US3656231A - Method of insulating electrical conductors - Google Patents

Method of insulating electrical conductors Download PDF

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Publication number
US3656231A
US3656231A US831306A US3656231DA US3656231A US 3656231 A US3656231 A US 3656231A US 831306 A US831306 A US 831306A US 3656231D A US3656231D A US 3656231DA US 3656231 A US3656231 A US 3656231A
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US
United States
Prior art keywords
concrete
electrical
mould
reinforcement means
electrical 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
Application number
US831306A
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English (en)
Inventor
Robert Sheldon
Geoffrey Brian Stapleton
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Science Research Council
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Science Research Council
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Filing date
Publication date
Priority claimed from GB550269A external-priority patent/GB1269052A/en
Application filed by Science Research Council filed Critical Science Research Council
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Publication of US3656231A publication Critical patent/US3656231A/en
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Expired - Lifetime legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B28—WORKING CEMENT, CLAY, OR STONE
    • B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
    • B28B23/00—Arrangements specially adapted for the production of shaped articles with elements wholly or partly embedded in the moulding material; Production of reinforced objects

Definitions

  • the invention relates to the insulation of electrical conductors and more particularly to the insulation and mechanical support of electrical conductors.
  • the invention provides a method of manufacturing an electrical apparatus comprising supporting an electrical conductor or electrical conductors in a mould in the desired configuration for carrying electrical current when incorporated in the apparatus, and introducing concrete into the mould so as to embed the electrical conductor or conductors in concrete, reinforcement means being provided and arranged for permanently compressively stressing the concrete.
  • the stress applied to the concrete is such as to minimize the effect of the differential in temperature coefficients of expansion between the concrete and the electrical conductor or conductors.
  • the reinforcement means is preferably arranged so as to maintain the concrete under volume compression.
  • the reinforcement means may comprise a vessel enclosing that portion of the electrical conductors which is to be supported in and insulated by concrete, the concrete being introduced, e.g. by pumping, into the vessel and pressurised, the pressure being maintained until the concrete has set.
  • the mould is comprised by the reinforcement means.
  • the reinforcement means may comprise reinforcement members which extend through the mould and which are arranged to be tensioned so as to compressively stress the concrete when set. If volume compressive stress is not secured, it is desirable that the compressive stress should be, so far as is possible, parallel with the length of the electrical conductor or conductors.
  • the invention includes an electrical apparatus made by the aforesaid method.
  • the invention is especially applicable to installations subject to nuclear radiation where use of organic material in the insulation of electrical conductors is undesirable because of its liability to failure as a result of radiation damage.
  • the invention includes an installation subject to nuclear radiation wherein electrical conductors are insulated by a cladding of inorganic cementatious material.
  • the electrical conductors may be encapsulated in an aggregate filled concrete.
  • the invention also provides an electrical installation subject to nuclear radiation wherein electrical conductors are embedded in concrete which provides mechanical support for the conductors and the electrical insulation, preferably the sole electrical insulation, between adjacent conductors, and which is so stressed as to minimize the effect of the differential in temperature coefficients of expansion between the concrete and the electrical conductors.
  • the invention also provides a method of manufacturing an electromagnet in an electrical machine for accelerating charged particles, which method comprises supporting in a mould in the required relative locations a beam tube, magnet core laminations and electrical coil windings of uninsulated electrical conductor, and embedding these components in concrete, reinforcement means being provided and arranged to permanently compressively stress the concrete to avoid or reduce the effects of the differential coefficient of expansion with temperature between the concrete and the electrical conductors.
  • FIG. 1 is a diagrammatic longitudinal section of part of an installation
  • FIG. 2 is a diagrammatic section on line 2-2 of FIG. 1, with some parts omitted,
  • FIG. 3 is a fragmentary perspective view of part of the installation of FIGS. 1 and 2, and
  • FIG. 4 is a diagrammatic cross-sectional view of another installation.
  • the apparatus is an electrical machine for accelerating charged particles and the drawings illustrate the construction of a large electromagnet around the stainless steel beam tube 11.
  • the electromagnet comprises a yoke of laminated structure formed in two halves 12, 13 and coil windings 14 of copper, which have central passages 14a therethrough for cooling fluid.
  • the beam tube 11 extends centrally through the yoke 12, 13.
  • the copper windings 14 extend through rectangular passages l5, 16 in the yoke on each side of the beam tube 11.
  • the windings 14 are formed in two halves. In one-half, the windings 14 extend through passage 15 parallel with the beam tube 11, loop over the beam tube 11, extend through passage 16 parallel with the beam tube 11, loop over the beam tube 11 and extend through passage 15 again, and so on. In the other half, the windings 14 follow a similar path but loop under the beam tube 11 at each end of the passages 15 and 16.
