US2722963A - Manufacture of insulated electric conductors - Google Patents

Manufacture of insulated electric conductors Download PDF

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Publication number
US2722963A
US2722963A US452106A US45210654A US2722963A US 2722963 A US2722963 A US 2722963A US 452106 A US452106 A US 452106A US 45210654 A US45210654 A US 45210654A US 2722963 A US2722963 A US 2722963A
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US
United States
Prior art keywords
tube
powder
pipe
container
gas
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
US452106A
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English (en)
Inventor
Mccleery James Alexander
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.)
Balfour Beatty PLC
Original Assignee
BICC PLC
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 BICC PLC filed Critical BICC PLC
Application granted granted Critical
Publication of US2722963A publication Critical patent/US2722963A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B13/00—Apparatus or processes specially adapted for manufacturing conductors or cables
    • H01B13/30—Drying; Impregnating
    • 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

  • This invention relates to electric conductors consisting of a wire or wires in a tube of metal insulated by powder, for instance magnesia or talc, the powder being compressed by a tamping method as it is fed into the tube around the wires.
  • a usual method of manufacturing such insulating conductors is to make the assembly with the parts of comparatively large size and then to reduce the diameter and extend the length by a drawing process.
  • the invention is concerned with the removal of air from the interior of the tube and its replacement by another gas which may be inert or protective, or have other useful properties.
  • an assembly is made of the tube containing the conductor, or conductors, closed at one end by a plug and suitably enclosed at the other end for the filling in of the powder; this assembly is then exhausted of air by connection to suitable vacuum apparatus and thereafter is charged with the other gas under pressure.
  • a container enclosing powder to serve as a supply for filling the tube is also exhausted of air and charged with the gas. This is preferably done as a separate operation, the tube assembly and the container being only put in communication after the charging with gas of each one of them has been completed.
  • the powder is then caused to flow from the container into the tube assembly and filling and tamping proceed until the operation is complete.
  • This operation is, accordingly, carried out in an atmosphere of the selected gas and the spaces Within the mass of compacted powder remain filled with this gas. It is preferred to leave a sup ply of gas under pressure in communication with the apparatus during the filling operation so as to maintain the pressure in spite of any leakage which may occur.
  • Figure 1 illustrates in elevation and diagrammatically one form of apparatus suitable for carrying out the invention and Figure 2 is a fragmentary View in elevation shown partly in section.
  • the reference numeral 1 indicates a vertically disposed metal tube and the reference numeral 2, a conductor which is disposed centrally of the tube and is insulated therefrom by an insulating powder 3.
  • the outer tube for example, may be of copper and the conductor have the form of a copper rod.
  • the powder is fed continuously into the upper end of the tube 1 from a container 4 through a pipe 5, the powder being discharged from the latter into the upper end of a funnel 6 attached to the upper end of the tube 1.
  • the upper end of the ram rod 9 is connected to a piston 11 working in a cylinder 12, by a piston rod 13, which is connected to the ram rod 9 by a sleeve 14 which engages the ram rod frictionally, permitting relative movement to take place between the sleeve and the ram rod when the head 8 of the ram is brought into contact with the powder 3 beneath it.
  • the head of the ram gradually rises up the tube 1.
  • the friction between the sleeve 14 and the ram rod 9 is sutficient to obtain effective tamping of the powder round the conductor 2.
  • the cylinder 12 is fitted with pipes 15 and 16 for the. admission of compressed air or other fluid to opposite sides of the piston 11 to cause the latter to reciprocate within the cylinder.
  • the tube and its contents are drawn through a die to produce elongation of the conductor 2 and a reduction in diameter of the tube with elongation of the latter.
  • this final product will contain air at atmospheric pressure. It is an advantage that the final product should contain some other gas at a pressure above atmospheric. The apparatus illustrated permits this result to be obtained.
  • a. vacuum pump 17 is connected to one side of a filter 18 by a pipe 19.
  • a pipe 20 provided with a valve 21 is connected to the other side of the filter and to a pipe 22.
  • To the latter is also connected a pipe 23 and to the latter is connected one end of a pipe 24' having a valve 25.
  • the other end of the pipe 24 is connected to a short pipe 26 connected to the upper end of the pipe 5 and to the lower end of the container 4.
  • the pipe 26 has a valve 27.
  • the upper end of the funnel has a cap 28 which makes a gas-tight fit with it and is provided with a gland 29 which permits the ram rod 9 to slide through it in a gas-tight manner.
  • the lower end of the tube 1 is fitted with a gland or plug 30 which makes a substantially gas-tight fit with the conductor 2, the latter passing through the gland 30 for a short distance.
  • the tunnel 6 is connected in a gas-tight manner with the upper end of the tube 1 by a gland 31. Communication can thus be established between the vacuum pump 17 and the tube 1.
  • a cylinder 32 containing a gas, other than air, under pressure, for example, nitrogen, is connected to the pipe 22 through a pipe 33 connected to the cylinder and to a pipe 34 provided with a valve 35, pipe 34 being connected to pipe 22. Communication can thus be established between the cylinder 32 and the tube 1.
