. American telephone practice . ora connection with a subscriber at the second office, after she hasdesignated to the incoming trunk operator at the distant office thenumber of the line and received from that operator the number ofthe trunk to be used, the A operator will insert the calling plug ofher pair of cords into the outgoing trunk jack designated. Assum-ing that the A operator inserts the calling plug into the outgoing-jack before the B operator inserts the trunk plug into the subscrib-ers multiple jack, the following conditions exist: The relay, A, atthe incoming trunk end will be ope
. American telephone practice . ora connection with a subscriber at the second office, after she hasdesignated to the incoming trunk operator at the distant office thenumber of the line and received from that operator the number ofthe trunk to be used, the A operator will insert the calling plug ofher pair of cords into the outgoing trunk jack designated. Assum-ing that the A operator inserts the calling plug into the outgoing-jack before the B operator inserts the trunk plug into the subscrib-ers multiple jack, the following conditions exist: The relay, A, atthe incoming trunk end will be operated from current received frombattery, B, at the first exchange, over the metallic circuit of thetrunk line, causing this relay to attract its armature. This will causethe lighting of the disconnect lamp over a path which may be tracedfrom ground through the back contact of the relay, C, the frontcontact of the relay, A, and the disconnect lamp to the negativeside of the battery, B2, at the second office. On account of the m\. FIG. 290.—CONNECTION BETWEEN TWO SUBSCRIBERS THROUGH TWOOFFICES—KELLOGG SYSTEM. TRUNKING SYSTEM BETWEEN COMMON BATTERY OFFICES. 369 very high resistance of the relay, A, the current flowing over themetallic circuit of the trunk line will not operate the supervisoryrelay, R3, of the A operators cord circuit which will, therefore,leave its contact in the calling supervisory lamp circuit closed. Theother supervisory relay, R4, of the A operators cord circuit will,however, be operated, current flowing from the live side of thebattery, B, through the winding of this relay in multiple throughthe winding of relays, A and R3, and the retardation coil connectedbetween the sleeve side of the outgoing trunk jacks and calling supervisory lamp, S2,o( the A operators cord, will, there-fore, be lighted. When the B operator inserts the trunk plug intothe multiple jack of the called subscriber the relay, C, will be atonce operated over a circuit which may
Size: 1219px × 2049px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., boo, bookcentury1900, bookdecade1900, bookidamericantelepho00mill