  • the electromagnet To construct the electromagnet a former is made in which the beam tube 11 extends through central apertures in spaced steel plates 17, 18. Reinforcement rods 19, 21 with threaded ends are positioned so as to extend through apertures in the plates 17, 18.
  • the number of reinforcement rods employed will depend upon the size of the magnet. For example, in a large magnet there will be at least eight reinforcement rods equispaced around the beam tube 11.
  • the windings 14, in this example, are separated and located with sintered alumina slips 22, not shown in FIGS. 1 and 2 but illustrated in FIG. 3.
  • the windings l4 and beam tube 11 are assembled in position in the yoke 12, 13.
  • the alumina slips 22 serve to support the windings 14 spaced from one another and from the yoke 12, 13 and from the beam tube 11.
  • Tension is applied to the reinforcement rods 19, 21 from an external structure (not shown). The whole structure is then encased to form a mould of which the steel plates l7, 18 form two side walls.
  • Concrete is introduced into the mould in stages and compacted so as to fill the interstices between the windings 11 and within the core structure 12, 13. This compaction is achieved for example by vibration and/or by the application of a vacuum to the enclosure formed by the mould.
  • the concrete may be introduced by pumping and applying pressure, either directly, by means of the pump, or by separate application of pressure, e.g. hydraulically.
  • adhesion may be improved by shot blasting the windings 14 prior to encapsulation. Further improvement of adhesion may be achieved by coating the copper, for example by flame spraying, with alumina or other suitable ceramic material.
  • compressive stress upon the concrete derived from the tension in the reinforcement rods 19, 21 is applied to the concrete by screwing nuts 22, 23, 24, 25 onto the threaded ends of the rods 19, 21 and releasing the externally applied tension.
  • Tension in the rods 19, 21 then applies compression onto the concrete via the steel plates 17, 18. This compression is arranged to be such as to minimize the effects of the differential coefficient of expansion with temperature between the concrete and the copper.
  • this assembly is supported, on lugs 35, centrally within a steel tube 36.
  • the ends of the tube 36 are sealed and concrete 37 is pumped into the enclosure thus formed. Pressure is applied, either by the pump or separately-e.g. hydraulically, and the pressure is maintained until the concrete has set.
  • the tube 36 is illustrated as comprising two half tubes 38, 39 secured together by bolted flanges 41, 42.
  • aggregate 100 parts by weight calcium aluminate cement 40 parts water
  • the aggregate comprised alumina particles of which 33% percent were in the size range 25 to 52 mesh and 66% percent were in the size range 14 to 25 mesh.
  • the concrete was cured at 150 C so as to achieve the desired electrical insulation properties of the concrete.
  • the alumina cement may have incorporated in it glass fibres, silica fibers or other inorganic fibrous or laminar materials such as asbestos or mica.
  • the insulation provided by the concrete is stable against ionising radiation, is cheap, and is resistant to high temperatures.
  • the apparatus of the foregoing example may thus be employed in high vacuum applications.
  • the use of alumina cement is advantageous for the insulation and support of electrical apparatus for use at low temperatures, especially coils at 4.2 K, because the thermal conductivity of the concrete is much higher than that of conventional organic insulation.
  • the invention is not restricted to the details of the foregoing example.
  • the method of manufacture described is especially suitable for magnet construction of large accelerators but is also likely to be useful in the construction of other apparatus or installations, in particular where subject to nuclear radiation, such as, for example, in thermonuclear reactors.
  • alumina cement While the use of alumina cement is preferred, Portland cement or other suitable cement may be used if desired.
  • a method of manufacturing an electrical apparatus comprising supporting at least one electrical conductor in a mould in the desired configuration for carrying electrical current when incorporated in the apparatus, introducing concrete into the mould so as to embed the electrical conductor in concrete so as to provide mechanical support for and electrical insulation of the conductor, and utilizing reinforcement means to permanently compressively stress the concrete, the stress applied to the concrete serving to minimize the effect of the differential in temperature coefficients of expansion between the concrete and the electrical conductor.
  • step of utilizing reinforcement means includes providing a plurality of reinforcement members which extend within said mould, tensioning said reinforcing members, pouring said concrete into said mould, and releasing the tension on said reinforcing members to provide said compressive stressing of the concrete.
  • the reinforcement means comprises a vessel enclosing that portion of the electrical conductor which is to be supported in and insulated by concrete, the concrete being introduced into the vessel and pressurized, the pressure being maintained until the concrete has set.
  • reinforcement means comprises reinforcement members which extend through the mould and which are arranged to be tensioned so as to compressively stress the concrete when set.
  • a method of manufacturing an electromagnet in an electrical machine for accelerating charged particles comprises supporting in a mould in the required relative locations a beam tube, magnet core laminations and electrical coil windings of uninsulated electrical conductor, embedding these components in concrete, and utilizing reinforcement means to permanently compressively stress the concrete so as to minimize the effects of the differential coefficient of expansion with temperature between the concrete and the electrical conductors.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical & Material Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Particle Accelerators (AREA)
US831306A 1968-06-12 1969-06-09 Method of insulating electrical conductors Expired - Lifetime US3656231A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB550269A GB1269052A (en) 1968-06-12 1968-06-12 Improvements in or relating to electrical apparatus
GB2804868 1968-06-12

