370 



THE IKDtTCTlON MOTOR. 



that the motor runs (except at very low voltage) at almost 

 the speed of synchronism, and (2) with the rotor rigidly 

 clamped, so that it remains stationary and the slip is 

 100 per cent. 



From the curves obtained under these two conditions 

 several important properties of motors may be observed. 

 The power supplied to the motor in either case is spent 

 in internal losses because the output is nil, and the power 

 measured will in the one case be the power spent in 

 driving the motor with (practically) no slip, and in the 

 other case with the maximum slip which the machine can 

 have as a motor. 



The discussion of the conclusions to be derived from 

 the tests will be given after the method of procedure has 

 been explained. 



EXPERIMENT L. NO-LOAD TEST OF AN INDUCTION MOTOR 

 AT VARYING VOLTAGES. 



DIAGRAM OF CONNECTIONS. 



FIG. 181. 



M l MI M 3 Source of three-phase alternating current. 



M Induction motor. 



AI Ammeter in supply circuit. 



AS Ammeter in rotor circuit. 



V Voltmeter reading supply voltage. 



W Wattmeter. 



S S S Three-pole switch. 



D S Two-way voltmeter switch. 



S S Motor starting switch. 



