CONTENTS. XI. 



CHAPTER VII. 



PAGE. 



ALTERNATORS 191 



Generation of electromotive force in the armature ; 

 voltage formula ; the magnetic circuit ; determination of 

 magnetisation curve at no-load and under load ; calcu- 

 lation of armature self-induction ; magnetisation curves 

 on inductive loads ; armature reactions ; characteristic 

 curve ; cause of voltage drop ; effect of armature currents 

 on field ; determination of variation of field current ; 

 characteristics on inductive and capacity load circuits ; 

 calculation of characteristics ; phase difference between 

 total volts and current ; determination of excitation to 

 maintain constant volts ; short-circuit characteristic ; 

 graphic determination of voltage at any power-factor ; 

 relation between speed and voltage, on no-load, at full 

 load, and on short-circuit ; losses in an alternator ; 

 their determination ; retardation method of measuring 

 iron losses ; alternators in parallel ; synchronisers ; 

 method of synchronising. 



CHAPTER VIII. 



SYNCHRONOUS MOTORS 266 



Principle of operation ; method of starting ; determination 

 of effect of variation of excitation ; discussion of experi- 

 mental curves ; variation of load with constant excitation : 

 graphic representation of conditions. 



CHAPTER IX. 



THE POLYPHASE CIRCUIT 294 



Generation of 2 and 3-phase currents ; 3-phase trans- 

 mission by three wires ; star and mesh connection ; 

 current and volt relations ; determination of power in 

 non-inductive and inductive 3-phase circuits by various 

 methods ; measurement in unbalanced circuits. 



