US1119246A - Electric cable. - Google Patents

Description

J. H. CUNTZ. ELECTRIC CABLE. APPLICATION FILED APR. 13, 1905.

1,1 1 9,246. Patented Dec. 1, 1914.

2 SHEETS-SHEET 1.

WITNESSES:

J. H. GUNTZ. ELECTRIC CABLE. APPLICATION FILED APR.13,1905.

Patented Dec. 1, 1914.

2 SHEETS-SHEET 2.

Fig.6.

INVMOR BY MM ATTORNEY WITNESSES:

ra rnn rfiormon.

JOHANN'ES H. CU'NZIZ, F HOBOKEN, NEW JERSEY.

ELECTRIC CABLE.

Specification of Letters Patent.

Patented Dec. 1, 1914.

Application filed April s. was. Serial No. 255,431,

To whom itmayconcern Be it known that I, Jonnxxns' H. CUNTZ,

acitizen of the'United States, and residentof Hoboken, in -the county of Hudson and State of NewJersey, (whose post-ofiicefaddress is Hoboken, New Jersey,) have invented certain. new and useful Improve now generally understood as denoting eel, 'tain'phenomena.' 'The'cause of such modifications is the combined infl'uenceof the resistance, the capacity and the. inductance of theline. In ordinary) long. distance lines,

particularlyon submarine and underground cables, the capacity and the resistance are primarilyw instrumental in producmg attenuation, \\'hi,le,the capacity causes distortion also- On .suchlines the capacity is sub stantially "uniformly distributed along their. length. v I

Myinvention relates to the construction of'cables and to .methods for whollyor in parttcounteracting the effects of the ca Imorderto applymysystem of long .distance electric wave transmission my prime object is to increase the inductance of the,

line sufliciently to substantially or partly,

as the case may demand, counteract the effects of. thedistributed capacity of the line. as electric lines of this sort" may be used in various ways, as submarine, underground or aerial, thecapacity whieh'it is necessary to counteract varies accordingly and between verywide limits. In the case of subarine cablesthere is large capacity which,

t'erefore, demands a large amount of insuch cables is great.

ductance. particularly where the length of By my construction a cable can be produced with van inductance as large as may be required for the given conditions, and what is more important, the amount can be predetermined andthe diunensions of the elements of my cable so adzjusted as to secure the proper amountin a w y mwhani albsupp nd cql ml c ally hesc modifications are such as dis-,

practicable. I am aware that there have been suggestions of constructions intended to increase inductance in a' line, but which invariably do not show means whereby such inductance can be sufiiciently increased for my purpose; or suchcons tructions have involved defects which would prevent successful operation of the line; more than this, in such suggestions it ha'svnot been shown how the exact amount of'inductance can be predetermined.

In myconstruction I carry my conductor in a helical path, which increases-the in" duc'tance of the lineto an extent that in some cases may beisulficient'; and moreover I use a core of paramagnetic material about which the conductor is helically wound, which one ables me to very materially further increase the inductance. As I can determinewith properties of theelements of my eonstruction .whichbeanu'pon, theresults, I can proportion the materialin and. the arrangement of the parts of my-c'ables to acconiplishthe desiredresults with certainty, and moreover can so selectand arrange them as to prevent complications which existed in suggestions which have at times been made, or which might exist except for theproper material and arrangement which I show and hereinafterinore specifically describe, and, particularly, when in up construction a magnetizable COleJSAlStl, thearrangement is such that the magnetization is so small as to avoid any deleterious eflects.

In the accompanying drawings, Figure I diagrammatically shows the embodiment of my improvement in along distance transmission. system. Figl 2 shows a portion of a cable, partly in section, embodying the es sential elements of my invention, Fig. 2" being a section of the same With'jts sheathing, while 2* shows a section of the same without sheathing. Fig. 3 is a portion of a construction intended to secure permanency vin the relative arrangement of parts, while 3 shows thesame in section. Fig. 4 shows a section of cable modified in certain details. Fig. 5 shows a portion 'of cable in which more detail of core and arrangement of conductors is illustrated, while 5" shows the fame in section. 6 shows a portion of cable modified in form for mechanical requirements of manufacture. Figs. 7, 8 and 9 show portions of three forms of cable with h rarts pr p for '75 exactness the var ous electrical andmagnetic given conditions and differing only in arrangement, while Figs. 7, 8" and 9" show respectively the sections of these different arrangements.

