7-B] 



INDUCTION REGULATORS. 



253 



simultaneously.) Plot a curve, as Fig. I, showing the secondary 

 potential for various angular positions of the rotor. Note the 

 ratio of maximum secondary to primary potential. 



7. (b) Use as Auto-transformer. The second and commer- 

 cially preferred method for use as a single-phase regulator is to 

 supply the primary with single-phase constant voltage as before, 

 and to connect the secondary in series with the load, as in Fig. 2, 



POSITION OF ROTOR 



FIG. 2. Connections. FIG. 3. Delivered voltage. 



Single-phase potential regulator used as auto-transformer. 



so that the delivered potential E taken from the machine, now 

 acting as an auto-transformer, is equal to the primary potential 

 E lt either increased or decreased by the potential E 2 of the sec- 

 ondary. This is either additive or subtractive, the apparatus 

 being a booster or a negative booster, according to the position 

 of the rotor. In this manner, the potential may be varied be- 

 tween the limits of E + E 2 and E^ E 2 . Measure E lf E 2 and 

 E. Plot a curve, as in Fig. 3, showing the delivered potential 

 for various positions of the rotor. Compare E with the algebraic 

 sum of EI and E 2 . What relation is there between the curves 

 in Figs. I and 3? 



8. A Comparison. In method (a), the output of the regu- 

 lator is equal to the volt-ampere capacity of the secondary; in 

 method (), the output of the same regulator is much greater. 

 Take, for example, a regulator with primary for 100 volts X 100 



