. The Bell System technical journal . current supply bus-bars insure regulation. In addition to stabilizing the voltage andreducing noise interference from the machines and between tele-phone circuits, the batteries perform the important function of keep-ing the exchange in operation during interruptions to the commercialpower service. Small motor generators furnish current for ringingsubscribers bells and drive commutators supplying various tones andsignals. Batteries or machines supply current for operating coin 74 BELL SYSTEM TECHNICAL JOURNAL boxes and pulse machines provide impulses for t
. The Bell System technical journal . current supply bus-bars insure regulation. In addition to stabilizing the voltage andreducing noise interference from the machines and between tele-phone circuits, the batteries perform the important function of keep-ing the exchange in operation during interruptions to the commercialpower service. Small motor generators furnish current for ringingsubscribers bells and drive commutators supplying various tones andsignals. Batteries or machines supply current for operating coin 74 BELL SYSTEM TECHNICAL JOURNAL boxes and pulse machines provide impulses for the operation of cer-tain of the machine switching apparatus. Whenever practicable, two or more commercial power services fromindependent generating stations are secured, either of which will keepthe office supplied. Where independent generating systems are notavailable a reserve gas engine supply (Fig. 17) is installed to takethe place of the incoming power service, such engine also beingequipped for emergency operation on Fig. 16—Battery Room for Two 10,000-Line Units All of the essential power machines and batteries are providedin duplicate and are arranged to come into action automaticallywherever this is necessary to insure continuity of service in the eventof loss of power or trouble with any of the power equipment. Alarmsare provided to detect variations in battery voltage, blowing of fuses,stopping of machines or any failure of service on all power busseswhich feed energy to the telephone or signaling circuits. The powerplant is thus designed to give an uninterrupted energy supply at alltimes even when the usual sources of power may have been tempor-arily discontinued. MACHINE SWITCHING TELEPHONE SYSTEM 75 Detailed Plan of Operation The following will give in some detail the plan of operation forhandling typical calls between various types of offices in a largemetropolitan area such as Newr York City. Calls Originating in Machine Switching Offices. Fig. 18 s
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
