ELECTRICAL DRYING OF TELEPHONE CABLE 



215 



where low voltage is required, the two generators are operated in 

 parallel. For the long lengths of small cable where higher voltage is 

 required, the generators are operated in series. Suitable switching 

 equipment on the control board provides ready means for changing 

 to either method of operating the generators through large contactors 

 located on the power panel, Fig. 5. Such an arrangement permitted 

 the maximum capacity of the unit to be reduced one-half and the 

 average starting load to be increased to 90 per cent of full load. This 

 not only increased operating efficiency but very greatly reduced instal- 

 lation costs. Three such generating units were provided for handling 

 the entire product at Kearny, one large, one intermediate and one small. 



<0 40 



o 



600 800 1000 1200 



CURRENT IN AMPERES 



Fig. 6 — Curves showing a desired theoretical voltage regulation and actual 

 performance of the d-c. generators. 



One of the chief factors contributing to simplification in operating 

 electrical drying is to have the heating period the same for all sizes 

 and lengths of cable. Theoretically, this requires the same voltage 

 regulation at all conditions of the load, from the extreme of high 

 current and low voltage to high voltage and low current. Two such 

 theoretical curves are shown by the dotted lines in Fig. 6. The actual 

 voltage regulation curves for one of the special generators are shown 

 by the heavy lines on the same figure. The maximum amount of 



