408 ELEMENTS OF ELECTRICAL ENGINEERING. 



ing the effects of magnetizing current, coil resistance, and mag- 

 netic leakage, (a) find the frequency and value of the voltage 

 between each pair of rotor collector rings. 



The rotor collector rings are Y-connected to three similar re- 

 ceiving circuits of which the power factor is 0.85 and of which 

 the impedance is 10 ohms. Find (&) the total electrical power 

 delivered by the rotor ; (c) the total electrical power delivered to 

 the stator and (d) the total mechanical power required to drive 

 the rotor. 



CHAPTER XIII. THE GENERAL THEORY OF THE 

 INDUCTION MOTOR. 



132. A 2-phase 6-pole induction motor takes current from 2- 

 phase supply mains across each pair of which the electromotive 

 force is I , I oo volts, frequency 60 cycles per second. When the 

 motor is run at zero load, an ammeter indicates 5.2 amperes in 

 each phase of the stator winding, and a wattmeter indicates a 

 delivery of 1,200 watts to each phase of the stator. At stand- 

 still the current delivered to each phase is observed to be 75 

 amperes and the power delivered to each phase is observed to be 

 14,000 watts. The resistance of each stator winding as deter- 

 mined by direct-current ammeter and voltmeter is i.i ohms. 

 From these data construct a circular diagram of the induction 

 motor, and plot performance curves similar to Fig. 243. 



133. One stator winding only in the above induction motor is 

 to be used, thus making it a single-phase motor. When the 

 motor is driven at zero load, an ammeter indicates 10.6 amperes 

 delivered to the stator, and a wattmeter indicates 2,450 watts. 

 At standstill the current delivered to the stator winding is observed 

 to be 75 amperes and the power as measured by a wattmeter is 

 found to be 14, 500 watts. From these data construct a circular 

 diagram for the motor (single-phase) and plot performance curves 

 somewhat similar to Fig. 243. 



