236 



ALTERNATORS. 



To obtain the total volts generated, a horizontal line B D 

 (Fig. 1 12) was drawn to represent 103 terminals volts. At D 

 the line D A was drawn, making the angle C D A equal to the 

 angle of lag given in the table. Thus for the load of 3 amperes 



1 23 4 



Amperes, load. 



FIG. ill. TOTAL VOLTAGE AND TOTAL ANGLE OF LAG IN ALTERNATOR 

 ARMATURE. 



the angle C D A was made 57 '5. The length of D A was 

 made equal to the voltage spent in overcoming armature 

 impedance at this load, in this case 15-3 volts. The line B A 

 then gives the total voltage which must be generated in order 



TERMINAL VOLTS 

 SCALE OF VOLTS 



I I I I I I 



= 



90 



10 20 30 40 50 60 70 80 90 100 

 Fi<;. 112. DIAGRAM OF VOLTS IN ALTERNATOR ARMATURE. 



to overcome the armature impedance, and maintain the required 

 terminal voltage. This being repeated for a number of values 

 of the current gave the total voltage generated in the armature 

 at each load. 



The diagram of voltages constructed in this manner is a 



