102 



ELEMENTS OF ELECTRICAL ENGINEERING. 



of the collector rings, No. 4 in Fig. 94, forms a common ter- 

 minal for all three armature windings. 



The essential features of the windings of a three-phase arma- 

 ture are shown in Fig. 95. The figure shows each winding dis- 

 tributed in two slots per field pole (the A winding only is shown 

 complete, windings B and C are exactly like A), and it repre- 

 sents the simple case in which each slot contains but one con- 

 ductor. The straight radial lines represent the conductors lying 

 in the slots, the curved lines outside the circular row of radial 

 lines represent the end-connections at one end of the armature, 



Fig. 94- 



and the curved lines inside of the circular row of radial lines 

 represent the end-connections at the other end of the armature. 

 One terminal of each winding is connected to ring 4 (or to a neu- 

 tral connection N, Fig. 94, if ring 4 is dispensed with), and 

 the other terminals of windings of A, B and C are connected 

 to rings i, 2 and 3 respectively. 



52. The three-ring three-wire arrangement of the three-phase 



alternator, (a) The Y-connection. Let the three lines a, b and 