In Fig. 1 A is an electrical conductor, B is a core, or support for the conductor, 6 is a source of electric energy, f is a key which, with 6, shows conventionally means of imparting electrical impulses to the conductor A, while 9 indicates aconnection to earth. h indicates an instrument to receive electrical impulses, and indicates a connection to earth. C is insulation. The electricalimpulses or waves emanating from e f pass along the conductor A to the instrument h. In this drawing the conductor is shown. as broken away in the middle, to indicate length. 1

In Figs. 2 and 2 the conductor A with its small amount of insulation is wound helically around the core B and this is 'incased in insulation C about which is the sheathing D which can be used to take the strain to which the cable may be subjected, while in other cases the construction shown in Fig. 2 without sheathing may be usedand the strains, if there are any, taken by the core.

In Figs. 3 and 3 the core B is so made as to present a helical groove whichis followed by the conductor A, while A is flattened as may be desirable in cases as hereinafter shown, and should the core be of electrically conducting material, A is insulated as shown. This construction might be used where the capacity of a line is relatively small and the desired inductance can be obtained simply from the'helical disposition of the conductor, and where it might be desirable to avoid the use of a paramagnetic core.

In Fig. 4, the conductor in several strands A", properly insulated, is laid around the central portion of the stranded core B, so as to be substantially flush with the outer' layer of the core 13". This would have mechanical advantages in aiforcling'a more compact construction, in which also the outside strands of the core would cooperate to hold the conductor in its helical position; in addition to which I am hereby enabled to more completely fill the area inclosed by my hellical conductor with paramagnetic matel'la In Figs. 5 and 5 the core B is shown more in detail, revealing the strands, the construction which I would generally use in the practical embodiment of my invention, while my conductor as here shown consists of a plurality of wires, each individually insulated for mechanical simplicity, although the insulation between the conducting material and the core is primarily important, and which I may accomplish by wrapping the bunch of conductors within insulation in such a way that only the convolutions of the sets of conductors will be insulated from each other. In this arrangement it will be seen that the conductors are wound in the opposite direction from the strands of the core, which under certain co ditions will give me better electro-magnetic results. The conductor is wound in opposite directions from the strands of the core, so as to cross the latter more nearly at right angles, in view of which any eddy currents which might possibly be induced in the core strands will be reduced to a minimum.

In the use of my invention for certain con ditions of line and also for possible mechanical requirements in construction I. find that advantages may be obtained by using the arrangement as shown in Fig. 6. In this the conductor, or its several parts. is wound around the stranded corein the same direction as the surface strands of the core and for a, certain length'at the sam'e pitch. This will insure the conductor fitting the surface of the core more closely, preventing among other things displacement, while portions of the conductor are then wound at a. decreased .pitch, this increasing the number of turns sufficiently to give the required inductance. In my construction of cable in all its various forms where a core of paramagnetic material is used, said core is of that material solely to increase the inductance of the line.

and is not intended to carry current.

In Figs. 7, 8 and 9 there is shown a practical form of cable designed to satisfy the conditions of a concrete case. The only difference in the three figures is the disposition of the conductor, except that in Figs. 7 and 8 the strands of the core are simply indicated as parallel to its axis, whereas in Fig. 9 the strands are shown in the preferred arrangement. I have here assumed a submarine cable with capacity and resistance such as are encountered in actual practice, and I have calculated the amount of inductance necessary to be given to such a line in order to permit the transmission of telephonic messages. cure the proper amount of inductance, the dimensions" and arrangement of core and conductor are substantially as shown. In the three illustrations the total area of section of conductor is the same. In Fig. 8 the conductor is flattened. This permits of a more compact, mechanical construction and at the same time makes it a better conductor for rapidly alternating currents, as it affords a larger surface for the same cross section. It is true that this increased surface would also increase the capacity, but its mechanical arrangement ermits a greater thickness of insulation En' a given outside diameter of cable, which greater thickness of insulation will reduce the capacity. In

