ARMATURE CONSTRUCTION 



CHAPTER I 



INTRODUCTORY 



A DYNAMO electric machine comprises a stator and a rotor, i.e. a 

 stationary element and a rotating element. The armature is that 

 part of the machine, whether stationary or rotatory, on which, 

 in a suitably arranged system of electrical conductors, there are 

 induced electromotive forces consequent upon the relative motion 

 of the armature system and the magnetic field. 



The armature is connected to the mains ; in the case of genera- 

 tors it supplies current to the mains, and in the case of motors 

 it receives current from them. In commercial dynamos and 

 motors of the continuous-current type the armature is the rotor ; 

 in alternating current dynamos and motors it is generally the 

 stator. A modern armature for either of these classes of dynamo 

 electric machinery comprises a laminated iron core, upon which 

 insulated circuits of copper, constituting the armature winding, 

 are suitably located. In the case of continuous-current machinery, 

 as well as in some types of alternating-current machinery, the 

 armature winding is suitably connected to the segments of a 

 commutator Armature core, armature winding and commutator, 

 together with the spider or spiders, and shaft, constitute the 

 armature of a continuous-current dynamo-electric machine ; the 

 magnet frame and the field windings constituting the so-called 

 " field." In the case of the stationary armatures of alternating- 

 current dynamo-electric machines, the armature core and windings 

 are still the principal components. The commutator is absent, the 

 ends of the windings being carried to suitable terminals. Instead 

 of the spider and the shaft, other suitable structural parts are 

 provided. As the armature core and the armature windings are 

 common to both rotating and stationary armatures, their construc- 



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