ROTARY CONVERTERS 101 



in series per slot and 24 slots per pole. Neglect the resistance 

 and the leakage reactance of the armature winding. What are 

 the demagnetizing ampere turns per pole for the specified 

 load? 



50. 1 A 3-phase, 25-cycle rotary converter has a full-load 

 capacity of 300 kw. at 600 volts. The armature has 96 slots 

 with b' inductors in series per slot. The field structure has 4 

 poles. Neglect the resistance and leakage reactance of the arma- 

 ture winding. When this rotary receives a line current of 540 

 amperes at 367 volts and is overexcited so that it operates at a 

 power factor of 0.90 what are the demagnetizing ampere turns 

 per pole? 



51. l A 6-phase, 60-cycle, 600-volt rotary converter has a full- 

 load capacity of 1000 kw. when operating at unit power factor. 

 The armature has 180 slots with 6 inductors in series per slot. 

 The field structure has 12 poles each of which is wound with 864 

 turns. When this rotary is overexcited so that it operates at 

 0.95 power factor and is delivering its rated output on the direct 

 current side the efficiency is 92.9 per cent. How much greater 

 i< the field current than its normal value, i.e., if the power factor 

 w-re unity? 



52. l At full load and when operating at unit power factor a 

 3-phase. 2.~>-cycle rotary converter receives a line current of 499 

 amperes at 367 volts and delivers on the direct-current side 500 

 amperes at 600 volts. The armature has 96 slots with 6 inductors 

 in series per slot. The field structure has 4 poles with 2340 turns 

 in the shunt windings per pole. The resistance of this field 

 circuit with t he regulating rheostat cut out is 120.5 ohms. When 

 thU rotary receives its rated current what is the least power 

 factor at which it can be operated and still maintain it- rated 

 voltage? Normal excitation, /'.r., when operating at unit 

 factor, is 3.25 amperes. 



53. ' At full load and when operating at unit power factor a it- 

 cycle compound rotary converter receives a line current 

 of sin amprres at a voltage of 212 volts between adjacent slip 

 and deliven <>n the direct-current side 16<>7 amperes at I'.IHI 

 volts lh. armatuir has 168 slots with <> inductors in series per 



1 In r:il<Mil:itmu tin- armature reaction do not inflect tin- tli->tnl>utioii ni" 

 tin- win.Iiim. ;m<l a^in,,,. th.it the constant usually ni\vn as 0.707 is 0.60. 

 Tin- makes an approximate correction for the effect of the ratio of pol* an 

 to pole pitch 



