US1691869A - Electrical conductor - Google Patents

Description

Nov. 13, 1928'.

. F. F. FOWLE ELECTRICAL CONDUCTOR Filed July 5, 1924 WBON CONTENT 0f TEEL .l

vPatented Nov. 13, 1928.A

`UNITE-D- STATES rmx F. rowIn, or cHIcaoo, ILLINOIS.

ELECTRICAL CONDUCTOR.

Application mea my s,

This invention relates to electrical conductors.

One object of my invention is to provide an improved and superior type ofcomposite electrical conductor comprised chieiy of two metals, one for mechanical strength and one forelectrical conductivity.

Another` object is to provide an improved composite electrical conductor in which the l0 'metal for conducting most of the current is encased within a metal of high strength, low

magnetic permeability and in which the socalled skin eect is reduced to a minimum. Another object is to provide an improved HL composite electrical conductor adapted to meet the various requirements under service conditions.

These and other objects are' accomplished b means ofthe arrangements disclosed on' tli'e accompanying sheet of drawings, in which-'- Figure 1 is a cross sectional view of a seven wire cable, the center wire being of copper and the six outer wires being of steel and each of said wires being zinc-coated.

Figure'2 is a longitudinal .view of a piece of such seven-'wire cable. l Figure 3 is a cross-sectional view of another cable in which the seven centerwires are of .copper and are stranded to form` a core, and the outer wires of steel comprise two layers in a concentric-lay cable. K Figure 4 is a cross sectional view ofanother cable,known as a rope-lay cable., in which there are seven main strands placed concentrically and each of these strands in turn consists of seven wires iii concentric-lay,the cenv tral strand forming a coppercore and each of the other strands having a single copper'core with a covering of six steel wires.

covered copper wire having a protective coating of zinc applied to the .outer surface of the steel; preferably the steel and copperare united as by brazing or welding, Y

Figure 6 is a oros-sectional view of a comsite stranded cable in which the center wire 1s of copper and each of the other wires is a steel-covered copper wire,.each of said Aseven wires being zinc-coated. f

Figure 7 isa dia am showing the relationship between car n contentof steel and Figure 5 is a cross-sectional view ofa steel- 1924:.` Serial No. 723,863;

While in the description of these figures reference has been made to copper wire or filaments, it will be understood that a aluminum wire or filaments may be used in place thereof and non-corrosive coatings other than zinc may he used; also that many more modiications and arrangements of wires and strands lmay be made within the spirit of the invention.

A s above indicated, in carrying out one embodlment of my invention, I provide a sevenwlre cable, as shown in Figure 1, including a central core wire 10 and six wires 11 laid thereon in helical convolutions, or so-called concentric-lay. The six 'outer wires 11 are made of high-carbon steel. and are provided wlth a coating- 12 of zinc for protection against corrosion. The core wire 10 preferably is made of copper and is' rovided with a coating 13 of zinc'to secure fiirther protectlon from corrosion by having only like metals in actual superficial contact with each o ther, that is, in this case, zinc in contact with zinc.

Among the advantages of this construction 1s the mechanical protection of the copper by the surroundmg wires of hard, tough steel, which protects the copper from injury in han'- dllng'or installing the conductor, and particularly these hard steelfwires protect harddrawn copper from accidental surface nicks or scratcheswhich ordinarily cause i-t to lbe-v come more susceptible to fracture. Furthermore, the surrounding steel wires completely enclose the copper from' the weather and thus tend to prevent electrolytic corrosion of the steel by reason'of the contact with the copper and the possible presence of an electrolyte in contact with both metals.' However, as above indicated reliance is not placed entirely upon the fact that the steel wires surround and enclose the copper wires, but a protective coating of zinc'on'the steel wires and asimilar coating on the copper wire is employed.

I' Another advantageisithe ability to comb ine copper` and steel elements in one conductor with the use ofsmall ratios of copper to steell without making the outer metal of such small thickness that it lacks good mechanical properties. VA copper-covered steel wire of the-type which has been used with a small l ratio of copper ,to steel, for example,

e30 percent, has a very thin coating of copper,

`so thin,in fact, as tolack mechanical .properties and be subject to injury, sueh'fas cracks, and abrasions, exposingthe steel.`

vThe defect is'overcome by placing the steel outsideof the copper, eit er in a'composite' strandedcable or in a composite solid wire.

