US3401246A - High voltage circuit interrupter - Google Patents

High voltage circuit interrupter Download PDF

Info

Publication number
US3401246A
US3401246A US663126A US66312667A US3401246A US 3401246 A US3401246 A US 3401246A US 663126 A US663126 A US 663126A US 66312667 A US66312667 A US 66312667A US 3401246 A US3401246 A US 3401246A
Authority
US
United States
Prior art keywords
blocks
conducting
bore
casing
auxiliary
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 - Lifetime
Application number
US663126A
Other languages
English (en)
Inventor
Calvin C Patterson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Westinghouse Electric Corp
Original Assignee
Westinghouse Electric Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Westinghouse Electric Corp filed Critical Westinghouse Electric Corp
Priority to US663126A priority Critical patent/US3401246A/en
Priority to GB34072/68A priority patent/GB1200707A/en
Priority to BE719027A priority patent/BE719027A/xx
Priority to FR163800A priority patent/FR1578502A/fr
Priority to SE11423/68A priority patent/SE344138B/xx
Priority to JP5994968A priority patent/JPS4614019B1/ja
Priority to ES357491A priority patent/ES357491A1/es
Application granted granted Critical
Publication of US3401246A publication Critical patent/US3401246A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H85/00—Protective devices in which the current flows through a part of fusible material and this current is interrupted by displacement of the fusible material when this current becomes excessive
    • H01H85/02—Details
    • H01H85/04—Fuses, i.e. expendable parts of the protective device, e.g. cartridges
    • H01H85/041—Fuses, i.e. expendable parts of the protective device, e.g. cartridges characterised by the type
    • H01H85/042—General constructions or structure of high voltage fuses, i.e. above 1000 V
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H85/00—Protective devices in which the current flows through a part of fusible material and this current is interrupted by displacement of the fusible material when this current becomes excessive
    • H01H85/02—Details
    • H01H85/38—Means for extinguishing or suppressing arc

