (11)
1. In a cutout mounting having first and second contact assemblies between which a fuse tube of predetermined length is supportable, the fuse tube being selectively placeable in, and, when so placed, being rotatable in the first contact assembly, an improved second contact assembly of the type which includes-(a) a generally J-shaped spring contact, the long leg of the J being attached to a rigid, straight recoil bar, a portion of the recoil bar extending into the space between the legs of the J, the short leg of which has a concavity formed therein for selectively receiving an end of the fuse tube and a convexity comple-mentary with the concavity;
(b) a pin freely passing through a hole in the extending portion of the recoil bar and being attached between the long leg and the convexity, both legs being constrained to move together as the pin moves through the hole and the long leg flexes out of a rest location about its point of attachment to the recoil bar; and (c) resilient means acting between the short leg and the recoil bar for setting the rest location of the long leg;
closure of the cutout by rotating the fuse tube in the first contact assembly inserting an end of the fuse tube into the concavity so that the legs are deflected against the action of the resilient means and the flexing of the long leg out of its rest location; operation of the cutout causing the fuse tube to thrust both against and transverse to the concavity, such thrust (i) applying a bending force to the fuse tube which may fracture as a result thereof, (ii) randomly transversely moving the short leg and the pin until the pin engages the walls of the hole, and (iii) further deflecting the legs against the action of the resilient means and the flexing of the long leg; wherein the improvement comprises:
an offset formed in the recoil bar to position the extending portion and the hole substantially closer to the short leg and the convexity to (1) limit the extent of the random transverse motion which the short leg can experience before the pin engages the hole walls, thereby limiting the bending force on the fuse tube, and (2) accurately position the convexity sufficiently close to the recoil bar to accurately limit the amount of movement of the short leg before it engages the recoil bar, thereby eariier transferring force caused by such thrust to the recoil bar.
(b) a pin freely passing through a hole in the extending portion of the recoil bar and being attached between the long leg and the convexity, both legs being constrained to move together as the pin moves through the hole and the long leg flexes out of a rest location about its point of attachment to the recoil bar; and (c) resilient means acting between the short leg and the recoil bar for setting the rest location of the long leg;
closure of the cutout by rotating the fuse tube in the first contact assembly inserting an end of the fuse tube into the concavity so that the legs are deflected against the action of the resilient means and the flexing of the long leg out of its rest location; operation of the cutout causing the fuse tube to thrust both against and transverse to the concavity, such thrust (i) applying a bending force to the fuse tube which may fracture as a result thereof, (ii) randomly transversely moving the short leg and the pin until the pin engages the walls of the hole, and (iii) further deflecting the legs against the action of the resilient means and the flexing of the long leg; wherein the improvement comprises:
an offset formed in the recoil bar to position the extending portion and the hole substantially closer to the short leg and the convexity to (1) limit the extent of the random transverse motion which the short leg can experience before the pin engages the hole walls, thereby limiting the bending force on the fuse tube, and (2) accurately position the convexity sufficiently close to the recoil bar to accurately limit the amount of movement of the short leg before it engages the recoil bar, thereby eariier transferring force caused by such thrust to the recoil bar.
2. An improved second contact assembly as in Claim 1, the fuse tube and the first contact assembly being of a type further including normally spaced-apart features which engage after the further deflection of the legs during cutout operation to apply thrust-caused force to the first contact assembly, wherein the improvement further comprises:
the distance between the convexity and the recoil bar after the closure of the cutout, but before the further deflection of the legs, being equal to the normal spacing between the features so that after the further deflection of the legs, the thrust-caused force is simultaneously transferred to the first contact assembly and the recoil bar.
the distance between the convexity and the recoil bar after the closure of the cutout, but before the further deflection of the legs, being equal to the normal spacing between the features so that after the further deflection of the legs, the thrust-caused force is simultaneously transferred to the first contact assembly and the recoil bar.
3. The improved second contact assembly of Claim 2, wherein the pre-determined length of the fuse tube is a standard length which need not be altered for use in the cutout.
