AUXILIARY APPARATUS 423 



different positions when connected to lines of different 

 frequency. Such an instrument is shown in Fig. 279. 



Power-factor Meter. The power-factor meter is an 

 instrument which is calibrated to read directly cos <j>, the 

 power factor of the load to which it is connected. Such 

 an instrument is very useful for getting the proper adjust- 

 ment of field current on a synchronous converter, synchro- 

 nous motor, etc. In a station where several alternators are 

 operating in parallel this instrument is used to show whether 



FIG. 279. A Frequency Meter, with the Outer Case Removed to Show 



the Internal Construction. General Electric Co. 



the different generators are all operating with proper field 

 excitation. If one alternator shows a low power factor 

 compared to the others, its field excitation is either too 

 high or too low. By watching the power-factor meter the 

 operator can immediately bring the field current to its proper 



value. 



As the power factor of a circuit depends upon the phase 

 relation of the voltage and current in the circuit, there must 