Definitions

  • Separable conducting means are disposed in the main and auxiliary bores which are connected electrically in series with a fusible means disposed adjacent to one end of the associated casing and which are axially movable through the respective bores during an interrupting operation and means is provided for limiting the gas pressure.
  • one or more of the blocks of the body of arc-extinguishing material adjacent to the fusible means includes a recess which is spaced laterally from and extends substantially around the large opening of the block with the peripheral ends of the recess being adjacent to and spaced from the small opening of the block, said recess extending axially from one end of the associated block to an axial position which is spaced from the other end of the block to thereby define inner and outer walls in the block.
  • one or more blocks adjacent to the fusible means may include a plurality of axially spaced grooves around the outer periphery thereof which terminate short of the small opening in the block and a generally tubular member formed from a gas evolving material having a greater mechanical strength than that of the material from which the block is formed is disposed between the grooved block or blocks and the outer casing of the interrupter with the grooved block or blocks tending to break up when subjected to the same conditions described above to thereby increase the effective I size or volume of the main bore.
  • a further object of this invention is to provide an improved high voltage power fuse construction of the dualbore type including means for limiting the gas pressure which results when the power fuse is called upon to interrupt relatively high currents.
  • a more specific object of this invention is to provide an improved high voltage power fuse construction of the dual-bore type including a plurality ofblocks of gas evolving arc-extinguishing material through which the respective bores pass with one or more of the blocks adapted to break up when subjected to the intense heat and gas pressure which results when the power fuse is interrupting relatively high currents to increase the effective size or 3,401,246 Patented Sept. 10, 1968 volume of the main bore to thereby limit the gas pressure in the power fuse structure to a lower value than that would otherwise result.
  • FIGURE 1 is a side elevational view of a high voltage power fuse structure which embodies the principles of the present invention and which is shown in the normally closed operating condition;
  • FIG. 2 is an enlarged, longitudinal, sectional view of a fuse unit which forms part of the fuse structure shown in FIG. 1 with portions of the end fittings of the fuse unit omitted;
  • FIG. 3 is an enlarged top plan view of a generally annular block of gas evolving material which forms part of a body of arc-extinguishing material which is incorporated in the fuse unit of FIG. 2;
  • FIG. 4 is an enlarged side elevational view of the block of gas evolving material shown in FIG. 3;
  • FIG. 5 is an enlarged, partial, side elevational view of an alternative construction for a portion of the fuse unit shown in FIG. 2;
  • FIG. 6 is an enlarged top plan view of a generally annular block of gas evolving material which forms part of the alternative fuse unit construction shown in FIG. 5;
  • FIG. 7 is an enlarged, side elevational view of the block of gas evolving material which is shown in FIG. 6.
  • the structure shown comprises a power fuse structure of the high voltage, drop-out type, the general arrangement of which is set forth more fully in copending application Ser. No. 663,020, filed Aug. 24, 1967, by R. E. Frink and C. T. Walker, which is assigned to the same assignee as the present application.
  • the fuse structure 10 includes a base (not shown) formed of sheet metal and a pair of outwardly extending insulator supports 272 and 282.
  • the upper insulator support 272 fixedly supports in position a latching assembly 250 which includes a relatively stationary break contact 252 as described in greater detail in the copending application just mentioned.
  • the lower insulator support 282 supports a hinge assembly 260 which, in turn, pivotally supports a fuse unit and which includes a relatively stationary hinge contact 262, as described in the copending application just mentioned.
  • the fuse unit 100 serves to electrically bridge the upper break contact 252 and the lower hinge contact 262 so that electric current will normally pass therebetween by way of terminal pads (not shown) to which an external electrical circuit may be connected.
  • the fuse unit 100 includes a generally tubular fuse holder or casing 32 which is formed from a suitable weather-proof, electrically insulating material, such as a filament wound glass epoxy material or the like, and a pair of upper and lower end fittings or terminals 34 and 36, respectively, which are disposed at the opposite ends of the holder 32 and which are formed from an electrically conducting material.
  • the upper and lower end fittings or terminals 34 and 36, respectively, are securely fastened to the opposite ends of the associated holder or tube 32 by suitable means, such as cement, and a plurality of pins (not shown) which pass transversely through both the end of fittings 34 and 36 and the associated holder 32.
  • the fuse unit 100 also includes a hook eye 274 which is pivotally mounted on a laterally projecting portion 34A of the upper end fitting 34, as shown in FIG. 2, and which may be utilized for effecting opening and closing movements of the fuse unit 100 by means of a conventional hook-stick.
  • the lower end fitting 36 includes a hinge lifting eye 284 which may be formed integrally with the lower end fitting 36 and which may be employed in conjunction with a conventional hook-stick to effect physical removal of the fuse unit 100 from the hinge assembly 260 for replacement or insertion of the fuse unit 100.
  • the lower end fitting or terminal 36 also includes an inwardly projecting flange portion 36B against which the lower end of the holder or casing 32 bears, as shown in FIG. 2.
  • the fuse unit 100 further includes a renewable or refillable unit 20 which is mounted or disposed within the holder structure which includes the outer tube 32 and the upper and lower end fittings or terminals 34 and 36, respectively.
  • the renewable unit 100 includes its own supporting tube or insulating casing 110 which is formed from a suitable electrically insulating material having sufficient strength to withstand the internal gas pressures and intense heat which result during an interrupting operation of the fuse unit 100, such as a filament wound glass epoxy material.
  • a body of gas evolving, arc-extinguishing material, such as boric acid, is disposed inside the tube or casing 110 and axially spaced from the ends thereof.
  • the body of gas evolving material may include a plurality of generally annular blocks 122, 124, 126 and 128, each of which includes a relatively larger central opening as indicated at 125 for the block 128 in FIG. 3 and a relatively smaller opening at one side thereof, as indicated at 127 for the block 128 in FIG. 3, both of the openings in each block extending axially through the respective blocks.
  • a main bore 130 is formed through the body of gas evolving, arc-extinguishing material which includes said blocks and a relatively smaller auxiliary bore 192 is formed through a body of gas evolving, arc-extinguishing material.
  • the meeting surfaces of the blocks 122, 124, 126 and 128 are structurally joined to one another around the relatively smaller openings which form the auxiliary bore 192 by a sealing and bonding material having a relatively high dielectric strength, such as an epoxy resin.