4 An improved second contact assembly as in Claim 1, being of the type further including a washer interposed between the resilient means and the top of the convexity, wherein the improvement further comprises:
a resilient member acting directly between the base of the convexity and the recoil bar.
a resilient member acting directly between the base of the convexity and the recoil bar.
5. An improved second contact assembly as in claim 4, wherein the improvement further comprises:
the washer being eliminated and the length of the resilient member being less than the length of the resilient means.
the washer being eliminated and the length of the resilient member being less than the length of the resilient means.
6. An improved second contact assembly as in Claim 1, being of the type further including an apertured bushing held in the hole, the pin freely passing through the aperture, thrust-caused force on the fuse tube further deflecting the legs until the convexity abuts an extending portion of the bushing; wherein the improvement comprises:
the bushing being eliminated so that the convexity direclty abuts the recoil bar during the further deflection of the legs.
the bushing being eliminated so that the convexity direclty abuts the recoil bar during the further deflection of the legs.
7. An improved second contact assembly as in Claim 6, being of the type further including a washer interposed between the resilient means and the top of the convexity, wherein the improvement further comprises:
the washer being eliminated so that the convexity directly abuts the recoil bar during the further deflection of the legs.
the washer being eliminated so that the convexity directly abuts the recoil bar during the further deflection of the legs.
8. An improved cutout mounting of the type having first and second contact assemblies between which an elongated fuse tube of predetermined length is supportable, a first fitting on one end of the fuse tube and the first contact assembly each including normally spaced apart features which engage during cutout operation to apply thrust-caused forces on the fuse tube to the first contact assembly; the second contact assembly being of the type which includes:
(a) a spring contact one end of which is attached to a rigid recoil bar which overlies at least a portion of the spring contact, the spring contact having both a concavity, formed in a free end thereof for selectively receiving a second fitting on the other end of the fuse tube, and a convexity complementary to the concavity;
(b) a pin freely passing through a hole in the recoil bar and being attached to the convexity, the pin moving through the hole as the spring contact flexes out of a rest location about its point of attachment to the recoil bar; and (c) resilient means acting between the spring contact and the recoil bar for setting the rest location of the spring contact;
closure of the cutout, effected by rotating the first fitting in the first contact assembly, inserting the second fitting on the other end of the fuse tube into the concavity so that the spring contact is deflected against the action of the resilient means and the flexing of the spring contact out of its rest location;
operation of the cutout causing the fuse tube to thrust the second fitting both against and transverse to the concavity, such thrust (i) applying a bending force to the fuse tube which may fracture as a result thereof, (ii) randomly transversely moving the spring contact and the pin until the pin engages the walls of the hole and (iii) further deflecting the spring contact against the action of the resilient means and the flexing of the spring contact; wherein the improvement comprises:
the recoil bar having a configuration and location which positions it and the hole substantially closer to the spring contact for limiting the maximum amount of deflection the spring contact can experience, the maximum amount of spring contact deflection representing a maximum amount of movement which the con-vexity can experience after closure of the cutout and during the further deflection of the spring contact, which maximum amount of movement of the convexity is equal to the normal spacing between the features so that after the further deflection of the spring contact, thrust-caused forces are simultaneously trans-ferred to the first contact assembly and the recoil bar, whereby the extent of the random transverse motion which the spring contact can experience until the pin engages the hole walls is limited to limit the bending force on the fuse tube and to prevent the first fitting on the one end of the fuse tube from becoming disengaged from the concavity before the thrust of the fuse tube subsides.
