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BELL SYSTEM TECHNICAL JOURNAL 



out of the dryer. The dome is fitted with a gasket to provide for 

 sealing with the base during evacuation. Steam coils are also pro- 

 vided inside the dome for keeping the dryer up to temperature during 

 operation and provide a slight amount of heat to the cable during the 

 short electrical heating period. The bus bars, vacuum connections 

 and thermocouple leads enter through the base. The bus bars end 

 in large vise-like clamps for firmly holding the ends of the cable. In 

 the units for drying the larger cables the clamps are water cooled for 

 carrying away the heat due to contact resistance. The core truck 

 and cable are insulated from ground in order to minimize the danger 



Fig. 8 — Removal of paper from cable end and testing of circuits preparatory 



to drying. 



from short circuit should the cable ground on the core truck. The 

 push-button control for raising and lowering the domes is interlocked 

 with the control for the heating cycles so that voltage cannot be 

 applied at the clamp when the domes are up. 



For the sizes and lengths of cables to be dried it was found advisable 

 to have three dome dryers to one motor generator set, since all cables 

 need some additional vacuum drying after the heating period is over. 

 This arrangement also permits the removal of the dried cable and the 

 loading of the next cable to be dried while the other two units are in 

 operation. When the current is automatically disconnected at the 