  • the apparatus also includes means for exhausting the container 4 and charging it with the gas under pressure in the cylinder 32.
  • the pipe 23 is connected to a pipe 36 provided with a valve 37, the pipe 36 being connected in a gas-tight manner to the upper end of the container 4.
  • the evacuation and charging of the tube 1 and the evacuation and charging of the container 4, preferably, are carried out as separate operations, the container and the tube 1 being placed in communication with each other when both contain the gas under pressure. This communication is established by opening the valve 27 in the pipe 26.
  • the container 4 is filled with an appropriate quantity of powder before being evacuated and charged with gas. This quantity of powder, preferably, is sufiicient to filll several of the tubes 1.
  • the tube 1 is to be evacuated and charged with gas before the container 4, evacuation of the tube is efiected by opening valves 21 and 25, valves 35, 37 and 27 being closed. Charging of the tube 1 with gas under the required pressure is effected by closing valve 21 and opening valve 35, valve 25 being open and valves 37 and 27 being closed. Evacuation of the container 4 is effected by opening valves 25 and 37, valves 35 and 27 being closed and valve 21 being opened. Gas under pressure is admitted to the container 4 by closing valve 21, opening valves 35 and 37, valves 25 and 27 being closed. Upon obtaining equal gas pressures in the tube 1 and the container 4, the valve 27 is opened to commence the feeding of the powder from the container into the tube 1 and the reciprocation of the ram 7 within the tube. By equalizing the pressures in the tube and the container, there is little tendency for the gas to leak from the tube 1. Should there be any tendency at the gland or plug 30, the packing of the powder by the ram assists in facilitating the sealing at that end of the tube.
  • the yielding friction provided between the sleeve 14 and the ram rod 9 facilitates the mounting of the tube assembly and its connection to the container 4 and to the various pipe connections for evacuation and supply of gas.
  • the pipe 22 is provided with a pressure gauge 38, which can be used for measuring the air pressure in the container 4 and the tube 1 while being exhausted and the gas pressure in those parts during filling with gas.
  • a gauge 39 may be provided to indicate the gas pressure available in the cylinder 32, and a valve 40 in the pipe 22, should it be required to reduce the pressure at any time to atmospheric. This valve will be kept closed when the apparatus is in operation.
  • the container 4 may be filled with powder through a pipe 41 provided with an air-tight cap 42.
  • the tube and its contents may be drawn through a die to reduce the diameter of the tube and of the conductor and increase their length to provide a cable having one or more conductors insulated with tightly compacted powder containing a desired gas under pressure and a sheath which fits tightly over the powder insulation.
  • Apparatus for attachment to the open end of a metal tube closed at its other end and containing a conductor to be insulated from the metal tube by powder comprising a container for the powder, a dclivery vessel for sealed attachment to the open end of the tube, a pipe connecting the powder container and the delivery vessel, a gland, a ram rod extending through the gland into the delivery vessel and having a longitudinally extending passage closed at one end and open at the other, means for reciprocating the ram rod, a valve in the pipe between the container and the delivery vessel, means for removing air from the powder container and from the metal tube and for filling the container and tube with some other gas under pressure.
  • Apparatus for attachment to the open end of a metal tube closed at its other end and containing a conductor to be insulated from the metal tube by powder comprising a container for the powder, a delivery vessel for sealed attachment to the open end of the tube, a powder delivery pipe connecting the powder container and the delivery vessel, a valve in said powder delivery pipe, a gland at the upper part of the delivery vessel, a ram rod extending through the gland into the delivery vessel and having a longitudinally extending passage therein open at its lower end and closed at its upper end, means for reciprocating the ram rod, a source of gas under pressure, other than air, a pipe connecting said source to the powder container at the upper part thereof, a valve in said pipe, air evacuating means connected to the upper part of the container, a pipe connected to the powder delivery pipe on the delivery vessel side of the valve in the powder delivery pipe, said pipe being connected to the source of gas pressure and air evacuating means, and valves for shutting off said source and air evacuating means from
  • an electric conductor comprising one or more wires insulated by powder enclosed in a metal tube
  • steps which comprise assembling a conductor in a metal tube, sealing the latter and removing the air therefrom and from a confined volume of insulating powder, charging the metal tube and the confined volume of insulating powder with a gas under pressure, other than air, the removal of the air and the charging of the confined volume of insulating powder with gas under pressure being carried out as operations which are independent of the removal of the air from and charging of the metal tube with gas under pressure, the metal tube being thereafter charged with the insulating powder and the latter tamped around the conductor.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Superconductors And Manufacturing Methods Therefor (AREA)
  • Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)
  • Basic Packing Technique (AREA)
US452106A 1953-09-10 1954-08-25 Manufacture of insulated electric conductors Expired - Lifetime US2722963A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB25087/53A GB745263A (en) 1953-09-10 1953-09-10 Improvements relating to the manufacture of powder-insulated electric cables

