CHARACTERISTICS 31 



6. A 10-kw., long-shunt, compound generator has armature, 

 shunt and series-field resistances 0.05, 22 and 0.03 ohms. It is 

 supplying at its terminals 200 55-watt 110-volt lamps. Re- 

 quired the total generated e.m.f. and the total armature current. 

 (1 min.) 



6. If the machine of problem 5 is connected as a short shunt 

 with the same terminal e.m.f., required the generated e.m.f. and 

 current. (1 min.) 



7. If the generator in problem 5 has a regulating "shunt" of 

 0.1 ohm resistance, in parallel with its series turns, how will the 

 series ampere-turns be changed? (1 min.) 



8. A long-shunt, compound, 80-kw. generator is supplying 

 through a feeder having 0.2 ohm resistance the following load: 

 A 220-volt motor taking 22 kw. and 1100 16-c.p., 220-volt carbon 

 lamps taking four watts per candle power. The armature resist- 

 ance is 0.02 ohms, and the shunt and series-field resistances are 22 

 and 0.01 ohms. Required the armature current and the generated 

 e.m.f. (2 min.) 



9. The following data are obtained from a test of a shunt 

 machine : 



Volts 110 100 90 80 70 60 50 40 



Amperes 40 59 65 67 65 59 50 



The armature and field resistances are 0.12 and 30 ohms. Plot 

 this curve, and from it plot the total characteristic. (10 min.) 



10. Given the following data for a series external characteristic: 



Volts 20 40 60 80 100 120 132 135 133 120 



Amperes'.... 10 19 26 35 45 60 80 100 120 150 



R a = 0.1 and R/ = 0.05. Plot this curve, and from it plot 

 the total characteristic. Also plot the latter curve if the speed be 

 increased 20%. (10 min.) 



11. Given these data for a shunt total characteristic: 



Volts 143 140 136 130 120 110 90 



Amperes 10 22 40 60 70 75 78 



Plot this curve and from it plot the external characteristic, 

 having given R a = 0.08, R. = 30. (10 min.) 



12. Given the following data of an external shunt character! 



Volts 216 207 197 187 175 161 146 



Amperes 4 8 12 16 20 24 