  • the meeting surfaces of the blocks 122, 124, 126 and 128 each includes a recess or groove as indicated at 128B in FIG. 3 for the block 128 which extends substantially around the relatively smaller opening in each of said blocks and forms with the adjacent block a combined passageway which is substantially filled with the sealing and bonding material, as indicated at 132 in FIG. 2. It is to be noted that the manner in which the blocks 122, 124, and 128 are bonded to one another around the auxiliary bore 192 substantially prevents the entrance of the sealing and bonding material into either the auxiliary bore 192 or into the main bore 130.
  • each of the blocks 126 and 128 as illustrated includes a recess as indicated at 129 which extends axially from one end of each of said blocks to an axial position or point which is axially spaced from the other end of the respective blocks, as best shown in FIGS. 3 and 4 for the block 128. It is to be noted that the recess 129 of the block 128, as
  • each of the recesses 129 is laterally or radially spaced from the large opening of the associated block, as indicated at 125 in FIG. 3 for the block 128, and extends around the large opening in a generally C-shaped configuration with the peripheral ends of the recess 129 terminating short of the portion of the associated block which includes the relatively smaller opening which forms part of the auxiliary bore 192.
  • Each of the blocks 126 and 128 includes therefore around the major portion of its periphery and outer wall, as indicated at 128E for the block 128 in FIGS. 3 and 4, and a frangible inner wall, as indicated at 126A and 128A, respectively in FIGS. 2, 3 and 4 for the respective blocks 126 and 128, which tends or is adapted to break up or disintegrate when the fuse unit is called upon to interrupt relatively large currents and the blocks 126 and 128 are subjected to intense heat and relatively high gas pressures within the main bore 130.
  • the size or volume of the main bore 130 through the blocks 126 and 128 is effectively increased by the breaking up of the inner walls 126A and 128A of the blocks 126 and 128, respectively, to thereby increase the size or volume of the gass passageway through said blocks and to limit the gas pressure which results in the main bore to a value less than that which would otherwise result.
  • the blocks 126 and 128 are assembled with the open ends of the recesses 129 facing each other and with the closed ends of the blocks 126 and 128 axially spaced away from one another as best shown in FIG. 2.
  • the integrity of the main bore 130 is normally maintained through the blocks 126 and 128 when the fuse unit 100 is interrupting currents less than those which result in the breaking up of the frangible inner walls of the blocks 126 and 128 to thereby more elfectively confine the arc and result in suflicient gas pressure as required to interrupt the particular magnitude of current which the fuse unit 100 is interrupting.
  • the presence of the recesses 129 and the blocks 126 and 128 has the effect of structurally weakening the blocks 126 and 128 to permit the increase in the size or volume of the main bore 130 through said blocks during the interrup tion of relatively high currents, while at the same time maintaining a normal size gas passageway through the main bore 130 as it extends through the blocks 126 and 128 when the fuse unit 100 is interrupting currents which result in relatively lower gas pressures which would not be high enough to rupture the outer tube or casing 110.
  • the breaking up of the frangible inner walls 126A and 128A of the blocks 126 and 128, respectively, when the (fuse unit 100 is called upon to interrupt relatively large currents results in a sudden increase in the volume of the gas base inside the tube or casing as the pieces of the frangible inner walls 126A and 128A are blown out of the lower end of the refillable unit 20 to thereby limit the gas pressure inside the tube or casing 110 to a safe value within its rupture strength.
  • the outer surfaces of said blocks may be coated with a suitable cement, such as an epoxy bonding material, prior to the assembly of the blocks inside the casing 110, said cement serving to bond said blocks to the casing.
  • a generally annular retaining member or plug member 189 may be disposed at the upper end of the blocks 122, 124, 126 and 128 with the major portion of the retaining member 189 extending axially inside the casing 110 as shown in FIG. 2.
  • the retaining member 189 may be formed or molded from a suitable electrically insulating material having sufiicient strength to assist in retaining said blocks in assembled relationship with the casing 110 during an interrupting operation of the fuse unit 100, such as a glass-polyester material.
  • a washer 183 formed from similar material may be disposed between the retaining member 189 and the uppermost block 122, as viewed in FIG. 2, and may be employed during the assembly and bonding of said blocks together prior to the assembly of said blocks inside the casing 110. It is to be noted that the retaining member 189 as well as the washer 183 includes a relatively larger central opening which forms an extension of the main bore 130 and a relatively smaller opening which forms an extension of the auxiliary bore 192.
  • the outer surface of the retaining memher 189 and the inner surface of the tube or casing 110 at the upper end of said casing include adjacent helical grooves which together form a passageway in which a helical wire 181 is disposed to firmly secure the retaining member 189 in assembled relation with the casing 110.
  • the retaining member 189 may be assembled with the upper end of the casing 110 by first assembling the helical wire 181 in the groove around the outer surface of the retaining member 189 and then screwing the retaining member 189 into the upper end of the casing 100 to the final position shown in FIG. 2.
  • a generally tubular member 185 is disposed in concentric or nested relation with the retaining member 189, as shown in FIG. 2, and is preferably formed from an electrically insulating material having a relatively low coeflicient of friction, such as polytetrafluoroethylene which is sold under the trademark Teflon.
  • a shoulder portion 185A is provided at the upper end of the tubular member 185 and includes an opening of reduced cross-section or size through which the conducting member 83 passes and which forms a substantially gas-tight seal with the conducting member 83 during an interrupting operation of the fuse unit 100 when the conducting member is actuated to move axially upwardly, as
  • the tubular member 185 also acts as a bearing to guide the axial movement of the conducting member 83.
  • the retaining member 189 includes an inner shoulder portion against which the upper end of the tubular member 185 bears, as shown in FIG. 2.
  • the escape of ionized gases from the upper end of the renewable unit 20 from the auxiliary bore 192 may be adequately prevented by reducing the size of the relatively smaller opening through the retaining member 189 through which the auxiliary conductor 182 passes so that the cross-section of the auxiliary conductor 182 substantially fills the relatively smaller opening through the retaining member 189.
  • a generally tubular or annular retaining member 142 is dis posed inside the casing 110 at the lower end of the blocks 122, 124, 126 and 128, as shown in FIG. 2, and is formed or molded from an electrically insulating material having sufficient strength to assist in retaining the blocks 122 through 128 inside the casing 110 during such an interrupting operation, such as a glass-polyester material.
  • the outer surface of the retaining member 142 is preferably coated with a suitable cement or bonding material, such as an epoxy bonding material, prior to the assembly of the retaining member 142 inside the tube 108.
  • the retaining member 142 includes a relatively larger opening which extends axially therethrough, as indicated at 142A, into which the lower end of the main bore 130 opens and which may serve as an exhaust passageway for high pressure gases which result during the operation of the fuse unit 100.
