2 ARMATURX CONSTRUCTION 



tion will be taken up in the earlier sections of this treatise, the 

 discussion of commutators being deferred to a subsequent chapter, 

 since they are required only in rotating armatures. 



The extensive introduction in recent years of the terms "rotor '' 

 and "stator" is liable to lead to misunderstandings. The terms 

 are not synonymous with the terms " armature " and " field." 

 Thus Fig. 1 illustrates the rotor of a dynamo-electric machine ; 

 the part "A" is, however, an armature, and the pat"t "B" is a 

 field. Structures such as " A " come within the scope of this 



FIG. 1. Rotor of Alternating Current Generator with Exciter Armature. 

 Dick, Kerr & Co. 



treatise ; structures such as " B " do not. " A " is an internal 

 rotating armature ; " B " is an internal rotating field. 



Fig. 2 is another example of an internal rotating armature. 

 " C," the commutator, " D," the armature core, and " E," the 

 armature winding, will in this treatise all be considered as 

 components of the armature, as will also the armature spider, an 

 instance of which may best be seen at "S" in the unwound 

 armature of Fig. 3. In the example shown in Fig. 3, the annatmv 

 spider comprises a hub H, arms A, and end flanges FF. In this 

 case the commutator spider, B, constitutes an integral part of the 

 armature spider, but a separate spider is often employed for the 

 commutator. The commutator clamping rings are seen at 1! K : 



