EP0793248B1 - Safety fuse, in particular for armoured electrical resistance elements - Google Patents

Safety fuse, in particular for armoured electrical resistance elements Download PDF

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Publication number
EP0793248B1
EP0793248B1 EP96119859A EP96119859A EP0793248B1 EP 0793248 B1 EP0793248 B1 EP 0793248B1 EP 96119859 A EP96119859 A EP 96119859A EP 96119859 A EP96119859 A EP 96119859A EP 0793248 B1 EP0793248 B1 EP 0793248B1
Authority
EP
European Patent Office
Prior art keywords
fuse
slider
metal
metal block
terminal
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
EP96119859A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0793248A2 (en
EP0793248A3 (en
Inventor
Duilio Capraro
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.)
IRCA SpA Industria Resistenze Corazzate e Affini
Original Assignee
IRCA SpA Industria Resistenze Corazzate e Affini
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 IRCA SpA Industria Resistenze Corazzate e Affini filed Critical IRCA SpA Industria Resistenze Corazzate e Affini
Priority to SI9630413T priority Critical patent/SI0793248T1/xx
Publication of EP0793248A2 publication Critical patent/EP0793248A2/en
Publication of EP0793248A3 publication Critical patent/EP0793248A3/en
Application granted granted Critical
Publication of EP0793248B1 publication Critical patent/EP0793248B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H37/00—Thermally-actuated switches
    • H01H37/74—Switches in which only the opening movement or only the closing movement of a contact is effected by heating or cooling
    • H01H37/76—Contact member actuated by melting of fusible material, actuated due to burning of combustible material or due to explosion of explosive material
    • H01H37/761—Contact member actuated by melting of fusible material, actuated due to burning of combustible material or due to explosion of explosive material with a fusible element forming part of the switched circuit
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H37/00—Thermally-actuated switches
    • H01H37/74—Switches in which only the opening movement or only the closing movement of a contact is effected by heating or cooling
    • H01H37/76—Contact member actuated by melting of fusible material, actuated due to burning of combustible material or due to explosion of explosive material
    • H01H37/761—Contact member actuated by melting of fusible material, actuated due to burning of combustible material or due to explosion of explosive material with a fusible element forming part of the switched circuit
    • H01H2037/762—Contact member actuated by melting of fusible material, actuated due to burning of combustible material or due to explosion of explosive material with a fusible element forming part of the switched circuit using a spring for opening the circuit when the fusible element melts

Definitions

  • This invention relates to a safety fuse for armoured electrical resistance elements.
  • Armoured electrical resistance elements consisting of an electrical resistance element housed in a metal sheath or armour and mantained electrically insulated from the walls of this latter, which is connected to earth.
  • the resistance element is dimensioned for correct operation under specific operating conditions, which differ according to the use for which it is intended (operation in water or air) .
  • a resistance element comprising a tubular sheath surrounding an electrical heating spiral.
  • a safety device is provided at one end of the sheath and comprises an electrical conductor arranged in a cavity in the end of the sheath and having one end electrically connected to the heating spiral.
  • a rod of deformable material extends into the sheath from the closed end to make contact with a normally closed positioned external to the sheath and connected in series with the resistance element and hence with the heating spiral.
  • the rod deforms and consequently forces the switch into its open position, so interrupting power to the spiral and consequently interrupting the heating of the resistance element.
  • This device satisfactorily solves the control problem in that it offers a high degree of reliability and very rapid intervention, but at the same time it suffers from certain limits, and in particular:
  • US-A-4.032.877 discloses a heat-sensitive protector having an elongated non-fusing element which moves from a retracted position to an extended position to perform the function of an indicator when that protector responds to heat to open the electric circuit.
  • the object of the invention is to provide a thermal switch which is of small bulk while at the same time being of high reliability.
  • the thermal fuse according to the invention comprises substantially a cylindrical bush 1 within which there is housed a metal sleeve 2 formed in two parts 3,4 of different diameter.
  • the head 5 of a metal slider, indicated overall by 6, is inserted into the larger-diameter part 4.
  • the head 5 supports a plurality of blades 7 (eight in the illustrated example) which slide along the inner walls of the sleeve 2. That end of the rod 8 not involved with the blades is inserted through a hole 9 provided in the base of a cup element 10 and is maintained stable in this configuration by being embedded in a block 11 of thermofusible material (lead, tin, etc.).
  • the fuse of the invention is mounted within the tubular metal sheath 13 of an armoured resistance element 14, such that the end contact 15 of the spiral is inserted into the cup element 10.
  • the other contact 16 is then inserted into the portion 4 of the sleeve 2 after interposing an insulating closure plug 17.
  • the metal block 11 melts and consequently slackens its grip on the end of the rod 8.
  • the elastic reaction of the spring 12 then axially shifts the slider 6, which disengages from the metal block 11 to hence interrupt circuit continuity.
  • the coil spring is positioned on the other side of the slider head and has its end connected to this latter and to the end of the portion 4 which borders on the portion 3.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Combustion & Propulsion (AREA)
  • Fuses (AREA)
  • Fixed Capacitors And Capacitor Manufacturing Machines (AREA)
  • Non-Adjustable Resistors (AREA)
EP96119859A 1996-03-01 1996-12-11 Safety fuse, in particular for armoured electrical resistance elements Expired - Lifetime EP0793248B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
SI9630413T SI0793248T1 (en) 1996-03-01 1996-12-11 Safety fuse, in particular for armoured electrical resistance elements

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ITVE960008U 1996-03-01
IT1996VE000008U IT242160Y1 (it) 1996-03-01 1996-03-01 Fusibile di sicurezza, in particolare per resistenze elettrichecorazzate

Publications (3)

Publication Number Publication Date
EP0793248A2 EP0793248A2 (en) 1997-09-03
EP0793248A3 EP0793248A3 (en) 1998-11-25
EP0793248B1 true EP0793248B1 (en) 2001-10-24

Family

ID=11424166

Family Applications (1)

Application Number Title Priority Date Filing Date
EP96119859A Expired - Lifetime EP0793248B1 (en) 1996-03-01 1996-12-11 Safety fuse, in particular for armoured electrical resistance elements

Country Status (6)

Country Link
EP (1) EP0793248B1 (it)
AT (1) ATE207654T1 (it)
DE (1) DE69616270T2 (it)
ES (1) ES2163576T3 (it)
IT (1) IT242160Y1 (it)
SI (1) SI0793248T1 (it)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10226357B4 (de) * 2002-06-13 2004-06-24 INTER CONTROL Hermann Köhler Elektrik GmbH & Co KG Thermische Sicherung

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3930215A (en) * 1974-11-29 1975-12-30 Texas Instruments Inc Nonresettable thermally actuated switch
US4032877A (en) * 1976-05-03 1977-06-28 Mcgraw-Edison Company Protector for electric circuits
US4189697A (en) * 1977-09-09 1980-02-19 Nifco Inc. Thermal cut-off fuse
US4276531A (en) * 1979-04-20 1981-06-30 Davis Merwyn C Nonresetable thermally actuated switch
DE8715851U1 (it) * 1987-11-30 1988-02-18 Elpag Ag Chur, Chur, Ch

Also Published As

Publication number Publication date
DE69616270T2 (de) 2002-05-23
DE69616270D1 (de) 2001-11-29
EP0793248A2 (en) 1997-09-03
IT242160Y1 (it) 2001-06-04
EP0793248A3 (en) 1998-11-25
ES2163576T3 (es) 2002-02-01
SI0793248T1 (en) 2002-06-30
ITVE960008U1 (it) 1997-09-01
ATE207654T1 (de) 2001-11-15

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