ALTERNATING-CURRENT WINDING 



197 



opposite. Any of the phases, if the winding is polyphase, could be 

 treated in a similar way. 



In connection with this subject we give a number of photo- 

 graphs of various windings, most of which types have occurred in 

 the foregoing study of polyphase windings. We have drawn out 

 the winding diagram corresponding to each of these photos, and a 

 study of the two together is very instructive. 



(A) 



FIG. 236. Alternating-current Winding Classification. Types of Coils. 



In Figs. 236 to 239 our system of alternating-current wind- 

 ing classification and nomenclature, as employed in the preceding 

 descriptions and explanations, is diagrammatical ly tabulated. 1 

 The terms employed may be re-stated as follows: 



By a " coil " we designate the group of turns subtending one 

 pole belonging to one phase irrespective of the number of turns in 

 the coil. 



Fig. 236, A, B, E, and F, show diagrammatic representations of 

 the four types of coil to which reference has already been made. 

 These are respectively 



(A) Spiral coil. (B) Lap coil. 



(E) Skew coil. (F) Short coil 



1 A chart showing the derivation of all these types of windings is given in 

 Plate XIV. 



