US2351056A - Electric conductor - Google Patents

Electric conductor Download PDF

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Publication number
US2351056A
US2351056A US258571A US25857139A US2351056A US 2351056 A US2351056 A US 2351056A US 258571 A US258571 A US 258571A US 25857139 A US25857139 A US 25857139A US 2351056 A US2351056 A US 2351056A
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US
United States
Prior art keywords
insulating material
insulating
conductor
calcium oxide
electric conductor
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
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US258571A
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English (en)
Inventor
Lepetit Jean
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.)
Pyrotenax Ltd
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Individual
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Filing date
Publication date
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Application granted granted Critical
Publication of US2351056A publication Critical patent/US2351056A/en
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Assigned to PYROTENAX LIMITED reassignment PYROTENAX LIMITED ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: PRECISION MECANIQUE LABINAL, SOCIETE ALSACIENNE CONSTRUCTIONS MECANIQUES
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/40—Heating elements having the shape of rods or tubes
    • H05B3/42—Heating elements having the shape of rods or tubes non-flexible
    • H05B3/48—Heating elements having the shape of rods or tubes non-flexible heating conductor embedded in insulating material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B7/00—Insulated conductors or cables characterised by their form
    • H01B7/16—Rigid-tube cables

Definitions

  • the present invention relates to the manufacture of electric conductors composed of one or a plurality of singleor divided conducting or resistant cores which are insulated from a metal sheath by a powdered mineral insulating material.
  • the insulating material usually employed hitherto in such cables is ordinary magnesium oxide.
  • said value is about 100,000 ohms when the radial thickness of the insulating material is 1.5 mm. and in the above circumstances of exposure.
  • the conductor is cut at a certain length, for example at a few centimetres, from-each of the ends of the section. substantially the initial value of insulating resistance is found again.
  • the variation of insulating resistance observed is an end phenomenon and, independently of the insulating resistance per kilometre of the conductor itself or of the lineformed by same, it is possible to define a "limiting insulating resistance per free en In the above mentioned case.
  • the mean value of the lim ting insulating resistance per free end is about'200.000 ohms.
  • the decrease of the insulating resistance may be considerable, in particular when the insulating material is ordinary magnesium oxide.
  • the drawing illustrates a cross-section of a conductor made in accordance with this invention.
  • insulating materials are employed such that the conductors manufactured have a higher limiting insulating resist ance per free end than that obtained with ordinary magnesium oxide, i. 'e. higher than 0.2 megohm for a radial thickness of insulating material of 1.5 mm.
  • the insulating material may be so chosen that the absolute value of the limiting insulating resistance of the line itself is higher than a predetermined value taking into account the number of free ends.
  • oxides or compounds of calcium or of other similar substances will be chosen in particular.
  • the limiting insulating resistance per end was found to be higher than 20 megohms, for a radial thickness of insulating material of 1.5 mm.
  • Powdered insulating materials which are capable of swelling are generally suitable for this purpose, that is to say those, such as calcium oxides or compounds, which cannot absorb moisture or in a general manner combine with air or its constituents without increasing in volume.
  • the insulating material is, in fact, bound by the owing to a natural action such as that of the carbonic acid of the air, are also suitable.
  • the powdered insulating material used is totally dehydrated before the usual mechanical treatments of shaping, drawing, etc., theinsulating material being introduced into the rough shape, either in the powdered state, or in the shape of agglomerated blocks in a highly compact state, or in any other shape, or by means of any other methods. It is possible, in particular, to effect the total dehydration by heating the insulating material under appropriate conditions until it no longer loses weight; in practice, for ordinary calcium exide, such dehydration is complete when it has been subjected to a temperature of 900 to 1000 C. for several hours.
  • the invention also covers the use of insulating materials having the properties claimed, and in particular calcium oxide, either in the state of homogeneous mixtures, or by radial or longitudinal juxtaposition of different insulating mate rials in contact with each other.
  • Theinvention covers in particular th wires, cables or conductors of the category in question which have the properties described and in which the dielectric is binary and is formed by calcium oxide and magnesium oxide, whatever be the proportion of the two substances. The applicant ha proved. that in this. case, the highest limiting insulation resistance is obtained when the proportion of.
  • the improvedinsulating material such as calcium oxide, boron oxide or the like may 7 be introduced into the homogeneous ,powdered insulating material only in th zone of each end -of--t he conductor.
  • the invention also covers above.
  • the conductors may be manufactured as above set forth and using for example at least for those portions adjacent the ends a mixture containing from 25 to 40% calcium oxide and 75 to 60% of magnesia. Thereafter each of the ends of the conductor may be dipped in' a boric acid solution.
  • An electric conductor comprising a core; a
  • An electric conductor comprising a ,core, a metallic sheath and a powdered insulating material located'b'etween. said core andsheath, said insulating material comprising a mixture of calcium oxide, magnesia and boric oxide, said calcium oxide comprising between 25 and 40% and said boric oxide comprising about 1% of. said mixture and said magnesia the remainder of 'said mixture.
  • An electric conductor comprising a a core, a metallic sheath and a powdered insulating material located between said core and sheath, said insulating material located at the ends'of' said conductor comprising a mixture of about 25 to 40% of calcium oxide and to 60% of magnesia.
  • An electric conductor comprising a. core, a metallic sheath and a powdered insulating material located between said core and sheath, said insulating material comprising a mixture :of about 25 to 40% 'of calcium oxide, 74" to 59% of magnesia and 1% of boric oxide.