  • the opening 142A also serves as a chamber in which the fusible means 160 is disposed.
  • the retaining member 142 also includes a relatively smaller opening 142B which extends axially therethrough.
  • the lower end of the auxiliary bore 192 opens into the opening 14213 and the lower end of the auxiliary conductor 182 projects in the same opening.
  • insulating wall or partition 142C which is formed integrally with the retaining member 142 around the relatively smaller opening 142B through the retaining member 142 assists in preventing certain arc products which may result during the operation of the fuse unit in a relatively smaller opening 14213 of the retaining member 142 from being deflected into the relatively larger opening 142A of the retaining member 142 and impinging on parts of .the fusible means 160.
  • the retaining member 142 also includes an upwardly projecting tubular portion 142D adjacent to the relatively smaller opening 142B through the retaining member 142 with the projecting portion 142Dbeing joined to the adjacent block 128 around a recess in the block 128 which is adapted to receive the projecting portion 142D by a flexible bonding material, such as silicon rubber.
  • This joint between the retaining member 142 and the block 128 around the auxiliary bore 192 assists in preventing the travel or escape of ionized gases between the auxiliary bore 192 and the main bore 130 and between the auxiliary bore 192 and the relatively larger opening 142 through the retaining member 142 during an interrupting operation of the fuse unit 100.
  • the elongated conducting member or rod 83 of the refillable unit 20 is normally disposed, as shown in FIG. 2, to extend through the main bore 130 with the upper end of the conducting rod 83 projecting axially beyond the upper end of the casing 110 and with the upper portion of the conducting rod being externally threaded, .as indicated at 83A.
  • the conducting rod 83 is normally held in the position shown in FIG. 2 by a connection through the fusible means 160 to the generally annular or tubular lower conducting member or contact 150.
  • the fusible means 160 comprises a strain element 162 and a fusible element or link 164.
  • the upper end of the strain element 162 is secured by suitable means, such as brazing, to the lower end of the conducting rod 83, while the other end of the strain element 162 is secured by suitable means, such as brazing, to the connecting conductor or terminal 156 which is of the flat strip type.
  • the connecting conductor 156 is secured in turn to the lower contact adjacent to the upper end of the lower contact 150 by suitable means, such as brazing.
  • the upper end of the fusible element or link 164 is secured to the lower end of the conducting rod 83 by suitable means, such as brazing, while the lower end of the fusible element or link is secured to the lower contact 150 adjacent to the upper end of the lower contact 150 by suitable means, such as brazing. It is to be noted that the strain element 162 and the fusible element 164 are electrically connected in parallel between the lower end of the conducting rod 83 and the lower contact 150 of the renewable unit 20'.
  • the auxiliary conductor 182 which is of a relatively smaller cross-section or size than the conducting rod 83 normally extends through the auxiliary bore 192 with the upper end of the auxiliary conductor 182 extending axially beyond the upper end of the auxiliary bore 192 and being both mechanically and electrically connected to the upper portion of the conducting rod 83 by a transversely extending spring pin 184.
  • the pin 184 is disposed in a transversely extending recess or opening provided at the upper end of the retaining member 189 to prevent rotation of the conducting rod 83 after assembly of the rod 83 in the renewable unit 20.
  • the upper end of the auxiliary conductor 182 may be formed as a loop which is assembled over the conducting spring pin 184 and retained thereon by the head 186 of the spring pin 184.
  • the lower end of the auxiliary conductor 182 extends or projects into the relatively smaller opening 142B of the retaining member 142, as shown in FIG. 2, and is electrically connected through a helical conducting wire of reduced cross-section, as indicated at 194, to an angleshaped auxiliary stationary terminal 157 which is secured to the tubular conducting member 150 adjacent to the upper end of the member 150 by suitable means, such as brazing.
  • the upper end of the helical wire 194 which is disposed inside the relatively smaller opening 142B of the retaining member 142 is secured to the lower end of the auxiliary conductor 182 by suitable means, such as brazing, and the lower end of the helical wire 194 is securedto the auxiliary terminal 157 by suitable means, such as crimping or brazing, as disclosed in greater detail in copending application Ser. No. 663,127, filed Aug. 24, 1967, by C. W. Upton, C. C. Patterson and F. L. Cameron which is assigned to the same assignee as th present application.
  • the lower contact or conducting member 150 also includes an elongated arcing terminal 158, as disclosed in the copending application just mentioned, which projects upwardly from the upper end of the contact 150 into the relatively smaller opening 142B of the retaining member 142 to axially overlap the lower end of the auxiliary conducting member 182 with the lower portion of the arcing terminal 158 being disposed adjacent to and generally parallel to the axis of the helical wire 194.
  • the arcing terminal 158 is electrically insulated along its length by a coating or film of electrical insulating material, such as an insulating enamel, which is provided on the arcing terminal 158- to prevent the electrical shorting out of the helical wire 194.
  • the arcing terminal 158 which is formed from an electrically conducting material may be structurally secured to the upper end of the lower contact 150 at the inner periphery thereof by suitably means, such as brazing, or may be formed integrally therewith in a particular application. It is to be noted that the auxiliary current path which extends from the upper portion of the conducting rod 83, through the cross pin 184, the auxiliary conductor 182 and the helical wire 194 to the auxiliary terminal 157 on the lower contact 150 is also electrically connected in parallel with the conducting paths which include, respectively, the strain element 162 and the fusible element 164.
  • the lower tubular conducting member or contact 150 includes a main portion 152 which extends axially inwardly from the lower end of the casing 110 to bear against the lower end of the retaining member 142.
  • the lower contact 150 also includes a flange portion 154 at the lower end thereof against which the lower end of the casing 110 bears when the conducting member 150 is assembled with the casing 110.
  • a generally tubular external terminal member or ferrule 172 is disposed to telescope over the lower end of the casing 110.
  • the internal surface of the external terminal member 172 and the external surface of the portion of the casing 110 adjacent to the member 172 include adjacent helical grooves which, when the par-ts are assembled, form a helical passageway in which a helical wire 173 is disposed.
  • the helical wire 173 may be first assembled in the helical groove on the lower end of the casing 110 and the external terminal member 172 may then be screwed onto the lower end of the casing 110 until the parts reach their final positions, as shown in FIG. 2.
  • the outer surface of the casing and the inner surface of the external terminal member 172 may be coated with a cement or bonding material, such as an epoxy bonding material, prior to the assembly of the external terminal member 172 on the lower end of the casing 110.
  • the external terminal member 172 also includes an inwardly projecting flange portion 172A around a central opening 172B which bears against the adjacent flange portion 154 of the tubular conducting member to assist in retaining the tubular conducting member 150 in assembled relation with the other parts of the renewable unit 20.
