. The Street railway journal . sixrotary converter sub-stations. For cable conduits terra cotta ducts have been adopted asstandard. These ducts are laid in single-duct formation, and are underground cables, the sections have been increased in length andin size. Most of the trouble in the underground cables is due tomechanical injury of one form or another. Mechanical injury inmanholes is now being avoided by assigning each cable a certainhanger in the manhole, and the cable is thoroughly secured in theposition allotted to it. Feeder taps are taken off at intervals of from 500 to 1000 the
. The Street railway journal . sixrotary converter sub-stations. For cable conduits terra cotta ducts have been adopted asstandard. These ducts are laid in single-duct formation, and are underground cables, the sections have been increased in length andin size. Most of the trouble in the underground cables is due tomechanical injury of one form or another. Mechanical injury inmanholes is now being avoided by assigning each cable a certainhanger in the manhole, and the cable is thoroughly secured in theposition allotted to it. Feeder taps are taken off at intervals of from 500 to 1000 the feeder sections. The feeder sections vary in length from2000 ft. to 5000 ft. The taps are brought up the feeder polesthrough 2 Yi-in. iron pipe. The tap cables are insulated with6-32-in. rubber compound covered with ]/&-in. lead and pro-tected outside the lead with a weather-proof braid. A cast-ironswitch-box containing a 250-amp. switch is placed near the topof each feeder pole, and the tap cable is brought through this. SECTION OF FEEDER POLE, SHOWING STANDARD CONSTRUCTION surrounded by 3 ins. of cement concrete. On straightawaystretches elliptical manholes are placed at frequent intervals, themanholes being for the most part 9 ft. long, and varying in depthand width according to the size and location of the manholes are placed at the junction points. The manholesare connected with the sewers by terra cotta drain pipe, and eachhole is thoroughly cleansed every two months. The d. c. cables differ in size, but the standard sizes are 1,000,-000 circ. mil, 1,500,000 circ. mil and 2,000,000 circ. , jute and paper insulations for cables are in use, but thestandard cable is covered with 5-32-in. saturated paper insula-tion, with a 5-32-in. wall of lead. The size of the cables isfigured on a basis of a maximum loss of 1 0 per cent voltage. Thesections to be fed were first made short, so that in case one cablebecame disabled the next section would be able to
Size: 1931px × 1294px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1880, booksubjectstreetr, bookyear1884