Not only is a superior composite conductor provided by placing the copperwire within ,the steel, either in the form of a solid composits wire. or a composite stranded. cable,

t a superior composite conductor also is.

provided assuming the proper kindo'f steel 'is used.

. at least as much as .30% content of chemically combined carbon and advantageously more than such amount. Inthe man f experiments WhichI have conducted, steel aring any content of carbon upwto substantially .66% has been'used, and, as a matterof fact, v

. the best results have 'been obtained'with-the latter ligure. Also -I have lfound-tha'tllwhen the carbon content of the steel is reduced to substantially .30%, the conductor is onthe.

verge of losing the advantageous combination of electrical and mechanical properties, and when the carbon content is reduced still further, Vthe ob'ect of my invention is substantially nullied. Y The novel and useful results obtained 'by this invention embrace superior electrical and mechanical properties of the composite conductor combined with light protective coatings of the two principal metals employed. The kind of steel which is advantageously employed makes .it possible to constant effective resistivity to electrical currents such as are used in electrical power transmission, both with direct current and n with alternating current, at the commercial fr uencies invcommon use. Furthermore,

- the ard, tough steel which is used for giving the desired strength to the conductor also takes a superior quality of zinc coatin as compared'with those steels and irons w ich will not produce the resultsobtained by this invention.

By usingv steel having at least a .30% chemically combined carbon, 'and preferably more, the magnetic permeability under the internal inagneto-motivedore created by the i current in the conductor itself apparently is of insignificant magnitude. Also as thecarbon content in the. steel is increased not only does the magnetic permeability decrease, `but alsol the skineiect decreases, as shown, :for example, in Figure 7;

Re eri-ing to the diagram shown in F'gure 7, it will be noted that there is shown a rskin steel strand three-eighths of an inch 1n diamin the steel.

' 'p directly.

Y eiect resistance increase in a copper-core passing therethrough. Curve 14 shows the effect when a ampere current is used; curve 15 when a 20 ampere current is used; curve 16 when a 30 ampere current is used; and curve 17 when a 40 ampere current lis used. Each curve shows that the skin effect is at its lowest value where the carbon eontentof the steel is above .66%, and that the .skin

the carbon content of the steel, a critical point being reached at about .30% carbon content As the carbon content of the steel is decreased from .30% the skin effect greatly increases, showing that the object of my invention is nullified or defeated where steel is used in a composite electrical conductor in which the carbon content of the steel is less than .30%.

effect gradually increases with a decrease in v The invention is applicable to composite cables of various descriptions, as indicated hereinabove; for exam le, in Figure 3, there is shown the core itselllbeing stranded .and comprising seven cop r wires 18, there being two layers V19 an 20 'of steel wires in a concentricQ-laycable.

-In Figure 4 a rope-lay cable is shown, in which there are seven main strands 21, 22, 23, 24, 25, 26, and 27 placed inconcentric-lay, and each of these strands in turn consisting of seven wires in concentric-lay. The core strand 21 consists, for example, of seven wires ofzinc-coated'copper, and each of the six outer strands 22 to 27, inclusive, consists of six zinc-'coated steel wires with a zinc-coated copper wire 28 in' the center.

In Figure 5 another form is slown. In this instance a steel-covered copper wire is shown v strands and cables in concentric-lay or in krope-lay, and in any other combination, as

desired. In Figure 6 a composite strand vcf cable is shown in which the center wire '32 is coplpe 'r provided with a zinc coating 33l and eac of the outside wires is al composite conductor f havin a copper .core 34 and a steel casing 35 wit 4a zinc coating 36. Y Steel of the pro er carbon content, as indicated, when 'com ined with copper in the Y various 'modifications shown, and in other modifications, provides a composite electrical conductor adaptedlt'o meet all ofthe require-- ments for the intended uses. f 1' I define a composite electrical conductor 'as a conductor in which all of the constituent parts or elements areemployed for conduct in electrical current and whichare in lineta icv contact with each other/directly or 'in- In the claims when I refer to low magnetic permeability or low skin effect I mean a low magnetic permeibility or a low skin eect 'prising two metals,

such as results when there is steel used or iron base material which has at least .30% chemically combined carbon.

