US 293775 A
Description (OCR text may contain errors)
W. R. PATTERSON.
Patented Feb. 19,1884..
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WILLIAM R. PATTERSON, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE VESTw EBN ELECTRIC COMPANY, OF SAME PLACE.
SPECIFICATION forming part or" Letters Patent No. 293,775, dated February 19, 1884.
Application filed December 15,1S'r3. (No model.)
protected by a lead pipe or by other water? proof covering. The individual wires of the 15 core are insulated by some fibrous material, the interstices being filled with para-fline or kindred substance. Fibrous material like cotton and jute, though saturated with parafine, is not sufficient to keep the wires from becoming grounded in case the pipe becomes broken or injured to such an extent as to admit water. Therefore, in case of injury t the pipe, water permeates the core and the wires become grounded. The fault must then be located and the damage repaired before the cable can be of further service.
The object of my invention is to provide means whereby faults ot' this character may be located with greater certainty than heretofore, without the aid of cumbersome and eX- pensive apparatus sueh as has been heretofore used.
My invention consists in providing special test-wires of different lengths, the lengths of the different test-wires increasing, preferably, in arithmetical ratio, while the length of the shortest test-wire is preferably made equal to the common difference. These special testwires are distinguished from each other and from the other wires of the core by colored threads, the shortest test-wire having, for instance, in its covering one thread of red yarn, the next in length two threads or strands of red, and so on, the longest test-wire having as many colored threads as there are testwires. These special test-wires may be placed among the conductors of the core, and should all be accessible at one end of a section of cable. The number of test-wires may be varied o as desired, according to the length ofthe sec' tions and the difficulties in the way of getting at the cable for making splices. For a section twelve hundred feet long, eleven, iive, or three special test-wires may be used, as may be thought necessary. For ordinary fiftyconductor telephone-cables I usually provide a test-wire for every two hundred feet-that is to say, a section twelve hundred feet long would require five special test-wires, the shortest being two hundred feet in length and the longest one thousand feet, while the common difference would be two hundred feet. Each test-wire is normally left open, and has no function except when used for testing.
Vhen the cable is to be laid under ground, I so arrange the sections that all the test-wires of two sections may be accessible ata given station. The repairer may thus test for a fault in two sections at each alternate teststation. This is done simply by connecting a battery successively to the different testwires in each of the sections and introducing preferably the tongue into the' circuit. If one test-wire is found open and the next closed, it will be known that the trouble is in the cable somewhere between the two inner ends of the two test-wires. A simple leak may be located by including a telephone in the circuit and charging the wires from the battery successively through the telephone, provided the original insulation is sufliciently high. By listening at the telephone as the battery is closed successively to charge a given testwire, it will be observed that the first contact will produce the loudest click, while the sounds produced by the succeeding contacts or clicks will grow less and less. A very slight escape, however, will cause the charge to leak out so quick that all contacts will give substantially the same sound. while if the inge sulation be perfect the first will be the loudest.
My invention is illustrated in the accompanying drawings, in which Figures l and 2 show diagrams of the special testwires. Fig. 3 is a sectional view ofthe cable, the five special test-wires being distinguished as shown. Suppose the section or piece of cable shown in Eig. l to be five hundred feet in length, and test-wire e to be one hundred feet in length, test-wire b two hundred feet in length, test-wire c three hundred, and test-wire d four hundred. Suppose, now, moisture should IOO than two hundred feet from the end.
penetrate the cable at c. The conductors will be grounded, and the problem is to locate the fault. The repairer will irst apply his battery, for example, to wire a. This will be found open, and he will know that the fault is more than a hundred feet from the end of the cable. IIe will then apply the battery to wire b, and will know that the fault is more Now he will apply the battery to wire e, and if he finds circuit he will know that the fault is not more than three hundred feet away. lVhere there is escape the test-wires may be charged through a telephone-receiver, as hereinbefore described, for the purpose of locating approximately the fault.
In Fig. 2, A B C represent three test-stations, and D E F G sections of cable, each provided with three test-wires. The sections are so placed that the special test-wires of two sections may be accessible at each alternate test-station. rIhus the special tests for faults in sections D and E may be made at station A, and the special tests for sections F and G may be made at test-station C, while only the ordinary tests are Iliade at station B. The test-wires ot' a submarine cable should be so arranged that all the special tests may be made upon land. The fault being located as within a given hundred, two hundred, or three hundred feet, as the case may be, I underrun the portion of the cable containing the fault, and search for a break or flaw in the pipe. In case I find an imperfect joint or damage caused by an anchor, I simply splice in a new piece of cable at the damaged place. If there is no visible injury to the pipe, I splice in a new piece a hundred,.two hundred, or three hundred feet long, as the case may be.
My invention is of great utility in ease a cable begins to fail, since the fault may be discovered readily and the damage repaired without seriously interrupting business.
I claim as new and original- I. The combination, in a telegraph-cable, of special test-wires of different lengths, whereby faults may be located approximately, substantially as and for the purpose speciiied.
2. The combination, in a telegraph-cable, V
cfspeeial test-wires, the wires in a given sec-- tion differing in length by a common difference', whereby faults may be located approximately, substantially as and for the purpose specified.
3. The combination of two sections of telegraph-cable, each provided with special testwires, said test-wires being all accessible at the test-station between said sections, whereby both sections may be tested from said station, as and for the purpose specified.
In witness whereof I hereunto subscribe my name this 13th day of December, A. D. 1883.
VILLIAM R. PATTERSON.
PAUL A. S'rnLnY, R. H. Winnrcoirn.