SYNCHRONOUS GENERATORS 41 



(a) What is the regulation of this generator, calculated by the 

 magnetomotive-force method, for an inductive load which re- 

 quires full-load current at 0.5 power factor? 



(b) What is the regulation for a condensive load which re- 

 quires full-load current at 0.5 power factor? 



63. A 3-phase, A-connected alternating-current generator 

 has a full-load capacity of 15 kv.-a. at 230 volts. The effective 

 armature resistance and synchronous reactance are respectively 

 0.302 and 4.36 ohms per phase. Three reactors each of which 

 has an effective resistance of 2.5 ohms and a reactance of 10 

 ohms are connected in A across the terminals of the generator. 

 If the terminal voltage is adjusted to its rated value to what will 

 it rise when the coils are removed? 



(b) If the coils are connected in Y and the terminal voltage 

 adjusted as before to what will it rise when the coils are removed? 



(c) What is the power output of the generator in each case? 



64. In problem 63 if the open-circuit voltage of the generator 

 is adjusted to 300 volts to what will it fall when the coils are 

 connected in A across the terminals? What is the power out- 

 put of the generator? 



65. A 3-phase, 1500-kv.-a., 5500-volt alternating-current 

 generator delivers full-load current to an inductive load at 0.85 

 power factor. The effective resistance and synchronous react- 

 ance of this alternator are respectively 0.36 and 8.5 ohms per 

 phase. The armature winding is Y-connected. With the field 

 excitation unchanged what will be the terminal voltage if the 

 alternator delivers its rated current to a condensive load at 0.85 

 pow.T factor'.' 



66. A special 6-pole, 60-cycle alternating-current generator 

 has six similar and independent armature windings. The 

 windings arc equally spaced so that their voltages differ by 30 



On the equal armature and field heating losses and of 



equal frequencies compare the rated outputs kilovolt-anip< n- 

 and terminal voltage of this alternator when the windings are 

 connected (1) for an open-coil single-phase winding and (2) for a 

 'J-phase winding. 



67. (a' In problem nil compare the rated outputs on the same 

 basis when tin- winding* an- connected (1) for an Open-coil >inglr- 

 phase winding and (2) for a :{-piuise mesh winding. 



(b) Compare the rated outputs on thr same basis when the 



