DIRECT CURRENT RAILWAY MOTORS 



85 



are taken on a sufficient number of motors of the same 

 class, type and form, the horse-power rating for 75 deg. 

 C. rise may be obtained for any length of run from 

 one-half hour to continuous running. Before starting 



/oo 



2 S 4 S 6 



Hoars Run 



Fig. 25. Thermal Characteristics of a 75 H.P., 600/1200 Volt Railway Motor 



a heat run, cold resistances and temperatures should 

 be taken. After the motor has run continuously for 

 the specified time, with all covers off and all openings 

 unrestricted and with amperes and volts held constant, 

 it is shut down, hot resistances measured and all tem- 

 peratures taken. The results of the thermal heat run 



OF ELECTRICAL 



FACULTY OF ALLIED 



