File:The practical telephone handbook and guide to the telephonic exchange (1906) (14569569959).jpg

Identifier: practicaltelepho00pool (find matches)
Title: The practical telephone handbook and guide to the telephonic exchange
Year: 1906 (1900s)
Authors: Poole, Joseph
Subjects: Telephone
Publisher: New York, Macmillan Co.
Contributing Library: Northeastern University, Snell Library
Digitizing Sponsor: Boston Library Consortium Member Libraries

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, until the linesmanarrives at a point where the contact does not disappear. Thefault will then lie between the two last disconnections. Onlong trunk fines test-boxes are fixed along the route, into whichthe lines are led by covered wires, and attached to doubleterminals, so that tests may be easily made. (2.) Earth Faults.—The procedure followed in tracing anearth fault is much the same as for a contact. (3.) Breaks.—If a line is broken down, the linesman walksover the route until he comes to the broken span. On longlines, and when the fault is a difficult one to find, an earthedbattery is connected to one end of the broken line, and thelinesman from time to time connects the faulty line to earth FAULTS AND THEIR LOCALISATION 437 through his galvo, and notes if lie gets an indication of thecurrent on the line. When he has passed the break thedeflection will not be obtained. For partial breaks, when the wire shows a very high re-sistance, the same procedure may be followed. A much
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Fig. 413.—Portable Test Set weakened deflection will then be obtained when the fault ispassed. Intermittent line faults are a source of great trouble inlocating, as in the case of similar instrument faults. Such faults are readily detected in C.B. exchanges, asmomentary earth contacts which would scarcely be noticedin a magneto exchange will actuate the signals every time thecontact occurs, and the operator at once reports to the test-clerk for further testing. Portable Testing Sets.—Linesmen should be provided witha light testing set, such as that shown in Fig. 413* This set,made by the Ericsson Co., weighs only 8J lbs., and comprises 438 PRACTICAL TELEPHONE HANDBOOK telescopic hand-micro magneto bell, generator, two small drycells, shoulder strap, and outer leather case for protection.The connections are as shown in Fig. 414. Inspections of Instruments.—In order to ensure that theinstruments are kept up to a proper state of efficiency, it isnecessary that there shall be regula

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