9-B] 



INDUCTION GENERATOR. 



301 



14. For each reading, calculate 



Power current, / P = /cos0 = W-- 



Wattless current, 7 Q = 7 sin & = yi 2 7 P 2 . 



Plot results as in Fig. 3 by laying off wattless current as 

 abscissae and power current as ordinates. Compare Fig. 5, 

 Exp. 8-A. 



15. Load Test. Connect to a non-inductive* load by closing 

 the switch S z , Fig. 2. With load constant, vary the speed of the 

 induction generator and note instruments. The load receives 

 power from both generators or from only one; W z =W i -\- W 2 . 

 When W \ and W 2 are positive, both machines are supplying power 

 as generators. When W or W 2 is zero, the corresponding ma- 

 chine is neither supplying nor taking power. When W \ or W 2 is 

 negative, one machine is taking power as a motor, all the power 

 being supplied by the other machine. 



For several sets of readings, compare the values of IcosO and 

 / sin as calculated for each of the three circuits. 



In commercial use, the machines would be so operated that both 

 machines are supplying power, the division of the load depending 

 upon their relative speeds. 



1 6. Tests can be made with variable load under any desired 

 arrangement of conditions. 



17. (b) Operation in Parallel with a Synchronous Motor or 

 Converter. In this test the synchronous machine, hereafter re- 

 ferred to as the converter, may be either a motor or converter. 

 The connections are as shown in Fig. 2. The converter can be 

 readily brought up to speed with direct current, as a direct cur- 

 rent motor. 



After the induction generator and the converterf have been 



* Loads that are not non-inductive can be made the subject of special 

 investigation. 



t (i7a). When a synchronous motor is used, a good procedure is to 

 close S 2 and bring the machines to speed before exciting the motor field. 

 The motor field current is then gradually increased until the induction 

 generator gives the desired voltage. 



