. Electrical instruments and telephones of the Signal corps . U. S. SIGNAL CORPS. This method is particuhirly applicable to paj^er cables where a leakhas made the insulation of all the conductors faulty. Loedtioii of hreal in rondurfor.—The method ap]-)licable when thewire is broken inside the insulation, leaving the latter intact, is givenbelow. This is the character of the fault generally produced when aconductor parts in a paper cable. Owing to the small capacity of thiskind of cable the metliod is useful because of the practical difficultyin getting correct capacity values by galvanom
. Electrical instruments and telephones of the Signal corps . U. S. SIGNAL CORPS. This method is particuhirly applicable to paj^er cables where a leakhas made the insulation of all the conductors faulty. Loedtioii of hreal in rondurfor.—The method ap]-)licable when thewire is broken inside the insulation, leaving the latter intact, is givenbelow. This is the character of the fault generally produced when aconductor parts in a paper cable. Owing to the small capacity of thiskind of cable the metliod is useful because of the practical difficultyin getting correct capacity values by galvanometer methods in smalllengths of this cable. The connections for the test are the same as that described in figureIGl, except the telephone receiver is used in place of the point ff. instead of representing a fault in insulation, in this caserepresents the location of a break in the wire. It is best to use quite anumber of cells, say 20 or 30, if available. The battery circuit isreversed and interrupted rapidly Avhile a point is sought with the. FIG. 164. searcher along the resistance wire where the clicks are no longer heardin the receiver. AMien this j^oint of balance is reached the distanceto the break is then read off on the scale along the resistance wirefrom C to the point G, as explained in locating insulation faults. Inthis case the point G is in the corresponding position on the upperwire. In the last-named test an interrupted current of rather high voltageis required. A method of getting this with only two dry cells is totake a local battery telephone induction coil (/ in the figure) andattach it to a wooden base, together Avith an ordinary small metalbuzzer .^.* The connections are as shown in figure 164. AMien the battery isconnected the buzzer sends a vibratory current through the ])rimarycoil. A vil)ratory current of much higher voltage is induced in thesecondary, and this is utilized in place of the battery currents, asshown in the foreffoinir t
Size: 2809px × 889px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, bookpublisherwashingtongovtprin