I claim: v A 1. A composite electrical conductor comprising two metals, one having the quality of relatively high electrical conductivity and the other being an iron-base met-al of relatively great mechanical strength and containing atleast as much as thirty hundredths er cent content of chemically combined caron, said iron-base metal being so disposed in the body high conductivity is substantially enclosed thereby. s

2. A composite electrical conductor comprising two metals, one being copper for high electrical conductivity and the other being an ironbase metal of relatively great tensile strength and containing at least as much as thirty hundredths per cent content of chemically combined carbon for minimizing magnetic permeability, said-,copper being so disposed in the body of the conductor that 1t 1s substantially enveloped by the said ironbase metal.

3. A composite electrical conductor comrising two metals, one having relatively liigh electrical conductivity and the other being steel containing substantially thirty hundredths per cent content' ror Umore' of chemically combined carbon, said steel forming substantially the outer boundary of said conductor.

v4. A composite electrical conductor comone being copper for high el trical conductivity and the other bef one kind being ling steel for high tensile strength and containing at least thirty hundredths per c ent chemicall combined carbon for substantially minimizing the electro-magnetic sltin effeet, said copper being so disposed 1n the body of the conductor that all the filaments of copper are substantially surrounded by laments of the said steel.

5. A composite electrical conductor composed of laments comprising two metals, vof relativelyhlgh electrical conductivity and the other kind being steel of relatively high tensile strength and relatively low magnetic permeability, said filaments being so disposed in the bodyof the conductor that the exterior surface of the conduct-'or consists substantially of ilaments of the said steel. A v

y6. A composite'electrical conductor` comprisingtwo metals, one forming a non-ferelectrlcall conductivityl rous core having high and the other forming a ferrous covering of high tensile strength and relatively low magnetic permeability.

7. A composite electrical conductor co m osed of two metals, one having the quality of high electrical conductivity and the. other having an iron-base with the qualities of of the conductor that the met-al of' high tensile strength and relatively low ma netic permeability, the latter being so distri uted in the conductor that the filaments of the metal of high electrical conductivity are electrical conductivityl are substantially env closed by it, both of said metals having protective coatings to retard corrosion.

9. A composite electrical 'conductor comprising two metals, one having the quality of relatively high electrical conductivity and the other having the qualities of relatively greatstrength and relatively low magnetic `permeability and so disposed within the conductor and its filaments substantially enclose the filaments of the metal of high electrical conductivity.

10. A composite electrical conductor comprising two metals, one having the quality of good electrical conductivity and the other be y.

ing steel'and lhaving relatively low magnetic permeability, every ilamentof the 'said metal of good electrical conductivity being substantiallly surrounded by filaments of the said stee 11. A composite electrical conductor comprising two metals, one forming a core hav' ing the quality of good electrical conductivity and the other forming a covering having an iron-base with the qualities of high strength and low magnetic permeability.

12. A composite electrical conductor comprising two metals, one having the quality of los good electrical conductivity and the other having an iron-base with the qualities of high strength and low magnetic ermeability, the exterior of said conductor eing comprised substantially of said metal of high strength and-low permeability.

13. A composite electrical conductor comprising two metals, one forming a core having the qualit of good electrical conductivity and the ot er forming a covering having an iron-base with the qualities of high strength and low magnetic permeability, one

- of said metals having a coating of material to protect against corrosion.

14. A composite electrlcal conductor comprising two metals, one forming a core havity and the other forming a coveringhaving an 4iron-base with the qualities of high strength and low magnetic permeability,

Aing the quality of good electrical conductiv- 1 both of said metals having coatmgs of material to protect them from corrosion.

15. A composite electrical conductor comyma v54..'substantially muumum electrical skin-eect, {substantially-none of said metal of hi h.con

vvd d uctivity being' at the periphery oft e con-` z uctor. v A

16. A composite electrical conductor comrising two metals, .one forming a'core havu great tensile strength and it and eot 'er formingaferrou's covering 0 4relatively great mechanical strengt percent of chemically oombindcarbon 'for mmlmizmg magneticl 'usability'.

of June, 1924.V

h'eontaining at least' as much` as'thirty hundredths x5

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