US369394A - Electrical conductor - Google Patents

Description

(No Model.)

H. F. CAMPBELL. ELBGTRIGAL CONDUCTOR. 1No. 369,394. Patented Sept. 6, 1887.

N. PETERS. PhnIn-Lilhogmphlr, Whhinllfln. 0.6.

UNITED STATES PATENT OFFICE.

HENRY F. CAMPBELL, OF CONCORD, NEW' HAMPSHIRE, ASSIGNOR TO THE CAMPBELL ELECTRIC COMPANY, OF NEIV HAMPSHIRE.

ELECTRICAL CONDUCTOR.

SPECIFICATION forming part of Letters Patent No. 369,394, dated September 6, 1887.

(No model.)

To aZZ whom it may concern:

Be it known that I, HENRY F. CAMP ELL, of Concord, county of Merrimac, State of New Hampshire, have invented an Improvement in Electrical Conductors, of which the following description, in connection with the accompanying drawings, is a specification, like letters on the drawings representing like parts.

My invention relating to electric conductr0 ors has for its object to prevent disturbances arising from induction from neighboring wires or other disturbing influences.

Electric cables have been made in which each independent conductor, covered with the usual insulating material, is provided with an outer metallic covering, usually composed of a lead or copper tube, or of a covering of tinfoil, it having been supposed that such a COV. ering would prevent the transmission of distll1'bl[lg currents to the wire. Experiment, however, has shown that such coverings are ineffectual, 'at least for cutting ofl such currents as will produce disturbances in the tele phonic instruments of the present day.

I have discovered after long investigation that while an ordinary covering composed of the metals usually employed for this purpose viz., copper, lead, or tin, all good conductors of electricityareincfficient, there are certain 0 substances which, when employed as a covering or shield for an insulated wire,will greatly diminish or entirely annul the disturbances referred to.

In another] application for Letters Patent,

3 5 No. 97,028, filed June 4,1883, I have described and claimed a shield composed of paramagnetic and diamagnetic materials,it being many times more effectual than the coverings composed of diamagnetic material alone heretoro fore employed. While the shield therein described is the best known to me for this purpose, there are other materials besides such a combination of paramagnetic and diamagnetic substances which can be employed, and will 5 give far better results than the materials formerly used.

All my investigations have shown that while the materials known and classed as ,diamagnetic materials, including copper, lead, and

5c tin, which have been most commonly used on account of their abundance, their electrical conductivity, andthe ease with which they may be manipulated, are ineffectual. All the paramagnetic elements are found to be effective in a very high degree; and the presentinvention consists, mainly, in the combination, with an insulated conductor, of a covering or shield composed ol'one or more paramagnetic materials and with means to connect the said shield in an electric circuit, whereby the cur- 6 rent generated in the said shield may be conducted away from it without passing to or affecting the conductor incloscd in the said shield and protected thereby.

Figure 1 shows in transverse section a cable 5 5 composed of electric conductors embodying my invention, and Fig. 2 a longitudinal section thereof.

As herein shown, a series of independent conductors are united to form a cable, the said conductors c, of any usual kind, being each intended to form .a portion of the circuit of telephonic or other electrical instruments, and each being provided with a covering, 1), oiany usual and suitable insulating material, to prevent the currents from escaping from it.

Each insulated conductor a b is provided with an anti-inductive shield or covering, 0, which in this instance is composed of paramagnetic material, either a single substance, such as iron, manganese, cobalt, nickel, or a composition of two or more of the said substances. Iron is considered the best paramagnetic when used alone, or as the chief element in quantity when two substances are used, as it stands at the head of the list of materials classed as paramagnetics. The said covering 0 can be most conveniently made of a strip of iron annealed, or of a soft and flexible nature wound spirally upon the outside of the 0 insulating material I), care being taken that each successive turn of the strip is in close contact with or partially overlaps the edge of the one already applied, so as to form a complete uninterrupted coverin In order to render the shields effective, to prevent the transmission of electric impulses from one to another of the wires incloscd therein, it is essential to provide means for dis sipating the currents generated in the shields. ion This may be accomplished by making the said shields a portion of a complete circuit, as hereinafter described, and by certain peculiar arrangements of the shielded conductors with relation to one another, which will form the subject of other applications for Letters Patent.

\Vhen the shields c of the different wires a are to form a part of a complete electric circuit, they may be insulated from one another, or, if desired, may be in electrical contact with one another, as shown. In the former case each individual wire will be connected by a terminal, as described in my former application referred to, with the ground or other return circuit for conveying the currents away from the said shields, and thus preventing them from passing upon or affecting the wires a, inclosed within them.

\Vhen the shields are in contact with one another, as shown, they constitute practically a single conductor, and single terminals, t, of a similar nature to those described in my former application, may be employed at each end of the cable to connect the said shields with the ground or with a metallic conductor, forming the return-circuit for the said shields, as described in another application for Letters Patent, filed August 20, 1883, and numbered 104,214.

I consider that the employment of an annealed strip or ribbon of steel, or of homogeneous iron or steel without fiber, or, in fact, any annealed or soft ribbon composed of iron as the base, is within my invention.

I am aware that awrought-iron pipe ortube has been used with an insulated conductor to increase the tensile strength, and for purposes of defense against abrasion and the action of water, as shown in United States Patents Nos. 91,093 and 201,477.

I claim 1. An electric conductor having a covering of insulating material, combined with an antiinductive shield composed of paramagnetic material, substantially as described.

2. An electric conductor consisting of a con- I ducting-core, an insulating covering therefor,

and an external shield of iron capable of ready magnetization and demagnetization, as and for the purpose described.

In testimony whereof I have signed my name to this specification in the presence of two sub scribing witnesses.

HENRY F. CAMPBELL.

W'itnesses:

Jos. P. LIvEnMoRn, W. H. SIGSTON.

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