ELEMENTS OF ELECTRICAL ENGINEERING. 



Resolution. A given harmonic electromotive force (or cur- 

 rent) may be resolved into a number of parts each of which is a 

 harmonic electromotive force (or current) of the same frequency 

 as the given harmonic electromotive force (or current). Thus 

 the line E, Fig. 45, represents a given harmonic electromotive 

 force, and the lines E 1 and E 2 represent two parts into which 

 the given electromotive force may be resolved. 



Examples of composition and resolution. (a) Two alternating- 

 current generators, A and B, running in synchronism, are 

 connected in series between mains as shown in Fig. 46*2, and the 

 total electromotive force between the mains is related to the 

 electromotive forces of the respective machines as shown in 



Fig. 46a. 



Fig. 46<*. 



Fig. 46$. The phase difference between E a and E 6 may have 

 any value whatever. 



(b] Two alternating-current generators, A and B, running 

 in synchronism are connected in parallel between mains as shown 

 in Fig. 47#, and the total current delivered to the mains is related 

 to the currents delivered by the respective machines as shown in 

 Fig. 47^. The phase difference 6 may have any value whatever. 



(c) Figure 48<7 shows two coils (or receiving units of any kind) 

 A and B y connected in series between alternating-current supply 

 mains. The voltage between the mains is represented by the 



