104 PROBLEMS IN ALTERNATING CURRENT MACHINERY 



DATA ON ROTARY CONVERTERS 



D. C. SATURATION CURVES AND CORE LOSSES 



Ordinates 



Abscissae 



60. 1 Calculate the efficiency of the rotary B when it delivers 

 1000 kw. at 650 volts and the shunt field rheostat is cut out. 

 Assume that the running temperature is 70 C. What are the 

 line current and power factor on the alternating-current side? 



61. l Calculate the efficiency of the rotary C when it delivers 

 1000 kw. at 650 volts and the excitation is greater than normal 

 and is adjusted so that the power factor is 0.95. Assume that 

 the running temperature is 70 C. 



1 In calculating the armature reaction do not neglect the distribution of 

 the winding, and assume that the constant usually given as 0.707 is 0.60. 

 This makes an approximate correction for the effect of the ratio of pole arc 

 to pole pitch. 



2 The shunt field has a regulating rheostat in series with it, the loss in 

 which should be included in calculating the efficiency. 