  • the external terminal member 172 also includes an external flange portion 172C which bears against the inwardly projecting flange portion 36B of the lower end fitting 36.
  • the electrically conducting path thus formed extends from the lower contact 150 through the inwardly projecting flange portion 172A of the external terminal 172 and through the externally projecting flange portion 172C to the inwardly projecting flange portion 36C of the lower end fitting 36.
  • the area of the current transfer path between the external terminal member 172 of the renewable unit 20 and the lower end fitting 36 may also be augmented by the contact ring which may be formed of electrically conducting material and which is disposed to threadedly engage the internally threaded opening at the lower end of the end fitting 36 and bear against the external terminal member 172 of the renewable unit 20, as shown in FIG. 2.
  • the upper end of the lower contact 150 extends axially beyond the upper end of the external terminal member 172 toward the other end of the casing 110 a minimum distance to prevent such a concentration of relatively high potential stresses externally of the casing 100 adjacent to the external terminal member 172, as disclosed in greater detail in copending application Ser. No. 663,029, filed Aug. 24, 1967, by F. L. Cameron.
  • a spring and cable assembly 30 is disposed inside the outer tube 32 between the renewable unit 20 and the upper end fitting 34, as disclosed and claimed in copending application Ser. No. 663,021, filed Aug. 24, 1967, by C. C. Patterson which is assigned to the same assignee as the present application.
  • the spring and cable assembly 30 includes at its lower end a generally tubular conducting member or socket 84 having an internally threaded central opening, as indicated at 84A, to receive the upper threaded end 83A of the conducting rod 83.
  • the lower spring seat member 86 is fixedly mounted on the socket 84 for movement therewith by assembling the spring seat 86 over the outer periphery of the socket 84 with the lower end of the spring seat 96 bearing against a shoulder provided on the outer periphery of the socket 84 and with the upper end of the spring seat 86 being engaged by a plurality of portions of the socket 8-4 at the upper end of the socket 84 which serve to stake or secure the spring seat 86 on the socket 84.
  • the spring and cable assembly 30 also includes an upper spring seat 74 which is slidably disposed over the lower portion 60A of a generally cylindrical conducting member 60 whose integral upper portion 60B extends' axially through an opening 34B in the upper end fitting 34 and is externally threaded at the.
  • the generally cylindrical conducting member 60 may be secured to the upper end fitting 34 by an internally threaded end cap 44 which may be screwed down on the upper threaded portion 60C of the conducting member 60 until the flange portion 44A of. the end cap 44 bears against the upper end fitting 34 around a flange or shoulder portion, as indicated at 34C 'in FIG. 2.
  • a helical tension spring 76 is secured at its upper end to the external, helically threaded portion of the upper spring seat 74, while the lower end of the spring 76 is secure-d to the external, helically threaded portion of the lower spring seat 86 to bias the conducting rod 83, as well as the auxiliary conductor 182, in a generally upward direction, as viewed in FIG. 2, away from the lower contact 150.
  • the turns of the spring 76 are generally rectangular or square in crosssection to substantially prevent any overlapping of the turns 76 and the consequent damage to the spring 76 that might otherwise result during an interrupting operation of the fuse unit 100, as explained in greater detail in copending application Ser. No. 663,021, just mentioned.
  • a plurality of helically coiled flexible cables or conductors 8-2 are electrically and structurally connected at the bottom ends thereof to the conducting socket 84 into separate openings (not shown) provided in the socket 84 by suitable means, such as brazing or by staking, and at the upper ends thereof are secured to the conducting member 60 in separate openings provided in the conducting member 60 by suitable means, such as brazing or staking.
  • a washer 54 formed of electrically conducting material may be disposed between the shoulder which is formed at the intersection of the upper and lower portions 60A and 60B, respectively, of the conducting member 60 and the shoulder which is formed inside the upper end fitting 34, as indicated at 34D around the central opening 34B.
  • a pair of spring pins 58 may be disposed in associated openings provided at the opposite sides of the upper portion 60B of the conducting member 60 to be positioned finally within an enlarged central opening or recess 34E in the upper end fitting 34, as shown in FIG. 2.
  • a tripping rod or member 52 is slidably disposed inside a central opening or passageway 72 which is provided in the conducting member 60 with the upper end of the tripping rod 52 being normally positioned below the top of the end cap 44, as shown in FIG. 2.
  • the lower end of the tripping rod 52 is fixedly coupled to the upper spring seat 74 for axial movement therewith by the cross pin 56 which passes laterally through aligned transverse openings in the tripping rod 52 and the upper spring seat 74 and through a pair of elongated slots 62 provided at the opposite sides of the conducting member 60 with the cross pin 56 being normally positioned at the lower end of the slots 62, as shown in FIG. 2.
  • the top of the end cap 44 includes a central opening 46 through which the tripping rod 52 may pass to actuate the release of the latching assembly 250 shown in FIG. 1.
  • the latching assembly 250 When the latching assembly 250 is released by the movement of the tripping rod 52, the upper end of the fuse unit 100 will be actuated to rotate in a clockwise direction, as viewed in FIG. 1, 'about the lower hinge assembly 260 to thereby provide an electrically insulating gap between the upper break contact 252 and the lower stationary hinge contact 62 by such drop-out action.
  • the outer holder 32 In order to assemble the renewable unit 20 and the associatedspring and cable assembly 30 into, the outer holder 32, the threaded end of the conducting rod 83 is first screwed into the socket 84 at the lower end ofthe spring and cable assembly 30. A refill fusing tool (not shown) is then screwed into the internally threaded central opening or passageway 72 at the other end of the spring and cable assembly 30. The spring and cable assembly 30 is then inserted into the outer holder 32 with the upper end of the spring and cable assembly 30 being inserted first into the lower end of the outer holder 32, as viewed in FIG. 2, until the refill tool (not shown) passes through the central opening 348 of the upper end fitting 34.
  • the spring 76 is stretched and placed in tension until the cross pins 58 mounted at the sides of the conducting member 60 are drawn upwardly through a pair of radial slots (not shown) provided in the upper end fitting 34 around the central opening 34B.
  • the upper conducting member 60 and the spring and cable assembly 30 are then rotated until the pins 58 rest on the shoulder provided at the bottom of the enlarged opening 34E in the upper end fitting 34.
  • the end cap 44 may then be screwed down on the upper threaded portion 600 of the conducting member 60 to further stretch the spring 76 to the final condition or position shown in FIG. 2 in which the cross pins 58 are drawn upwardly away from the shoulder in the upper end fitting 34 at the bottom of the enlarged opening 34E.
