Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H39/00—Switching devices actuated by an explosion produced within the device and initiated by an electric current
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04M—TELEPHONIC COMMUNICATION
  • H04M3/00—Automatic or semi-automatic exchanges
  • H04M3/18—Automatic or semi-automatic exchanges with means for reducing interference or noise; with means for reducing effects due to line faults with means for protecting lines
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
  • H01R13/00—Details of coupling devices of the kinds covered by groups H01R12/70 or H01R24/00 - H01R33/00
  • H01R13/46—Bases; Cases
  • H01R13/52—Dustproof, splashproof, drip-proof, waterproof, or flameproof cases
  • H01R13/5216—Dustproof, splashproof, drip-proof, waterproof, or flameproof cases characterised by the sealing material, e.g. gels or resins
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
  • H01R4/00—Electrically-conductive connections between two or more conductive members in direct contact, i.e. touching one another; Means for effecting or maintaining such contact; Electrically-conductive connections having two or more spaced connecting locations for conductors and using contact members penetrating insulation
  • H01R4/24—Connections using contact members penetrating or cutting insulation or cable strands
  • H01R4/2416—Connections using contact members penetrating or cutting insulation or cable strands the contact members having insulation-cutting edges, e.g. of tuning fork type
  • H01R4/242—Connections using contact members penetrating or cutting insulation or cable strands the contact members having insulation-cutting edges, e.g. of tuning fork type the contact members being plates having a single slot
  • H01R4/2425—Flat plates, e.g. multi-layered flat plates
  • H01R4/2429—Flat plates, e.g. multi-layered flat plates mounted in an insulating base
  • H01R4/2433—Flat plates, e.g. multi-layered flat plates mounted in an insulating base one part of the base being movable to push the cable into the slot
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
  • H01T1/00—Details of spark gaps
  • H01T1/14—Means structurally associated with spark gap for protecting it against overload or for disconnecting it in case of failure
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04Q—SELECTING
  • H04Q1/00—Details of selecting apparatus or arrangements
  • H04Q1/02—Constructional details
  • H04Q1/028—Subscriber network interface devices