Publications (1)

Publication Number Publication Date
US2722963A true US2722963A (en) 1955-11-08

Family

ID=10221991

Family Applications (1)

Application Number Title Priority Date Filing Date
US452106A Expired - Lifetime US2722963A (en) 1953-09-10 1954-08-25 Manufacture of insulated electric conductors

Country Status (3)

Country Link
US (1) US2722963A (fr)
FR (1) FR1111087A (fr)
GB (1) GB745263A (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4100002A (en) * 1975-04-01 1978-07-11 Northern Telecom Limited Method for producing powder filled cable

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2341718A (en) * 1998-06-17 2000-03-22 Oliver Sanders Johnson Mineral insulated electric cable with gas filled spaces

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1765804A (en) * 1927-05-05 1930-06-24 Frank W Preston Method of and apparatus for making clay pots
US2477273A (en) * 1942-08-28 1949-07-26 Bendix Aviat Corp Method of making ignition apparatus
US2680086A (en) * 1950-11-14 1954-06-01 W T Glover & Co Ltd Manufacture of insulated electric conductors

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1765804A (en) * 1927-05-05 1930-06-24 Frank W Preston Method of and apparatus for making clay pots
US2477273A (en) * 1942-08-28 1949-07-26 Bendix Aviat Corp Method of making ignition apparatus
US2680086A (en) * 1950-11-14 1954-06-01 W T Glover & Co Ltd Manufacture of insulated electric conductors

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4100002A (en) * 1975-04-01 1978-07-11 Northern Telecom Limited Method for producing powder filled cable

Also Published As

Publication number Publication date
GB745263A (en) 1956-02-22
FR1111087A (fr) 1956-02-22

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