TELEPHONE EQUIPMENT FOR LONG CABLE CIRCUITS 121 



installations, the current drain on the 130-volt plate batteries has 

 sometimes reached values as great as four or five amperes, so that it 

 is now planned to float these batteries also, instead of operating on the 

 charge and discharge basis. It is expected by this means to obtain 

 regulation of the plate voltage within plus or minus five volts from 

 the normal value of 130, at all times. 



Consideration is being given to another possible improvement 

 in the power arrangements for large repeater installations. This 

 involves the proposal to use a storage battery common to all of the 

 repeaters for supplying the grid potential. If it is found that this 

 arrangement is practical, it will permit the elimination of the individual 

 dry cell batteries which have been employed, with a consequent saving 



Fig. 9 — Typical Storage Battery Room for Cable Repeater Station 



in maintenance that might be appreciable. It seems likely that a 

 very small storage battery would serve for this purpose since the cur- 

 rent drain is negligible. 



The amount of power required to operate the vacuum tubes in a 

 large telephone repeater installation is considerable. Each filament 

 requires a current in the neighborhood of one ampere and, while the 

 filaments are connected in series in such a way as to utilize as efficiently 

 as practicable the full potential of the central office battery, the load 

 on this battery sometimes amounts to several hundred amperes. 



