380 



THE BELL SYSTEM TECHXICAL JOURNAL, MARCH 1957 



The alternative supply uses oxj-gen-depolarized primary cells having 

 an alkaline electroMe, and has been used for many \'ears in railway 

 signaling circuits and in the telephone plant. Sixteen batter}- cells are 

 connected in series to provide enough power for three years of operation 

 of a remote terminal or about one year for a remote repeater. The battery 

 is discarded when fulh- discharged and is then replaced by a new battery. 



7. APPLICATIOX OF PI CARRIER TO RURAL TELEPHONE LINES 



The Pi carrier system is to be applied to normal exchange loop plant 

 facilities engineered in accordance with the present Resistance Design 



Fig. 25 — Primary battery power plant. 



