X. CONTENTS. 



>* 



CHAPTER IV. 



PAGE. 



VIRTUAL VALUE OF AN ALTERNATING CURRENT 84 



Curve tracing by contact-maker ; determination of 

 wave form of an alternator ; determination of simul- 

 taneous curves of current and voltage ; comparison 

 01 values of alternating and direct current ; R. M.S. value ; 

 graduation of instruments ; example of Cardew volt- 

 meter ; average power. 



CHAPTER V. 

 EFFECT OF CAPACITY . . 97 



General explanation of effect of capacity in a circuit ; 

 relation between voltage and current ; impedance of 

 circuit containing capacity ; determination of effect of 

 condenser upon phase relations in a circuit ; determina- 

 tion of variation of current with capacity, frequency, and 

 voltage ; measurement of power in circuit with capacity ; 

 circuit containing resistance, self-induction, and capacity; 

 determination of power and phase relations in such a 

 circuit ; resonance ; capacity and inductance in series 

 and in parallel. 



CHAPTER VI. 

 THE TRANSFORMER 125 



General principles ; ratio of voltages ; effect of current in 

 secondary winding ; voltage drop in windings ; determina- 

 tion of regulation ; direct-reading method ; measurement 

 of ratio of transformation with direct current ; no-load 

 current of a transformer ; determination of magnetising 

 current ; losses due to defective insulation ; losses at 

 various frequencies ; iron losses ; their separation ; 

 separate determination of copper losses ; magnetic 

 leakage ; effect of power-factor of secondary circuit ; effi- 

 ciency test on non-inductive and inductive loads ; indirect 

 methods of measuring efficiency ; graphic determination of 

 drop at any power-factor ; efficiency by double conversion ; 

 split dynamometer method; Sumpner's method of testing; 

 makers' tests ; the auto-transformer ; transformer 

 diagrams for various loads and power-factors ; curve 

 tracing of primary and secondary volts. 