  • the cross pin 56 which couples the upper spring seat 74 to the tripping rod 52 is disposed at the bottom of the slots 62 at the opposite sides of the conducting member 60 to permit limited upward travel of the upper spring seat 74 along with the cross pin 56 and the tripping rod 52 to a final position of the tripping rod 52 in which the tripping rod 52 projects beyond the end cap 44 axially to release the latching assembly 250 as previously mentioned.
  • the washer 54 also acts as a stop surface against which the upper end of the spring seat 74 bears to limit the upward travel of the tripping rod 52, the cross pin 56 and the spring seat 74.
  • the current paths which include, respectively, the strain element 162, the fusible element 164 and the helical wire 194, which are connected in series with the auxiliary conductor 182, are all electrically connected in parallel between the upper end of the conducting rod 83 and the lower contact 150 at the lower end of the renewable unit 20.
  • the resistance of the current path which includes the fusible element 164 and which is calibrated to have predetermined time-current characteristics is arranged to be relatively much less than the resistance of either the path which includes the strain element 162 or the path which includes the helical wire 194 so that normally most of the current which flows through the fuse unit is carried by the fusible element 164.
  • the resistance of the current path which includes the strain element 162 is relatively greater than the resistance of the path which includes the fusible member 164, the resistance of the path which includes the strain element 162 is relatively less than that of the path which includes the helical wire 194 so that when the fusible element 164 melts or blows, most of the current which was formerly carried by the fusible element 164 is then transferred to the strain element 162.
  • the current which is flowing through the fuse unit 100 increases to a value which is of sufficient magnitude and duration to melt or blow the fuse element 164, most of the current which is flowing through the fuse unit 100 then transfers to the strain element 162.
  • the current which is transferred to the strain ele ment 162 after the melting of the fusible element 164 is suflicient to melt or blow the strain element 162
  • the current which was previously carried by the strain element 162 is finally transferred to the current path through the auxiliary bore 192 which includes the auxiliary conductor 182 and the helical wire 194. No arcing occurs as the elements 162 and 164 melt because of the parallel electrical path through the helical wire 194.
  • the conducting rod 83 When the strain element 162 melts or blows, the conducting rod 83 is no longer restrain-ed from upward movement under the influence of the biasing spring 76 and the conducting rod 83 and the auxiliary conductor 182 will start to move upwardly under the influence of the spring 76 to thereby stretch the helical wire 194 which is electrically connected to the bottom of the auxiliary conductor 182. It is to be noted that the stretching of the helical wire 194 permits limited travel of both the conducting rod 83 and the auxiliary conductor 182 while maintaining a continuous electrical circuit through the auxiliary bore 192 and that as long as the current path which includes the auxiliary conductor 182 and the helical wire 194 is intact, no arcing will take place in either the main bore 130 or in the auxiliary bore 192.
  • the stretching of the helical wire 194 during the initial movement of the conducting rod 83 and the auxiliary conductor 182 following the melting or blowing of the fusible element 164 and the strain element 162 will permit the formation of an electrically insulating gap in the main bore 130, while initially maintaining a conducting path and delaying the formation of an insulating gap in the auxiliary bore 192.
  • the helical wire 194 will either fracture mechanically when stretched to its limit or the current transferred to the current path which includes the auxiliary conductor 182 and the helical wire 194 will be sutficient to melt or blow the helical wire 194 which is of reduced cross-section compared with that of the auxiliary conductor or rod 182. After the helical wire 194 is melted or otherwise broken, an arc will be initiated between the retreating end of either the broken.
  • the insulating gap in the main bore 130 between the separated ends of the conducting pants will increase at a faster rate than the formation of an insulating gap in the auxiliary bore 192 due to both the delay in the formation of an arc in the auxiliary bore 192 because of the presence of the helical wire 194 and due to the overlapping of the auxiliary conductor 182 by the arcing terminal 158. It is also important to note that the arcing which takes place in the fuse unit 100 during an interrupting operation will always take place initially in the auxiliary bore 192, as just explained.
  • the insulating gap which is formed in the auxiliary bore 192, along with the corresponding increased dielectric strength, will be sufficient to interrupt the alternating current following a particular current zero in the auxiliary bore 192.
  • the insulating gap which is formed simultaneously in the main gap 132 of the fuse unit at a relatively faster rate will have sutlicient dielectric strength considering the instantaneous potential difference between the separating conducting parts in the main bore 130 of the fuse unit 100 to prevent a restrike of the arc in the main bore 130 for such relatively low fault currents.
  • the arcing which is initiated in the fuse unit 100 will still be initiated in the auxiliary bore 192 in the manner just described.
  • the gas pressure which builds up in the auxiliary bore 192 during an interrupting operation and the burning back of the separated conducting parts in the auxiliary bore 192 will result in a relatively higher dielectric strength in the auxiliary bore 192 compared with that in the main bore 130 between the separated conducting parts in the main bore 130.
  • the arc will restrike in the main bore 130 to thereby cause the evolution of un-ionized gases in the main bore 130 to thereby increase the gas pressure in the main bore 130, as well as the corresponding dielectric strength in the main bore 130.
  • the anc which restrikes in the main bore 130 will be elongated both by the upward movement of the conducting rod 83 and by the burning back of the separated conducting parts in the main bore to thereby increase the quantity of un-ionized gases evolved from the gas evolving material around the main bore 130.
  • the are in the main bore 130 will be finally interrupted following a particular current zero in the alternating current which is being interrupted when the insulating gap and the corresponding dielectric strength in the main bore 130 is sufiicient to withstand the instantaneous potential difference between the separated conducting parts in the main bore 130.
  • the gas pressure in the main bore 130 along with the intense heat which results will be suflicient to break up or disintegrate the frangible inner walls 126A and 128A of the blocks 126 and 128, respectively, to thereby limit the gas pressure of evolved gases because of the increase in the size or volume of the gas passageway or volume of the gas space inside the refillable unit 20 to thereby limit the gas pressure of the evolved gases to a value Within the rupture strength of the casing as previously explained.
  • the gas seal and joint structure between the successive blocks 122, 124, 126 and 128, as previously described substantially preven s the escape of ionized gases from the auxiliary bore 192 in which all arcing initially takes place to the main bore 130 along the meeting surfaces of the successive blocks in the renewable unit 20.
