POLYPHASE CIRCUITS 123 



is 25.2 amperes and the power is 3070 watts. The core loss 

 at the rated voltage is 2130 watts. 



The calculated resistance and reactance of the transmission 

 line are 15.7 ohms and 16.2 ohms per conductor. 



With the low-tension windings of the transformers short-cir- 

 cuited what must be the terminal voltage of the generator in 

 order that it will deliver its full-load current? When the trans- 

 formers deliver a load of 1000 kv.-a. at 0.90 power factor and a 

 line voltage of 420 volts what is the necessary excitation of the 

 generator, and what is the combined efficiency of the generator, 

 lino and transform* : 



71. An SoO-kv.-a., 11,000-volt, Y-connected generator delivers 

 nt rry over a trail-mission line and through transformers, that 

 are connected in V on the high-tension and in delta on the low- 

 tension sides, to a load of induction motors and a synchronous 

 motor. The iv-i>tanre and reactance of the line are 11.4 ohms 

 and 10.6 ohms \ HT < .nductor respectively. The transformers are 

 each rated to deliver 300 kw. with a ratio of transformation of 

 >:660 volts. 



I OR CHARACTERISTICS 



The ohmic resistance of the armature between terminal* is 

 3.32 ohms at the running temperature. Tin- HiVrtive resis- 

 tance is 1.45 times the <>hmi< resistance. The Held resistance is 

 0.723 ohm. The core and friction losses are 26 kw. at the rated 

 voltage. 



TRANSFORM li: Ml \K.\CTERI8TIC8 



\\ith the lou-trn-ion winding short-circuit, d and with 2-10 

 volts impressed on the high-tension winding tin- current is 47 

 amperes and the power, 2^ core loss at the rated vol- 



tage is 2.6 kw. 



The induction motors t:i n-tant In.-id of 'J-0 kw, :t 0.83 