Definitions

• This invention relates to surge arrestors for preventing damage to telecommunications and other electronic equipment due to lightning strikes, power line cross-overs and the like.
• the invention more specifically relates to an improved fail safe thermal overload mechanism for a surge arrestor.
• Surge arrestors are well known in the telecommunications and related electronic arts. They commonly consist of a tubular housing having ground and one or two line electrodes spaced along its length. When the arrestor is subjected to a current surge condition over a long period of time, as might occur for instance due to a power line crossing, the heat generated by the arrestor may be sufficient to present a fire hazard. In an effort to prevent the foregoing, it has heretofore been proposed to short circuit the ground and line electrodes when the arrestor is subjected to a thermal overload.
• a commonly employed means for establishing the short circuit includes a spring that is normally maintained in an inactive position by solder or other meltable material.
• U.S. Patent 4,851,946 discloses a different type of fail safe thermal overload mechanism in which molten solder material directly forms a short circuit between ground and line electrodes when the arrestor is subjected to a thermal overload.
• the fail safe thermal overload mechanism of the present invention is similar to that disclosed in the above noted prior patent, in that it employs solder material that melts and directly forms the desired short circuit when the arrestor is subjected to a thermal overload.
• the fail safe mechanism is of highly reliable in its operation and is relatively inexpensive.
• the fail safe mechanism includes solder flux upon the outer surface of the housing of the arrestor, a solder billet overlying the arrestor housing, and channel and spring members that overlie the billet and bias it to a location closely adjacent and preferably butting the arrestor body. Solder flux may also be provided upon the inner and/or outer surfaces of the solder billet.
• a preferred flux is a rosin based one that under normal (i.e., no thermal overload) conditions, cleans and protects the surfaces to which it is applied, and has good dielectric properties and acts as an insulator.
• the flux causes the molten solder to thoroughly wet surfaces of the arrestor housing and the channel member of the fail mechanism so as to facilitate preferential flow of molten solder from the solder billet to one or more locations establishing a highly conductive, low resistance short circuit between the arrestor electrodes.
• the channel member is preferably of generally V-shaped configuration and has first and second sections that extend angularly relative to each other and meet at an apex that overlies and extends generally parallel to the central axis of a the arrestor housing.
• the channel member permits relatively free flow of molten solder from the solder billet in a first direction, which in the illustrative embodiment is generally parallel to the longitudinal axis of the arrestor housing, while limiting flow of the molten solder in a second, transverse direction.
• FIG. 1 is a vertically exploded perspective view of a surge arrestor having a fail safe thermal overload mechanism in accordance with invention
• FIG. 2 is a end view of the arrestor and components of the overload mechanism in an assembled condition
• FIG. 3 is a side elevational view of the surge arrestor
• FIG. 4 is a top plan view of the assembly of Fig. 2, showing in phantom lines a solder billet whose opposite ends are spaced from line electrodes at opposite ends of the arrestor housing;
• FIG. 5 is a view similar to Figure 4 showing in phantom lines a solder billet whose ends extend to electrodes at opposite ends of the body of the arrestor;
• FIG. 6 is a fragmentary end view of the arrestor housing and of a solder billet and overlying channel member of the fail safe mechanism
• FIG. 7 is a view similar to Fig. 6, but showing the components in positions assumed during a thermal overload.
• FIG. 8 is a view similar to Fig. 6 showing gel or other protective sealant material encapsulating the arrestor and components of the fail safe mechanism.
• the surge arrestor 10 shown in the drawings is illustratively of a known type having a cylindrical housing 12 that includes disk-shaped line electrodes 14 at its opposite ends, a disk-shaped ground electrode 16 intermediate the length of the housing, and insulating material 17 intermediate electrode 16 and each of the line electrodes 14.
• Arrestor 10 may and illustratively does further include pin-type lead elements 18 that extend downwardly from respective ones of the electrodes.
• At least some, and illustratively substantially all, of the exterior surface of housing 12 is overlaid by a film, foil or coating of solder flux material 20 which is indicated in the drawings by stippling.
• Flux material 20 is preferably of a rosin-based type that under normal temperatures of housing 12 has strong dielectric properties, and protects the housing and other members engaged thereby from contaminants and other materials such as soft textured encapsulants 44 (e.g., gels, oils, greases, etc.) such as shown in Fig. 8. Under thermal overload conditions the flux greatly facilitates flow of molten solder along the housing and other members engaged thereby.
• Flux of the foregoing type is sold by M. W. Dunton Co. of Buffalo, Rhode Island, under the trademark ELECTRO-ROSIN RA50, and is comprised essentially of natural rosin, alcohol and proprietary activators.
• a channel-shaped solder billet 22 overlies and extends longitudinally of the upper surface of housing 12.
• Billet 22 is illustratively of inverted V-shaped configuration and has opposite side sections that extend angularly downwardly from each other and from an apex 24 upon the upper surface of the billet.
• the undersurface of the billet preferably and illustratively has a concave contour complementary to the cylindrical outer surface of housing 12, and may have a film or coating 20-1 of flux 20 thereon.
• the thickness of billet 22 is greatest in the portion thereof underlying apex 24 and is of a lesser magnitude adjacent the opposite side edges of the billet.
• the upper surface of the billet has a semispherical protuberance 26 generally centrally thereof, and may have a foil, film or coating 20-2 of flux 20 upon such upper surface.
• flux material 20-2 may be present upon the undersurface of a conductive channel member 28 of the thermal overload mechanism.
• member 28 is preferably of generally channel-like V-shaped configuration, and has opposite side sections that closely overlie the opposite side sections of billet 22.
• a centrally located semispherical socket 30 upon the upper surface of member 28 receives billet protuberance 26 and allows limited adjustive movement of billet 22 relative to plate 28 and arrestor housing 12.
• FIG. 1 The aforesaid components of FIG. 1 are secured to each other and to arrestor housing 12 by a generally U-shaped resilient spring member 32.
• Spring 32 has generally horizontally extending upper and lower legs 34, 36 that extend in parallel relationship to each other from a generally vertically extending section 38. Legs 34, 36 have vertically aligned openings 40, 42 adjacent their free outer ends. The center one of the conductive pins 18 extends downwardly through opening 42 of leg 36 of arrestor housing 12. Opening 40 of upper spring leg 34 receives the protuberance 30 of channel member 28, and permits limited adjustive movement of plate 30 and underlying solder billet 22 relative to arrestor housing 12 and spring 32. Spring forces imposed by spring 32 upon the assembled components bias member 28 and billet 22 downwardly to a position wherein billet 22 is firmly seated upon the upper surface of arrestor housing 12.
• the opposite side edges of member 28 preferably extend beyond the opposite side edges of the underlying solder billet 22, and the opposite end portions of member 28 preferably extend beyond the opposite ends of billet 28 and the opposite ends of arrestor housing 12.
• the central portion of billet 22 overlies ground electrode 16 of arrestor 10, and opposite end portions of billet 22 overlie respective adjacent ones of line electrodes 14 of arrestor housing 12.
• the embodiment of Fig. 4 differs from that of Fig. 5 primarily in that the opposite ends of billet 22 portions are spaced axially from, and do not overlie, electrodes 14. Consequently, while the solder flux employed in the Fig. 4 embodiment may be of the previously described flux 20 type, other flux not having the dielectric insulating properties of flux 20 may instead be used in the embodiment of Fig. 5.
• the axial flow of molten solder from billet 22 is enhanced by the generally V-shaped configuration of channel member 28.
• the opposite side edges of member 28 preferably extend outwardly beyond the opposite side edges of billet 22, and normally are spaced slightly above the underlying cylindrical surface of arrestor housing 12.
• solder flux 20 is provided upon substantially all of the exterior surfaces of arrestor housing 12, the flux might instead be applied, in bands or the like, only to selected surfaces of the housing upon which solder is to flow.
• solder flux may be integral with the solder material of billet 22.

Landscapes

• Engineering & Computer Science (AREA)
• Computer Networks & Wireless Communication (AREA)
• Signal Processing (AREA)
• Chemical & Material Sciences (AREA)
• Dispersion Chemistry (AREA)
• Fuses (AREA)
• Emergency Protection Circuit Devices (AREA)
• Thermistors And Varistors (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=25423287

Family Applications (1)

Country Status (9)

Families Citing this family (2)

Citations (1)

Family Cites Families (1)

• 1993
  • 1993-06-29 CA CA002139327A patent/CA2139327A1/en not_active Abandoned
  • 1993-06-29 AU AU47702/93A patent/AU4770293A/en not_active Abandoned
  • 1993-06-29 JP JP6502670A patent/JPH07508397A/ja active Pending
  • 1993-06-29 EP EP93918148A patent/EP0648372A1/en not_active Withdrawn
  • 1993-06-29 BR BR9306641A patent/BR9306641A/pt not_active Application Discontinuation
  • 1993-06-29 MX MX9303916A patent/MX9303916A/es unknown
  • 1993-06-29 WO PCT/US1993/006361 patent/WO1994000864A1/en not_active Application Discontinuation
  • 1993-06-30 CN CN93107663A patent/CN1082256A/zh active Pending
• 1994
  • 1994-12-29 KR KR1019940704806A patent/KR950702334A/ko not_active Application Discontinuation

Patent Citations (1)

Non-Patent Citations (1)

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