  • FIG. 5 there is illustrated an alternative construction of a fuse unit embodying the invention as indicated at 100' in FIG. 5 which includes a modified refillable or renewable unit which is structurally the same as the renewable unit 20 previously described except that the renewable unit 20' includes a pair of blocks 13-5 and 137 along with a generally tubular member 133 which are located at the lower end of the body of arcextinguishing material provided instead of the blocks 126 and 128 which are provided as part of the renewable unit 20. More specifically, as shown in FIG. 5, each of the generally annular blocks of gas evolving, arcextinguishing material, such as 'boric acid, includes a relatively large central opening as indicated at 139 for the block 137 in FIGS.
  • each of the blocks 135 and 137 cludes a plurality of axially spaced grooves as indicated at 131 for the block 137 which extend around the outer periphery of the associated block with the ends of each groove or recess being spaced from or terminating short of the portion of the associated block which includes the smaller opening of the block, as indicated at 141 for the block 137 in FIGS. 6 and 7.
  • the meeting surfaces of the blocks 135 and 137 are structurally joined together with each other and with the surfaces of the associated blocks 122 and 124 by a suitable sealing and bonding material, such as an epoxy bonding material, similarly to the structure of the refillable unit 20 as previously described with the meeting surfaces of the adjacent blocks each including a groove or recess which extends around the smaller opening in the respective blocks, as indicated at 135A for the block 137, the combined passageway which is formed when the grooves in the adjacent blocks are brought together being filled with said bonding material.
  • a suitable sealing and bonding material such as an epoxy bonding material
  • an axially projecting tubular portion remains at the ends of the blocks 135 and 137, as indicated at 137B for the block in 137 in FIGS. 6 and 7, when the recess or groove is provided around the small opening in the respective block as indicated at 135A for the block 137.
  • the generally tubular member 133 is disposed generally between the blocks 135 and 137 and the associated casing or tube as shown in FIG. 5 with the generaly tubular member 133 extending substantially around the outer periphery of the associated blocks and 137 from at least the portions of said blocks which include the relatively smaller openings, as indicated at 141 for the block 137 in FIGS. 6 and 7.
  • the generally tubular member 132 may include a recess at its lower inner periphery to receive the flange portion 137E of the block 137 which is disposed between the generally tubular member 133 and the lower retaining member 142, as shown in FIG. 5 to assist in retaining the blocks 135 and 137 in assembled relation inside the casing or tube 110'.
  • the generally tubular member 133 is preferably formed from a gas evolving, arc-extinguishing material having a greater mechanical strength than the material from which the blocks 135 and 137 is formed, such as a high molecular weight polyoxymethylene which is sold under the trademark Delrin.
  • the meeting ends of the blocks 135 and 137 include central wall portions which meet to close off the grooves or recesses at the outer periphery of the respective blocks, as indicated at 137F for the block 137 in FIGS. 6 and 7.
  • the operation of the fuse unit 100 including the modified refillable unit 20' is the same as the fuse unit 100 previously described except that for the relatively highest currents to be interrupted by the fuse unit 100, the intense heat and gas pressure which result in the main bore 130' of the fuse unit 100 are suflicient to break up the blocks 135 and 137 which are structurally weakened by the presence of the grooves at the outer periphery as previously described.
  • teachings of the applicants invention may be applied to Power fuses for high voltage applications which are not of the drop-out type as disclosed in my copending application Ser. No. 663,021 filed Aug. 24, 1967, which is assigned to the same assignee as the present application. It is also to be understood that the teachings of the applicants invention may be applied to power fuses for high voltage applications which do not include a tubular conducting member or shield, such as the lower contact 150 shown in FIG. 2, but which instead employs a lower contact ring of the type disclosed in copending application Ser. No. 663,127 previously mentioned.
  • a body of gas evolving arc-extinguishing materials including a plurality of blocks as disclosed with certain of the blocks being stnucturally weakened to permit the limitation of gas pressure during the interruption of relatively high currents preserves the effectiveness of the arc extinction at relatively lower currents when the gas pressure is not sufficient to cause the breaking up of the weakened blocks as previously explained.
  • the weakened blocks of gas evolving arc-extinguishing material may be formed as unitary members without requiring the assembly of composite layers of gas evolving materials as have been proposed in certain prior art structures.
  • the construction of the body of arc-extinguishing material particularly lends itself to a power fuse structure of the dual-bore type since the construction of the blocks as disclosed lends itself to a sealing arrangement which prevents the travel of ionized gases between the main and auxiliary bores as disclosed.
  • a circuit interrupter comprising a tubular electrically insulating casing, a body of gas evolving, arc-ext inguishing material disposed inside of and spaced from the ends of the casing, said body of arc-extinguishing material including a plurality of generally cylindrical blocks stacked axially in end-to-end relation, each of said blocks having a relatively larger opening and a relatively smaller opening extending axially therethrough with the larger openings and the smaller openings, respectively, of the successive blocks being substantially aligned to form a large bore and a small bore, respectively, through the body of arc-extinguishing material, separable conducting means between which an arc is drawn during an interrupt ing operation of the circuit interrupter and interrupted in the small bore for smaller currents and in the larger bore for relatively larger currents, said separable conducting means including fusible means disposed inside the casing adjacent to one end of the body of arc-extinguishing material, one or more of the blocks adjacent to said fusible means including a recess space
  • a circuit interrupter comprising a tubular electrically insulating casing, a body of gas evolving, arc-extinguishing material disposed inside of and spaced from the ends of the casing, said body of arc-extinguishing material including a plurality of generally cylindrical blocks stacked axially in end-to-end relation, each of said blocks having a relatively larger opening and a relatively smaller opening extending axially therethrough with the larger openings and the smaller openings, respectively, of the successive blocks being substantially aligned to form a large bore and a small bore, respectively, through the body of arc-extinguishing material, separable conducting means between which an arc is drawn during an interrupting operation of the circuit interrupter and interrupted in the small bore for smaller currents and in the larger bore for relatively larger currents, said separable conducting means including fusible means disposed inside the casing adjacent to one end of the body of arc-extinguishing material, one or more of the blocks adjacent to said fusible means including a plurality of
  • the block having grooves which is disposed at the end of the body of arc-extinguishing material near the fusible means includes an outwardly projecting flange portion and the tubular member includes a recess adapted to receive the outwardly projecting flange portion of said block to assist 17 in retaining the blocks of the body of arc-extinguishing material in assembled relation inside said casing 7.
  • an additional means is provided for actuating the separable conducting means to separate upon the fusing of the fus ible conducting means.

