.-IM ELECTRICAL FREQUENCY ANALYZER 319 



pt-aks for all friHiuiMuii-s hi-Iow lOOO cncK's and ari' iint (Iclcilahli- 

 for till- liiglu-r fr»'(|iK-iicii's. 



l-"ig. i;} is a cloiiMi- ri-coril showing (lu- anaKsis of the wave from* 

 a buzzer as fetl into a common type of loud speaking receiver and 

 the acoustic output as picke<l up hy a condenser transmitter placed 

 in front of it at a distance of al)oiit lo inches. The analysis of the 

 input current wave to the loud speaker is shown by the comparatively 

 continuously decreasing series of peaks. The acoustic output is 

 represented by the scries having maxima in the ncighborhoocl of 

 SOO cycles and 2200 cycles. This record cannot be taken as an 

 adequate analysis of this loud speaker because of probable reverbera- 

 tion etTects in the room. 



The analyzer has thus far not been used in the study of power 

 problems. A few illustrative records have been taken, however, 

 on transformers and generators and will be shown as suggestive of 

 the use of this method of attack in such problems. 



Fig. 14 is a double record showing applied voltage and exciting 

 current of a small 110-volt, 60-cycle transformer operating at normal 

 voltage and frequency under the no-load condition. The presence 

 of the well known third and fifth harmonics in the exciting current 

 is clearly shown. Because of the rise in the calibration curve of 

 the analyzer at the low end of the lower frequency range, a scale 

 of ordinatcs is not shown on this record. Instead, the values of the 

 analyzer current at each frequency are noted on the record. The 

 circuit used in making this record is drawn on the figure. A com- 

 putation of the components of the exciting current from the record 

 and constants of the circuit shows that at 60 cycles the current was 

 175 milliamperes, at 180 cycles, 65 milliampercs and at 300 cycles, 

 17 milliamperes. The total r. m. s. exciting current was therefore 

 187 milliamperes. 



The operation of this transformer under full load is shown in V'lg. 

 15, where, as before, the primary voltage and current are analyzed. 

 The transformer load consisted of a pure resistance. It will be noted 

 that the third and fifth harmonics have become very small com- 

 pared with the fundamental. The analyzer currents at each fre- 

 quency are again noted on the record. In obtaining the analysis 

 of the current it was necessary to further shunt the analyzer. The 

 primary currertt was 310 milliamperes. 



Problems relating to commutation may also be conveniently 

 studied qualitatively and quantitatively by means of the analyzer. 

 The use of an apparatus which will indicate the source and measure 

 the extent of parasitic frequencies is obvious. Information has 