Publications (1)

Publication Number Publication Date
US3656231A true US3656231A (en) 1972-04-18

Family

ID=26239933

Family Applications (1)

Application Number Title Priority Date Filing Date
US831306A Expired - Lifetime US3656231A (en) 1968-06-12 1969-06-09 Method of insulating electrical conductors

Country Status (5)

Country Link
US (1) US3656231A (enrdf_load_stackoverflow)
CH (1) CH512132A (enrdf_load_stackoverflow)
DE (1) DE1929717C3 (enrdf_load_stackoverflow)
FR (1) FR2011928B1 (enrdf_load_stackoverflow)
NL (1) NL6908992A (enrdf_load_stackoverflow)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4936006A (en) * 1989-03-01 1990-06-26 General Atomics Method of making prestressed concrete articles
US5065795A (en) * 1989-03-01 1991-11-19 General Atomics Prestressed concrete articles
US6380833B1 (en) 1999-04-07 2002-04-30 Saint-Gobain Performance Plastics Corporation Encapsulated magnet assembly and method for making the same
US6757351B1 (en) * 1998-02-25 2004-06-29 General Electric Company Modified large natural circulation reactor

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2590821A (en) * 1948-11-04 1952-03-25 Melpar Inc Potted electrical subassembly
US2911572A (en) * 1958-05-20 1959-11-03 Sippican Corp High density electronic packaging
US2915686A (en) * 1958-08-28 1959-12-01 Burroughs Corp Diode matrix
US3188422A (en) * 1961-04-20 1965-06-08 Lab For Electronics Inc Treadle-operated traffic detector having means for refilling while mounted in a roadway
US3426426A (en) * 1967-02-27 1969-02-11 David E Born Sliced circuitry

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1579883A (en) * 1920-11-19 1926-04-06 Thomas E Murray Reactance coil
FR1403035A (fr) * 1964-05-06 1965-06-18 Conducteurs polyphasés et leur fabrication

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2590821A (en) * 1948-11-04 1952-03-25 Melpar Inc Potted electrical subassembly
US2911572A (en) * 1958-05-20 1959-11-03 Sippican Corp High density electronic packaging
US2915686A (en) * 1958-08-28 1959-12-01 Burroughs Corp Diode matrix
US3188422A (en) * 1961-04-20 1965-06-08 Lab For Electronics Inc Treadle-operated traffic detector having means for refilling while mounted in a roadway
US3426426A (en) * 1967-02-27 1969-02-11 David E Born Sliced circuitry

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4936006A (en) * 1989-03-01 1990-06-26 General Atomics Method of making prestressed concrete articles
US5065795A (en) * 1989-03-01 1991-11-19 General Atomics Prestressed concrete articles
US6757351B1 (en) * 1998-02-25 2004-06-29 General Electric Company Modified large natural circulation reactor
US6380833B1 (en) 1999-04-07 2002-04-30 Saint-Gobain Performance Plastics Corporation Encapsulated magnet assembly and method for making the same

Also Published As

Publication number Publication date
DE1929717C3 (de) 1980-09-04
NL6908992A (enrdf_load_stackoverflow) 1969-12-16
FR2011928B1 (enrdf_load_stackoverflow) 1974-11-15
CH512132A (de) 1971-08-31
DE1929717B2 (enrdf_load_stackoverflow) 1980-01-03
FR2011928A1 (enrdf_load_stackoverflow) 1970-03-13
DE1929717A1 (de) 1969-12-18

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