Fig. 9 I divide my conductor in order to give I find then that in order to se- I greater security against parting of the conductor, and also to secure a more simple and commercially practicable method of manufacture. In this the conductor consists of a plurality of wires, each insulated When varying electric currents are transmitted over long circuits they are attenuated in a manner which is indicated by the formula if or that is, at any distance :0 from the sou cc of current, its strength will have decreased from unity to e'", or in that proportion: where e is the base of the Naperian system of logarithms, a is the distance, in any convenient units of length, and p, which may be termeri the attenuation constant, is equal In this formula, C is the electrostatic capacity, R the resistance, and L the inductance, all per unit length, and m is equal to 21: times the frequency of the current. When a current is composed of waves of different frequencies, these component waves will be attenuated in difl'erent degrees, and the resulting current, or combined wave, will be not only attenuated but distorted. This is notably the case in telephonic transmission. When the inductance of a circuit, L, is practically zero, the abox e formula reduces to V ,ICLUR 2 When, however, the inductance, L, is

made large com ared with the resistance, R,

the expression or p becomes which is independent of the fre uency, so that currents made up of waves 0 different frequencies will have their components attenuated in the same de rec and will not suffer distortion. And a so, by increasing L, the attenuation can be minimized.

The inductance of a circuit constructedv on my system can be calculated by the formula tended primarily for submarine work, of a length of 2,000 nautical miles. I take a. conductor of .164 square centimeters in cross-sectional area, having a resistance of 2 ohms to :1 nautical mile, and a capacity of 0.3 microfarads per nautical mile; and a core of 0.5 square centimeters in area, which will be 0.8 centimeters in diameter; the pitch of the helical conductor I make equal to 2 centimeters. Then, making allowance for the thickness of conductor and insulation, as well as the compression of the insulation and other minor features, the average diameter of the helix is brought to one centimeter. On such a line the length of the conductor is increased in the ratio of 1.85 to 1, and the resistance of the conductor, therefore, equals 3.7 ohms per nautical mile; allowing thatthe capacity is increased in the safne proportion, it will be 0.555 microfarads per nautieel mile. The attenuation constant will then be If"? "Tifi2'' and the attefflfatbn therefore will be:

Hi l

= groom; 72

, and this for a cable of 2,000 nautical miles; and this attenuation in my construction is, furthermore, independent of the frequency.

As a partial basis of comparison to show the relative entire impracticability of an ordinary cable, as compared with one of my construction, consider such an ordinary cable 2000 nautical miles in length, with a resistance .of 2 ohms and a capacitywf 0.3 microfarads per mile. he inductance of such a cable is extremely small, and t e formula for the attenuation constant is there fore:

CwR P 2 Substituting the above values, and assuming the frequency to be 500,

' 0.3x27FY5tYl3ZT2 1 p= ,,/942=.031.

The attenuation for a 2000 mile cable will therefore be:

1 1 1 5,2 ado 3172666) 55 r.

ap roximately. Moreover, this attenuation wi l vary with the frequen y. 4

I make the strands of the core of fine softiron wire. These wires may be insulated from each other by a coating of their oxid, or they may have a thin coating of insulating compound. In cases where it mi ht be found advantageous to have the core e ectromagnetically non-continuous longitudinally,

the plumiity of strands in my efmezi' form afiord the opportunity of-stil preservin'g mechanical continuity by staggering the 1011118;

I do not wish to confine myself to the exact constructions or dimensions of parts as herein specifically set forth, but What I- and increasing itscapacity in a lesser degree, substantially as described.

2. The method of wnn'teract'ing the capacity'of anelectric' cable, which consists in increasing the efl'ective inductance of the cable throughout all portions of the length tl icreof, and increasing its resistance in a lcsserdegr'ee'.

In testimony whereof, I have signed my -1 name to this specification, in the presence of two subscribing witnesses, this 12th day of April, 1905.

JOHANNES H; GUNTZ; Witnesses:-

P. KENNEM,

F. Con-rm

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