. American telephone practice . being necessary to ground the same pole as is 412 AMERICAN TELEPHONE PRACTICE. grounded in the main office. With the batteries so connected theflow of current through the private branch battery will be in theproper direction to charge it. A resistance coil, R, is placed in thelead which feeds the trunk line circuit at the main office, thisresistance being so proportioned as to allow the proper amount ofcurrent to pass to keep the private branch battery fully charged Sometimes in private branch exchange work it becomes desirableto use party lines and to afford me
. American telephone practice . being necessary to ground the same pole as is 412 AMERICAN TELEPHONE PRACTICE. grounded in the main office. With the batteries so connected theflow of current through the private branch battery will be in theproper direction to charge it. A resistance coil, R, is placed in thelead which feeds the trunk line circuit at the main office, thisresistance being so proportioned as to allow the proper amount ofcurrent to pass to keep the private branch battery fully charged Sometimes in private branch exchange work it becomes desirableto use party lines and to afford means for the different parties onthe line to call each other without calling the central office, or tocall the central office without calling the other stations on the is often desirable in large institutions covering considerableterritory. In giving such service as this in connection with mod-ern exchange systems, it is customary while supplying all currentfor talking purposes from a common battery to resort to manual.
Size: 1317px × 1896px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., boo, bookcentury1900, bookdecade1900, bookidamericantelepho00mill
