US851747A - Process of drying electric cables. - Google Patents

Description

UNITED sTATEs PATENT yoEEroE WILLIAM B. HALE, COMPANY,

OF MEXICO, )I

XICO, ASSIGNORl TO WESTERN ELECTRIC OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

PROCESS OF DRYING ELECTRIC CABLES NQ.A 851,747.

To all 1071/0711/ if i12/tty concern:

Be it known that I, IVILLIAM B. HALE, a

. citizen of the United States, residing at Mexvtromotive force or difference .duct-ors, and the ico city, Mexico, have invented a certain new and useful Improvement in Processes of Drying Electric Cables, of which the following is a full, clear, concise, and exact description.

My invention relates to a process of drving `the coresof electric cables, and has for its object to provide an improved method which will be simple, rapid, economical and effective.

The common method of drying cables involves the passage of a strong current through the conductors thereof. to heat the cable sufficiently to vaporize the moisture contained therein, the vapor being then withdrawn by means of an air pump applied to the end of the cable. This process, besides requiring the use of special apparatus, is somewhat slow and expensive.

In accordance with my invention, an elecof potential is established between different conductors of the cable sufficient to cause a flow of current through the moisture remaining in the insulating medium which separates said conmoistureis thereby electrolytically decomposed. As decomposition progresses' the insulation resistance gradually increases and in order to maintain a flow of current strong enough for such decomposition, y(that is, above the critical value required for electrolysis) the impressed elecy current necessary tromotive force may be gradually raised, but not, of course, beyond the dielectric strength of thel cable. If required, in some cases, the to carry on the process of electrolysis may be further maintained by temporarily reducing the resistance of the path across the insulation by means of heat, which may be developed either in the conductors of the cable by current flowing therein, orin the dielectric itself by the applica.- tion of an alternating electromotive force.

In the accompanying drawing I have illustrated one of a number of arrangements of apparatus which may. be adopted in practicmg my process.

1 is a telephone cable of the well known type comprising a certain number of conductors twisted into pairs, formed 4into a core and covered with a lead sheath. In the Speccaton of Letters Patent. Anelication filati March 12, 1906. Serial No. 305,73'8.

required value.

Patented Apru so, 190'?.v

divided into groups 2 and 3, each of said groups comprising a conductor from'each pair in the cable. The two groups are connected to a required range of voltage, a connected to each terminal. Regulating the voltage by means of a field regulator 6 or otherwise, so that the voltmeter fconnected across the terminals indicates' an electromot-ive force' of say one hundred volts, the voltage may be gradually increased, at intervals of half an hour or so, as the insulation resistance rises, due to the decomposition of moisture, until said resistance is increased to the This may take say from two to six hours. The increase in voltage is, of course, limited by the dielectric strength or breaking-down point of the cable bein(r dried; and if the insulation resistance is, stil below the desired value when this limit is approached, the intensity of current required forelectrolysis may then be' further maintained by temporarily increasing theconductivit y of the moisture remaining in the insulating medium, by means of heat. This may be produced by applying an alternating e. m. f. from.a suitable generator to the two groups of wires 2, 3, to develop lthe heat in the dielectric itself by molecular action set up therein; or strong current may be passed through some or all of the conductors of the cable toheat said conductors by the 12R effect. To facilitate the drying out of the cable any or all of the foregoing ymeans may be employed; but ordinari y a cable would have sufficient dielectric strength to witlistand the voltage required to produce the necessary elect-rolyzing current,without resorting to the heating process.

Although I have chosen to illustrate my one group bein(r process .by describing its application to a cable of the above mentioned type, it will readily be understood that it is e ually` applicable to other forms. Mqreover, t 1e disposition of the wiresdescribed herein is only one of the many arrangements that may be employed. For example, the electrolyzing current ma be passed from all the wires to the metallic sheath of the cable, from one layer of wires to another, from one wire to another, or from any group of wires to a single wire or to another group of wires.

By theprocess herein described, the insulation resista-nce of a cable when exceedingly generator capable of giving the IOO ' which consists in duct-ors, sufficient to electrolyze the moisture jloW.,

raised to meet Whichconsists in establishing a iiow of curmit the maintenance of said current above the critical value for electrolysis. v

5. The process of drying electric cables which consists in establishing, by an iml pressed electromotive force, a flow of current through the insulating medium of said cable, 'such current being sufficient to electrolytically decompose the moisture therein, lan heating said medium to temporarilyincrease its conductivity to a point which will permit the maintenance of said current at the required intensity for such decomposition without increasing the impressed electromotive force to a point beyond the dielectric resisting strength of the cable, said heating being produced due to the presence of moisture, may be standard requirements. he removal of the moisture furthermore inaterially reduces the capacity of thecable.

1. The process of drying electric .cables maintaining a flow of electric current through the insulating material of the cable, of sufiicient strength .to electrolyzethe moisture therein.

.2. The process of drying electric' .cables, which consistsin establishing a'difference of l potential'between derent conductors of the l cable, and thereby causing a flow of current through the insulation surrounding said conductors sufficient'to decompose the moisture therein. j

3. The process oi' drying electric cables Whichconsists in establishing an electronic-v tive force -between different conductors of the. cable, thereby causing a now of current through the insulation surrounding said conby the application of a suitable electromotive force to the conductors' of said cable.

6. The process of drying electric cables, which consists in establishing a iow of current between different conductors of the cable through the moisture remaining in the insulating medium, said current being sufficient to cause electiolytic decomposition of such moisture, and heating said insulating i medium to temporarily reduce the insulation i resistance of the cable so as to increase the current which will iiow under a given electroniotive force.

therein, and progressively increasing the impressed electromotive force as t-he insulation resistance rises, to maintain t-he current iioiv above the critical value for electrolysis.

. 4. The process' of drying electric cables,

`rent between different conductors of the cable through the moisture remaining in the my name this 26th day of February A. D..

insulating medium, said current. being suiiil 1906. f

cient to cause electrolytic decomposition of WILLIAM B. HALE. Asuch moisture, and'electricall'y heating said Witnesses:

insulating medium to temporarily increase THOMAS G. NEE,

the' conductivity otsaid moisture so as to per- FERNANDO GIL.

In Witness whereof, I, hereunto subscribe-

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