POWER AND POWER-FACTOR. 



81 



EXPERIMENT XIV. MEASUREMENT OF POWER BY THE 

 . 3-AMMETER METHOD. 



DIAGRAM OF CONNECTIONS. 



M t M 2 Source of alternating current. 



r Inductive resistance. 



R Non-inductive resistance. 



R^ Resistance for varying current. 



A l Ammeter measuring current in inductive circuit. 



A 2 Ammeter measuring current in non-inductive 



circuit. 



A 3 Ammeter measuring total current. 



V Voltmeter measuring voltage of circuit. 



W Wattmeter measuring total power of circuit. 



Note. The wattmeter may be connected so as to read 

 the power in the inductive circuit only by placing the 

 current coil in the branch circuit instead of the main 

 circuit. 



Instructions. Connect in parallel an inductive and anon- 

 inductive resistance, each in series with an ammeter. 

 Connect the joint resistance thus formed to a source of 

 alternating current in series with an ammeter and a 

 variable resistance for changing the current. Connect 

 a voltmeter to measure the voltage applied to the branch 

 circuits, and insert a wattmeter to read the power in 

 them. 



For several values of the current read all the instru- 

 ments, and tabulate the results as below. The figures 

 in the table are taken from actual readings and given 

 as an example: 