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  • Inorganic Insulating Materials (AREA)
US258571A 1939-02-16 1939-02-25 Electric conductor Expired - Lifetime US2351056A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR160239X 1939-02-16
FR843062T 1939-02-16

Publications (1)

Publication Number Publication Date
US2351056A true US2351056A (en) 1944-06-13

Family

ID=26213827

Family Applications (1)

Application Number Title Priority Date Filing Date
US258571A Expired - Lifetime US2351056A (en) 1939-02-16 1939-02-25 Electric conductor

Country Status (7)

Country Link
US (1) US2351056A (US08080257-20111220-C00005.png)
BE (1) BE432967A (US08080257-20111220-C00005.png)
CH (1) CH213329A (US08080257-20111220-C00005.png)
DE (1) DE882437C (US08080257-20111220-C00005.png)
FR (1) FR843062A (US08080257-20111220-C00005.png)
GB (1) GB528677A (US08080257-20111220-C00005.png)
NL (1) NL54441C (US08080257-20111220-C00005.png)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2890263A (en) * 1952-11-18 1959-06-09 Hackethal Draht & Kabelwerk Ag Coaxial cables
US3239784A (en) * 1961-01-23 1966-03-08 Schwartz Charles Aaron Coil structure for a welding transformer
US3909555A (en) * 1974-10-16 1975-09-30 Kaman Sciences Corp Phase stable transmission cable with controlled thermal expansion characteristics
US4085653A (en) * 1976-09-15 1978-04-25 General Electric Company Ignition device
DE3544801A1 (de) * 1984-12-21 1986-06-26 Philips Nv Mit mineralischem isoliermittel abgeschirmtes kabel
US5247158A (en) * 1992-07-17 1993-09-21 Watlow Electric Manufacturing Company Electrical heater
US6830374B1 (en) * 1999-08-16 2004-12-14 Temperature Management Systems (Proprietary) Limited Metallurgical thermocouple
US20110100667A1 (en) * 2009-11-04 2011-05-05 Peter Hardie Audio cable with vibration reduction
US11871486B2 (en) 2017-02-01 2024-01-09 Nvent Services Gmbh Low smoke, zero halogen self-regulating heating cable

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4280932A (en) * 1979-02-12 1981-07-28 General Electric Company Magnesia insulated heating elements
DE8900876U1 (de) * 1989-01-26 1989-08-10 Siemens AG, 1000 Berlin und 8000 München Heizelement

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2890263A (en) * 1952-11-18 1959-06-09 Hackethal Draht & Kabelwerk Ag Coaxial cables
US3239784A (en) * 1961-01-23 1966-03-08 Schwartz Charles Aaron Coil structure for a welding transformer
US3909555A (en) * 1974-10-16 1975-09-30 Kaman Sciences Corp Phase stable transmission cable with controlled thermal expansion characteristics
US4085653A (en) * 1976-09-15 1978-04-25 General Electric Company Ignition device
DE3544801A1 (de) * 1984-12-21 1986-06-26 Philips Nv Mit mineralischem isoliermittel abgeschirmtes kabel
US4689443A (en) * 1984-12-21 1987-08-25 U.S. Philips Corporation Armored cable having mineral insulation
US5247158A (en) * 1992-07-17 1993-09-21 Watlow Electric Manufacturing Company Electrical heater
US6830374B1 (en) * 1999-08-16 2004-12-14 Temperature Management Systems (Proprietary) Limited Metallurgical thermocouple
US20110100667A1 (en) * 2009-11-04 2011-05-05 Peter Hardie Audio cable with vibration reduction
US11871486B2 (en) 2017-02-01 2024-01-09 Nvent Services Gmbh Low smoke, zero halogen self-regulating heating cable
US11956865B2 (en) 2017-02-01 2024-04-09 Nvent Services Gmbh Low smoke, zero halogen self-regulating heating cable

Also Published As

Publication number Publication date
FR843062A (fr) 1939-06-26
NL54441C (US08080257-20111220-C00005.png)
GB528677A (en) 1940-11-05
DE882437C (de) 1953-05-28
BE432967A (US08080257-20111220-C00005.png)
CH213329A (fr) 1941-01-31

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