(a) a spring contact one end of which is attached to a rigid recoil bar which overlies at least a portion of the spring contact, the spring contact having both a concavity, formed in a free end thereof for selectively receiving a second fitting on the other end of the fuse tube, and a convexity complementary to the concavity;
(b) a pin freely passing through a hole in the recoil bar and being attached to the convexity, the pin moving through the hole as the spring contact flexes out of a rest location about its point of attachment to the recoil bar; and (c) resilient means acting between the spring contact and the recoil bar for setting the rest location of the spring contact;
closure of the cutout, effected by rotating the first fitting in the first contact assembly, inserting the second fitting on the other end of the fuse tube into the concavity so that the spring contact is deflected against the action of the resilient means and the flexing of the spring contact out of its rest location;
operation of the cutout causing the fuse tube to thrust the second fitting both against and transverse to the concavity, such thrust (i) applying a bending force to the fuse tube which may fracture as a result thereof, (ii) randomly transversely moving the spring contact and the pin until the pin engages the walls of the hole and (iii) further deflecting the spring contact against the action of the resilient means and the flexing of the spring contact; wherein the improvement comprises:
the recoil bar having a configuration and location which positions it and the hole substantially closer to the spring contact for limiting the maximum amount of deflection the spring contact can experience, the maximum amount of spring contact deflection representing a maximum amount of movement which the con-vexity can experience after closure of the cutout and during the further deflection of the spring contact, which maximum amount of movement of the convexity is equal to the normal spacing between the features so that after the further deflection of the spring contact, thrust-caused forces are simultaneously trans-ferred to the first contact assembly and the recoil bar, whereby the extent of the random transverse motion which the spring contact can experience until the pin engages the hole walls is limited to limit the bending force on the fuse tube and to prevent the first fitting on the one end of the fuse tube from becoming disengaged from the concavity before the thrust of the fuse tube subsides.
9. An improved cutout mounting as in Claim 8, wherein the improvement further comprises:
the resilient means acting directly between the base of the convexity and the recoil bar.
the resilient means acting directly between the base of the convexity and the recoil bar.
10. An improved cutout mounting as in Claim 8, wherein the improvement further comprises:
the resilient means acting between the convexity and the recoil bar.
the resilient means acting between the convexity and the recoil bar.
11. The improved second contact assembly of Claim 9 or 10, wherein the predetermined length of the fuse tube is a standard length which need not be altered for use in the cutout.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US13292480A | 1980-03-24 | 1980-03-24 | |
| US132,924 | 1980-03-24 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1146198A true CA1146198A (en) | 1983-05-10 |
Family
ID=22456198
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000373559A Expired CA1146198A (en) | 1980-03-24 | 1981-03-20 | Fuse cutout |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1146198A (en) |
-
1981
- 1981-03-20 CA CA000373559A patent/CA1146198A/en not_active Expired
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4414527A (en) | Contact assembly for a fuse cutout | |
| US4307369A (en) | High-voltage fuse cutout | |
| AU667953B2 (en) | Current limiting fuse and dropout fuseholder for interchangeable cutout mounting | |
| CA2483509C (en) | Fuse cutout with improved dropout performance | |
| US3827010A (en) | Composite sectionalized open-type drop-out-type fusible output with series enclosed current limiting fuse | |
| CN101563819B (en) | Pluggable surge arrester | |
| US4011537A (en) | Composite dropout fuse device | |
| CA2139023A1 (en) | Current limiting fuse and dropout fuseholder | |
| US2794095A (en) | Striker pin structures | |
| CA1145798A (en) | Cutout fuse tube having a mildly tapered bore | |
| EP2067157A2 (en) | Vacuum recloser | |
| CA1146198A (en) | Fuse cutout | |
| US2324044A (en) | Fuse cutout | |
| CA1139337A (en) | Fuse link for a fuse cutout | |
| CA2007779A1 (en) | Fuse assembly, for a cutout, with accelerated arc extinction | |
| US2821604A (en) | Fuse constructions | |
| US2655576A (en) | Drop out fuse switch | |
| CA2796580C (en) | Multiple operation cutout | |
| US5566423A (en) | Delay mechanism for retarding relative movement between two members | |
| US2630508A (en) | Circuit interrupter | |
| ES356615A1 (en) | Circuit interrupter having dual-bore arc extinguishing means | |
| US3194923A (en) | Current limiting fuse | |
| US2361666A (en) | Electrical fuse | |
| US2829218A (en) | Circuit interrupter | |
| US3781746A (en) | Expulsion fuse and support means |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry | ||
| MKEX | Expiry |
Effective date: 20000510 |