Landscapes

  • Fuses (AREA)
  • Arc-Extinguishing Devices That Are Switches (AREA)
US663126A 1967-08-24 1967-08-24 High voltage circuit interrupter Expired - Lifetime US3401246A (en)

Priority Applications (7)

Application Number Priority Date Filing Date Title
US663126A US3401246A (en) 1967-08-24 1967-08-24 High voltage circuit interrupter
GB34072/68A GB1200707A (en) 1967-08-24 1968-07-17 High voltage circuit interrupter
BE719027A BE719027A (cs) 1967-08-24 1968-08-02
FR163800A FR1578502A (cs) 1967-08-24 1968-08-22
SE11423/68A SE344138B (cs) 1967-08-24 1968-08-23
JP5994968A JPS4614019B1 (cs) 1967-08-24 1968-08-23
ES357491A ES357491A1 (es) 1967-08-24 1968-08-23 Un dispositivo de interruptor de circuito.

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US663126A US3401246A (en) 1967-08-24 1967-08-24 High voltage circuit interrupter

Publications (1)

Publication Number Publication Date
US3401246A true US3401246A (en) 1968-09-10

Family

ID=24660580

Family Applications (1)

Application Number Title Priority Date Filing Date
US663126A Expired - Lifetime US3401246A (en) 1967-08-24 1967-08-24 High voltage circuit interrupter

Country Status (7)

Country Link
US (1) US3401246A (cs)
JP (1) JPS4614019B1 (cs)
BE (1) BE719027A (cs)
ES (1) ES357491A1 (cs)
FR (1) FR1578502A (cs)
GB (1) GB1200707A (cs)
SE (1) SE344138B (cs)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3855563A (en) * 1973-11-21 1974-12-17 Westinghouse Electric Corp Circuit interrupter
US4952900A (en) * 1989-12-04 1990-08-28 Westinghouse Electric Corp. Controlled seal for an expulsion fuse and method of assembling same
US4995886A (en) * 1989-12-04 1991-02-26 Westinghouse Electric Corp. Method of assembling a controlled seal for an expulsion fuse

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0629878Y2 (ja) * 1990-10-11 1994-08-10 エス・オー・シー株式会社 高遮断超小型ヒューズ
US9117615B2 (en) 2010-05-17 2015-08-25 Littlefuse, Inc. Double wound fusible element and associated fuse

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2183728A (en) * 1936-06-17 1939-12-19 Schweitzer & Conrad Inc Fuse
US2594315A (en) * 1950-10-25 1952-04-29 Chase Shawmut Co Current-limiting fuse
US2961514A (en) * 1959-01-19 1960-11-22 S & C Electric Co Circuit interrupter
US2976381A (en) * 1959-05-15 1961-03-21 S & C Electric Co Circuit interrupter
US3230331A (en) * 1965-04-26 1966-01-18 S & C Electric Co Circuit interrupter construction with improved condenser
US3258568A (en) * 1965-04-26 1966-06-28 Westinghouse Electric Corp Discharge filter for circuit interrupter

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2183728A (en) * 1936-06-17 1939-12-19 Schweitzer & Conrad Inc Fuse
US2594315A (en) * 1950-10-25 1952-04-29 Chase Shawmut Co Current-limiting fuse
US2961514A (en) * 1959-01-19 1960-11-22 S & C Electric Co Circuit interrupter
US2976381A (en) * 1959-05-15 1961-03-21 S & C Electric Co Circuit interrupter
US3230331A (en) * 1965-04-26 1966-01-18 S & C Electric Co Circuit interrupter construction with improved condenser
US3258568A (en) * 1965-04-26 1966-06-28 Westinghouse Electric Corp Discharge filter for circuit interrupter

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3855563A (en) * 1973-11-21 1974-12-17 Westinghouse Electric Corp Circuit interrupter
US4952900A (en) * 1989-12-04 1990-08-28 Westinghouse Electric Corp. Controlled seal for an expulsion fuse and method of assembling same
US4995886A (en) * 1989-12-04 1991-02-26 Westinghouse Electric Corp. Method of assembling a controlled seal for an expulsion fuse

Also Published As

Publication number Publication date
JPS4614019B1 (cs) 1971-04-15
FR1578502A (cs) 1969-08-14
SE344138B (cs) 1972-03-27
ES357491A1 (es) 1970-03-16
GB1200707A (en) 1970-07-29
BE719027A (cs) 1969-01-16

Similar Documents

Publication Publication Date Title
US4307369A (en) High-voltage fuse cutout
US2794095A (en) Striker pin structures
US3304390A (en) Current-limiting fuse with dual element release and having extensions of the current-limiting elements cut by arc blasts in arc chutes and by a mechanical cutter
US4692733A (en) Fuse for an alternating current power circuit
US4952900A (en) Controlled seal for an expulsion fuse and method of assembling same
US2400408A (en) Electrical circuit breaking fuse of the controlled operation type
US3401243A (en) Circuit interrupter having dual-bore arc extinguishing means
US9805897B2 (en) Fuse with carbon fiber fusible element
US3401246A (en) High voltage circuit interrupter
US3401244A (en) Spring and shunt assembly for circuit interrupters
US4870386A (en) Fuse for use in high-voltage circuit
US3401247A (en) Circuit interrupter of the dual bore type
US3401245A (en) Circuit breaker having improved flashover characteristics
US2976381A (en) Circuit interrupter
US3374329A (en) Fuse cutout
US2183728A (en) Fuse
US3508184A (en) Fuse having improved means for reducing the force applied to a fusible means
US3735317A (en) Electric multibreak forming cartridge fuse
US4001749A (en) Electric fuse for elevated circuit voltages
US4189694A (en) Current limiting fuse with improved low current clearing capability
US2458307A (en) Electric circuit interrupter
US2594315A (en) Current-limiting fuse
US2251409A (en) Electric fuse
US3886512A (en) Spring and shunt assembly for circuit interrupter
US3268690A (en) Fuse constructions including a gas filled reservoir