358 



BELL SYSTEM TECHNICAL JOURNAL 



For correct operation of the equipment, temperature limits of 32 to 

 110 degrees Fahrenheit are desirable. Also, it is necessary that there 

 be no precipitation of moisture on wiring or equipment. To maintain 

 the desired conditions, each of the huts is equipped with a 2 kw. blower 

 type electric heater arranged to operate at low temperature or high 

 relative humidity, but with operation blocked when the temperature 



Fig. 13 — Equipment in unattended repeater station. 



reaches 95 degrees. Each new unattended repeater station is equipped 

 with a 4 kw. heater similarly controlled, and, on account of the heat 

 dissipation of power plant and vacuum tubes, also has forced ventila- 

 tion which is operative under conditions of high temperature. The 

 system of forced ventilation consists of spun glass intake filter, exhaust 

 fan, electric solenoid controlled shutters at intake and exhaust, and 

 thermostat, and is interconnected with the office alarms to prevent fan 

 operation in case of fire. 



