INDUCTION MOTORS 79 



the break-down torque? (c) At what load is the power factor a 

 maximum? 



36. Draw the Heyland diagram for motor No. B. (a) What 

 are the power factor, the slip, and the efficiency at full load? 

 (b) at one-half of full load? (c) What is the break-down torque? 

 (d) At what load is the power factor a maximum 



37. Draw the Heyland diagram for motor No. C. (a) What 

 are the power factor, the slip and the efficiency at full load? 

 (b) What is the break-down torque? Cc) At what load is the 

 power factor a maximum? 



38. Draw the Heyland diagram for motor No. D. (a) What 

 are the power factor, the slip and the efficiency at full load? (b) 

 at one-half full load? (c) What is the break-down torque? 



39. Draw the Heyland diagram for motor No. E. (a) What 

 are the power factor, the slip and the efficiency at full load.' 

 (b) What is the break-down torque? (c) At what load is the 

 power factor a maximum? 



40. l The following data are given on a 5-h.p., 110- volt, 8- 

 pole, 60-cycle, 3-phase induction motor. The stator and rotor 

 windings are both connected in delta, and the former has an ef- 

 fective resistance of 0.24 ohm and a leakage reactance of 0.70 ohm 

 per phase. The ohmic resistance of the rotor winding referred 

 to the stator is 0.36 ohm per phase. At no load the motor takes 

 300 watts at 110 volts and a power factor of 0.15. 



When this motor takes 5100 watts at 110 volts and a power 

 factor of 0.835 what are the slip, the power output and the 

 torque? 



41. l A 3-phase, 1000-h.p. induction motor U taking 910 k\v. 

 from a 2200-volt circuit at a power factor of 0.914. At no load 

 with an impressed voltage of 2200 volts the line current is 75 .1 

 amperes ;md the power is 15.2 kw. The effective resistance and 

 the leakage reactance of the stator winding, which i> Y -connected, 



118 ohm and 0.32 ohm per phase. The ohmic restate! 

 the rotor winding referred to the stator i- 0.10 ohm per pha-e. 

 What is the output for the ^peciiied load? What i< the -lip'.' 



42. ' A :*-phase, 2600-h.p. induction motor is taking 2272 kw. 

 from a 6470-volt circuit, and the line current i - 245 amperes. At 

 no load with an impressed voltage of 6400 volts the line current 

 is 89. 5 an i d the power il 17.~kw. Theohmicre-M;,- 



'Use cither thr tnUttformer diagram "t- tin- r.pnvalmt rirniit 111 the 

 solution of this problem 



